moc/bluetooth/venv/lib/python3.7/site-packages/pip/_vendor/pyparsing.py

# -*- coding: utf-8 -*-
# module pyparsing.py
#
# Copyright (c) 2003-2019  Paul T. McGuire
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#

__doc__ = \
"""
pyparsing module - Classes and methods to define and execute parsing grammars
=============================================================================

The pyparsing module is an alternative approach to creating and
executing simple grammars, vs. the traditional lex/yacc approach, or the
use of regular expressions.  With pyparsing, you don't need to learn
a new syntax for defining grammars or matching expressions - the parsing
module provides a library of classes that you use to construct the
grammar directly in Python.

Here is a program to parse "Hello, World!" (or any greeting of the form
``"<salutation>, <addressee>!"``), built up using :class:`Word`,
:class:`Literal`, and :class:`And` elements
(the :class:`'+'<ParserElement.__add__>` operators create :class:`And` expressions,
and the strings are auto-converted to :class:`Literal` expressions)::

    from pip._vendor.pyparsing import Word, alphas

    # define grammar of a greeting
    greet = Word(alphas) + "," + Word(alphas) + "!"

    hello = "Hello, World!"
    print (hello, "->", greet.parseString(hello))

The program outputs the following::

    Hello, World! -> ['Hello', ',', 'World', '!']

The Python representation of the grammar is quite readable, owing to the
self-explanatory class names, and the use of '+', '|' and '^' operators.

The :class:`ParseResults` object returned from
:class:`ParserElement.parseString` can be
accessed as a nested list, a dictionary, or an object with named
attributes.

The pyparsing module handles some of the problems that are typically
vexing when writing text parsers:

  - extra or missing whitespace (the above program will also handle
    "Hello,World!", "Hello  ,  World  !", etc.)
  - quoted strings
  - embedded comments


Getting Started -
-----------------
Visit the classes :class:`ParserElement` and :class:`ParseResults` to
see the base classes that most other pyparsing
classes inherit from. Use the docstrings for examples of how to:

 - construct literal match expressions from :class:`Literal` and
   :class:`CaselessLiteral` classes
 - construct character word-group expressions using the :class:`Word`
   class
 - see how to create repetitive expressions using :class:`ZeroOrMore`
   and :class:`OneOrMore` classes
 - use :class:`'+'<And>`, :class:`'|'<MatchFirst>`, :class:`'^'<Or>`,
   and :class:`'&'<Each>` operators to combine simple expressions into
   more complex ones
 - associate names with your parsed results using
   :class:`ParserElement.setResultsName`
 - access the parsed data, which is returned as a :class:`ParseResults`
   object
 - find some helpful expression short-cuts like :class:`delimitedList`
   and :class:`oneOf`
 - find more useful common expressions in the :class:`pyparsing_common`
   namespace class
"""

__version__ = "2.4.2"
__versionTime__ = "29 Jul 2019 02:58 UTC"
__author__ = "Paul McGuire <ptmcg@users.sourceforge.net>"

import string
from weakref import ref as wkref
import copy
import sys
import warnings
import re
import sre_constants
import collections
import pprint
import traceback
import types
from datetime import datetime
from operator import itemgetter
import itertools
from functools import wraps

try:
    # Python 3
    from itertools import filterfalse
except ImportError:
    from itertools import ifilterfalse as filterfalse

try:
    from _thread import RLock
except ImportError:
    from threading import RLock

try:
    # Python 3
    from collections.abc import Iterable
    from collections.abc import MutableMapping, Mapping
except ImportError:
    # Python 2.7
    from collections import Iterable
    from collections import MutableMapping, Mapping

try:
    from collections import OrderedDict as _OrderedDict
except ImportError:
    try:
        from ordereddict import OrderedDict as _OrderedDict
    except ImportError:
        _OrderedDict = None

try:
    from types import SimpleNamespace
except ImportError:
    class SimpleNamespace: pass

# version compatibility configuration
__compat__ = SimpleNamespace()
__compat__.__doc__ = """
    A cross-version compatibility configuration for pyparsing features that will be
    released in a future version. By setting values in this configuration to True,
    those features can be enabled in prior versions for compatibility development
    and testing.

     - collect_all_And_tokens - flag to enable fix for Issue #63 that fixes erroneous grouping
       of results names when an And expression is nested within an Or or MatchFirst; set to
       True to enable bugfix released in pyparsing 2.3.0, or False to preserve
       pre-2.3.0 handling of named results
"""
__compat__.collect_all_And_tokens = True

__diag__ = SimpleNamespace()
__diag__.__doc__ = """
Diagnostic configuration (all default to False)
     - warn_multiple_tokens_in_named_alternation - flag to enable warnings when a results
       name is defined on a MatchFirst or Or expression with one or more And subexpressions
       (only warns if __compat__.collect_all_And_tokens is False)
     - warn_ungrouped_named_tokens_in_collection - flag to enable warnings when a results
       name is defined on a containing expression with ungrouped subexpressions that also
       have results names
     - warn_name_set_on_empty_Forward - flag to enable warnings whan a Forward is defined
       with a results name, but has no contents defined
     - warn_on_multiple_string_args_to_oneof - flag to enable warnings whan oneOf is
       incorrectly called with multiple str arguments
     - enable_debug_on_named_expressions - flag to auto-enable debug on all subsequent
       calls to ParserElement.setName()
"""
__diag__.warn_multiple_tokens_in_named_alternation = False
__diag__.warn_ungrouped_named_tokens_in_collection = False
__diag__.warn_name_set_on_empty_Forward = False
__diag__.warn_on_multiple_string_args_to_oneof = False
__diag__.enable_debug_on_named_expressions = False

# ~ sys.stderr.write("testing pyparsing module, version %s, %s\n" % (__version__, __versionTime__))

__all__ = ['__version__', '__versionTime__', '__author__', '__compat__', '__diag__',
           'And', 'CaselessKeyword', 'CaselessLiteral', 'CharsNotIn', 'Combine', 'Dict', 'Each', 'Empty',
           'FollowedBy', 'Forward', 'GoToColumn', 'Group', 'Keyword', 'LineEnd', 'LineStart', 'Literal',
           'PrecededBy', 'MatchFirst', 'NoMatch', 'NotAny', 'OneOrMore', 'OnlyOnce', 'Optional', 'Or',
           'ParseBaseException', 'ParseElementEnhance', 'ParseException', 'ParseExpression', 'ParseFatalException',
           'ParseResults', 'ParseSyntaxException', 'ParserElement', 'QuotedString', 'RecursiveGrammarException',
           'Regex', 'SkipTo', 'StringEnd', 'StringStart', 'Suppress', 'Token', 'TokenConverter',
           'White', 'Word', 'WordEnd', 'WordStart', 'ZeroOrMore', 'Char',
           'alphanums', 'alphas', 'alphas8bit', 'anyCloseTag', 'anyOpenTag', 'cStyleComment', 'col',
           'commaSeparatedList', 'commonHTMLEntity', 'countedArray', 'cppStyleComment', 'dblQuotedString',
           'dblSlashComment', 'delimitedList', 'dictOf', 'downcaseTokens', 'empty', 'hexnums',
           'htmlComment', 'javaStyleComment', 'line', 'lineEnd', 'lineStart', 'lineno',
           'makeHTMLTags', 'makeXMLTags', 'matchOnlyAtCol', 'matchPreviousExpr', 'matchPreviousLiteral',
           'nestedExpr', 'nullDebugAction', 'nums', 'oneOf', 'opAssoc', 'operatorPrecedence', 'printables',
           'punc8bit', 'pythonStyleComment', 'quotedString', 'removeQuotes', 'replaceHTMLEntity',
           'replaceWith', 'restOfLine', 'sglQuotedString', 'srange', 'stringEnd',
           'stringStart', 'traceParseAction', 'unicodeString', 'upcaseTokens', 'withAttribute',
           'indentedBlock', 'originalTextFor', 'ungroup', 'infixNotation', 'locatedExpr', 'withClass',
           'CloseMatch', 'tokenMap', 'pyparsing_common', 'pyparsing_unicode', 'unicode_set',
           'conditionAsParseAction',
           ]

system_version = tuple(sys.version_info)[:3]
PY_3 = system_version[0] == 3
if PY_3:
    _MAX_INT = sys.maxsize
    basestring = str
    unichr = chr
    unicode = str
    _ustr = str

    # build list of single arg builtins, that can be used as parse actions
    singleArgBuiltins = [sum, len, sorted, reversed, list, tuple, set, any, all, min, max]

else:
    _MAX_INT = sys.maxint
    range = xrange

    def _ustr(obj):
        """Drop-in replacement for str(obj) that tries to be Unicode
        friendly. It first tries str(obj). If that fails with
        a UnicodeEncodeError, then it tries unicode(obj). It then
        < returns the unicode object | encodes it with the default
        encoding | ... >.
        """
        if isinstance(obj, unicode):
            return obj

        try:
            # If this works, then _ustr(obj) has the same behaviour as str(obj), so
            # it won't break any existing code.
            return str(obj)

        except UnicodeEncodeError:
            # Else encode it
            ret = unicode(obj).encode(sys.getdefaultencoding(), 'xmlcharrefreplace')
            xmlcharref = Regex(r'&#\d+;')
            xmlcharref.setParseAction(lambda t: '\\u' + hex(int(t[0][2:-1]))[2:])
            return xmlcharref.transformString(ret)

    # build list of single arg builtins, tolerant of Python version, that can be used as parse actions
    singleArgBuiltins = []
    import __builtin__

    for fname in "sum len sorted reversed list tuple set any all min max".split():
        try:
            singleArgBuiltins.append(getattr(__builtin__, fname))
        except AttributeError:
            continue

_generatorType = type((y for y in range(1)))

def _xml_escape(data):
    """Escape &, <, >, ", ', etc. in a string of data."""

    # ampersand must be replaced first
    from_symbols = '&><"\''
    to_symbols = ('&' + s + ';' for s in "amp gt lt quot apos".split())
    for from_, to_ in zip(from_symbols, to_symbols):
        data = data.replace(from_, to_)
    return data

alphas = string.ascii_uppercase + string.ascii_lowercase
nums = "0123456789"
hexnums = nums + "ABCDEFabcdef"
alphanums = alphas + nums
_bslash = chr(92)
printables = "".join(c for c in string.printable if c not in string.whitespace)


def conditionAsParseAction(fn, message=None, fatal=False):
    msg = message if message is not None else "failed user-defined condition"
    exc_type = ParseFatalException if fatal else ParseException
    fn = _trim_arity(fn)

    @wraps(fn)
    def pa(s, l, t):
        if not bool(fn(s, l, t)):
            raise exc_type(s, l, msg)

    return pa

class ParseBaseException(Exception):
    """base exception class for all parsing runtime exceptions"""
    # Performance tuning: we construct a *lot* of these, so keep this
    # constructor as small and fast as possible
    def __init__(self, pstr, loc=0, msg=None, elem=None):
        self.loc = loc
        if msg is None:
            self.msg = pstr
            self.pstr = ""
        else:
            self.msg = msg
            self.pstr = pstr
        self.parserElement = elem
        self.args = (pstr, loc, msg)

    @classmethod
    def _from_exception(cls, pe):
        """
        internal factory method to simplify creating one type of ParseException
        from another - avoids having __init__ signature conflicts among subclasses
        """
        return cls(pe.pstr, pe.loc, pe.msg, pe.parserElement)

    def __getattr__(self, aname):
        """supported attributes by name are:
           - lineno - returns the line number of the exception text
           - col - returns the column number of the exception text
           - line - returns the line containing the exception text
        """
        if aname == "lineno":
            return lineno(self.loc, self.pstr)
        elif aname in ("col", "column"):
            return col(self.loc, self.pstr)
        elif aname == "line":
            return line(self.loc, self.pstr)
        else:
            raise AttributeError(aname)

    def __str__(self):
        if self.pstr:
            if self.loc >= len(self.pstr):
                foundstr = ', found end of text'
            else:
                foundstr = (', found %r' % self.pstr[self.loc:self.loc + 1]).replace(r'\\', '\\')
        else:
            foundstr = ''
        return ("%s%s  (at char %d), (line:%d, col:%d)" %
                   (self.msg, foundstr, self.loc, self.lineno, self.column))
    def __repr__(self):
        return _ustr(self)
    def markInputline(self, markerString=">!<"):
        """Extracts the exception line from the input string, and marks
           the location of the exception with a special symbol.
        """
        line_str = self.line
        line_column = self.column - 1
        if markerString:
            line_str = "".join((line_str[:line_column],
                                markerString, line_str[line_column:]))
        return line_str.strip()
    def __dir__(self):
        return "lineno col line".split() + dir(type(self))

class ParseException(ParseBaseException):
    """
    Exception thrown when parse expressions don't match class;
    supported attributes by name are:
    - lineno - returns the line number of the exception text
    - col - returns the column number of the exception text
    - line - returns the line containing the exception text

    Example::

        try:
            Word(nums).setName("integer").parseString("ABC")
        except ParseException as pe:
            print(pe)
            print("column: {}".format(pe.col))

    prints::

       Expected integer (at char 0), (line:1, col:1)
        column: 1

    """

    @staticmethod
    def explain(exc, depth=16):
        """
        Method to take an exception and translate the Python internal traceback into a list
        of the pyparsing expressions that caused the exception to be raised.

        Parameters:

         - exc - exception raised during parsing (need not be a ParseException, in support
           of Python exceptions that might be raised in a parse action)
         - depth (default=16) - number of levels back in the stack trace to list expression
           and function names; if None, the full stack trace names will be listed; if 0, only
           the failing input line, marker, and exception string will be shown

        Returns a multi-line string listing the ParserElements and/or function names in the
        exception's stack trace.

        Note: the diagnostic output will include string representations of the expressions
        that failed to parse. These representations will be more helpful if you use `setName` to
        give identifiable names to your expressions. Otherwise they will use the default string
        forms, which may be cryptic to read.

        explain() is only supported under Python 3.
        """
        import inspect

        if depth is None:
            depth = sys.getrecursionlimit()
        ret = []
        if isinstance(exc, ParseBaseException):
            ret.append(exc.line)
            ret.append(' ' * (exc.col - 1) + '^')
        ret.append("{0}: {1}".format(type(exc).__name__, exc))

        if depth > 0:
            callers = inspect.getinnerframes(exc.__traceback__, context=depth)
            seen = set()
            for i, ff in enumerate(callers[-depth:]):
                frm = ff[0]

                f_self = frm.f_locals.get('self', None)
                if isinstance(f_self, ParserElement):
                    if frm.f_code.co_name not in ('parseImpl', '_parseNoCache'):
                        continue
                    if f_self in seen:
                        continue
                    seen.add(f_self)

                    self_type = type(f_self)
                    ret.append("{0}.{1} - {2}".format(self_type.__module__,
                                                      self_type.__name__,
                                                      f_self))
                elif f_self is not None:
                    self_type = type(f_self)
                    ret.append("{0}.{1}".format(self_type.__module__,
                                                self_type.__name__))
                else:
                    code = frm.f_code
                    if code.co_name in ('wrapper', '<module>'):
                        continue

                    ret.append("{0}".format(code.co_name))

                depth -= 1
                if not depth:
                    break

        return '\n'.join(ret)


class ParseFatalException(ParseBaseException):
    """user-throwable exception thrown when inconsistent parse content
       is found; stops all parsing immediately"""
    pass

class ParseSyntaxException(ParseFatalException):
    """just like :class:`ParseFatalException`, but thrown internally
    when an :class:`ErrorStop<And._ErrorStop>` ('-' operator) indicates
    that parsing is to stop immediately because an unbacktrackable
    syntax error has been found.
    """
    pass

#~ class ReparseException(ParseBaseException):
    #~ """Experimental class - parse actions can raise this exception to cause
       #~ pyparsing to reparse the input string:
        #~ - with a modified input string, and/or
        #~ - with a modified start location
       #~ Set the values of the ReparseException in the constructor, and raise the
       #~ exception in a parse action to cause pyparsing to use the new string/location.
       #~ Setting the values as None causes no change to be made.
       #~ """
    #~ def __init_( self, newstring, restartLoc ):
        #~ self.newParseText = newstring
        #~ self.reparseLoc = restartLoc

class RecursiveGrammarException(Exception):
    """exception thrown by :class:`ParserElement.validate` if the
    grammar could be improperly recursive
    """
    def __init__(self, parseElementList):
        self.parseElementTrace = parseElementList

    def __str__(self):
        return "RecursiveGrammarException: %s" % self.parseElementTrace

class _ParseResultsWithOffset(object):
    def __init__(self, p1, p2):
        self.tup = (p1, p2)
    def __getitem__(self, i):
        return self.tup[i]
    def __repr__(self):
        return repr(self.tup[0])
    def setOffset(self, i):
        self.tup = (self.tup[0], i)

class ParseResults(object):
    """Structured parse results, to provide multiple means of access to
    the parsed data:

       - as a list (``len(results)``)
       - by list index (``results[0], results[1]``, etc.)
       - by attribute (``results.<resultsName>`` - see :class:`ParserElement.setResultsName`)

    Example::

        integer = Word(nums)
        date_str = (integer.setResultsName("year") + '/'
                        + integer.setResultsName("month") + '/'
                        + integer.setResultsName("day"))
        # equivalent form:
        # date_str = integer("year") + '/' + integer("month") + '/' + integer("day")

        # parseString returns a ParseResults object
        result = date_str.parseString("1999/12/31")

        def test(s, fn=repr):
            print("%s -> %s" % (s, fn(eval(s))))
        test("list(result)")
        test("result[0]")
        test("result['month']")
        test("result.day")
        test("'month' in result")
        test("'minutes' in result")
        test("result.dump()", str)

    prints::

        list(result) -> ['1999', '/', '12', '/', '31']
        result[0] -> '1999'
        result['month'] -> '12'
        result.day -> '31'
        'month' in result -> True
        'minutes' in result -> False
        result.dump() -> ['1999', '/', '12', '/', '31']
        - day: 31
        - month: 12
        - year: 1999
    """
    def __new__(cls, toklist=None, name=None, asList=True, modal=True):
        if isinstance(toklist, cls):
            return toklist
        retobj = object.__new__(cls)
        retobj.__doinit = True
        return retobj

    # Performance tuning: we construct a *lot* of these, so keep this
    # constructor as small and fast as possible
    def __init__(self, toklist=None, name=None, asList=True, modal=True, isinstance=isinstance):
        if self.__doinit:
            self.__doinit = False
            self.__name = None
            self.__parent = None
            self.__accumNames = {}
            self.__asList = asList
            self.__modal = modal
            if toklist is None:
                toklist = []
            if isinstance(toklist, list):
                self.__toklist = toklist[:]
            elif isinstance(toklist, _generatorType):
                self.__toklist = list(toklist)
            else:
                self.__toklist = [toklist]
            self.__tokdict = dict()

        if name is not None and name:
            if not modal:
                self.__accumNames[name] = 0
            if isinstance(name, int):
                name = _ustr(name)  # will always return a str, but use _ustr for consistency
            self.__name = name
            if not (isinstance(toklist, (type(None), basestring, list)) and toklist in (None, '', [])):
                if isinstance(toklist, basestring):
                    toklist = [toklist]
                if asList:
                    if isinstance(toklist, ParseResults):
                        self[name] = _ParseResultsWithOffset(ParseResults(toklist.__toklist), 0)
                    else:
                        self[name] = _ParseResultsWithOffset(ParseResults(toklist[0]), 0)
                    self[name].__name = name
                else:
                    try:
                        self[name] = toklist[0]
                    except (KeyError, TypeError, IndexError):
                        self[name] = toklist

    def __getitem__(self, i):
        if isinstance(i, (int, slice)):
            return self.__toklist[i]
        else:
            if i not in self.__accumNames:
                return self.__tokdict[i][-1][0]
            else:
                return ParseResults([v[0] for v in self.__tokdict[i]])

    def __setitem__(self, k, v, isinstance=isinstance):
        if isinstance(v, _ParseResultsWithOffset):
            self.__tokdict[k] = self.__tokdict.get(k, list()) + [v]
            sub = v[0]
        elif isinstance(k, (int, slice)):
            self.__toklist[k] = v
            sub = v
        else:
            self.__tokdict[k] = self.__tokdict.get(k, list()) + [_ParseResultsWithOffset(v, 0)]
            sub = v
        if isinstance(sub, ParseResults):
            sub.__parent = wkref(self)

    def __delitem__(self, i):
        if isinstance(i, (int, slice)):
            mylen = len(self.__toklist)
            del self.__toklist[i]

            # convert int to slice
            if isinstance(i, int):
                if i < 0:
                    i += mylen
                i = slice(i, i + 1)
            # get removed indices
            removed = list(range(*i.indices(mylen)))
            removed.reverse()
            # fixup indices in token dictionary
            for name, occurrences in self.__tokdict.items():
                for j in removed:
                    for k, (value, position) in enumerate(occurrences):
                        occurrences[k] = _ParseResultsWithOffset(value, position - (position > j))
        else:
            del self.__tokdict[i]

    def __contains__(self, k):
        return k in self.__tokdict

    def __len__(self):
        return len(self.__toklist)

    def __bool__(self):
        return (not not self.__toklist)
    __nonzero__ = __bool__

    def __iter__(self):
        return iter(self.__toklist)

    def __reversed__(self):
        return iter(self.__toklist[::-1])

    def _iterkeys(self):
        if hasattr(self.__tokdict, "iterkeys"):
            return self.__tokdict.iterkeys()
        else:
            return iter(self.__tokdict)

    def _itervalues(self):
        return (self[k] for k in self._iterkeys())

    def _iteritems(self):
        return ((k, self[k]) for k in self._iterkeys())

    if PY_3:
        keys = _iterkeys
        """Returns an iterator of all named result keys."""

        values = _itervalues
        """Returns an iterator of all named result values."""

        items = _iteritems
        """Returns an iterator of all named result key-value tuples."""

    else:
        iterkeys = _iterkeys
        """Returns an iterator of all named result keys (Python 2.x only)."""

        itervalues = _itervalues
        """Returns an iterator of all named result values (Python 2.x only)."""

        iteritems = _iteritems
        """Returns an iterator of all named result key-value tuples (Python 2.x only)."""

        def keys(self):
            """Returns all named result keys (as a list in Python 2.x, as an iterator in Python 3.x)."""
            return list(self.iterkeys())

        def values(self):
            """Returns all named result values (as a list in Python 2.x, as an iterator in Python 3.x)."""
            return list(self.itervalues())

        def items(self):
            """Returns all named result key-values (as a list of tuples in Python 2.x, as an iterator in Python 3.x)."""
            return list(self.iteritems())

    def haskeys(self):
        """Since keys() returns an iterator, this method is helpful in bypassing
           code that looks for the existence of any defined results names."""
        return bool(self.__tokdict)

    def pop(self, *args, **kwargs):
        """
        Removes and returns item at specified index (default= ``last``).
        Supports both ``list`` and ``dict`` semantics for ``pop()``. If
        passed no argument or an integer argument, it will use ``list``
        semantics and pop tokens from the list of parsed tokens. If passed
        a non-integer argument (most likely a string), it will use ``dict``
        semantics and pop the corresponding value from any defined results
        names. A second default return value argument is supported, just as in
        ``dict.pop()``.

        Example::

            def remove_first(tokens):
                tokens.pop(0)
            print(OneOrMore(Word(nums)).parseString("0 123 321")) # -> ['0', '123', '321']
            print(OneOrMore(Word(nums)).addParseAction(remove_first).parseString("0 123 321")) # -> ['123', '321']

            label = Word(alphas)
            patt = label("LABEL") + OneOrMore(Word(nums))
            print(patt.parseString("AAB 123 321").dump())

            # Use pop() in a parse action to remove named result (note that corresponding value is not
            # removed from list form of results)
            def remove_LABEL(tokens):
                tokens.pop("LABEL")
                return tokens
            patt.addParseAction(remove_LABEL)
            print(patt.parseString("AAB 123 321").dump())

        prints::

            ['AAB', '123', '321']
            - LABEL: AAB

            ['AAB', '123', '321']
        """
        if not args:
            args = [-1]
        for k, v in kwargs.items():
            if k == 'default':
                args = (args[0], v)
            else:
                raise TypeError("pop() got an unexpected keyword argument '%s'" % k)
        if (isinstance(args[0], int)
                or len(args) == 1
                or args[0] in self):
            index = args[0]
            ret = self[index]
            del self[index]
            return ret
        else:
            defaultvalue = args[1]
            return defaultvalue

    def get(self, key, defaultValue=None):
        """
        Returns named result matching the given key, or if there is no
        such name, then returns the given ``defaultValue`` or ``None`` if no
        ``defaultValue`` is specified.

        Similar to ``dict.get()``.

        Example::

            integer = Word(nums)
            date_str = integer("year") + '/' + integer("month") + '/' + integer("day")

            result = date_str.parseString("1999/12/31")
            print(result.get("year")) # -> '1999'
            print(result.get("hour", "not specified")) # -> 'not specified'
            print(result.get("hour")) # -> None
        """
        if key in self:
            return self[key]
        else:
            return defaultValue

    def insert(self, index, insStr):
        """
        Inserts new element at location index in the list of parsed tokens.

        Similar to ``list.insert()``.

        Example::

            print(OneOrMore(Word(nums)).parseString("0 123 321")) # -> ['0', '123', '321']

            # use a parse action to insert the parse location in the front of the parsed results
            def insert_locn(locn, tokens):
                tokens.insert(0, locn)
            print(OneOrMore(Word(nums)).addParseAction(insert_locn).parseString("0 123 321")) # -> [0, '0', '123', '321']
        """
        self.__toklist.insert(index, insStr)
        # fixup indices in token dictionary
        for name, occurrences in self.__tokdict.items():
            for k, (value, position) in enumerate(occurrences):
                occurrences[k] = _ParseResultsWithOffset(value, position + (position > index))

    def append(self, item):
        """
        Add single element to end of ParseResults list of elements.

        Example::

            print(OneOrMore(Word(nums)).parseString("0 123 321")) # -> ['0', '123', '321']

            # use a parse action to compute the sum of the parsed integers, and add it to the end
            def append_sum(tokens):
                tokens.append(sum(map(int, tokens)))
            print(OneOrMore(Word(nums)).addParseAction(append_sum).parseString("0 123 321")) # -> ['0', '123', '321', 444]
        """
        self.__toklist.append(item)

    def extend(self, itemseq):
        """
        Add sequence of elements to end of ParseResults list of elements.

        Example::

            patt = OneOrMore(Word(alphas))

            # use a parse action to append the reverse of the matched strings, to make a palindrome
            def make_palindrome(tokens):
                tokens.extend(reversed([t[::-1] for t in tokens]))
                return ''.join(tokens)
            print(patt.addParseAction(make_palindrome).parseString("lskdj sdlkjf lksd")) # -> 'lskdjsdlkjflksddsklfjkldsjdksl'
        """
        if isinstance(itemseq, ParseResults):
            self.__iadd__(itemseq)
        else:
            self.__toklist.extend(itemseq)

    def clear(self):
        """
        Clear all elements and results names.
        """
        del self.__toklist[:]
        self.__tokdict.clear()

    def __getattr__(self, name):
        try:
            return self[name]
        except KeyError:
            return ""

    def __add__(self, other):
        ret = self.copy()
        ret += other
        return ret

    def __iadd__(self, other):
        if other.__tokdict:
            offset = len(self.__toklist)
            addoffset = lambda a: offset if a < 0 else a + offset
            otheritems = other.__tokdict.items()
            otherdictitems = [(k, _ParseResultsWithOffset(v[0], addoffset(v[1])))
                              for k, vlist in otheritems for v in vlist]
            for k, v in otherdictitems:
                self[k] = v
                if isinstance(v[0], ParseResults):
                    v[0].__parent = wkref(self)

        self.__toklist += other.__toklist
        self.__accumNames.update(other.__accumNames)
        return self

    def __radd__(self, other):
        if isinstance(other, int) and other == 0:
            # useful for merging many ParseResults using sum() builtin
            return self.copy()
        else:
            # this may raise a TypeError - so be it
            return other + self

    def __repr__(self):
        return "(%s, %s)" % (repr(self.__toklist), repr(self.__tokdict))

    def __str__(self):
        return '[' + ', '.join(_ustr(i) if isinstance(i, ParseResults) else repr(i) for i in self.__toklist) + ']'

    def _asStringList(self, sep=''):
        out = []
        for item in self.__toklist:
            if out and sep:
                out.append(sep)
            if isinstance(item, ParseResults):
                out += item._asStringList()
            else:
                out.append(_ustr(item))
        return out

    def asList(self):
        """
        Returns the parse results as a nested list of matching tokens, all converted to strings.

        Example::

            patt = OneOrMore(Word(alphas))
            result = patt.parseString("sldkj lsdkj sldkj")
            # even though the result prints in string-like form, it is actually a pyparsing ParseResults
            print(type(result), result) # -> <class 'pyparsing.ParseResults'> ['sldkj', 'lsdkj', 'sldkj']

            # Use asList() to create an actual list
            result_list = result.asList()
            print(type(result_list), result_list) # -> <class 'list'> ['sldkj', 'lsdkj', 'sldkj']
        """
        return [res.asList() if isinstance(res, ParseResults) else res for res in self.__toklist]

    def asDict(self):
        """
        Returns the named parse results as a nested dictionary.

        Example::

            integer = Word(nums)
            date_str = integer("year") + '/' + integer("month") + '/' + integer("day")

            result = date_str.parseString('12/31/1999')
            print(type(result), repr(result)) # -> <class 'pyparsing.ParseResults'> (['12', '/', '31', '/', '1999'], {'day': [('1999', 4)], 'year': [('12', 0)], 'month': [('31', 2)]})

            result_dict = result.asDict()
            print(type(result_dict), repr(result_dict)) # -> <class 'dict'> {'day': '1999', 'year': '12', 'month': '31'}

            # even though a ParseResults supports dict-like access, sometime you just need to have a dict
            import json
            print(json.dumps(result)) # -> Exception: TypeError: ... is not JSON serializable
            print(json.dumps(result.asDict())) # -> {"month": "31", "day": "1999", "year": "12"}
        """
        if PY_3:
            item_fn = self.items
        else:
            item_fn = self.iteritems

        def toItem(obj):
            if isinstance(obj, ParseResults):
                if obj.haskeys():
                    return obj.asDict()
                else:
                    return [toItem(v) for v in obj]
            else:
                return obj

        return dict((k, toItem(v)) for k, v in item_fn())

    def copy(self):
        """
        Returns a new copy of a :class:`ParseResults` object.
        """
        ret = ParseResults(self.__toklist)
        ret.__tokdict = dict(self.__tokdict.items())
        ret.__parent = self.__parent
        ret.__accumNames.update(self.__accumNames)
        ret.__name = self.__name
        return ret

    def asXML(self, doctag=None, namedItemsOnly=False, indent="", formatted=True):
        """
        (Deprecated) Returns the parse results as XML. Tags are created for tokens and lists that have defined results names.
        """
        nl = "\n"
        out = []
        namedItems = dict((v[1], k) for (k, vlist) in self.__tokdict.items()
                          for v in vlist)
        nextLevelIndent = indent + "  "

        # collapse out indents if formatting is not desired
        if not formatted:
            indent = ""
            nextLevelIndent = ""
            nl = ""

        selfTag = None
        if doctag is not None:
            selfTag = doctag
        else:
            if self.__name:
                selfTag = self.__name

        if not selfTag:
            if namedItemsOnly:
                return ""
            else:
                selfTag = "ITEM"

        out += [nl, indent, "<", selfTag, ">"]

        for i, res in enumerate(self.__toklist):
            if isinstance(res, ParseResults):
                if i in namedItems:
                    out += [res.asXML(namedItems[i],
                                      namedItemsOnly and doctag is None,
                                      nextLevelIndent,
                                      formatted)]
                else:
                    out += [res.asXML(None,
                                      namedItemsOnly and doctag is None,
                                      nextLevelIndent,
                                      formatted)]
            else:
                # individual token, see if there is a name for it
                resTag = None
                if i in namedItems:
                    resTag = namedItems[i]
                if not resTag:
                    if namedItemsOnly:
                        continue
                    else:
                        resTag = "ITEM"
                xmlBodyText = _xml_escape(_ustr(res))
                out += [nl, nextLevelIndent, "<", resTag, ">",
                        xmlBodyText,
                                                "</", resTag, ">"]

        out += [nl, indent, "</", selfTag, ">"]
        return "".join(out)

    def __lookup(self, sub):
        for k, vlist in self.__tokdict.items():
            for v, loc in vlist:
                if sub is v:
                    return k
        return None

    def getName(self):
        r"""
        Returns the results name for this token expression. Useful when several
        different expressions might match at a particular location.

        Example::

            integer = Word(nums)
            ssn_expr = Regex(r"\d\d\d-\d\d-\d\d\d\d")
            house_number_expr = Suppress('#') + Word(nums, alphanums)
            user_data = (Group(house_number_expr)("house_number")
                        | Group(ssn_expr)("ssn")
                        | Group(integer)("age"))
            user_info = OneOrMore(user_data)

            result = user_info.parseString("22 111-22-3333 #221B")
            for item in result:
                print(item.getName(), ':', item[0])

        prints::

            age : 22
            ssn : 111-22-3333
            house_number : 221B
        """
        if self.__name:
            return self.__name
        elif self.__parent:
            par = self.__parent()
            if par:
                return par.__lookup(self)
            else:
                return None
        elif (len(self) == 1
              and len(self.__tokdict) == 1
              and next(iter(self.__tokdict.values()))[0][1] in (0, -1)):
            return next(iter(self.__tokdict.keys()))
        else:
            return None

    def dump(self, indent='', full=True, include_list=True, _depth=0):
        """
        Diagnostic method for listing out the contents of
        a :class:`ParseResults`. Accepts an optional ``indent`` argument so
        that this string can be embedded in a nested display of other data.

        Example::

            integer = Word(nums)
            date_str = integer("year") + '/' + integer("month") + '/' + integer("day")

            result = date_str.parseString('12/31/1999')
            print(result.dump())

        prints::

            ['12', '/', '31', '/', '1999']
            - day: 1999
            - month: 31
            - year: 12
        """
        out = []
        NL = '\n'
        if include_list:
            out.append(indent + _ustr(self.asList()))
        else:
            out.append('')

        if full:
            if self.haskeys():
                items = sorted((str(k), v) for k, v in self.items())
                for k, v in items:
                    if out:
                        out.append(NL)
                    out.append("%s%s- %s: " % (indent, ('  ' * _depth), k))
                    if isinstance(v, ParseResults):
                        if v:
                            out.append(v.dump(indent=indent, full=full, include_list=include_list, _depth=_depth + 1))
                        else:
                            out.append(_ustr(v))
                    else:
                        out.append(repr(v))
            elif any(isinstance(vv, ParseResults) for vv in self):
                v = self
                for i, vv in enumerate(v):
                    if isinstance(vv, ParseResults):
                        out.append("\n%s%s[%d]:\n%s%s%s" % (indent,
                                                            ('  ' * (_depth)),
                                                            i,
                                                            indent,
                                                            ('  ' * (_depth + 1)),
                                                            vv.dump(indent=indent,
                                                                    full=full,
                                                                    include_list=include_list,
                                                                    _depth=_depth + 1)))
                    else:
                        out.append("\n%s%s[%d]:\n%s%s%s" % (indent,
                                                            ('  ' * (_depth)),
                                                            i,
                                                            indent,
                                                            ('  ' * (_depth + 1)),
                                                            _ustr(vv)))

        return "".join(out)

    def pprint(self, *args, **kwargs):
        """
        Pretty-printer for parsed results as a list, using the
        `pprint <https://docs.python.org/3/library/pprint.html>`_ module.
        Accepts additional positional or keyword args as defined for
        `pprint.pprint <https://docs.python.org/3/library/pprint.html#pprint.pprint>`_ .

        Example::

            ident = Word(alphas, alphanums)
            num = Word(nums)
            func = Forward()
            term = ident | num | Group('(' + func + ')')
            func <<= ident + Group(Optional(delimitedList(term)))
            result = func.parseString("fna a,b,(fnb c,d,200),100")
            result.pprint(width=40)

        prints::

            ['fna',
             ['a',
              'b',
              ['(', 'fnb', ['c', 'd', '200'], ')'],
              '100']]
        """
        pprint.pprint(self.asList(), *args, **kwargs)

    # add support for pickle protocol
    def __getstate__(self):
        return (self.__toklist,
                (self.__tokdict.copy(),
                 self.__parent is not None and self.__parent() or None,
                 self.__accumNames,
                 self.__name))

    def __setstate__(self, state):
        self.__toklist = state[0]
        self.__tokdict, par, inAccumNames, self.__name = state[1]
        self.__accumNames = {}
        self.__accumNames.update(inAccumNames)
        if par is not None:
            self.__parent = wkref(par)
        else:
            self.__parent = None

    def __getnewargs__(self):
        return self.__toklist, self.__name, self.__asList, self.__modal

    def __dir__(self):
        return dir(type(self)) + list(self.keys())

    @classmethod
    def from_dict(cls, other, name=None):
        """
        Helper classmethod to construct a ParseResults from a dict, preserving the
        name-value relations as results names. If an optional 'name' argument is
        given, a nested ParseResults will be returned
        """
        def is_iterable(obj):
            try:
                iter(obj)
            except Exception:
                return False
            else:
                if PY_3:
                    return not isinstance(obj, (str, bytes))
                else:
                    return not isinstance(obj, basestring)

        ret = cls([])
        for k, v in other.items():
            if isinstance(v, Mapping):
                ret += cls.from_dict(v, name=k)
            else:
                ret += cls([v], name=k, asList=is_iterable(v))
        if name is not None:
            ret = cls([ret], name=name)
        return ret

MutableMapping.register(ParseResults)

def col (loc, strg):
    """Returns current column within a string, counting newlines as line separators.
   The first column is number 1.

   Note: the default parsing behavior is to expand tabs in the input string
   before starting the parsing process.  See
   :class:`ParserElement.parseString` for more
   information on parsing strings containing ``<TAB>`` s, and suggested
   methods to maintain a consistent view of the parsed string, the parse
   location, and line and column positions within the parsed string.
   """
    s = strg
    return 1 if 0 < loc < len(s) and s[loc-1] == '\n' else loc - s.rfind("\n", 0, loc)

def lineno(loc, strg):
    """Returns current line number within a string, counting newlines as line separators.
    The first line is number 1.

    Note - the default parsing behavior is to expand tabs in the input string
    before starting the parsing process.  See :class:`ParserElement.parseString`
    for more information on parsing strings containing ``<TAB>`` s, and
    suggested methods to maintain a consistent view of the parsed string, the
    parse location, and line and column positions within the parsed string.
    """
    return strg.count("\n", 0, loc) + 1

def line(loc, strg):
    """Returns the line of text containing loc within a string, counting newlines as line separators.
       """
    lastCR = strg.rfind("\n", 0, loc)
    nextCR = strg.find("\n", loc)
    if nextCR >= 0:
        return strg[lastCR + 1:nextCR]
    else:
        return strg[lastCR + 1:]

def _defaultStartDebugAction(instring, loc, expr):
    print(("Match " + _ustr(expr) + " at loc " + _ustr(loc) + "(%d,%d)" % (lineno(loc, instring), col(loc, instring))))

def _defaultSuccessDebugAction(instring, startloc, endloc, expr, toks):
    print("Matched " + _ustr(expr) + " -> " + str(toks.asList()))

def _defaultExceptionDebugAction(instring, loc, expr, exc):
    print("Exception raised:" + _ustr(exc))

def nullDebugAction(*args):
    """'Do-nothing' debug action, to suppress debugging output during parsing."""
    pass

# Only works on Python 3.x - nonlocal is toxic to Python 2 installs
#~ 'decorator to trim function calls to match the arity of the target'
#~ def _trim_arity(func, maxargs=3):
    #~ if func in singleArgBuiltins:
        #~ return lambda s,l,t: func(t)
    #~ limit = 0
    #~ foundArity = False
    #~ def wrapper(*args):
        #~ nonlocal limit,foundArity
        #~ while 1:
            #~ try:
                #~ ret = func(*args[limit:])
                #~ foundArity = True
                #~ return ret
            #~ except TypeError:
                #~ if limit == maxargs or foundArity:
                    #~ raise
                #~ limit += 1
                #~ continue
    #~ return wrapper

# this version is Python 2.x-3.x cross-compatible
'decorator to trim function calls to match the arity of the target'
def _trim_arity(func, maxargs=2):
    if func in singleArgBuiltins:
        return lambda s, l, t: func(t)
    limit = [0]
    foundArity = [False]

    # traceback return data structure changed in Py3.5 - normalize back to plain tuples
    if system_version[:2] >= (3, 5):
        def extract_stack(limit=0):
            # special handling for Python 3.5.0 - extra deep call stack by 1
            offset = -3 if system_version == (3, 5, 0) else -2
            frame_summary = traceback.extract_stack(limit=-offset + limit - 1)[offset]
            return [frame_summary[:2]]
        def extract_tb(tb, limit=0):
            frames = traceback.extract_tb(tb, limit=limit)
            frame_summary = frames[-1]
            return [frame_summary[:2]]
    else:
        extract_stack = traceback.extract_stack
        extract_tb = traceback.extract_tb

    # synthesize what would be returned by traceback.extract_stack at the call to
    # user's parse action 'func', so that we don't incur call penalty at parse time

    LINE_DIFF = 6
    # IF ANY CODE CHANGES, EVEN JUST COMMENTS OR BLANK LINES, BETWEEN THE NEXT LINE AND
    # THE CALL TO FUNC INSIDE WRAPPER, LINE_DIFF MUST BE MODIFIED!!!!
    this_line = extract_stack(limit=2)[-1]
    pa_call_line_synth = (this_line[0], this_line[1] + LINE_DIFF)

    def wrapper(*args):
        while 1:
            try:
                ret = func(*args[limit[0]:])
                foundArity[0] = True
                return ret
            except TypeError:
                # re-raise TypeErrors if they did not come from our arity testing
                if foundArity[0]:
                    raise
                else:
                    try:
                        tb = sys.exc_info()[-1]
                        if not extract_tb(tb, limit=2)[-1][:2] == pa_call_line_synth:
                            raise
                    finally:
                        try:
                            del tb
                        except NameError:
                            pass

                if limit[0] <= maxargs:
                    limit[0] += 1
                    continue
                raise

    # copy func name to wrapper for sensible debug output
    func_name = "<parse action>"
    try:
        func_name = getattr(func, '__name__',
                            getattr(func, '__class__').__name__)
    except Exception:
        func_name = str(func)
    wrapper.__name__ = func_name

    return wrapper


class ParserElement(object):
    """Abstract base level parser element class."""
    DEFAULT_WHITE_CHARS = " \n\t\r"
    verbose_stacktrace = False

    @staticmethod
    def setDefaultWhitespaceChars(chars):
        r"""
        Overrides the default whitespace chars

        Example::

            # default whitespace chars are space, <TAB> and newline
            OneOrMore(Word(alphas)).parseString("abc def\nghi jkl")  # -> ['abc', 'def', 'ghi', 'jkl']

            # change to just treat newline as significant
            ParserElement.setDefaultWhitespaceChars(" \t")
            OneOrMore(Word(alphas)).parseString("abc def\nghi jkl")  # -> ['abc', 'def']
        """
        ParserElement.DEFAULT_WHITE_CHARS = chars

    @staticmethod
    def inlineLiteralsUsing(cls):
        """
        Set class to be used for inclusion of string literals into a parser.

        Example::

            # default literal class used is Literal
            integer = Word(nums)
            date_str = integer("year") + '/' + integer("month") + '/' + integer("day")

            date_str.parseString("1999/12/31")  # -> ['1999', '/', '12', '/', '31']


            # change to Suppress
            ParserElement.inlineLiteralsUsing(Suppress)
            date_str = integer("year") + '/' + integer("month") + '/' + integer("day")

            date_str.parseString("1999/12/31")  # -> ['1999', '12', '31']
        """
        ParserElement._literalStringClass = cls

    def __init__(self, savelist=False):
        self.parseAction = list()
        self.failAction = None
        # ~ self.name = "<unknown>"  # don't define self.name, let subclasses try/except upcall
        self.strRepr = None
        self.resultsName = None
        self.saveAsList = savelist
        self.skipWhitespace = True
        self.whiteChars = set(ParserElement.DEFAULT_WHITE_CHARS)
        self.copyDefaultWhiteChars = True
        self.mayReturnEmpty = False # used when checking for left-recursion
        self.keepTabs = False
        self.ignoreExprs = list()
        self.debug = False
        self.streamlined = False
        self.mayIndexError = True # used to optimize exception handling for subclasses that don't advance parse index
        self.errmsg = ""
        self.modalResults = True # used to mark results names as modal (report only last) or cumulative (list all)
        self.debugActions = (None, None, None)  # custom debug actions
        self.re = None
        self.callPreparse = True # used to avoid redundant calls to preParse
        self.callDuringTry = False

    def copy(self):
        """
        Make a copy of this :class:`ParserElement`.  Useful for defining
        different parse actions for the same parsing pattern, using copies of
        the original parse element.

        Example::

            integer = Word(nums).setParseAction(lambda toks: int(toks[0]))
            integerK = integer.copy().addParseAction(lambda toks: toks[0] * 1024) + Suppress("K")
            integerM = integer.copy().addParseAction(lambda toks: toks[0] * 1024 * 1024) + Suppress("M")

            print(OneOrMore(integerK | integerM | integer).parseString("5K 100 640K 256M"))

        prints::

            [5120, 100, 655360, 268435456]

        Equivalent form of ``expr.copy()`` is just ``expr()``::

            integerM = integer().addParseAction(lambda toks: toks[0] * 1024 * 1024) + Suppress("M")
        """
        cpy = copy.copy(self)
        cpy.parseAction = self.parseAction[:]
        cpy.ignoreExprs = self.ignoreExprs[:]
        if self.copyDefaultWhiteChars:
            cpy.whiteChars = ParserElement.DEFAULT_WHITE_CHARS
        return cpy

    def setName(self, name):
        """
        Define name for this expression, makes debugging and exception messages clearer.

        Example::

            Word(nums).parseString("ABC")  # -> Exception: Expected W:(0123...) (at char 0), (line:1, col:1)
            Word(nums).setName("integer").parseString("ABC")  # -> Exception: Expected integer (at char 0), (line:1, col:1)
        """
        self.name = name
        self.errmsg = "Expected " + self.name
        if __diag__.enable_debug_on_named_expressions:
            self.setDebug()
        return self

    def setResultsName(self, name, listAllMatches=False):
        """
        Define name for referencing matching tokens as a nested attribute
        of the returned parse results.
        NOTE: this returns a *copy* of the original :class:`ParserElement` object;
        this is so that the client can define a basic element, such as an
        integer, and reference it in multiple places with different names.

        You can also set results names using the abbreviated syntax,
        ``expr("name")`` in place of ``expr.setResultsName("name")``
        - see :class:`__call__`.

        Example::

            date_str = (integer.setResultsName("year") + '/'
                        + integer.setResultsName("month") + '/'
                        + integer.setResultsName("day"))

            # equivalent form:
            date_str = integer("year") + '/' + integer("month") + '/' + integer("day")
        """
        return self._setResultsName(name, listAllMatches)

    def _setResultsName(self, name, listAllMatches=False):
        newself = self.copy()
        if name.endswith("*"):
            name = name[:-1]
            listAllMatches = True
        newself.resultsName = name
        newself.modalResults = not listAllMatches
        return newself

    def setBreak(self, breakFlag=True):
        """Method to invoke the Python pdb debugger when this element is
           about to be parsed. Set ``breakFlag`` to True to enable, False to
           disable.
        """
        if breakFlag:
            _parseMethod = self._parse
            def breaker(instring, loc, doActions=True, callPreParse=True):
                import pdb
                # this call to pdb.set_trace() is intentional, not a checkin error
                pdb.set_trace()
                return _parseMethod(instring, loc, doActions, callPreParse)
            breaker._originalParseMethod = _parseMethod
            self._parse = breaker
        else:
            if hasattr(self._parse, "_originalParseMethod"):
                self._parse = self._parse._originalParseMethod
        return self

    def setParseAction(self, *fns, **kwargs):
        """
        Define one or more actions to perform when successfully matching parse element definition.
        Parse action fn is a callable method with 0-3 arguments, called as ``fn(s, loc, toks)`` ,
        ``fn(loc, toks)`` , ``fn(toks)`` , or just ``fn()`` , where:

        - s   = the original string being parsed (see note below)
        - loc = the location of the matching substring
        - toks = a list of the matched tokens, packaged as a :class:`ParseResults` object

        If the functions in fns modify the tokens, they can return them as the return
        value from fn, and the modified list of tokens will replace the original.
        Otherwise, fn does not need to return any value.

        If None is passed as the parse action, all previously added parse actions for this
        expression are cleared.

        Optional keyword arguments:
        - callDuringTry = (default= ``False``) indicate if parse action should be run during lookaheads and alternate testing

        Note: the default parsing behavior is to expand tabs in the input string
        before starting the parsing process.  See :class:`parseString for more
        information on parsing strings containing ``<TAB>`` s, and suggested
        methods to maintain a consistent view of the parsed string, the parse
        location, and line and column positions within the parsed string.

        Example::

            integer = Word(nums)
            date_str = integer + '/' + integer + '/' + integer

            date_str.parseString("1999/12/31")  # -> ['1999', '/', '12', '/', '31']

            # use parse action to convert to ints at parse time
            integer = Word(nums).setParseAction(lambda toks: int(toks[0]))
            date_str = integer + '/' + integer + '/' + integer

            # note that integer fields are now ints, not strings
            date_str.parseString("1999/12/31")  # -> [1999, '/', 12, '/', 31]
        """
        if list(fns) == [None,]:
            self.parseAction = []
        else:
            if not all(callable(fn) for fn in fns):
                raise TypeError("parse actions must be callable")
            self.parseAction = list(map(_trim_arity, list(fns)))
            self.callDuringTry = kwargs.get("callDuringTry", False)
        return self

    def addParseAction(self, *fns, **kwargs):
        """
        Add one or more parse actions to expression's list of parse actions. See :class:`setParseAction`.

        See examples in :class:`copy`.
        """
        self.parseAction += list(map(_trim_arity, list(fns)))
        self.callDuringTry = self.callDuringTry or kwargs.get("callDuringTry", False)
        return self

    def addCondition(self, *fns, **kwargs):
        """Add a boolean predicate function to expression's list of parse actions. See
        :class:`setParseAction` for function call signatures. Unlike ``setParseAction``,
        functions passed to ``addCondition`` need to return boolean success/fail of the condition.

        Optional keyword arguments:
        - message = define a custom message to be used in the raised exception
        - fatal   = if True, will raise ParseFatalException to stop parsing immediately; otherwise will raise ParseException

        Example::

            integer = Word(nums).setParseAction(lambda toks: int(toks[0]))
            year_int = integer.copy()
            year_int.addCondition(lambda toks: toks[0] >= 2000, message="Only support years 2000 and later")
            date_str = year_int + '/' + integer + '/' + integer

            result = date_str.parseString("1999/12/31")  # -> Exception: Only support years 2000 and later (at char 0), (line:1, col:1)
        """
        for fn in fns:
            self.parseAction.append(conditionAsParseAction(fn, message=kwargs.get('message'),
                                                           fatal=kwargs.get('fatal', False)))

        self.callDuringTry = self.callDuringTry or kwargs.get("callDuringTry", False)
        return self

    def setFailAction(self, fn):
        """Define action to perform if parsing fails at this expression.
           Fail acton fn is a callable function that takes the arguments
           ``fn(s, loc, expr, err)`` where:
           - s = string being parsed
           - loc = location where expression match was attempted and failed
           - expr = the parse expression that failed
           - err = the exception thrown
           The function returns no value.  It may throw :class:`ParseFatalException`
           if it is desired to stop parsing immediately."""
        self.failAction = fn
        return self

    def _skipIgnorables(self, instring, loc):
        exprsFound = True
        while exprsFound:
            exprsFound = False
            for e in self.ignoreExprs:
                try:
                    while 1:
                        loc, dummy = e._parse(instring, loc)
                        exprsFound = True
                except ParseException:
                    pass
        return loc

    def preParse(self, instring, loc):
        if self.ignoreExprs:
            loc = self._skipIgnorables(instring, loc)

        if self.skipWhitespace:
            wt = self.whiteChars
            instrlen = len(instring)
            while loc < instrlen and instring[loc] in wt:
                loc += 1

        return loc

    def parseImpl(self, instring, loc, doActions=True):
        return loc, []

    def postParse(self, instring, loc, tokenlist):
        return tokenlist

    # ~ @profile
    def _parseNoCache(self, instring, loc, doActions=True, callPreParse=True):
        TRY, MATCH, FAIL = 0, 1, 2
        debugging = (self.debug)  # and doActions)

        if debugging or self.failAction:
            # ~ print ("Match", self, "at loc", loc, "(%d, %d)" % (lineno(loc, instring), col(loc, instring)))
            if self.debugActions[TRY]:
                self.debugActions[TRY](instring, loc, self)
            try:
                if callPreParse and self.callPreparse:
                    preloc = self.preParse(instring, loc)
                else:
                    preloc = loc
                tokensStart = preloc
                if self.mayIndexError or preloc >= len(instring):
                    try:
                        loc, tokens = self.parseImpl(instring, preloc, doActions)
                    except IndexError:
                        raise ParseException(instring, len(instring), self.errmsg, self)
                else:
                    loc, tokens = self.parseImpl(instring, preloc, doActions)
            except Exception as err:
                # ~ print ("Exception raised:", err)
                if self.debugActions[FAIL]:
                    self.debugActions[FAIL](instring, tokensStart, self, err)
                if self.failAction:
                    self.failAction(instring, tokensStart, self, err)
                raise
        else:
            if callPreParse and self.callPreparse:
                preloc = self.preParse(instring, loc)
            else:
                preloc = loc
            tokensStart = preloc
            if self.mayIndexError or preloc >= len(instring):
                try:
                    loc, tokens = self.parseImpl(instring, preloc, doActions)
                except IndexError:
                    raise ParseException(instring, len(instring), self.errmsg, self)
            else:
                loc, tokens = self.parseImpl(instring, preloc, doActions)

        tokens = self.postParse(instring, loc, tokens)

        retTokens = ParseResults(tokens, self.resultsName, asList=self.saveAsList, modal=self.modalResults)
        if self.parseAction and (doActions or self.callDuringTry):
            if debugging:
                try:
                    for fn in self.parseAction:
                        try:
                            tokens = fn(instring, tokensStart, retTokens)
                        except IndexError as parse_action_exc:
                            exc = ParseException("exception raised in parse action")
                            exc.__cause__ = parse_action_exc
                            raise exc

                        if tokens is not None and tokens is not retTokens:
                            retTokens = ParseResults(tokens,
                                                      self.resultsName,
                                                      asList=self.saveAsList and isinstance(tokens, (ParseResults, list)),
                                                      modal=self.modalResults)
                except Exception as err:
                    # ~ print "Exception raised in user parse action:", err
                    if self.debugActions[FAIL]:
                        self.debugActions[FAIL](instring, tokensStart, self, err)
                    raise
            else:
                for fn in self.parseAction:
                    try:
                        tokens = fn(instring, tokensStart, retTokens)
                    except IndexError as parse_action_exc:
                        exc = ParseException("exception raised in parse action")
                        exc.__cause__ = parse_action_exc
                        raise exc

                    if tokens is not None and tokens is not retTokens:
                        retTokens = ParseResults(tokens,
                                                  self.resultsName,
                                                  asList=self.saveAsList and isinstance(tokens, (ParseResults, list)),
                                                  modal=self.modalResults)
        if debugging:
            # ~ print ("Matched", self, "->", retTokens.asList())
            if self.debugActions[MATCH]:
                self.debugActions[MATCH](instring, tokensStart, loc, self, retTokens)

        return loc, retTokens

    def tryParse(self, instring, loc):
        try:
            return self._parse(instring, loc, doActions=False)[0]
        except ParseFatalException:
            raise ParseException(instring, loc, self.errmsg, self)

    def canParseNext(self, instring, loc):
        try:
            self.tryParse(instring, loc)
        except (ParseException, IndexError):
            return False
        else:
            return True

    class _UnboundedCache(object):
        def __init__(self):
            cache = {}
            self.not_in_cache = not_in_cache = object()

            def get(self, key):
                return cache.get(key, not_in_cache)

            def set(self, key, value):
                cache[key] = value

            def clear(self):
                cache.clear()

            def cache_len(self):
                return len(cache)

            self.get = types.MethodType(get, self)
            self.set = types.MethodType(set, self)
            self.clear = types.MethodType(clear, self)
            self.__len__ = types.MethodType(cache_len, self)

    if _OrderedDict is not None:
        class _FifoCache(object):
            def __init__(self, size):
                self.not_in_cache = not_in_cache = object()

                cache = _OrderedDict()

                def get(self, key):
                    return cache.get(key, not_in_cache)

                def set(self, key, value):
                    cache[key] = value
                    while len(cache) > size:
                        try:
                            cache.popitem(False)
                        except KeyError:
                            pass

                def clear(self):
                    cache.clear()

                def cache_len(self):
                    return len(cache)

                self.get = types.MethodType(get, self)
                self.set = types.MethodType(set, self)
                self.clear = types.MethodType(clear, self)
                self.__len__ = types.MethodType(cache_len, self)

    else:
        class _FifoCache(object):
            def __init__(self, size):
                self.not_in_cache = not_in_cache = object()

                cache = {}
                key_fifo = collections.deque([], size)

                def get(self, key):
                    return cache.get(key, not_in_cache)

                def set(self, key, value):
                    cache[key] = value
                    while len(key_fifo) > size:
                        cache.pop(key_fifo.popleft(), None)
                    key_fifo.append(key)

                def clear(self):
                    cache.clear()
                    key_fifo.clear()

                def cache_len(self):
                    return len(cache)

                self.get = types.MethodType(get, self)
                self.set = types.MethodType(set, self)
                self.clear = types.MethodType(clear, self)
                self.__len__ = types.MethodType(cache_len, self)

    # argument cache for optimizing repeated calls when backtracking through recursive expressions
    packrat_cache = {} # this is set later by enabledPackrat(); this is here so that resetCache() doesn't fail
    packrat_cache_lock = RLock()
    packrat_cache_stats = [0, 0]

    # this method gets repeatedly called during backtracking with the same arguments -
    # we can cache these arguments and save ourselves the trouble of re-parsing the contained expression
    def _parseCache(self, instring, loc, doActions=True, callPreParse=True):
        HIT, MISS = 0, 1
        lookup = (self, instring, loc, callPreParse, doActions)
        with ParserElement.packrat_cache_lock:
            cache = ParserElement.packrat_cache
            value = cache.get(lookup)
            if value is cache.not_in_cache:
                ParserElement.packrat_cache_stats[MISS] += 1
                try:
                    value = self._parseNoCache(instring, loc, doActions, callPreParse)
                except ParseBaseException as pe:
                    # cache a copy of the exception, without the traceback
                    cache.set(lookup, pe.__class__(*pe.args))
                    raise
                else:
                    cache.set(lookup, (value[0], value[1].copy()))
                    return value
            else:
                ParserElement.packrat_cache_stats[HIT] += 1
                if isinstance(value, Exception):
                    raise value
                return value[0], value[1].copy()

    _parse = _parseNoCache

    @staticmethod
    def resetCache():
        ParserElement.packrat_cache.clear()
        ParserElement.packrat_cache_stats[:] = [0] * len(ParserElement.packrat_cache_stats)

    _packratEnabled = False
    @staticmethod
    def enablePackrat(cache_size_limit=128):
        """Enables "packrat" parsing, which adds memoizing to the parsing logic.
           Repeated parse attempts at the same string location (which happens
           often in many complex grammars) can immediately return a cached value,
           instead of re-executing parsing/validating code.  Memoizing is done of
           both valid results and parsing exceptions.

           Parameters:

           - cache_size_limit - (default= ``128``) - if an integer value is provided
             will limit the size of the packrat cache; if None is passed, then
             the cache size will be unbounded; if 0 is passed, the cache will
             be effectively disabled.

           This speedup may break existing programs that use parse actions that
           have side-effects.  For this reason, packrat parsing is disabled when
           you first import pyparsing.  To activate the packrat feature, your
           program must call the class method :class:`ParserElement.enablePackrat`.
           For best results, call ``enablePackrat()`` immediately after
           importing pyparsing.

           Example::

               from pip._vendor import pyparsing
               pyparsing.ParserElement.enablePackrat()
        """
        if not ParserElement._packratEnabled:
            ParserElement._packratEnabled = True
            if cache_size_limit is None:
                ParserElement.packrat_cache = ParserElement._UnboundedCache()
            else:
                ParserElement.packrat_cache = ParserElement._FifoCache(cache_size_limit)
            ParserElement._parse = ParserElement._parseCache

    def parseString(self, instring, parseAll=False):
        """
        Execute the parse expression with the given string.
        This is the main interface to the client code, once the complete
        expression has been built.

        Returns the parsed data as a :class:`ParseResults` object, which may be
        accessed as a list, or as a dict or object with attributes if the given parser
        includes results names.

        If you want the grammar to require that the entire input string be
        successfully parsed, then set ``parseAll`` to True (equivalent to ending
        the grammar with ``StringEnd()``).

        Note: ``parseString`` implicitly calls ``expandtabs()`` on the input string,
        in order to report proper column numbers in parse actions.
        If the input string contains tabs and
        the grammar uses parse actions that use the ``loc`` argument to index into the
        string being parsed, you can ensure you have a consistent view of the input
        string by:

        - calling ``parseWithTabs`` on your grammar before calling ``parseString``
          (see :class:`parseWithTabs`)
        - define your parse action using the full ``(s, loc, toks)`` signature, and
          reference the input string using the parse action's ``s`` argument
        - explictly expand the tabs in your input string before calling
          ``parseString``

        Example::

            Word('a').parseString('aaaaabaaa')  # -> ['aaaaa']
            Word('a').parseString('aaaaabaaa', parseAll=True)  # -> Exception: Expected end of text
        """
        ParserElement.resetCache()
        if not self.streamlined:
            self.streamline()
            # ~ self.saveAsList = True
        for e in self.ignoreExprs:
            e.streamline()
        if not self.keepTabs:
            instring = instring.expandtabs()
        try:
            loc, tokens = self._parse(instring, 0)
            if parseAll:
                loc = self.preParse(instring, loc)
                se = Empty() + StringEnd()
                se._parse(instring, loc)
        except ParseBaseException as exc:
            if ParserElement.verbose_stacktrace:
                raise
            else:
                # catch and re-raise exception from here, clears out pyparsing internal stack trace
                raise exc
        else:
            return tokens

    def scanString(self, instring, maxMatches=_MAX_INT, overlap=False):
        """
        Scan the input string for expression matches.  Each match will return the
        matching tokens, start location, and end location.  May be called with optional
        ``maxMatches`` argument, to clip scanning after 'n' matches are found.  If
        ``overlap`` is specified, then overlapping matches will be reported.

        Note that the start and end locations are reported relative to the string
        being parsed.  See :class:`parseString` for more information on parsing
        strings with embedded tabs.

        Example::

            source = "sldjf123lsdjjkf345sldkjf879lkjsfd987"
            print(source)
            for tokens, start, end in Word(alphas).scanString(source):
                print(' '*start + '^'*(end-start))
                print(' '*start + tokens[0])

        prints::

            sldjf123lsdjjkf345sldkjf879lkjsfd987
            ^^^^^
            sldjf
                    ^^^^^^^
                    lsdjjkf
                              ^^^^^^
                              sldkjf
                                       ^^^^^^
                                       lkjsfd
        """
        if not self.streamlined:
            self.streamline()
        for e in self.ignoreExprs:
            e.streamline()

        if not self.keepTabs:
            instring = _ustr(instring).expandtabs()
        instrlen = len(instring)
        loc = 0
        preparseFn = self.preParse
        parseFn = self._parse
        ParserElement.resetCache()
        matches = 0
        try:
            while loc <= instrlen and matches < maxMatches:
                try:
                    preloc = preparseFn(instring, loc)
                    nextLoc, tokens = parseFn(instring, preloc, callPreParse=False)
                except ParseException:
                    loc = preloc + 1
                else:
                    if nextLoc > loc:
                        matches += 1
                        yield tokens, preloc, nextLoc
                        if overlap:
                            nextloc = preparseFn(instring, loc)
                            if nextloc > loc:
                                loc = nextLoc
                            else:
                                loc += 1
                        else:
                            loc = nextLoc
                    else:
                        loc = preloc + 1
        except ParseBaseException as exc:
            if ParserElement.verbose_stacktrace:
                raise
            else:
                # catch and re-raise exception from here, clears out pyparsing internal stack trace
                raise exc

    def transformString(self, instring):
        """
        Extension to :class:`scanString`, to modify matching text with modified tokens that may
        be returned from a parse action.  To use ``transformString``, define a grammar and
        attach a parse action to it that modifies the returned token list.
        Invoking ``transformString()`` on a target string will then scan for matches,
        and replace the matched text patterns according to the logic in the parse
        action.  ``transformString()`` returns the resulting transformed string.

        Example::

            wd = Word(alphas)
            wd.setParseAction(lambda toks: toks[0].title())

            print(wd.transformString("now is the winter of our discontent made glorious summer by this sun of york."))

        prints::

            Now Is The Winter Of Our Discontent Made Glorious Summer By This Sun Of York.
        """
        out = []
        lastE = 0
        # force preservation of <TAB>s, to minimize unwanted transformation of string, and to
        # keep string locs straight between transformString and scanString
        self.keepTabs = True
        try:
            for t, s, e in self.scanString(instring):
                out.append(instring[lastE:s])
                if t:
                    if isinstance(t, ParseResults):
                        out += t.asList()
                    elif isinstance(t, list):
                        out += t
                    else:
                        out.append(t)
                lastE = e
            out.append(instring[lastE:])
            out = [o for o in out if o]
            return "".join(map(_ustr, _flatten(out)))
        except ParseBaseException as exc:
            if ParserElement.verbose_stacktrace:
                raise
            else:
                # catch and re-raise exception from here, clears out pyparsing internal stack trace
                raise exc

    def searchString(self, instring, maxMatches=_MAX_INT):
        """
        Another extension to :class:`scanString`, simplifying the access to the tokens found
        to match the given parse expression.  May be called with optional
        ``maxMatches`` argument, to clip searching after 'n' matches are found.

        Example::

            # a capitalized word starts with an uppercase letter, followed by zero or more lowercase letters
            cap_word = Word(alphas.upper(), alphas.lower())

            print(cap_word.searchString("More than Iron, more than Lead, more than Gold I need Electricity"))

            # the sum() builtin can be used to merge results into a single ParseResults object
            print(sum(cap_word.searchString("More than Iron, more than Lead, more than Gold I need Electricity")))

        prints::

            [['More'], ['Iron'], ['Lead'], ['Gold'], ['I'], ['Electricity']]
            ['More', 'Iron', 'Lead', 'Gold', 'I', 'Electricity']
        """
        try:
            return ParseResults([t for t, s, e in self.scanString(instring, maxMatches)])
        except ParseBaseException as exc:
            if ParserElement.verbose_stacktrace:
                raise
            else:
                # catch and re-raise exception from here, clears out pyparsing internal stack trace
                raise exc

    def split(self, instring, maxsplit=_MAX_INT, includeSeparators=False):
        """
        Generator method to split a string using the given expression as a separator.
        May be called with optional ``maxsplit`` argument, to limit the number of splits;
        and the optional ``includeSeparators`` argument (default= ``False``), if the separating
        matching text should be included in the split results.

        Example::

            punc = oneOf(list(".,;:/-!?"))
            print(list(punc.split("This, this?, this sentence, is badly punctuated!")))

        prints::

            ['This', ' this', '', ' this sentence', ' is badly punctuated', '']
        """
        splits = 0
        last = 0
        for t, s, e in self.scanString(instring, maxMatches=maxsplit):
            yield instring[last:s]
            if includeSeparators:
                yield t[0]
            last = e
        yield instring[last:]

    def __add__(self, other):
        """
        Implementation of + operator - returns :class:`And`. Adding strings to a ParserElement
        converts them to :class:`Literal`s by default.

        Example::

            greet = Word(alphas) + "," + Word(alphas) + "!"
            hello = "Hello, World!"
            print (hello, "->", greet.parseString(hello))

        prints::

            Hello, World! -> ['Hello', ',', 'World', '!']

        ``...`` may be used as a parse expression as a short form of :class:`SkipTo`.

            Literal('start') + ... + Literal('end')

        is equivalent to:

            Literal('start') + SkipTo('end')("_skipped*") + Literal('end')

        Note that the skipped text is returned with '_skipped' as a results name,
        and to support having multiple skips in the same parser, the value returned is
        a list of all skipped text.
        """
        if other is Ellipsis:
            return _PendingSkip(self)

        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        if not isinstance(other, ParserElement):
            warnings.warn("Cannot combine element of type %s with ParserElement" % type(other),
                          SyntaxWarning, stacklevel=2)
            return None
        return And([self, other])

    def __radd__(self, other):
        """
        Implementation of + operator when left operand is not a :class:`ParserElement`
        """
        if other is Ellipsis:
            return SkipTo(self)("_skipped*") + self

        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        if not isinstance(other, ParserElement):
            warnings.warn("Cannot combine element of type %s with ParserElement" % type(other),
                          SyntaxWarning, stacklevel=2)
            return None
        return other + self

    def __sub__(self, other):
        """
        Implementation of - operator, returns :class:`And` with error stop
        """
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        if not isinstance(other, ParserElement):
            warnings.warn("Cannot combine element of type %s with ParserElement" % type(other),
                          SyntaxWarning, stacklevel=2)
            return None
        return self + And._ErrorStop() + other

    def __rsub__(self, other):
        """
        Implementation of - operator when left operand is not a :class:`ParserElement`
        """
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        if not isinstance(other, ParserElement):
            warnings.warn("Cannot combine element of type %s with ParserElement" % type(other),
                          SyntaxWarning, stacklevel=2)
            return None
        return other - self

    def __mul__(self, other):
        """
        Implementation of * operator, allows use of ``expr * 3`` in place of
        ``expr + expr + expr``.  Expressions may also me multiplied by a 2-integer
        tuple, similar to ``{min, max}`` multipliers in regular expressions.  Tuples
        may also include ``None`` as in:
         - ``expr*(n, None)`` or ``expr*(n, )`` is equivalent
              to ``expr*n + ZeroOrMore(expr)``
              (read as "at least n instances of ``expr``")
         - ``expr*(None, n)`` is equivalent to ``expr*(0, n)``
              (read as "0 to n instances of ``expr``")
         - ``expr*(None, None)`` is equivalent to ``ZeroOrMore(expr)``
         - ``expr*(1, None)`` is equivalent to ``OneOrMore(expr)``

        Note that ``expr*(None, n)`` does not raise an exception if
        more than n exprs exist in the input stream; that is,
        ``expr*(None, n)`` does not enforce a maximum number of expr
        occurrences.  If this behavior is desired, then write
        ``expr*(None, n) + ~expr``
        """
        if other is Ellipsis:
            other = (0, None)
        elif isinstance(other, tuple) and other[:1] == (Ellipsis,):
            other = ((0, ) + other[1:] + (None,))[:2]

        if isinstance(other, int):
            minElements, optElements = other, 0
        elif isinstance(other, tuple):
            other = tuple(o if o is not Ellipsis else None for o in other)
            other = (other + (None, None))[:2]
            if other[0] is None:
                other = (0, other[1])
            if isinstance(other[0], int) and other[1] is None:
                if other[0] == 0:
                    return ZeroOrMore(self)
                if other[0] == 1:
                    return OneOrMore(self)
                else:
                    return self * other[0] + ZeroOrMore(self)
            elif isinstance(other[0], int) and isinstance(other[1], int):
                minElements, optElements = other
                optElements -= minElements
            else:
                raise TypeError("cannot multiply 'ParserElement' and ('%s', '%s') objects", type(other[0]), type(other[1]))
        else:
            raise TypeError("cannot multiply 'ParserElement' and '%s' objects", type(other))

        if minElements < 0:
            raise ValueError("cannot multiply ParserElement by negative value")
        if optElements < 0:
            raise ValueError("second tuple value must be greater or equal to first tuple value")
        if minElements == optElements == 0:
            raise ValueError("cannot multiply ParserElement by 0 or (0, 0)")

        if optElements:
            def makeOptionalList(n):
                if n > 1:
                    return Optional(self + makeOptionalList(n - 1))
                else:
                    return Optional(self)
            if minElements:
                if minElements == 1:
                    ret = self + makeOptionalList(optElements)
                else:
                    ret = And([self] * minElements) + makeOptionalList(optElements)
            else:
                ret = makeOptionalList(optElements)
        else:
            if minElements == 1:
                ret = self
            else:
                ret = And([self] * minElements)
        return ret

    def __rmul__(self, other):
        return self.__mul__(other)

    def __or__(self, other):
        """
        Implementation of | operator - returns :class:`MatchFirst`
        """
        if other is Ellipsis:
            return _PendingSkip(self, must_skip=True)

        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        if not isinstance(other, ParserElement):
            warnings.warn("Cannot combine element of type %s with ParserElement" % type(other),
                          SyntaxWarning, stacklevel=2)
            return None
        return MatchFirst([self, other])

    def __ror__(self, other):
        """
        Implementation of | operator when left operand is not a :class:`ParserElement`
        """
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        if not isinstance(other, ParserElement):
            warnings.warn("Cannot combine element of type %s with ParserElement" % type(other),
                          SyntaxWarning, stacklevel=2)
            return None
        return other | self

    def __xor__(self, other):
        """
        Implementation of ^ operator - returns :class:`Or`
        """
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        if not isinstance(other, ParserElement):
            warnings.warn("Cannot combine element of type %s with ParserElement" % type(other),
                          SyntaxWarning, stacklevel=2)
            return None
        return Or([self, other])

    def __rxor__(self, other):
        """
        Implementation of ^ operator when left operand is not a :class:`ParserElement`
        """
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        if not isinstance(other, ParserElement):
            warnings.warn("Cannot combine element of type %s with ParserElement" % type(other),
                          SyntaxWarning, stacklevel=2)
            return None
        return other ^ self

    def __and__(self, other):
        """
        Implementation of & operator - returns :class:`Each`
        """
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        if not isinstance(other, ParserElement):
            warnings.warn("Cannot combine element of type %s with ParserElement" % type(other),
                          SyntaxWarning, stacklevel=2)
            return None
        return Each([self, other])

    def __rand__(self, other):
        """
        Implementation of & operator when left operand is not a :class:`ParserElement`
        """
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        if not isinstance(other, ParserElement):
            warnings.warn("Cannot combine element of type %s with ParserElement" % type(other),
                          SyntaxWarning, stacklevel=2)
            return None
        return other & self

    def __invert__(self):
        """
        Implementation of ~ operator - returns :class:`NotAny`
        """
        return NotAny(self)

    def __iter__(self):
        # must implement __iter__ to override legacy use of sequential access to __getitem__ to
        # iterate over a sequence
        raise TypeError('%r object is not iterable' % self.__class__.__name__)

    def __getitem__(self, key):
        """
        use ``[]`` indexing notation as a short form for expression repetition:
         - ``expr[n]`` is equivalent to ``expr*n``
         - ``expr[m, n]`` is equivalent to ``expr*(m, n)``
         - ``expr[n, ...]`` or ``expr[n,]`` is equivalent
              to ``expr*n + ZeroOrMore(expr)``
              (read as "at least n instances of ``expr``")
         - ``expr[..., n]`` is equivalent to ``expr*(0, n)``
              (read as "0 to n instances of ``expr``")
         - ``expr[...]`` and ``expr[0, ...]`` are equivalent to ``ZeroOrMore(expr)``
         - ``expr[1, ...]`` is equivalent to ``OneOrMore(expr)``
         ``None`` may be used in place of ``...``.

        Note that ``expr[..., n]`` and ``expr[m, n]``do not raise an exception
        if more than ``n`` ``expr``s exist in the input stream.  If this behavior is
        desired, then write ``expr[..., n] + ~expr``.
       """

        # convert single arg keys to tuples
        try:
            if isinstance(key, str):
                key = (key,)
            iter(key)
        except TypeError:
            key = (key, key)

        if len(key) > 2:
            warnings.warn("only 1 or 2 index arguments supported ({0}{1})".format(key[:5],
                                                                                '... [{0}]'.format(len(key))
                                                                                if len(key) > 5 else ''))

        # clip to 2 elements
        ret = self * tuple(key[:2])
        return ret

    def __call__(self, name=None):
        """
        Shortcut for :class:`setResultsName`, with ``listAllMatches=False``.

        If ``name`` is given with a trailing ``'*'`` character, then ``listAllMatches`` will be
        passed as ``True``.

        If ``name` is omitted, same as calling :class:`copy`.

        Example::

            # these are equivalent
            userdata = Word(alphas).setResultsName("name") + Word(nums + "-").setResultsName("socsecno")
            userdata = Word(alphas)("name") + Word(nums + "-")("socsecno")
        """
        if name is not None:
            return self._setResultsName(name)
        else:
            return self.copy()

    def suppress(self):
        """
        Suppresses the output of this :class:`ParserElement`; useful to keep punctuation from
        cluttering up returned output.
        """
        return Suppress(self)

    def leaveWhitespace(self):
        """
        Disables the skipping of whitespace before matching the characters in the
        :class:`ParserElement`'s defined pattern.  This is normally only used internally by
        the pyparsing module, but may be needed in some whitespace-sensitive grammars.
        """
        self.skipWhitespace = False
        return self

    def setWhitespaceChars(self, chars):
        """
        Overrides the default whitespace chars
        """
        self.skipWhitespace = True
        self.whiteChars = chars
        self.copyDefaultWhiteChars = False
        return self

    def parseWithTabs(self):
        """
        Overrides default behavior to expand ``<TAB>``s to spaces before parsing the input string.
        Must be called before ``parseString`` when the input grammar contains elements that
        match ``<TAB>`` characters.
        """
        self.keepTabs = True
        return self

    def ignore(self, other):
        """
        Define expression to be ignored (e.g., comments) while doing pattern
        matching; may be called repeatedly, to define multiple comment or other
        ignorable patterns.

        Example::

            patt = OneOrMore(Word(alphas))
            patt.parseString('ablaj /* comment */ lskjd') # -> ['ablaj']

            patt.ignore(cStyleComment)
            patt.parseString('ablaj /* comment */ lskjd') # -> ['ablaj', 'lskjd']
        """
        if isinstance(other, basestring):
            other = Suppress(other)

        if isinstance(other, Suppress):
            if other not in self.ignoreExprs:
                self.ignoreExprs.append(other)
        else:
            self.ignoreExprs.append(Suppress(other.copy()))
        return self

    def setDebugActions(self, startAction, successAction, exceptionAction):
        """
        Enable display of debugging messages while doing pattern matching.
        """
        self.debugActions = (startAction or _defaultStartDebugAction,
                             successAction or _defaultSuccessDebugAction,
                             exceptionAction or _defaultExceptionDebugAction)
        self.debug = True
        return self

    def setDebug(self, flag=True):
        """
        Enable display of debugging messages while doing pattern matching.
        Set ``flag`` to True to enable, False to disable.

        Example::

            wd = Word(alphas).setName("alphaword")
            integer = Word(nums).setName("numword")
            term = wd | integer

            # turn on debugging for wd
            wd.setDebug()

            OneOrMore(term).parseString("abc 123 xyz 890")

        prints::

            Match alphaword at loc 0(1,1)
            Matched alphaword -> ['abc']
            Match alphaword at loc 3(1,4)
            Exception raised:Expected alphaword (at char 4), (line:1, col:5)
            Match alphaword at loc 7(1,8)
            Matched alphaword -> ['xyz']
            Match alphaword at loc 11(1,12)
            Exception raised:Expected alphaword (at char 12), (line:1, col:13)
            Match alphaword at loc 15(1,16)
            Exception raised:Expected alphaword (at char 15), (line:1, col:16)

        The output shown is that produced by the default debug actions - custom debug actions can be
        specified using :class:`setDebugActions`. Prior to attempting
        to match the ``wd`` expression, the debugging message ``"Match <exprname> at loc <n>(<line>,<col>)"``
        is shown. Then if the parse succeeds, a ``"Matched"`` message is shown, or an ``"Exception raised"``
        message is shown. Also note the use of :class:`setName` to assign a human-readable name to the expression,
        which makes debugging and exception messages easier to understand - for instance, the default
        name created for the :class:`Word` expression without calling ``setName`` is ``"W:(ABCD...)"``.
        """
        if flag:
            self.setDebugActions(_defaultStartDebugAction, _defaultSuccessDebugAction, _defaultExceptionDebugAction)
        else:
            self.debug = False
        return self

    def __str__(self):
        return self.name

    def __repr__(self):
        return _ustr(self)

    def streamline(self):
        self.streamlined = True
        self.strRepr = None
        return self

    def checkRecursion(self, parseElementList):
        pass

    def validate(self, validateTrace=None):
        """
        Check defined expressions for valid structure, check for infinite recursive definitions.
        """
        self.checkRecursion([])

    def parseFile(self, file_or_filename, parseAll=False):
        """
        Execute the parse expression on the given file or filename.
        If a filename is specified (instead of a file object),
        the entire file is opened, read, and closed before parsing.
        """
        try:
            file_contents = file_or_filename.read()
        except AttributeError:
            with open(file_or_filename, "r") as f:
                file_contents = f.read()
        try:
            return self.parseString(file_contents, parseAll)
        except ParseBaseException as exc:
            if ParserElement.verbose_stacktrace:
                raise
            else:
                # catch and re-raise exception from here, clears out pyparsing internal stack trace
                raise exc

    def __eq__(self, other):
        if isinstance(other, ParserElement):
            if PY_3:
                self is other or super(ParserElement, self).__eq__(other)
            else:
                return self is other or vars(self) == vars(other)
        elif isinstance(other, basestring):
            return self.matches(other)
        else:
            return super(ParserElement, self) == other

    def __ne__(self, other):
        return not (self == other)

    def __hash__(self):
        return id(self)

    def __req__(self, other):
        return self == other

    def __rne__(self, other):
        return not (self == other)

    def matches(self, testString, parseAll=True):
        """
        Method for quick testing of a parser against a test string. Good for simple
        inline microtests of sub expressions while building up larger parser.

        Parameters:
         - testString - to test against this expression for a match
         - parseAll - (default= ``True``) - flag to pass to :class:`parseString` when running tests

        Example::

            expr = Word(nums)
            assert expr.matches("100")
        """
        try:
            self.parseString(_ustr(testString), parseAll=parseAll)
            return True
        except ParseBaseException:
            return False

    def runTests(self, tests, parseAll=True, comment='#',
                 fullDump=True, printResults=True, failureTests=False, postParse=None,
                 file=None):
        """
        Execute the parse expression on a series of test strings, showing each
        test, the parsed results or where the parse failed. Quick and easy way to
        run a parse expression against a list of sample strings.

        Parameters:
         - tests - a list of separate test strings, or a multiline string of test strings
         - parseAll - (default= ``True``) - flag to pass to :class:`parseString` when running tests
         - comment - (default= ``'#'``) - expression for indicating embedded comments in the test
              string; pass None to disable comment filtering
         - fullDump - (default= ``True``) - dump results as list followed by results names in nested outline;
              if False, only dump nested list
         - printResults - (default= ``True``) prints test output to stdout
         - failureTests - (default= ``False``) indicates if these tests are expected to fail parsing
         - postParse - (default= ``None``) optional callback for successful parse results; called as
              `fn(test_string, parse_results)` and returns a string to be added to the test output
         - file - (default=``None``) optional file-like object to which test output will be written;
              if None, will default to ``sys.stdout``

        Returns: a (success, results) tuple, where success indicates that all tests succeeded
        (or failed if ``failureTests`` is True), and the results contain a list of lines of each
        test's output

        Example::

            number_expr = pyparsing_common.number.copy()

            result = number_expr.runTests('''
                # unsigned integer
                100
                # negative integer
                -100
                # float with scientific notation
                6.02e23
                # integer with scientific notation
                1e-12
                ''')
            print("Success" if result[0] else "Failed!")

            result = number_expr.runTests('''
                # stray character
                100Z
                # missing leading digit before '.'
                -.100
                # too many '.'
                3.14.159
                ''', failureTests=True)
            print("Success" if result[0] else "Failed!")

        prints::

            # unsigned integer
            100
            [100]

            # negative integer
            -100
            [-100]

            # float with scientific notation
            6.02e23
            [6.02e+23]

            # integer with scientific notation
            1e-12
            [1e-12]

            Success

            # stray character
            100Z
               ^
            FAIL: Expected end of text (at char 3), (line:1, col:4)

            # missing leading digit before '.'
            -.100
            ^
            FAIL: Expected {real number with scientific notation | real number | signed integer} (at char 0), (line:1, col:1)

            # too many '.'
            3.14.159
                ^
            FAIL: Expected end of text (at char 4), (line:1, col:5)

            Success

        Each test string must be on a single line. If you want to test a string that spans multiple
        lines, create a test like this::

            expr.runTest(r"this is a test\\n of strings that spans \\n 3 lines")

        (Note that this is a raw string literal, you must include the leading 'r'.)
        """
        if isinstance(tests, basestring):
            tests = list(map(str.strip, tests.rstrip().splitlines()))
        if isinstance(comment, basestring):
            comment = Literal(comment)
        if file is None:
            file = sys.stdout
        print_ = file.write

        allResults = []
        comments = []
        success = True
        NL = Literal(r'\n').addParseAction(replaceWith('\n')).ignore(quotedString)
        BOM = u'\ufeff'
        for t in tests:
            if comment is not None and comment.matches(t, False) or comments and not t:
                comments.append(t)
                continue
            if not t:
                continue
            out = ['\n'.join(comments), t]
            comments = []
            try:
                # convert newline marks to actual newlines, and strip leading BOM if present
                t = NL.transformString(t.lstrip(BOM))
                result = self.parseString(t, parseAll=parseAll)
            except ParseBaseException as pe:
                fatal = "(FATAL)" if isinstance(pe, ParseFatalException) else ""
                if '\n' in t:
                    out.append(line(pe.loc, t))
                    out.append(' ' * (col(pe.loc, t) - 1) + '^' + fatal)
                else:
                    out.append(' ' * pe.loc + '^' + fatal)
                out.append("FAIL: " + str(pe))
                success = success and failureTests
                result = pe
            except Exception as exc:
                out.append("FAIL-EXCEPTION: " + str(exc))
                success = success and failureTests
                result = exc
            else:
                success = success and not failureTests
                if postParse is not None:
                    try:
                        pp_value = postParse(t, result)
                        if pp_value is not None:
                            if isinstance(pp_value, ParseResults):
                                out.append(pp_value.dump())
                            else:
                                out.append(str(pp_value))
                        else:
                            out.append(result.dump())
                    except Exception as e:
                        out.append(result.dump(full=fullDump))
                        out.append("{0} failed: {1}: {2}".format(postParse.__name__, type(e).__name__, e))
                else:
                    out.append(result.dump(full=fullDump))

            if printResults:
                if fullDump:
                    out.append('')
                print_('\n'.join(out))

            allResults.append((t, result))

        return success, allResults


class _PendingSkip(ParserElement):
    # internal placeholder class to hold a place were '...' is added to a parser element,
    # once another ParserElement is added, this placeholder will be replaced with a SkipTo
    def __init__(self, expr, must_skip=False):
        super(_PendingSkip, self).__init__()
        self.strRepr = str(expr + Empty()).replace('Empty', '...')
        self.name = self.strRepr
        self.anchor = expr
        self.must_skip = must_skip

    def __add__(self, other):
        skipper = SkipTo(other).setName("...")("_skipped*")
        if self.must_skip:
            def must_skip(t):
                if not t._skipped or t._skipped.asList() == ['']:
                    del t[0]
                    t.pop("_skipped", None)
            def show_skip(t):
                if t._skipped.asList()[-1:] == ['']:
                    skipped = t.pop('_skipped')
                    t['_skipped'] = 'missing <' + repr(self.anchor) + '>'
            return (self.anchor + skipper().addParseAction(must_skip)
                    | skipper().addParseAction(show_skip)) + other

        return self.anchor + skipper + other

    def __repr__(self):
        return self.strRepr

    def parseImpl(self, *args):
        raise Exception("use of `...` expression without following SkipTo target expression")


class Token(ParserElement):
    """Abstract :class:`ParserElement` subclass, for defining atomic
    matching patterns.
    """
    def __init__(self):
        super(Token, self).__init__(savelist=False)


class Empty(Token):
    """An empty token, will always match.
    """
    def __init__(self):
        super(Empty, self).__init__()
        self.name = "Empty"
        self.mayReturnEmpty = True
        self.mayIndexError = False


class NoMatch(Token):
    """A token that will never match.
    """
    def __init__(self):
        super(NoMatch, self).__init__()
        self.name = "NoMatch"
        self.mayReturnEmpty = True
        self.mayIndexError = False
        self.errmsg = "Unmatchable token"

    def parseImpl(self, instring, loc, doActions=True):
        raise ParseException(instring, loc, self.errmsg, self)


class Literal(Token):
    """Token to exactly match a specified string.

    Example::

        Literal('blah').parseString('blah')  # -> ['blah']
        Literal('blah').parseString('blahfooblah')  # -> ['blah']
        Literal('blah').parseString('bla')  # -> Exception: Expected "blah"

    For case-insensitive matching, use :class:`CaselessLiteral`.

    For keyword matching (force word break before and after the matched string),
    use :class:`Keyword` or :class:`CaselessKeyword`.
    """
    def __init__(self, matchString):
        super(Literal, self).__init__()
        self.match = matchString
        self.matchLen = len(matchString)
        try:
            self.firstMatchChar = matchString[0]
        except IndexError:
            warnings.warn("null string passed to Literal; use Empty() instead",
                            SyntaxWarning, stacklevel=2)
            self.__class__ = Empty
        self.name = '"%s"' % _ustr(self.match)
        self.errmsg = "Expected " + self.name
        self.mayReturnEmpty = False
        self.mayIndexError = False

        # Performance tuning: modify __class__ to select
        # a parseImpl optimized for single-character check
        if self.matchLen == 1 and type(self) is Literal:
            self.__class__ = _SingleCharLiteral

    def parseImpl(self, instring, loc, doActions=True):
        if instring[loc] == self.firstMatchChar and instring.startswith(self.match, loc):
            return loc + self.matchLen, self.match
        raise ParseException(instring, loc, self.errmsg, self)

class _SingleCharLiteral(Literal):
    def parseImpl(self, instring, loc, doActions=True):
        if instring[loc] == self.firstMatchChar:
            return loc + 1, self.match
        raise ParseException(instring, loc, self.errmsg, self)

_L = Literal
ParserElement._literalStringClass = Literal

class Keyword(Token):
    """Token to exactly match a specified string as a keyword, that is,
    it must be immediately followed by a non-keyword character.  Compare
    with :class:`Literal`:

     - ``Literal("if")`` will match the leading ``'if'`` in
       ``'ifAndOnlyIf'``.
     - ``Keyword("if")`` will not; it will only match the leading
       ``'if'`` in ``'if x=1'``, or ``'if(y==2)'``

    Accepts two optional constructor arguments in addition to the
    keyword string:

     - ``identChars`` is a string of characters that would be valid
       identifier characters, defaulting to all alphanumerics + "_" and
       "$"
     - ``caseless`` allows case-insensitive matching, default is ``False``.

    Example::

        Keyword("start").parseString("start")  # -> ['start']
        Keyword("start").parseString("starting")  # -> Exception

    For case-insensitive matching, use :class:`CaselessKeyword`.
    """
    DEFAULT_KEYWORD_CHARS = alphanums + "_$"

    def __init__(self, matchString, identChars=None, caseless=False):
        super(Keyword, self).__init__()
        if identChars is None:
            identChars = Keyword.DEFAULT_KEYWORD_CHARS
        self.match = matchString
        self.matchLen = len(matchString)
        try:
            self.firstMatchChar = matchString[0]
        except IndexError:
            warnings.warn("null string passed to Keyword; use Empty() instead",
                          SyntaxWarning, stacklevel=2)
        self.name = '"%s"' % self.match
        self.errmsg = "Expected " + self.name
        self.mayReturnEmpty = False
        self.mayIndexError = False
        self.caseless = caseless
        if caseless:
            self.caselessmatch = matchString.upper()
            identChars = identChars.upper()
        self.identChars = set(identChars)

    def parseImpl(self, instring, loc, doActions=True):
        if self.caseless:
            if ((instring[loc:loc + self.matchLen].upper() == self.caselessmatch)
                    and (loc >= len(instring) - self.matchLen
                         or instring[loc + self.matchLen].upper() not in self.identChars)
                    and (loc == 0
                         or instring[loc - 1].upper() not in self.identChars)):
                return loc + self.matchLen, self.match

        else:
            if instring[loc] == self.firstMatchChar:
                if ((self.matchLen == 1 or instring.startswith(self.match, loc))
                        and (loc >= len(instring) - self.matchLen
                             or instring[loc + self.matchLen] not in self.identChars)
                        and (loc == 0 or instring[loc - 1] not in self.identChars)):
                    return loc + self.matchLen, self.match

        raise ParseException(instring, loc, self.errmsg, self)

    def copy(self):
        c = super(Keyword, self).copy()
        c.identChars = Keyword.DEFAULT_KEYWORD_CHARS
        return c

    @staticmethod
    def setDefaultKeywordChars(chars):
        """Overrides the default Keyword chars
        """
        Keyword.DEFAULT_KEYWORD_CHARS = chars

class CaselessLiteral(Literal):
    """Token to match a specified string, ignoring case of letters.
    Note: the matched results will always be in the case of the given
    match string, NOT the case of the input text.

    Example::

        OneOrMore(CaselessLiteral("CMD")).parseString("cmd CMD Cmd10") # -> ['CMD', 'CMD', 'CMD']

    (Contrast with example for :class:`CaselessKeyword`.)
    """
    def __init__(self, matchString):
        super(CaselessLiteral, self).__init__(matchString.upper())
        # Preserve the defining literal.
        self.returnString = matchString
        self.name = "'%s'" % self.returnString
        self.errmsg = "Expected " + self.name

    def parseImpl(self, instring, loc, doActions=True):
        if instring[loc:loc + self.matchLen].upper() == self.match:
            return loc + self.matchLen, self.returnString
        raise ParseException(instring, loc, self.errmsg, self)

class CaselessKeyword(Keyword):
    """
    Caseless version of :class:`Keyword`.

    Example::

        OneOrMore(CaselessKeyword("CMD")).parseString("cmd CMD Cmd10") # -> ['CMD', 'CMD']

    (Contrast with example for :class:`CaselessLiteral`.)
    """
    def __init__(self, matchString, identChars=None):
        super(CaselessKeyword, self).__init__(matchString, identChars, caseless=True)

class CloseMatch(Token):
    """A variation on :class:`Literal` which matches "close" matches,
    that is, strings with at most 'n' mismatching characters.
    :class:`CloseMatch` takes parameters:

     - ``match_string`` - string to be matched
     - ``maxMismatches`` - (``default=1``) maximum number of
       mismatches allowed to count as a match

    The results from a successful parse will contain the matched text
    from the input string and the following named results:

     - ``mismatches`` - a list of the positions within the
       match_string where mismatches were found
     - ``original`` - the original match_string used to compare
       against the input string

    If ``mismatches`` is an empty list, then the match was an exact
    match.

    Example::

        patt = CloseMatch("ATCATCGAATGGA")
        patt.parseString("ATCATCGAAXGGA") # -> (['ATCATCGAAXGGA'], {'mismatches': [[9]], 'original': ['ATCATCGAATGGA']})
        patt.parseString("ATCAXCGAAXGGA") # -> Exception: Expected 'ATCATCGAATGGA' (with up to 1 mismatches) (at char 0), (line:1, col:1)

        # exact match
        patt.parseString("ATCATCGAATGGA") # -> (['ATCATCGAATGGA'], {'mismatches': [[]], 'original': ['ATCATCGAATGGA']})

        # close match allowing up to 2 mismatches
        patt = CloseMatch("ATCATCGAATGGA", maxMismatches=2)
        patt.parseString("ATCAXCGAAXGGA") # -> (['ATCAXCGAAXGGA'], {'mismatches': [[4, 9]], 'original': ['ATCATCGAATGGA']})
    """
    def __init__(self, match_string, maxMismatches=1):
        super(CloseMatch, self).__init__()
        self.name = match_string
        self.match_string = match_string
        self.maxMismatches = maxMismatches
        self.errmsg = "Expected %r (with up to %d mismatches)" % (self.match_string, self.maxMismatches)
        self.mayIndexError = False
        self.mayReturnEmpty = False

    def parseImpl(self, instring, loc, doActions=True):
        start = loc
        instrlen = len(instring)
        maxloc = start + len(self.match_string)

        if maxloc <= instrlen:
            match_string = self.match_string
            match_stringloc = 0
            mismatches = []
            maxMismatches = self.maxMismatches

            for match_stringloc, s_m in enumerate(zip(instring[loc:maxloc], match_string)):
                src, mat = s_m
                if src != mat:
                    mismatches.append(match_stringloc)
                    if len(mismatches) > maxMismatches:
                        break
            else:
                loc = match_stringloc + 1
                results = ParseResults([instring[start:loc]])
                results['original'] = match_string
                results['mismatches'] = mismatches
                return loc, results

        raise ParseException(instring, loc, self.errmsg, self)


class Word(Token):
    """Token for matching words composed of allowed character sets.
    Defined with string containing all allowed initial characters, an
    optional string containing allowed body characters (if omitted,
    defaults to the initial character set), and an optional minimum,
    maximum, and/or exact length.  The default value for ``min`` is
    1 (a minimum value < 1 is not valid); the default values for
    ``max`` and ``exact`` are 0, meaning no maximum or exact
    length restriction. An optional ``excludeChars`` parameter can
    list characters that might be found in the input ``bodyChars``
    string; useful to define a word of all printables except for one or
    two characters, for instance.

    :class:`srange` is useful for defining custom character set strings
    for defining ``Word`` expressions, using range notation from
    regular expression character sets.

    A common mistake is to use :class:`Word` to match a specific literal
    string, as in ``Word("Address")``. Remember that :class:`Word`
    uses the string argument to define *sets* of matchable characters.
    This expression would match "Add", "AAA", "dAred", or any other word
    made up of the characters 'A', 'd', 'r', 'e', and 's'. To match an
    exact literal string, use :class:`Literal` or :class:`Keyword`.

    pyparsing includes helper strings for building Words:

     - :class:`alphas`
     - :class:`nums`
     - :class:`alphanums`
     - :class:`hexnums`
     - :class:`alphas8bit` (alphabetic characters in ASCII range 128-255
       - accented, tilded, umlauted, etc.)
     - :class:`punc8bit` (non-alphabetic characters in ASCII range
       128-255 - currency, symbols, superscripts, diacriticals, etc.)
     - :class:`printables` (any non-whitespace character)

    Example::

        # a word composed of digits
        integer = Word(nums) # equivalent to Word("0123456789") or Word(srange("0-9"))

        # a word with a leading capital, and zero or more lowercase
        capital_word = Word(alphas.upper(), alphas.lower())

        # hostnames are alphanumeric, with leading alpha, and '-'
        hostname = Word(alphas, alphanums + '-')

        # roman numeral (not a strict parser, accepts invalid mix of characters)
        roman = Word("IVXLCDM")

        # any string of non-whitespace characters, except for ','
        csv_value = Word(printables, excludeChars=",")
    """
    def __init__(self, initChars, bodyChars=None, min=1, max=0, exact=0, asKeyword=False, excludeChars=None):
        super(Word, self).__init__()
        if excludeChars:
            excludeChars = set(excludeChars)
            initChars = ''.join(c for c in initChars if c not in excludeChars)
            if bodyChars:
                bodyChars = ''.join(c for c in bodyChars if c not in excludeChars)
        self.initCharsOrig = initChars
        self.initChars = set(initChars)
        if bodyChars:
            self.bodyCharsOrig = bodyChars
            self.bodyChars = set(bodyChars)
        else:
            self.bodyCharsOrig = initChars
            self.bodyChars = set(initChars)

        self.maxSpecified = max > 0

        if min < 1:
            raise ValueError("cannot specify a minimum length < 1; use Optional(Word()) if zero-length word is permitted")

        self.minLen = min

        if max > 0:
            self.maxLen = max
        else:
            self.maxLen = _MAX_INT

        if exact > 0:
            self.maxLen = exact
            self.minLen = exact

        self.name = _ustr(self)
        self.errmsg = "Expected " + self.name
        self.mayIndexError = False
        self.asKeyword = asKeyword

        if ' ' not in self.initCharsOrig + self.bodyCharsOrig and (min == 1 and max == 0 and exact == 0):
            if self.bodyCharsOrig == self.initCharsOrig:
                self.reString = "[%s]+" % _escapeRegexRangeChars(self.initCharsOrig)
            elif len(self.initCharsOrig) == 1:
                self.reString = "%s[%s]*" % (re.escape(self.initCharsOrig),
                                             _escapeRegexRangeChars(self.bodyCharsOrig),)
            else:
                self.reString = "[%s][%s]*" % (_escapeRegexRangeChars(self.initCharsOrig),
                                               _escapeRegexRangeChars(self.bodyCharsOrig),)
            if self.asKeyword:
                self.reString = r"\b" + self.reString + r"\b"

            try:
                self.re = re.compile(self.reString)
            except Exception:
                self.re = None
            else:
                self.re_match = self.re.match
                self.__class__ = _WordRegex

    def parseImpl(self, instring, loc, doActions=True):
        if instring[loc] not in self.initChars:
            raise ParseException(instring, loc, self.errmsg, self)

        start = loc
        loc += 1
        instrlen = len(instring)
        bodychars = self.bodyChars
        maxloc = start + self.maxLen
        maxloc = min(maxloc, instrlen)
        while loc < maxloc and instring[loc] in bodychars:
            loc += 1

        throwException = False
        if loc - start < self.minLen:
            throwException = True
        elif self.maxSpecified and loc < instrlen and instring[loc] in bodychars:
            throwException = True
        elif self.asKeyword:
            if (start > 0 and instring[start - 1] in bodychars
                    or loc < instrlen and instring[loc] in bodychars):
                throwException = True

        if throwException:
            raise ParseException(instring, loc, self.errmsg, self)

        return loc, instring[start:loc]

    def __str__(self):
        try:
            return super(Word, self).__str__()
        except Exception:
            pass

        if self.strRepr is None:

            def charsAsStr(s):
                if len(s) > 4:
                    return s[:4] + "..."
                else:
                    return s

            if self.initCharsOrig != self.bodyCharsOrig:
                self.strRepr = "W:(%s, %s)" % (charsAsStr(self.initCharsOrig), charsAsStr(self.bodyCharsOrig))
            else:
                self.strRepr = "W:(%s)" % charsAsStr(self.initCharsOrig)

        return self.strRepr

class _WordRegex(Word):
    def parseImpl(self, instring, loc, doActions=True):
        result = self.re_match(instring, loc)
        if not result:
            raise ParseException(instring, loc, self.errmsg, self)

        loc = result.end()
        return loc, result.group()


class Char(_WordRegex):
    """A short-cut class for defining ``Word(characters, exact=1)``,
    when defining a match of any single character in a string of
    characters.
    """
    def __init__(self, charset, asKeyword=False, excludeChars=None):
        super(Char, self).__init__(charset, exact=1, asKeyword=asKeyword, excludeChars=excludeChars)
        self.reString = "[%s]" % _escapeRegexRangeChars(''.join(self.initChars))
        if asKeyword:
            self.reString = r"\b%s\b" % self.reString
        self.re = re.compile(self.reString)
        self.re_match = self.re.match


class Regex(Token):
    r"""Token for matching strings that match a given regular
    expression. Defined with string specifying the regular expression in
    a form recognized by the stdlib Python  `re module <https://docs.python.org/3/library/re.html>`_.
    If the given regex contains named groups (defined using ``(?P<name>...)``),
    these will be preserved as named parse results.

    Example::

        realnum = Regex(r"[+-]?\d+\.\d*")
        date = Regex(r'(?P<year>\d{4})-(?P<month>\d\d?)-(?P<day>\d\d?)')
        # ref: https://stackoverflow.com/questions/267399/how-do-you-match-only-valid-roman-numerals-with-a-regular-expression
        roman = Regex(r"M{0,4}(CM|CD|D?{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})")
    """
    compiledREtype = type(re.compile("[A-Z]"))
    def __init__(self, pattern, flags=0, asGroupList=False, asMatch=False):
        """The parameters ``pattern`` and ``flags`` are passed
        to the ``re.compile()`` function as-is. See the Python
        `re module <https://docs.python.org/3/library/re.html>`_ module for an
        explanation of the acceptable patterns and flags.
        """
        super(Regex, self).__init__()

        if isinstance(pattern, basestring):
            if not pattern:
                warnings.warn("null string passed to Regex; use Empty() instead",
                              SyntaxWarning, stacklevel=2)

            self.pattern = pattern
            self.flags = flags

            try:
                self.re = re.compile(self.pattern, self.flags)
                self.reString = self.pattern
            except sre_constants.error:
                warnings.warn("invalid pattern (%s) passed to Regex" % pattern,
                              SyntaxWarning, stacklevel=2)
                raise

        elif isinstance(pattern, Regex.compiledREtype):
            self.re = pattern
            self.pattern = self.reString = str(pattern)
            self.flags = flags

        else:
            raise ValueError("Regex may only be constructed with a string or a compiled RE object")

        self.re_match = self.re.match

        self.name = _ustr(self)
        self.errmsg = "Expected " + self.name
        self.mayIndexError = False
        self.mayReturnEmpty = True
        self.asGroupList = asGroupList
        self.asMatch = asMatch
        if self.asGroupList:
            self.parseImpl = self.parseImplAsGroupList
        if self.asMatch:
            self.parseImpl = self.parseImplAsMatch

    def parseImpl(self, instring, loc, doActions=True):
        result = self.re_match(instring, loc)
        if not result:
            raise ParseException(instring, loc, self.errmsg, self)

        loc = result.end()
        ret = ParseResults(result.group())
        d = result.groupdict()
        if d:
            for k, v in d.items():
                ret[k] = v
        return loc, ret

    def parseImplAsGroupList(self, instring, loc, doActions=True):
        result = self.re_match(instring, loc)
        if not result:
            raise ParseException(instring, loc, self.errmsg, self)

        loc = result.end()
        ret = result.groups()
        return loc, ret

    def parseImplAsMatch(self, instring, loc, doActions=True):
        result = self.re_match(instring, loc)
        if not result:
            raise ParseException(instring, loc, self.errmsg, self)

        loc = result.end()
        ret = result
        return loc, ret

    def __str__(self):
        try:
            return super(Regex, self).__str__()
        except Exception:
            pass

        if self.strRepr is None:
            self.strRepr = "Re:(%s)" % repr(self.pattern)

        return self.strRepr

    def sub(self, repl):
        r"""
        Return Regex with an attached parse action to transform the parsed
        result as if called using `re.sub(expr, repl, string) <https://docs.python.org/3/library/re.html#re.sub>`_.

        Example::

            make_html = Regex(r"(\w+):(.*?):").sub(r"<\1>\2</\1>")
            print(make_html.transformString("h1:main title:"))
            # prints "<h1>main title</h1>"
        """
        if self.asGroupList:
            warnings.warn("cannot use sub() with Regex(asGroupList=True)",
                          SyntaxWarning, stacklevel=2)
            raise SyntaxError()

        if self.asMatch and callable(repl):
            warnings.warn("cannot use sub() with a callable with Regex(asMatch=True)",
                          SyntaxWarning, stacklevel=2)
            raise SyntaxError()

        if self.asMatch:
            def pa(tokens):
                return tokens[0].expand(repl)
        else:
            def pa(tokens):
                return self.re.sub(repl, tokens[0])
        return self.addParseAction(pa)

class QuotedString(Token):
    r"""
    Token for matching strings that are delimited by quoting characters.

    Defined with the following parameters:

        - quoteChar - string of one or more characters defining the
          quote delimiting string
        - escChar - character to escape quotes, typically backslash
          (default= ``None``)
        - escQuote - special quote sequence to escape an embedded quote
          string (such as SQL's ``""`` to escape an embedded ``"``)
          (default= ``None``)
        - multiline - boolean indicating whether quotes can span
          multiple lines (default= ``False``)
        - unquoteResults - boolean indicating whether the matched text
          should be unquoted (default= ``True``)
        - endQuoteChar - string of one or more characters defining the
          end of the quote delimited string (default= ``None``  => same as
          quoteChar)
        - convertWhitespaceEscapes - convert escaped whitespace
          (``'\t'``, ``'\n'``, etc.) to actual whitespace
          (default= ``True``)

    Example::

        qs = QuotedString('"')
        print(qs.searchString('lsjdf "This is the quote" sldjf'))
        complex_qs = QuotedString('{{', endQuoteChar='}}')
        print(complex_qs.searchString('lsjdf {{This is the "quote"}} sldjf'))
        sql_qs = QuotedString('"', escQuote='""')
        print(sql_qs.searchString('lsjdf "This is the quote with ""embedded"" quotes" sldjf'))

    prints::

        [['This is the quote']]
        [['This is the "quote"']]
        [['This is the quote with "embedded" quotes']]
    """
    def __init__(self, quoteChar, escChar=None, escQuote=None, multiline=False,
                 unquoteResults=True, endQuoteChar=None, convertWhitespaceEscapes=True):
        super(QuotedString, self).__init__()

        # remove white space from quote chars - wont work anyway
        quoteChar = quoteChar.strip()
        if not quoteChar:
            warnings.warn("quoteChar cannot be the empty string", SyntaxWarning, stacklevel=2)
            raise SyntaxError()

        if endQuoteChar is None:
            endQuoteChar = quoteChar
        else:
            endQuoteChar = endQuoteChar.strip()
            if not endQuoteChar:
                warnings.warn("endQuoteChar cannot be the empty string", SyntaxWarning, stacklevel=2)
                raise SyntaxError()

        self.quoteChar = quoteChar
        self.quoteCharLen = len(quoteChar)
        self.firstQuoteChar = quoteChar[0]
        self.endQuoteChar = endQuoteChar
        self.endQuoteCharLen = len(endQuoteChar)
        self.escChar = escChar
        self.escQuote = escQuote
        self.unquoteResults = unquoteResults
        self.convertWhitespaceEscapes = convertWhitespaceEscapes

        if multiline:
            self.flags = re.MULTILINE | re.DOTALL
            self.pattern = r'%s(?:[^%s%s]' % (re.escape(self.quoteChar),
                                              _escapeRegexRangeChars(self.endQuoteChar[0]),
                                              (escChar is not None and _escapeRegexRangeChars(escChar) or ''))
        else:
            self.flags = 0
            self.pattern = r'%s(?:[^%s\n\r%s]' % (re.escape(self.quoteChar),
                                                  _escapeRegexRangeChars(self.endQuoteChar[0]),
                                                  (escChar is not None and _escapeRegexRangeChars(escChar) or ''))
        if len(self.endQuoteChar) > 1:
            self.pattern += (
                '|(?:' + ')|(?:'.join("%s[^%s]" % (re.escape(self.endQuoteChar[:i]),
                                                   _escapeRegexRangeChars(self.endQuoteChar[i]))
                                      for i in range(len(self.endQuoteChar) - 1, 0, -1)) + ')')

        if escQuote:
            self.pattern += (r'|(?:%s)' % re.escape(escQuote))
        if escChar:
            self.pattern += (r'|(?:%s.)' % re.escape(escChar))
            self.escCharReplacePattern = re.escape(self.escChar) + "(.)"
        self.pattern += (r')*%s' % re.escape(self.endQuoteChar))

        try:
            self.re = re.compile(self.pattern, self.flags)
            self.reString = self.pattern
            self.re_match = self.re.match
        except sre_constants.error:
            warnings.warn("invalid pattern (%s) passed to Regex" % self.pattern,
                          SyntaxWarning, stacklevel=2)
            raise

        self.name = _ustr(self)
        self.errmsg = "Expected " + self.name
        self.mayIndexError = False
        self.mayReturnEmpty = True

    def parseImpl(self, instring, loc, doActions=True):
        result = instring[loc] == self.firstQuoteChar and self.re_match(instring, loc) or None
        if not result:
            raise ParseException(instring, loc, self.errmsg, self)

        loc = result.end()
        ret = result.group()

        if self.unquoteResults:

            # strip off quotes
            ret = ret[self.quoteCharLen: -self.endQuoteCharLen]

            if isinstance(ret, basestring):
                # replace escaped whitespace
                if '\\' in ret and self.convertWhitespaceEscapes:
                    ws_map = {
                        r'\t': '\t',
                        r'\n': '\n',
                        r'\f': '\f',
                        r'\r': '\r',
                    }
                    for wslit, wschar in ws_map.items():
                        ret = ret.replace(wslit, wschar)

                # replace escaped characters
                if self.escChar:
                    ret = re.sub(self.escCharReplacePattern, r"\g<1>", ret)

                # replace escaped quotes
                if self.escQuote:
                    ret = ret.replace(self.escQuote, self.endQuoteChar)

        return loc, ret

    def __str__(self):
        try:
            return super(QuotedString, self).__str__()
        except Exception:
            pass

        if self.strRepr is None:
            self.strRepr = "quoted string, starting with %s ending with %s" % (self.quoteChar, self.endQuoteChar)

        return self.strRepr


class CharsNotIn(Token):
    """Token for matching words composed of characters *not* in a given
    set (will include whitespace in matched characters if not listed in
    the provided exclusion set - see example). Defined with string
    containing all disallowed characters, and an optional minimum,
    maximum, and/or exact length.  The default value for ``min`` is
    1 (a minimum value < 1 is not valid); the default values for
    ``max`` and ``exact`` are 0, meaning no maximum or exact
    length restriction.

    Example::

        # define a comma-separated-value as anything that is not a ','
        csv_value = CharsNotIn(',')
        print(delimitedList(csv_value).parseString("dkls,lsdkjf,s12 34,@!#,213"))

    prints::

        ['dkls', 'lsdkjf', 's12 34', '@!#', '213']
    """
    def __init__(self, notChars, min=1, max=0, exact=0):
        super(CharsNotIn, self).__init__()
        self.skipWhitespace = False
        self.notChars = notChars

        if min < 1:
            raise ValueError("cannot specify a minimum length < 1; use "
                             "Optional(CharsNotIn()) if zero-length char group is permitted")

        self.minLen = min

        if max > 0:
            self.maxLen = max
        else:
            self.maxLen = _MAX_INT

        if exact > 0:
            self.maxLen = exact
            self.minLen = exact

        self.name = _ustr(self)
        self.errmsg = "Expected " + self.name
        self.mayReturnEmpty = (self.minLen == 0)
        self.mayIndexError = False

    def parseImpl(self, instring, loc, doActions=True):
        if instring[loc] in self.notChars:
            raise ParseException(instring, loc, self.errmsg, self)

        start = loc
        loc += 1
        notchars = self.notChars
        maxlen = min(start + self.maxLen, len(instring))
        while loc < maxlen and instring[loc] not in notchars:
            loc += 1

        if loc - start < self.minLen:
            raise ParseException(instring, loc, self.errmsg, self)

        return loc, instring[start:loc]

    def __str__(self):
        try:
            return super(CharsNotIn, self).__str__()
        except Exception:
            pass

        if self.strRepr is None:
            if len(self.notChars) > 4:
                self.strRepr = "!W:(%s...)" % self.notChars[:4]
            else:
                self.strRepr = "!W:(%s)" % self.notChars

        return self.strRepr

class White(Token):
    """Special matching class for matching whitespace.  Normally,
    whitespace is ignored by pyparsing grammars.  This class is included
    when some whitespace structures are significant.  Define with
    a string containing the whitespace characters to be matched; default
    is ``" \\t\\r\\n"``.  Also takes optional ``min``,
    ``max``, and ``exact`` arguments, as defined for the
    :class:`Word` class.
    """
    whiteStrs = {
        ' ' : '<SP>',
        '\t': '<TAB>',
        '\n': '<LF>',
        '\r': '<CR>',
        '\f': '<FF>',
        'u\00A0': '<NBSP>',
        'u\1680': '<OGHAM_SPACE_MARK>',
        'u\180E': '<MONGOLIAN_VOWEL_SEPARATOR>',
        'u\2000': '<EN_QUAD>',
        'u\2001': '<EM_QUAD>',
        'u\2002': '<EN_SPACE>',
        'u\2003': '<EM_SPACE>',
        'u\2004': '<THREE-PER-EM_SPACE>',
        'u\2005': '<FOUR-PER-EM_SPACE>',
        'u\2006': '<SIX-PER-EM_SPACE>',
        'u\2007': '<FIGURE_SPACE>',
        'u\2008': '<PUNCTUATION_SPACE>',
        'u\2009': '<THIN_SPACE>',
        'u\200A': '<HAIR_SPACE>',
        'u\200B': '<ZERO_WIDTH_SPACE>',
        'u\202F': '<NNBSP>',
        'u\205F': '<MMSP>',
        'u\3000': '<IDEOGRAPHIC_SPACE>',
        }
    def __init__(self, ws=" \t\r\n", min=1, max=0, exact=0):
        super(White, self).__init__()
        self.matchWhite = ws
        self.setWhitespaceChars("".join(c for c in self.whiteChars if c not in self.matchWhite))
        # ~ self.leaveWhitespace()
        self.name = ("".join(White.whiteStrs[c] for c in self.matchWhite))
        self.mayReturnEmpty = True
        self.errmsg = "Expected " + self.name

        self.minLen = min

        if max > 0:
            self.maxLen = max
        else:
            self.maxLen = _MAX_INT

        if exact > 0:
            self.maxLen = exact
            self.minLen = exact

    def parseImpl(self, instring, loc, doActions=True):
        if instring[loc] not in self.matchWhite:
            raise ParseException(instring, loc, self.errmsg, self)
        start = loc
        loc += 1
        maxloc = start + self.maxLen
        maxloc = min(maxloc, len(instring))
        while loc < maxloc and instring[loc] in self.matchWhite:
            loc += 1

        if loc - start < self.minLen:
            raise ParseException(instring, loc, self.errmsg, self)

        return loc, instring[start:loc]


class _PositionToken(Token):
    def __init__(self):
        super(_PositionToken, self).__init__()
        self.name = self.__class__.__name__
        self.mayReturnEmpty = True
        self.mayIndexError = False

class GoToColumn(_PositionToken):
    """Token to advance to a specific column of input text; useful for
    tabular report scraping.
    """
    def __init__(self, colno):
        super(GoToColumn, self).__init__()
        self.col = colno

    def preParse(self, instring, loc):
        if col(loc, instring) != self.col:
            instrlen = len(instring)
            if self.ignoreExprs:
                loc = self._skipIgnorables(instring, loc)
            while loc < instrlen and instring[loc].isspace() and col(loc, instring) != self.col:
                loc += 1
        return loc

    def parseImpl(self, instring, loc, doActions=True):
        thiscol = col(loc, instring)
        if thiscol > self.col:
            raise ParseException(instring, loc, "Text not in expected column", self)
        newloc = loc + self.col - thiscol
        ret = instring[loc: newloc]
        return newloc, ret


class LineStart(_PositionToken):
    r"""Matches if current position is at the beginning of a line within
    the parse string

    Example::

        test = '''\
        AAA this line
        AAA and this line
          AAA but not this one
        B AAA and definitely not this one
        '''

        for t in (LineStart() + 'AAA' + restOfLine).searchString(test):
            print(t)

    prints::

        ['AAA', ' this line']
        ['AAA', ' and this line']

    """
    def __init__(self):
        super(LineStart, self).__init__()
        self.errmsg = "Expected start of line"

    def parseImpl(self, instring, loc, doActions=True):
        if col(loc, instring) == 1:
            return loc, []
        raise ParseException(instring, loc, self.errmsg, self)

class LineEnd(_PositionToken):
    """Matches if current position is at the end of a line within the
    parse string
    """
    def __init__(self):
        super(LineEnd, self).__init__()
        self.setWhitespaceChars(ParserElement.DEFAULT_WHITE_CHARS.replace("\n", ""))
        self.errmsg = "Expected end of line"

    def parseImpl(self, instring, loc, doActions=True):
        if loc < len(instring):
            if instring[loc] == "\n":
                return loc + 1, "\n"
            else:
                raise ParseException(instring, loc, self.errmsg, self)
        elif loc == len(instring):
            return loc + 1, []
        else:
            raise ParseException(instring, loc, self.errmsg, self)

class StringStart(_PositionToken):
    """Matches if current position is at the beginning of the parse
    string
    """
    def __init__(self):
        super(StringStart, self).__init__()
        self.errmsg = "Expected start of text"

    def parseImpl(self, instring, loc, doActions=True):
        if loc != 0:
            # see if entire string up to here is just whitespace and ignoreables
            if loc != self.preParse(instring, 0):
                raise ParseException(instring, loc, self.errmsg, self)
        return loc, []

class StringEnd(_PositionToken):
    """Matches if current position is at the end of the parse string
    """
    def __init__(self):
        super(StringEnd, self).__init__()
        self.errmsg = "Expected end of text"

    def parseImpl(self, instring, loc, doActions=True):
        if loc < len(instring):
            raise ParseException(instring, loc, self.errmsg, self)
        elif loc == len(instring):
            return loc + 1, []
        elif loc > len(instring):
            return loc, []
        else:
            raise ParseException(instring, loc, self.errmsg, self)

class WordStart(_PositionToken):
    """Matches if the current position is at the beginning of a Word,
    and is not preceded by any character in a given set of
    ``wordChars`` (default= ``printables``). To emulate the
    ``\b`` behavior of regular expressions, use
    ``WordStart(alphanums)``. ``WordStart`` will also match at
    the beginning of the string being parsed, or at the beginning of
    a line.
    """
    def __init__(self, wordChars=printables):
        super(WordStart, self).__init__()
        self.wordChars = set(wordChars)
        self.errmsg = "Not at the start of a word"

    def parseImpl(self, instring, loc, doActions=True):
        if loc != 0:
            if (instring[loc - 1] in self.wordChars
                    or instring[loc] not in self.wordChars):
                raise ParseException(instring, loc, self.errmsg, self)
        return loc, []

class WordEnd(_PositionToken):
    """Matches if the current position is at the end of a Word, and is
    not followed by any character in a given set of ``wordChars``
    (default= ``printables``). To emulate the ``\b`` behavior of
    regular expressions, use ``WordEnd(alphanums)``. ``WordEnd``
    will also match at the end of the string being parsed, or at the end
    of a line.
    """
    def __init__(self, wordChars=printables):
        super(WordEnd, self).__init__()
        self.wordChars = set(wordChars)
        self.skipWhitespace = False
        self.errmsg = "Not at the end of a word"

    def parseImpl(self, instring, loc, doActions=True):
        instrlen = len(instring)
        if instrlen > 0 and loc < instrlen:
            if (instring[loc] in self.wordChars or
                    instring[loc - 1] not in self.wordChars):
                raise ParseException(instring, loc, self.errmsg, self)
        return loc, []


class ParseExpression(ParserElement):
    """Abstract subclass of ParserElement, for combining and
    post-processing parsed tokens.
    """
    def __init__(self, exprs, savelist=False):
        super(ParseExpression, self).__init__(savelist)
        if isinstance(exprs, _generatorType):
            exprs = list(exprs)

        if isinstance(exprs, basestring):
            self.exprs = [self._literalStringClass(exprs)]
        elif isinstance(exprs, ParserElement):
            self.exprs = [exprs]
        elif isinstance(exprs, Iterable):
            exprs = list(exprs)
            # if sequence of strings provided, wrap with Literal
            if any(isinstance(expr, basestring) for expr in exprs):
                exprs = (self._literalStringClass(e) if isinstance(e, basestring) else e for e in exprs)
            self.exprs = list(exprs)
        else:
            try:
                self.exprs = list(exprs)
            except TypeError:
                self.exprs = [exprs]
        self.callPreparse = False

    def append(self, other):
        self.exprs.append(other)
        self.strRepr = None
        return self

    def leaveWhitespace(self):
        """Extends ``leaveWhitespace`` defined in base class, and also invokes ``leaveWhitespace`` on
           all contained expressions."""
        self.skipWhitespace = False
        self.exprs = [e.copy() for e in self.exprs]
        for e in self.exprs:
            e.leaveWhitespace()
        return self

    def ignore(self, other):
        if isinstance(other, Suppress):
            if other not in self.ignoreExprs:
                super(ParseExpression, self).ignore(other)
                for e in self.exprs:
                    e.ignore(self.ignoreExprs[-1])
        else:
            super(ParseExpression, self).ignore(other)
            for e in self.exprs:
                e.ignore(self.ignoreExprs[-1])
        return self

    def __str__(self):
        try:
            return super(ParseExpression, self).__str__()
        except Exception:
            pass

        if self.strRepr is None:
            self.strRepr = "%s:(%s)" % (self.__class__.__name__, _ustr(self.exprs))
        return self.strRepr

    def streamline(self):
        super(ParseExpression, self).streamline()

        for e in self.exprs:
            e.streamline()

        # collapse nested And's of the form And(And(And(a, b), c), d) to And(a, b, c, d)
        # but only if there are no parse actions or resultsNames on the nested And's
        # (likewise for Or's and MatchFirst's)
        if len(self.exprs) == 2:
            other = self.exprs[0]
            if (isinstance(other, self.__class__)
                    and not other.parseAction
                    and other.resultsName is None
                    and not other.debug):
                self.exprs = other.exprs[:] + [self.exprs[1]]
                self.strRepr = None
                self.mayReturnEmpty |= other.mayReturnEmpty
                self.mayIndexError  |= other.mayIndexError

            other = self.exprs[-1]
            if (isinstance(other, self.__class__)
                    and not other.parseAction
                    and other.resultsName is None
                    and not other.debug):
                self.exprs = self.exprs[:-1] + other.exprs[:]
                self.strRepr = None
                self.mayReturnEmpty |= other.mayReturnEmpty
                self.mayIndexError  |= other.mayIndexError

        self.errmsg = "Expected " + _ustr(self)

        return self

    def validate(self, validateTrace=None):
        tmp = (validateTrace if validateTrace is not None else [])[:] + [self]
        for e in self.exprs:
            e.validate(tmp)
        self.checkRecursion([])

    def copy(self):
        ret = super(ParseExpression, self).copy()
        ret.exprs = [e.copy() for e in self.exprs]
        return ret

    def _setResultsName(self, name, listAllMatches=False):
        if __diag__.warn_ungrouped_named_tokens_in_collection:
            for e in self.exprs:
                if isinstance(e, ParserElement) and e.resultsName:
                    warnings.warn("{0}: setting results name {1!r} on {2} expression "
                                  "collides with {3!r} on contained expression".format("warn_ungrouped_named_tokens_in_collection",
                                                                                       name,
                                                                                       type(self).__name__,
                                                                                       e.resultsName),
                                  stacklevel=3)

        return super(ParseExpression, self)._setResultsName(name, listAllMatches)


class And(ParseExpression):
    """
    Requires all given :class:`ParseExpression` s to be found in the given order.
    Expressions may be separated by whitespace.
    May be constructed using the ``'+'`` operator.
    May also be constructed using the ``'-'`` operator, which will
    suppress backtracking.

    Example::

        integer = Word(nums)
        name_expr = OneOrMore(Word(alphas))

        expr = And([integer("id"), name_expr("name"), integer("age")])
        # more easily written as:
        expr = integer("id") + name_expr("name") + integer("age")
    """

    class _ErrorStop(Empty):
        def __init__(self, *args, **kwargs):
            super(And._ErrorStop, self).__init__(*args, **kwargs)
            self.name = '-'
            self.leaveWhitespace()

    def __init__(self, exprs, savelist=True):
        if exprs and Ellipsis in exprs:
            tmp = []
            for i, expr in enumerate(exprs):
                if expr is Ellipsis:
                    if i < len(exprs) - 1:
                        skipto_arg = (Empty() + exprs[i + 1]).exprs[-1]
                        tmp.append(SkipTo(skipto_arg)("_skipped*"))
                    else:
                        raise Exception("cannot construct And with sequence ending in ...")
                else:
                    tmp.append(expr)
            exprs[:] = tmp
        super(And, self).__init__(exprs, savelist)
        self.mayReturnEmpty = all(e.mayReturnEmpty for e in self.exprs)
        self.setWhitespaceChars(self.exprs[0].whiteChars)
        self.skipWhitespace = self.exprs[0].skipWhitespace
        self.callPreparse = True

    def streamline(self):
        # collapse any _PendingSkip's
        if self.exprs:
            if any(isinstance(e, ParseExpression) and e.exprs and isinstance(e.exprs[-1], _PendingSkip)
                   for e in self.exprs[:-1]):
                for i, e in enumerate(self.exprs[:-1]):
                    if e is None:
                        continue
                    if (isinstance(e, ParseExpression)
                            and e.exprs and isinstance(e.exprs[-1], _PendingSkip)):
                        e.exprs[-1] = e.exprs[-1] + self.exprs[i + 1]
                        self.exprs[i + 1] = None
                self.exprs = [e for e in self.exprs if e is not None]

        super(And, self).streamline()
        self.mayReturnEmpty = all(e.mayReturnEmpty for e in self.exprs)
        return self

    def parseImpl(self, instring, loc, doActions=True):
        # pass False as last arg to _parse for first element, since we already
        # pre-parsed the string as part of our And pre-parsing
        loc, resultlist = self.exprs[0]._parse(instring, loc, doActions, callPreParse=False)
        errorStop = False
        for e in self.exprs[1:]:
            if isinstance(e, And._ErrorStop):
                errorStop = True
                continue
            if errorStop:
                try:
                    loc, exprtokens = e._parse(instring, loc, doActions)
                except ParseSyntaxException:
                    raise
                except ParseBaseException as pe:
                    pe.__traceback__ = None
                    raise ParseSyntaxException._from_exception(pe)
                except IndexError:
                    raise ParseSyntaxException(instring, len(instring), self.errmsg, self)
            else:
                loc, exprtokens = e._parse(instring, loc, doActions)
            if exprtokens or exprtokens.haskeys():
                resultlist += exprtokens
        return loc, resultlist

    def __iadd__(self, other):
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        return self.append(other)  # And([self, other])

    def checkRecursion(self, parseElementList):
        subRecCheckList = parseElementList[:] + [self]
        for e in self.exprs:
            e.checkRecursion(subRecCheckList)
            if not e.mayReturnEmpty:
                break

    def __str__(self):
        if hasattr(self, "name"):
            return self.name

        if self.strRepr is None:
            self.strRepr = "{" + " ".join(_ustr(e) for e in self.exprs) + "}"

        return self.strRepr


class Or(ParseExpression):
    """Requires that at least one :class:`ParseExpression` is found. If
    two expressions match, the expression that matches the longest
    string will be used. May be constructed using the ``'^'``
    operator.

    Example::

        # construct Or using '^' operator

        number = Word(nums) ^ Combine(Word(nums) + '.' + Word(nums))
        print(number.searchString("123 3.1416 789"))

    prints::

        [['123'], ['3.1416'], ['789']]
    """
    def __init__(self, exprs, savelist=False):
        super(Or, self).__init__(exprs, savelist)
        if self.exprs:
            self.mayReturnEmpty = any(e.mayReturnEmpty for e in self.exprs)
        else:
            self.mayReturnEmpty = True

    def streamline(self):
        super(Or, self).streamline()
        if __compat__.collect_all_And_tokens:
            self.saveAsList = any(e.saveAsList for e in self.exprs)
        return self

    def parseImpl(self, instring, loc, doActions=True):
        maxExcLoc = -1
        maxException = None
        matches = []
        for e in self.exprs:
            try:
                loc2 = e.tryParse(instring, loc)
            except ParseException as err:
                err.__traceback__ = None
                if err.loc > maxExcLoc:
                    maxException = err
                    maxExcLoc = err.loc
            except IndexError:
                if len(instring) > maxExcLoc:
                    maxException = ParseException(instring, len(instring), e.errmsg, self)
                    maxExcLoc = len(instring)
            else:
                # save match among all matches, to retry longest to shortest
                matches.append((loc2, e))

        if matches:
            # re-evaluate all matches in descending order of length of match, in case attached actions
            # might change whether or how much they match of the input.
            matches.sort(key=itemgetter(0), reverse=True)

            if not doActions:
                # no further conditions or parse actions to change the selection of
                # alternative, so the first match will be the best match
                best_expr = matches[0][1]
                return best_expr._parse(instring, loc, doActions)

            longest = -1, None
            for loc1, expr1 in matches:
                if loc1 <= longest[0]:
                    # already have a longer match than this one will deliver, we are done
                    return longest

                try:
                    loc2, toks = expr1._parse(instring, loc, doActions)
                except ParseException as err:
                    err.__traceback__ = None
                    if err.loc > maxExcLoc:
                        maxException = err
                        maxExcLoc = err.loc
                else:
                    if loc2 >= loc1:
                        return loc2, toks
                    # didn't match as much as before
                    elif loc2 > longest[0]:
                        longest = loc2, toks

            if longest != (-1, None):
                return longest

        if maxException is not None:
            maxException.msg = self.errmsg
            raise maxException
        else:
            raise ParseException(instring, loc, "no defined alternatives to match", self)


    def __ixor__(self, other):
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        return self.append(other)  # Or([self, other])

    def __str__(self):
        if hasattr(self, "name"):
            return self.name

        if self.strRepr is None:
            self.strRepr = "{" + " ^ ".join(_ustr(e) for e in self.exprs) + "}"

        return self.strRepr

    def checkRecursion(self, parseElementList):
        subRecCheckList = parseElementList[:] + [self]
        for e in self.exprs:
            e.checkRecursion(subRecCheckList)

    def _setResultsName(self, name, listAllMatches=False):
        if (not __compat__.collect_all_And_tokens
                and __diag__.warn_multiple_tokens_in_named_alternation):
            if any(isinstance(e, And) for e in self.exprs):
                warnings.warn("{0}: setting results name {1!r} on {2} expression "
                              "may only return a single token for an And alternative, "
                              "in future will return the full list of tokens".format(
                    "warn_multiple_tokens_in_named_alternation", name, type(self).__name__),
                    stacklevel=3)

        return super(Or, self)._setResultsName(name, listAllMatches)


class MatchFirst(ParseExpression):
    """Requires that at least one :class:`ParseExpression` is found. If
    two expressions match, the first one listed is the one that will
    match. May be constructed using the ``'|'`` operator.

    Example::

        # construct MatchFirst using '|' operator

        # watch the order of expressions to match
        number = Word(nums) | Combine(Word(nums) + '.' + Word(nums))
        print(number.searchString("123 3.1416 789")) #  Fail! -> [['123'], ['3'], ['1416'], ['789']]

        # put more selective expression first
        number = Combine(Word(nums) + '.' + Word(nums)) | Word(nums)
        print(number.searchString("123 3.1416 789")) #  Better -> [['123'], ['3.1416'], ['789']]
    """
    def __init__(self, exprs, savelist=False):
        super(MatchFirst, self).__init__(exprs, savelist)
        if self.exprs:
            self.mayReturnEmpty = any(e.mayReturnEmpty for e in self.exprs)
        else:
            self.mayReturnEmpty = True

    def streamline(self):
        super(MatchFirst, self).streamline()
        if __compat__.collect_all_And_tokens:
            self.saveAsList = any(e.saveAsList for e in self.exprs)
        return self

    def parseImpl(self, instring, loc, doActions=True):
        maxExcLoc = -1
        maxException = None
        for e in self.exprs:
            try:
                ret = e._parse(instring, loc, doActions)
                return ret
            except ParseException as err:
                if err.loc > maxExcLoc:
                    maxException = err
                    maxExcLoc = err.loc
            except IndexError:
                if len(instring) > maxExcLoc:
                    maxException = ParseException(instring, len(instring), e.errmsg, self)
                    maxExcLoc = len(instring)

        # only got here if no expression matched, raise exception for match that made it the furthest
        else:
            if maxException is not None:
                maxException.msg = self.errmsg
                raise maxException
            else:
                raise ParseException(instring, loc, "no defined alternatives to match", self)

    def __ior__(self, other):
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        return self.append(other)  # MatchFirst([self, other])

    def __str__(self):
        if hasattr(self, "name"):
            return self.name

        if self.strRepr is None:
            self.strRepr = "{" + " | ".join(_ustr(e) for e in self.exprs) + "}"

        return self.strRepr

    def checkRecursion(self, parseElementList):
        subRecCheckList = parseElementList[:] + [self]
        for e in self.exprs:
            e.checkRecursion(subRecCheckList)

    def _setResultsName(self, name, listAllMatches=False):
        if (not __compat__.collect_all_And_tokens
                and __diag__.warn_multiple_tokens_in_named_alternation):
            if any(isinstance(e, And) for e in self.exprs):
                warnings.warn("{0}: setting results name {1!r} on {2} expression "
                              "may only return a single token for an And alternative, "
                              "in future will return the full list of tokens".format(
                    "warn_multiple_tokens_in_named_alternation", name, type(self).__name__),
                    stacklevel=3)

        return super(MatchFirst, self)._setResultsName(name, listAllMatches)


class Each(ParseExpression):
    """Requires all given :class:`ParseExpression` s to be found, but in
    any order. Expressions may be separated by whitespace.

    May be constructed using the ``'&'`` operator.

    Example::

        color = oneOf("RED ORANGE YELLOW GREEN BLUE PURPLE BLACK WHITE BROWN")
        shape_type = oneOf("SQUARE CIRCLE TRIANGLE STAR HEXAGON OCTAGON")
        integer = Word(nums)
        shape_attr = "shape:" + shape_type("shape")
        posn_attr = "posn:" + Group(integer("x") + ',' + integer("y"))("posn")
        color_attr = "color:" + color("color")
        size_attr = "size:" + integer("size")

        # use Each (using operator '&') to accept attributes in any order
        # (shape and posn are required, color and size are optional)
        shape_spec = shape_attr & posn_attr & Optional(color_attr) & Optional(size_attr)

        shape_spec.runTests('''
            shape: SQUARE color: BLACK posn: 100, 120
            shape: CIRCLE size: 50 color: BLUE posn: 50,80
            color:GREEN size:20 shape:TRIANGLE posn:20,40
            '''
            )

    prints::

        shape: SQUARE color: BLACK posn: 100, 120
        ['shape:', 'SQUARE', 'color:', 'BLACK', 'posn:', ['100', ',', '120']]
        - color: BLACK
        - posn: ['100', ',', '120']
          - x: 100
          - y: 120
        - shape: SQUARE


        shape: CIRCLE size: 50 color: BLUE posn: 50,80
        ['shape:', 'CIRCLE', 'size:', '50', 'color:', 'BLUE', 'posn:', ['50', ',', '80']]
        - color: BLUE
        - posn: ['50', ',', '80']
          - x: 50
          - y: 80
        - shape: CIRCLE
        - size: 50


        color: GREEN size: 20 shape: TRIANGLE posn: 20,40
        ['color:', 'GREEN', 'size:', '20', 'shape:', 'TRIANGLE', 'posn:', ['20', ',', '40']]
        - color: GREEN
        - posn: ['20', ',', '40']
          - x: 20
          - y: 40
        - shape: TRIANGLE
        - size: 20
    """
    def __init__(self, exprs, savelist=True):
        super(Each, self).__init__(exprs, savelist)
        self.mayReturnEmpty = all(e.mayReturnEmpty for e in self.exprs)
        self.skipWhitespace = True
        self.initExprGroups = True
        self.saveAsList = True

    def streamline(self):
        super(Each, self).streamline()
        self.mayReturnEmpty = all(e.mayReturnEmpty for e in self.exprs)
        return self

    def parseImpl(self, instring, loc, doActions=True):
        if self.initExprGroups:
            self.opt1map = dict((id(e.expr), e) for e in self.exprs if isinstance(e, Optional))
            opt1 = [e.expr for e in self.exprs if isinstance(e, Optional)]
            opt2 = [e for e in self.exprs if e.mayReturnEmpty and not isinstance(e, Optional)]
            self.optionals = opt1 + opt2
            self.multioptionals = [e.expr for e in self.exprs if isinstance(e, ZeroOrMore)]
            self.multirequired = [e.expr for e in self.exprs if isinstance(e, OneOrMore)]
            self.required = [e for e in self.exprs if not isinstance(e, (Optional, ZeroOrMore, OneOrMore))]
            self.required += self.multirequired
            self.initExprGroups = False
        tmpLoc = loc
        tmpReqd = self.required[:]
        tmpOpt  = self.optionals[:]
        matchOrder = []

        keepMatching = True
        while keepMatching:
            tmpExprs = tmpReqd + tmpOpt + self.multioptionals + self.multirequired
            failed = []
            for e in tmpExprs:
                try:
                    tmpLoc = e.tryParse(instring, tmpLoc)
                except ParseException:
                    failed.append(e)
                else:
                    matchOrder.append(self.opt1map.get(id(e), e))
                    if e in tmpReqd:
                        tmpReqd.remove(e)
                    elif e in tmpOpt:
                        tmpOpt.remove(e)
            if len(failed) == len(tmpExprs):
                keepMatching = False

        if tmpReqd:
            missing = ", ".join(_ustr(e) for e in tmpReqd)
            raise ParseException(instring, loc, "Missing one or more required elements (%s)" % missing)

        # add any unmatched Optionals, in case they have default values defined
        matchOrder += [e for e in self.exprs if isinstance(e, Optional) and e.expr in tmpOpt]

        resultlist = []
        for e in matchOrder:
            loc, results = e._parse(instring, loc, doActions)
            resultlist.append(results)

        finalResults = sum(resultlist, ParseResults([]))
        return loc, finalResults

    def __str__(self):
        if hasattr(self, "name"):
            return self.name

        if self.strRepr is None:
            self.strRepr = "{" + " & ".join(_ustr(e) for e in self.exprs) + "}"

        return self.strRepr

    def checkRecursion(self, parseElementList):
        subRecCheckList = parseElementList[:] + [self]
        for e in self.exprs:
            e.checkRecursion(subRecCheckList)


class ParseElementEnhance(ParserElement):
    """Abstract subclass of :class:`ParserElement`, for combining and
    post-processing parsed tokens.
    """
    def __init__(self, expr, savelist=False):
        super(ParseElementEnhance, self).__init__(savelist)
        if isinstance(expr, basestring):
            if issubclass(self._literalStringClass, Token):
                expr = self._literalStringClass(expr)
            else:
                expr = self._literalStringClass(Literal(expr))
        self.expr = expr
        self.strRepr = None
        if expr is not None:
            self.mayIndexError = expr.mayIndexError
            self.mayReturnEmpty = expr.mayReturnEmpty
            self.setWhitespaceChars(expr.whiteChars)
            self.skipWhitespace = expr.skipWhitespace
            self.saveAsList = expr.saveAsList
            self.callPreparse = expr.callPreparse
            self.ignoreExprs.extend(expr.ignoreExprs)

    def parseImpl(self, instring, loc, doActions=True):
        if self.expr is not None:
            return self.expr._parse(instring, loc, doActions, callPreParse=False)
        else:
            raise ParseException("", loc, self.errmsg, self)

    def leaveWhitespace(self):
        self.skipWhitespace = False
        self.expr = self.expr.copy()
        if self.expr is not None:
            self.expr.leaveWhitespace()
        return self

    def ignore(self, other):
        if isinstance(other, Suppress):
            if other not in self.ignoreExprs:
                super(ParseElementEnhance, self).ignore(other)
                if self.expr is not None:
                    self.expr.ignore(self.ignoreExprs[-1])
        else:
            super(ParseElementEnhance, self).ignore(other)
            if self.expr is not None:
                self.expr.ignore(self.ignoreExprs[-1])
        return self

    def streamline(self):
        super(ParseElementEnhance, self).streamline()
        if self.expr is not None:
            self.expr.streamline()
        return self

    def checkRecursion(self, parseElementList):
        if self in parseElementList:
            raise RecursiveGrammarException(parseElementList + [self])
        subRecCheckList = parseElementList[:] + [self]
        if self.expr is not None:
            self.expr.checkRecursion(subRecCheckList)

    def validate(self, validateTrace=None):
        if validateTrace is None:
            validateTrace = []
        tmp = validateTrace[:] + [self]
        if self.expr is not None:
            self.expr.validate(tmp)
        self.checkRecursion([])

    def __str__(self):
        try:
            return super(ParseElementEnhance, self).__str__()
        except Exception:
            pass

        if self.strRepr is None and self.expr is not None:
            self.strRepr = "%s:(%s)" % (self.__class__.__name__, _ustr(self.expr))
        return self.strRepr


class FollowedBy(ParseElementEnhance):
    """Lookahead matching of the given parse expression.
    ``FollowedBy`` does *not* advance the parsing position within
    the input string, it only verifies that the specified parse
    expression matches at the current position.  ``FollowedBy``
    always returns a null token list. If any results names are defined
    in the lookahead expression, those *will* be returned for access by
    name.

    Example::

        # use FollowedBy to match a label only if it is followed by a ':'
        data_word = Word(alphas)
        label = data_word + FollowedBy(':')
        attr_expr = Group(label + Suppress(':') + OneOrMore(data_word, stopOn=label).setParseAction(' '.join))

        OneOrMore(attr_expr).parseString("shape: SQUARE color: BLACK posn: upper left").pprint()

    prints::

        [['shape', 'SQUARE'], ['color', 'BLACK'], ['posn', 'upper left']]
    """
    def __init__(self, expr):
        super(FollowedBy, self).__init__(expr)
        self.mayReturnEmpty = True

    def parseImpl(self, instring, loc, doActions=True):
        # by using self._expr.parse and deleting the contents of the returned ParseResults list
        # we keep any named results that were defined in the FollowedBy expression
        _, ret = self.expr._parse(instring, loc, doActions=doActions)
        del ret[:]

        return loc, ret


class PrecededBy(ParseElementEnhance):
    """Lookbehind matching of the given parse expression.
    ``PrecededBy`` does not advance the parsing position within the
    input string, it only verifies that the specified parse expression
    matches prior to the current position.  ``PrecededBy`` always
    returns a null token list, but if a results name is defined on the
    given expression, it is returned.

    Parameters:

     - expr - expression that must match prior to the current parse
       location
     - retreat - (default= ``None``) - (int) maximum number of characters
       to lookbehind prior to the current parse location

    If the lookbehind expression is a string, Literal, Keyword, or
    a Word or CharsNotIn with a specified exact or maximum length, then
    the retreat parameter is not required. Otherwise, retreat must be
    specified to give a maximum number of characters to look back from
    the current parse position for a lookbehind match.

    Example::

        # VB-style variable names with type prefixes
        int_var = PrecededBy("#") + pyparsing_common.identifier
        str_var = PrecededBy("$") + pyparsing_common.identifier

    """
    def __init__(self, expr, retreat=None):
        super(PrecededBy, self).__init__(expr)
        self.expr = self.expr().leaveWhitespace()
        self.mayReturnEmpty = True
        self.mayIndexError = False
        self.exact = False
        if isinstance(expr, str):
            retreat = len(expr)
            self.exact = True
        elif isinstance(expr, (Literal, Keyword)):
            retreat = expr.matchLen
            self.exact = True
        elif isinstance(expr, (Word, CharsNotIn)) and expr.maxLen != _MAX_INT:
            retreat = expr.maxLen
            self.exact = True
        elif isinstance(expr, _PositionToken):
            retreat = 0
            self.exact = True
        self.retreat = retreat
        self.errmsg = "not preceded by " + str(expr)
        self.skipWhitespace = False

    def parseImpl(self, instring, loc=0, doActions=True):
        if self.exact:
            if loc < self.retreat:
                raise ParseException(instring, loc, self.errmsg)
            start = loc - self.retreat
            _, ret = self.expr._parse(instring, start)
        else:
            # retreat specified a maximum lookbehind window, iterate
            test_expr = self.expr + StringEnd()
            instring_slice = instring[:loc]
            last_expr = ParseException(instring, loc, self.errmsg)
            for offset in range(1, min(loc, self.retreat + 1)):
                try:
                    _, ret = test_expr._parse(instring_slice, loc - offset)
                except ParseBaseException as pbe:
                    last_expr = pbe
                else:
                    break
            else:
                raise last_expr
        # return empty list of tokens, but preserve any defined results names
        del ret[:]
        return loc, ret


class NotAny(ParseElementEnhance):
    """Lookahead to disallow matching with the given parse expression.
    ``NotAny`` does *not* advance the parsing position within the
    input string, it only verifies that the specified parse expression
    does *not* match at the current position.  Also, ``NotAny`` does
    *not* skip over leading whitespace. ``NotAny`` always returns
    a null token list.  May be constructed using the '~' operator.

    Example::

        AND, OR, NOT = map(CaselessKeyword, "AND OR NOT".split())

        # take care not to mistake keywords for identifiers
        ident = ~(AND | OR | NOT) + Word(alphas)
        boolean_term = Optional(NOT) + ident

        # very crude boolean expression - to support parenthesis groups and
        # operation hierarchy, use infixNotation
        boolean_expr = boolean_term + ZeroOrMore((AND | OR) + boolean_term)

        # integers that are followed by "." are actually floats
        integer = Word(nums) + ~Char(".")
    """
    def __init__(self, expr):
        super(NotAny, self).__init__(expr)
        # ~ self.leaveWhitespace()
        self.skipWhitespace = False  # do NOT use self.leaveWhitespace(), don't want to propagate to exprs
        self.mayReturnEmpty = True
        self.errmsg = "Found unwanted token, " + _ustr(self.expr)

    def parseImpl(self, instring, loc, doActions=True):
        if self.expr.canParseNext(instring, loc):
            raise ParseException(instring, loc, self.errmsg, self)
        return loc, []

    def __str__(self):
        if hasattr(self, "name"):
            return self.name

        if self.strRepr is None:
            self.strRepr = "~{" + _ustr(self.expr) + "}"

        return self.strRepr

class _MultipleMatch(ParseElementEnhance):
    def __init__(self, expr, stopOn=None):
        super(_MultipleMatch, self).__init__(expr)
        self.saveAsList = True
        ender = stopOn
        if isinstance(ender, basestring):
            ender = self._literalStringClass(ender)
        self.stopOn(ender)

    def stopOn(self, ender):
        if isinstance(ender, basestring):
            ender = self._literalStringClass(ender)
        self.not_ender = ~ender if ender is not None else None
        return self

    def parseImpl(self, instring, loc, doActions=True):
        self_expr_parse = self.expr._parse
        self_skip_ignorables = self._skipIgnorables
        check_ender = self.not_ender is not None
        if check_ender:
            try_not_ender = self.not_ender.tryParse

        # must be at least one (but first see if we are the stopOn sentinel;
        # if so, fail)
        if check_ender:
            try_not_ender(instring, loc)
        loc, tokens = self_expr_parse(instring, loc, doActions, callPreParse=False)
        try:
            hasIgnoreExprs = (not not self.ignoreExprs)
            while 1:
                if check_ender:
                    try_not_ender(instring, loc)
                if hasIgnoreExprs:
                    preloc = self_skip_ignorables(instring, loc)
                else:
                    preloc = loc
                loc, tmptokens = self_expr_parse(instring, preloc, doActions)
                if tmptokens or tmptokens.haskeys():
                    tokens += tmptokens
        except (ParseException, IndexError):
            pass

        return loc, tokens

    def _setResultsName(self, name, listAllMatches=False):
        if __diag__.warn_ungrouped_named_tokens_in_collection:
            for e in [self.expr] + getattr(self.expr, 'exprs', []):
                if isinstance(e, ParserElement) and e.resultsName:
                    warnings.warn("{0}: setting results name {1!r} on {2} expression "
                                  "collides with {3!r} on contained expression".format("warn_ungrouped_named_tokens_in_collection",
                                                                                       name,
                                                                                       type(self).__name__,
                                                                                       e.resultsName),
                                  stacklevel=3)

        return super(_MultipleMatch, self)._setResultsName(name, listAllMatches)


class OneOrMore(_MultipleMatch):
    """Repetition of one or more of the given expression.

    Parameters:
     - expr - expression that must match one or more times
     - stopOn - (default= ``None``) - expression for a terminating sentinel
          (only required if the sentinel would ordinarily match the repetition
          expression)

    Example::

        data_word = Word(alphas)
        label = data_word + FollowedBy(':')
        attr_expr = Group(label + Suppress(':') + OneOrMore(data_word).setParseAction(' '.join))

        text = "shape: SQUARE posn: upper left color: BLACK"
        OneOrMore(attr_expr).parseString(text).pprint()  # Fail! read 'color' as data instead of next label -> [['shape', 'SQUARE color']]

        # use stopOn attribute for OneOrMore to avoid reading label string as part of the data
        attr_expr = Group(label + Suppress(':') + OneOrMore(data_word, stopOn=label).setParseAction(' '.join))
        OneOrMore(attr_expr).parseString(text).pprint() # Better -> [['shape', 'SQUARE'], ['posn', 'upper left'], ['color', 'BLACK']]

        # could also be written as
        (attr_expr * (1,)).parseString(text).pprint()
    """

    def __str__(self):
        if hasattr(self, "name"):
            return self.name

        if self.strRepr is None:
            self.strRepr = "{" + _ustr(self.expr) + "}..."

        return self.strRepr

class ZeroOrMore(_MultipleMatch):
    """Optional repetition of zero or more of the given expression.

    Parameters:
     - expr - expression that must match zero or more times
     - stopOn - (default= ``None``) - expression for a terminating sentinel
          (only required if the sentinel would ordinarily match the repetition
          expression)

    Example: similar to :class:`OneOrMore`
    """
    def __init__(self, expr, stopOn=None):
        super(ZeroOrMore, self).__init__(expr, stopOn=stopOn)
        self.mayReturnEmpty = True

    def parseImpl(self, instring, loc, doActions=True):
        try:
            return super(ZeroOrMore, self).parseImpl(instring, loc, doActions)
        except (ParseException, IndexError):
            return loc, []

    def __str__(self):
        if hasattr(self, "name"):
            return self.name

        if self.strRepr is None:
            self.strRepr = "[" + _ustr(self.expr) + "]..."

        return self.strRepr


class _NullToken(object):
    def __bool__(self):
        return False
    __nonzero__ = __bool__
    def __str__(self):
        return ""

class Optional(ParseElementEnhance):
    """Optional matching of the given expression.

    Parameters:
     - expr - expression that must match zero or more times
     - default (optional) - value to be returned if the optional expression is not found.

    Example::

        # US postal code can be a 5-digit zip, plus optional 4-digit qualifier
        zip = Combine(Word(nums, exact=5) + Optional('-' + Word(nums, exact=4)))
        zip.runTests('''
            # traditional ZIP code
            12345

            # ZIP+4 form
            12101-0001

            # invalid ZIP
            98765-
            ''')

    prints::

        # traditional ZIP code
        12345
        ['12345']

        # ZIP+4 form
        12101-0001
        ['12101-0001']

        # invalid ZIP
        98765-
             ^
        FAIL: Expected end of text (at char 5), (line:1, col:6)
    """
    __optionalNotMatched = _NullToken()

    def __init__(self, expr, default=__optionalNotMatched):
        super(Optional, self).__init__(expr, savelist=False)
        self.saveAsList = self.expr.saveAsList
        self.defaultValue = default
        self.mayReturnEmpty = True

    def parseImpl(self, instring, loc, doActions=True):
        try:
            loc, tokens = self.expr._parse(instring, loc, doActions, callPreParse=False)
        except (ParseException, IndexError):
            if self.defaultValue is not self.__optionalNotMatched:
                if self.expr.resultsName:
                    tokens = ParseResults([self.defaultValue])
                    tokens[self.expr.resultsName] = self.defaultValue
                else:
                    tokens = [self.defaultValue]
            else:
                tokens = []
        return loc, tokens

    def __str__(self):
        if hasattr(self, "name"):
            return self.name

        if self.strRepr is None:
            self.strRepr = "[" + _ustr(self.expr) + "]"

        return self.strRepr

class SkipTo(ParseElementEnhance):
    """Token for skipping over all undefined text until the matched
    expression is found.

    Parameters:
     - expr - target expression marking the end of the data to be skipped
     - include - (default= ``False``) if True, the target expression is also parsed
          (the skipped text and target expression are returned as a 2-element list).
     - ignore - (default= ``None``) used to define grammars (typically quoted strings and
          comments) that might contain false matches to the target expression
     - failOn - (default= ``None``) define expressions that are not allowed to be
          included in the skipped test; if found before the target expression is found,
          the SkipTo is not a match

    Example::

        report = '''
            Outstanding Issues Report - 1 Jan 2000

               # | Severity | Description                               |  Days Open
            -----+----------+-------------------------------------------+-----------
             101 | Critical | Intermittent system crash                 |          6
              94 | Cosmetic | Spelling error on Login ('log|n')         |         14
              79 | Minor    | System slow when running too many reports |         47
            '''
        integer = Word(nums)
        SEP = Suppress('|')
        # use SkipTo to simply match everything up until the next SEP
        # - ignore quoted strings, so that a '|' character inside a quoted string does not match
        # - parse action will call token.strip() for each matched token, i.e., the description body
        string_data = SkipTo(SEP, ignore=quotedString)
        string_data.setParseAction(tokenMap(str.strip))
        ticket_expr = (integer("issue_num") + SEP
                      + string_data("sev") + SEP
                      + string_data("desc") + SEP
                      + integer("days_open"))

        for tkt in ticket_expr.searchString(report):
            print tkt.dump()

    prints::

        ['101', 'Critical', 'Intermittent system crash', '6']
        - days_open: 6
        - desc: Intermittent system crash
        - issue_num: 101
        - sev: Critical
        ['94', 'Cosmetic', "Spelling error on Login ('log|n')", '14']
        - days_open: 14
        - desc: Spelling error on Login ('log|n')
        - issue_num: 94
        - sev: Cosmetic
        ['79', 'Minor', 'System slow when running too many reports', '47']
        - days_open: 47
        - desc: System slow when running too many reports
        - issue_num: 79
        - sev: Minor
    """
    def __init__(self, other, include=False, ignore=None, failOn=None):
        super(SkipTo, self).__init__(other)
        self.ignoreExpr = ignore
        self.mayReturnEmpty = True
        self.mayIndexError = False
        self.includeMatch = include
        self.saveAsList = False
        if isinstance(failOn, basestring):
            self.failOn = self._literalStringClass(failOn)
        else:
            self.failOn = failOn
        self.errmsg = "No match found for " + _ustr(self.expr)

    def parseImpl(self, instring, loc, doActions=True):
        startloc = loc
        instrlen = len(instring)
        expr = self.expr
        expr_parse = self.expr._parse
        self_failOn_canParseNext = self.failOn.canParseNext if self.failOn is not None else None
        self_ignoreExpr_tryParse = self.ignoreExpr.tryParse if self.ignoreExpr is not None else None

        tmploc = loc
        while tmploc <= instrlen:
            if self_failOn_canParseNext is not None:
                # break if failOn expression matches
                if self_failOn_canParseNext(instring, tmploc):
                    break

            if self_ignoreExpr_tryParse is not None:
                # advance past ignore expressions
                while 1:
                    try:
                        tmploc = self_ignoreExpr_tryParse(instring, tmploc)
                    except ParseBaseException:
                        break

            try:
                expr_parse(instring, tmploc, doActions=False, callPreParse=False)
            except (ParseException, IndexError):
                # no match, advance loc in string
                tmploc += 1
            else:
                # matched skipto expr, done
                break

        else:
            # ran off the end of the input string without matching skipto expr, fail
            raise ParseException(instring, loc, self.errmsg, self)

        # build up return values
        loc = tmploc
        skiptext = instring[startloc:loc]
        skipresult = ParseResults(skiptext)

        if self.includeMatch:
            loc, mat = expr_parse(instring, loc, doActions, callPreParse=False)
            skipresult += mat

        return loc, skipresult

class Forward(ParseElementEnhance):
    """Forward declaration of an expression to be defined later -
    used for recursive grammars, such as algebraic infix notation.
    When the expression is known, it is assigned to the ``Forward``
    variable using the '<<' operator.

    Note: take care when assigning to ``Forward`` not to overlook
    precedence of operators.

    Specifically, '|' has a lower precedence than '<<', so that::

        fwdExpr << a | b | c

    will actually be evaluated as::

        (fwdExpr << a) | b | c

    thereby leaving b and c out as parseable alternatives.  It is recommended that you
    explicitly group the values inserted into the ``Forward``::

        fwdExpr << (a | b | c)

    Converting to use the '<<=' operator instead will avoid this problem.

    See :class:`ParseResults.pprint` for an example of a recursive
    parser created using ``Forward``.
    """
    def __init__(self, other=None):
        super(Forward, self).__init__(other, savelist=False)

    def __lshift__(self, other):
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        self.expr = other
        self.strRepr = None
        self.mayIndexError = self.expr.mayIndexError
        self.mayReturnEmpty = self.expr.mayReturnEmpty
        self.setWhitespaceChars(self.expr.whiteChars)
        self.skipWhitespace = self.expr.skipWhitespace
        self.saveAsList = self.expr.saveAsList
        self.ignoreExprs.extend(self.expr.ignoreExprs)
        return self

    def __ilshift__(self, other):
        return self << other

    def leaveWhitespace(self):
        self.skipWhitespace = False
        return self

    def streamline(self):
        if not self.streamlined:
            self.streamlined = True
            if self.expr is not None:
                self.expr.streamline()
        return self

    def validate(self, validateTrace=None):
        if validateTrace is None:
            validateTrace = []

        if self not in validateTrace:
            tmp = validateTrace[:] + [self]
            if self.expr is not None:
                self.expr.validate(tmp)
        self.checkRecursion([])

    def __str__(self):
        if hasattr(self, "name"):
            return self.name
        if self.strRepr is not None:
            return self.strRepr

        # Avoid infinite recursion by setting a temporary strRepr
        self.strRepr = ": ..."

        # Use the string representation of main expression.
        retString = '...'
        try:
            if self.expr is not None:
                retString = _ustr(self.expr)[:1000]
            else:
                retString = "None"
        finally:
            self.strRepr = self.__class__.__name__ + ": " + retString
        return self.strRepr

    def copy(self):
        if self.expr is not None:
            return super(Forward, self).copy()
        else:
            ret = Forward()
            ret <<= self
            return ret

    def _setResultsName(self, name, listAllMatches=False):
        if __diag__.warn_name_set_on_empty_Forward:
            if self.expr is None:
                warnings.warn("{0}: setting results name {0!r} on {1} expression "
                              "that has no contained expression".format("warn_name_set_on_empty_Forward",
                                                                        name,
                                                                        type(self).__name__),
                              stacklevel=3)

        return super(Forward, self)._setResultsName(name, listAllMatches)

class TokenConverter(ParseElementEnhance):
    """
    Abstract subclass of :class:`ParseExpression`, for converting parsed results.
    """
    def __init__(self, expr, savelist=False):
        super(TokenConverter, self).__init__(expr)  # , savelist)
        self.saveAsList = False

class Combine(TokenConverter):
    """Converter to concatenate all matching tokens to a single string.
    By default, the matching patterns must also be contiguous in the
    input string; this can be disabled by specifying
    ``'adjacent=False'`` in the constructor.

    Example::

        real = Word(nums) + '.' + Word(nums)
        print(real.parseString('3.1416')) # -> ['3', '.', '1416']
        # will also erroneously match the following
        print(real.parseString('3. 1416')) # -> ['3', '.', '1416']

        real = Combine(Word(nums) + '.' + Word(nums))
        print(real.parseString('3.1416')) # -> ['3.1416']
        # no match when there are internal spaces
        print(real.parseString('3. 1416')) # -> Exception: Expected W:(0123...)
    """
    def __init__(self, expr, joinString="", adjacent=True):
        super(Combine, self).__init__(expr)
        # suppress whitespace-stripping in contained parse expressions, but re-enable it on the Combine itself
        if adjacent:
            self.leaveWhitespace()
        self.adjacent = adjacent
        self.skipWhitespace = True
        self.joinString = joinString
        self.callPreparse = True

    def ignore(self, other):
        if self.adjacent:
            ParserElement.ignore(self, other)
        else:
            super(Combine, self).ignore(other)
        return self

    def postParse(self, instring, loc, tokenlist):
        retToks = tokenlist.copy()
        del retToks[:]
        retToks += ParseResults(["".join(tokenlist._asStringList(self.joinString))], modal=self.modalResults)

        if self.resultsName and retToks.haskeys():
            return [retToks]
        else:
            return retToks

class Group(TokenConverter):
    """Converter to return the matched tokens as a list - useful for
    returning tokens of :class:`ZeroOrMore` and :class:`OneOrMore` expressions.

    Example::

        ident = Word(alphas)
        num = Word(nums)
        term = ident | num
        func = ident + Optional(delimitedList(term))
        print(func.parseString("fn a, b, 100"))  # -> ['fn', 'a', 'b', '100']

        func = ident + Group(Optional(delimitedList(term)))
        print(func.parseString("fn a, b, 100"))  # -> ['fn', ['a', 'b', '100']]
    """
    def __init__(self, expr):
        super(Group, self).__init__(expr)
        self.saveAsList = True

    def postParse(self, instring, loc, tokenlist):
        return [tokenlist]

class Dict(TokenConverter):
    """Converter to return a repetitive expression as a list, but also
    as a dictionary. Each element can also be referenced using the first
    token in the expression as its key. Useful for tabular report
    scraping when the first column can be used as a item key.

    Example::

        data_word = Word(alphas)
        label = data_word + FollowedBy(':')
        attr_expr = Group(label + Suppress(':') + OneOrMore(data_word).setParseAction(' '.join))

        text = "shape: SQUARE posn: upper left color: light blue texture: burlap"
        attr_expr = (label + Suppress(':') + OneOrMore(data_word, stopOn=label).setParseAction(' '.join))

        # print attributes as plain groups
        print(OneOrMore(attr_expr).parseString(text).dump())

        # instead of OneOrMore(expr), parse using Dict(OneOrMore(Group(expr))) - Dict will auto-assign names
        result = Dict(OneOrMore(Group(attr_expr))).parseString(text)
        print(result.dump())

        # access named fields as dict entries, or output as dict
        print(result['shape'])
        print(result.asDict())

    prints::

        ['shape', 'SQUARE', 'posn', 'upper left', 'color', 'light blue', 'texture', 'burlap']
        [['shape', 'SQUARE'], ['posn', 'upper left'], ['color', 'light blue'], ['texture', 'burlap']]
        - color: light blue
        - posn: upper left
        - shape: SQUARE
        - texture: burlap
        SQUARE
        {'color': 'light blue', 'posn': 'upper left', 'texture': 'burlap', 'shape': 'SQUARE'}

    See more examples at :class:`ParseResults` of accessing fields by results name.
    """
    def __init__(self, expr):
        super(Dict, self).__init__(expr)
        self.saveAsList = True

    def postParse(self, instring, loc, tokenlist):
        for i, tok in enumerate(tokenlist):
            if len(tok) == 0:
                continue
            ikey = tok[0]
            if isinstance(ikey, int):
                ikey = _ustr(tok[0]).strip()
            if len(tok) == 1:
                tokenlist[ikey] = _ParseResultsWithOffset("", i)
            elif len(tok) == 2 and not isinstance(tok[1], ParseResults):
                tokenlist[ikey] = _ParseResultsWithOffset(tok[1], i)
            else:
                dictvalue = tok.copy()  # ParseResults(i)
                del dictvalue[0]
                if len(dictvalue) != 1 or (isinstance(dictvalue, ParseResults) and dictvalue.haskeys()):
                    tokenlist[ikey] = _ParseResultsWithOffset(dictvalue, i)
                else:
                    tokenlist[ikey] = _ParseResultsWithOffset(dictvalue[0], i)

        if self.resultsName:
            return [tokenlist]
        else:
            return tokenlist


class Suppress(TokenConverter):
    """Converter for ignoring the results of a parsed expression.

    Example::

        source = "a, b, c,d"
        wd = Word(alphas)
        wd_list1 = wd + ZeroOrMore(',' + wd)
        print(wd_list1.parseString(source))

        # often, delimiters that are useful during parsing are just in the
        # way afterward - use Suppress to keep them out of the parsed output
        wd_list2 = wd + ZeroOrMore(Suppress(',') + wd)
        print(wd_list2.parseString(source))

    prints::

        ['a', ',', 'b', ',', 'c', ',', 'd']
        ['a', 'b', 'c', 'd']

    (See also :class:`delimitedList`.)
    """
    def postParse(self, instring, loc, tokenlist):
        return []

    def suppress(self):
        return self


class OnlyOnce(object):
    """Wrapper for parse actions, to ensure they are only called once.
    """
    def __init__(self, methodCall):
        self.callable = _trim_arity(methodCall)
        self.called = False
    def __call__(self, s, l, t):
        if not self.called:
            results = self.callable(s, l, t)
            self.called = True
            return results
        raise ParseException(s, l, "")
    def reset(self):
        self.called = False

def traceParseAction(f):
    """Decorator for debugging parse actions.

    When the parse action is called, this decorator will print
    ``">> entering method-name(line:<current_source_line>, <parse_location>, <matched_tokens>)"``.
    When the parse action completes, the decorator will print
    ``"<<"`` followed by the returned value, or any exception that the parse action raised.

    Example::

        wd = Word(alphas)

        @traceParseAction
        def remove_duplicate_chars(tokens):
            return ''.join(sorted(set(''.join(tokens))))

        wds = OneOrMore(wd).setParseAction(remove_duplicate_chars)
        print(wds.parseString("slkdjs sld sldd sdlf sdljf"))

    prints::

        >>entering remove_duplicate_chars(line: 'slkdjs sld sldd sdlf sdljf', 0, (['slkdjs', 'sld', 'sldd', 'sdlf', 'sdljf'], {}))
        <<leaving remove_duplicate_chars (ret: 'dfjkls')
        ['dfjkls']
    """
    f = _trim_arity(f)
    def z(*paArgs):
        thisFunc = f.__name__
        s, l, t = paArgs[-3:]
        if len(paArgs) > 3:
            thisFunc = paArgs[0].__class__.__name__ + '.' + thisFunc
        sys.stderr.write(">>entering %s(line: '%s', %d, %r)\n" % (thisFunc, line(l, s), l, t))
        try:
            ret = f(*paArgs)
        except Exception as exc:
            sys.stderr.write("<<leaving %s (exception: %s)\n" % (thisFunc, exc))
            raise
        sys.stderr.write("<<leaving %s (ret: %r)\n" % (thisFunc, ret))
        return ret
    try:
        z.__name__ = f.__name__
    except AttributeError:
        pass
    return z

#
# global helpers
#
def delimitedList(expr, delim=",", combine=False):
    """Helper to define a delimited list of expressions - the delimiter
    defaults to ','. By default, the list elements and delimiters can
    have intervening whitespace, and comments, but this can be
    overridden by passing ``combine=True`` in the constructor. If
    ``combine`` is set to ``True``, the matching tokens are
    returned as a single token string, with the delimiters included;
    otherwise, the matching tokens are returned as a list of tokens,
    with the delimiters suppressed.

    Example::

        delimitedList(Word(alphas)).parseString("aa,bb,cc") # -> ['aa', 'bb', 'cc']
        delimitedList(Word(hexnums), delim=':', combine=True).parseString("AA:BB:CC:DD:EE") # -> ['AA:BB:CC:DD:EE']
    """
    dlName = _ustr(expr) + " [" + _ustr(delim) + " " + _ustr(expr) + "]..."
    if combine:
        return Combine(expr + ZeroOrMore(delim + expr)).setName(dlName)
    else:
        return (expr + ZeroOrMore(Suppress(delim) + expr)).setName(dlName)

def countedArray(expr, intExpr=None):
    """Helper to define a counted list of expressions.

    This helper defines a pattern of the form::

        integer expr expr expr...

    where the leading integer tells how many expr expressions follow.
    The matched tokens returns the array of expr tokens as a list - the
    leading count token is suppressed.

    If ``intExpr`` is specified, it should be a pyparsing expression
    that produces an integer value.

    Example::

        countedArray(Word(alphas)).parseString('2 ab cd ef')  # -> ['ab', 'cd']

        # in this parser, the leading integer value is given in binary,
        # '10' indicating that 2 values are in the array
        binaryConstant = Word('01').setParseAction(lambda t: int(t[0], 2))
        countedArray(Word(alphas), intExpr=binaryConstant).parseString('10 ab cd ef')  # -> ['ab', 'cd']
    """
    arrayExpr = Forward()
    def countFieldParseAction(s, l, t):
        n = t[0]
        arrayExpr << (n and Group(And([expr] * n)) or Group(empty))
        return []
    if intExpr is None:
        intExpr = Word(nums).setParseAction(lambda t: int(t[0]))
    else:
        intExpr = intExpr.copy()
    intExpr.setName("arrayLen")
    intExpr.addParseAction(countFieldParseAction, callDuringTry=True)
    return (intExpr + arrayExpr).setName('(len) ' + _ustr(expr) + '...')

def _flatten(L):
    ret = []
    for i in L:
        if isinstance(i, list):
            ret.extend(_flatten(i))
        else:
            ret.append(i)
    return ret

def matchPreviousLiteral(expr):
    """Helper to define an expression that is indirectly defined from
    the tokens matched in a previous expression, that is, it looks for
    a 'repeat' of a previous expression.  For example::

        first = Word(nums)
        second = matchPreviousLiteral(first)
        matchExpr = first + ":" + second

    will match ``"1:1"``, but not ``"1:2"``.  Because this
    matches a previous literal, will also match the leading
    ``"1:1"`` in ``"1:10"``. If this is not desired, use
    :class:`matchPreviousExpr`. Do *not* use with packrat parsing
    enabled.
    """
    rep = Forward()
    def copyTokenToRepeater(s, l, t):
        if t:
            if len(t) == 1:
                rep << t[0]
            else:
                # flatten t tokens
                tflat = _flatten(t.asList())
                rep << And(Literal(tt) for tt in tflat)
        else:
            rep << Empty()
    expr.addParseAction(copyTokenToRepeater, callDuringTry=True)
    rep.setName('(prev) ' + _ustr(expr))
    return rep

def matchPreviousExpr(expr):
    """Helper to define an expression that is indirectly defined from
    the tokens matched in a previous expression, that is, it looks for
    a 'repeat' of a previous expression.  For example::

        first = Word(nums)
        second = matchPreviousExpr(first)
        matchExpr = first + ":" + second

    will match ``"1:1"``, but not ``"1:2"``.  Because this
    matches by expressions, will *not* match the leading ``"1:1"``
    in ``"1:10"``; the expressions are evaluated first, and then
    compared, so ``"1"`` is compared with ``"10"``. Do *not* use
    with packrat parsing enabled.
    """
    rep = Forward()
    e2 = expr.copy()
    rep <<= e2
    def copyTokenToRepeater(s, l, t):
        matchTokens = _flatten(t.asList())
        def mustMatchTheseTokens(s, l, t):
            theseTokens = _flatten(t.asList())
            if theseTokens != matchTokens:
                raise ParseException('', 0, '')
        rep.setParseAction(mustMatchTheseTokens, callDuringTry=True)
    expr.addParseAction(copyTokenToRepeater, callDuringTry=True)
    rep.setName('(prev) ' + _ustr(expr))
    return rep

def _escapeRegexRangeChars(s):
    # ~  escape these chars: ^-]
    for c in r"\^-]":
        s = s.replace(c, _bslash + c)
    s = s.replace("\n", r"\n")
    s = s.replace("\t", r"\t")
    return _ustr(s)

def oneOf(strs, caseless=False, useRegex=True, asKeyword=False):
    """Helper to quickly define a set of alternative Literals, and makes
    sure to do longest-first testing when there is a conflict,
    regardless of the input order, but returns
    a :class:`MatchFirst` for best performance.

    Parameters:

     - strs - a string of space-delimited literals, or a collection of
       string literals
     - caseless - (default= ``False``) - treat all literals as
       caseless
     - useRegex - (default= ``True``) - as an optimization, will
       generate a Regex object; otherwise, will generate
       a :class:`MatchFirst` object (if ``caseless=True`` or ``asKeyword=True``, or if
       creating a :class:`Regex` raises an exception)
     - asKeyword - (default=``False``) - enforce Keyword-style matching on the
       generated expressions

    Example::

        comp_oper = oneOf("< = > <= >= !=")
        var = Word(alphas)
        number = Word(nums)
        term = var | number
        comparison_expr = term + comp_oper + term
        print(comparison_expr.searchString("B = 12  AA=23 B<=AA AA>12"))

    prints::

        [['B', '=', '12'], ['AA', '=', '23'], ['B', '<=', 'AA'], ['AA', '>', '12']]
    """
    if isinstance(caseless, basestring):
        warnings.warn("More than one string argument passed to oneOf, pass "
                      "choices as a list or space-delimited string", stacklevel=2)

    if caseless:
        isequal = (lambda a, b: a.upper() == b.upper())
        masks = (lambda a, b: b.upper().startswith(a.upper()))
        parseElementClass = CaselessKeyword if asKeyword else CaselessLiteral
    else:
        isequal = (lambda a, b: a == b)
        masks = (lambda a, b: b.startswith(a))
        parseElementClass = Keyword if asKeyword else Literal

    symbols = []
    if isinstance(strs, basestring):
        symbols = strs.split()
    elif isinstance(strs, Iterable):
        symbols = list(strs)
    else:
        warnings.warn("Invalid argument to oneOf, expected string or iterable",
                      SyntaxWarning, stacklevel=2)
    if not symbols:
        return NoMatch()

    if not asKeyword:
        # if not producing keywords, need to reorder to take care to avoid masking
        # longer choices with shorter ones
        i = 0
        while i < len(symbols) - 1:
            cur = symbols[i]
            for j, other in enumerate(symbols[i + 1:]):
                if isequal(other, cur):
                    del symbols[i + j + 1]
                    break
                elif masks(cur, other):
                    del symbols[i + j + 1]
                    symbols.insert(i, other)
                    break
            else:
                i += 1

    if not (caseless or asKeyword) and useRegex:
        # ~ print (strs, "->", "|".join([_escapeRegexChars(sym) for sym in symbols]))
        try:
            if len(symbols) == len("".join(symbols)):
                return Regex("[%s]" % "".join(_escapeRegexRangeChars(sym) for sym in symbols)).setName(' | '.join(symbols))
            else:
                return Regex("|".join(re.escape(sym) for sym in symbols)).setName(' | '.join(symbols))
        except Exception:
            warnings.warn("Exception creating Regex for oneOf, building MatchFirst",
                    SyntaxWarning, stacklevel=2)

    # last resort, just use MatchFirst
    return MatchFirst(parseElementClass(sym) for sym in symbols).setName(' | '.join(symbols))

def dictOf(key, value):
    """Helper to easily and clearly define a dictionary by specifying
    the respective patterns for the key and value.  Takes care of
    defining the :class:`Dict`, :class:`ZeroOrMore`, and
    :class:`Group` tokens in the proper order.  The key pattern
    can include delimiting markers or punctuation, as long as they are
    suppressed, thereby leaving the significant key text.  The value
    pattern can include named results, so that the :class:`Dict` results
    can include named token fields.

    Example::

        text = "shape: SQUARE posn: upper left color: light blue texture: burlap"
        attr_expr = (label + Suppress(':') + OneOrMore(data_word, stopOn=label).setParseAction(' '.join))
        print(OneOrMore(attr_expr).parseString(text).dump())

        attr_label = label
        attr_value = Suppress(':') + OneOrMore(data_word, stopOn=label).setParseAction(' '.join)

        # similar to Dict, but simpler call format
        result = dictOf(attr_label, attr_value).parseString(text)
        print(result.dump())
        print(result['shape'])
        print(result.shape)  # object attribute access works too
        print(result.asDict())

    prints::

        [['shape', 'SQUARE'], ['posn', 'upper left'], ['color', 'light blue'], ['texture', 'burlap']]
        - color: light blue
        - posn: upper left
        - shape: SQUARE
        - texture: burlap
        SQUARE
        SQUARE
        {'color': 'light blue', 'shape': 'SQUARE', 'posn': 'upper left', 'texture': 'burlap'}
    """
    return Dict(OneOrMore(Group(key + value)))

def originalTextFor(expr, asString=True):
    """Helper to return the original, untokenized text for a given
    expression.  Useful to restore the parsed fields of an HTML start
    tag into the raw tag text itself, or to revert separate tokens with
    intervening whitespace back to the original matching input text. By
    default, returns astring containing the original parsed text.

    If the optional ``asString`` argument is passed as
    ``False``, then the return value is
    a :class:`ParseResults` containing any results names that
    were originally matched, and a single token containing the original
    matched text from the input string.  So if the expression passed to
    :class:`originalTextFor` contains expressions with defined
    results names, you must set ``asString`` to ``False`` if you
    want to preserve those results name values.

    Example::

        src = "this is test <b> bold <i>text</i> </b> normal text "
        for tag in ("b", "i"):
            opener, closer = makeHTMLTags(tag)
            patt = originalTextFor(opener + SkipTo(closer) + closer)
            print(patt.searchString(src)[0])

    prints::

        ['<b> bold <i>text</i> </b>']
        ['<i>text</i>']
    """
    locMarker = Empty().setParseAction(lambda s, loc, t: loc)
    endlocMarker = locMarker.copy()
    endlocMarker.callPreparse = False
    matchExpr = locMarker("_original_start") + expr + endlocMarker("_original_end")
    if asString:
        extractText = lambda s, l, t: s[t._original_start: t._original_end]
    else:
        def extractText(s, l, t):
            t[:] = [s[t.pop('_original_start'):t.pop('_original_end')]]
    matchExpr.setParseAction(extractText)
    matchExpr.ignoreExprs = expr.ignoreExprs
    return matchExpr

def ungroup(expr):
    """Helper to undo pyparsing's default grouping of And expressions,
    even if all but one are non-empty.
    """
    return TokenConverter(expr).addParseAction(lambda t: t[0])

def locatedExpr(expr):
    """Helper to decorate a returned token with its starting and ending
    locations in the input string.

    This helper adds the following results names:

     - locn_start = location where matched expression begins
     - locn_end = location where matched expression ends
     - value = the actual parsed results

    Be careful if the input text contains ``<TAB>`` characters, you
    may want to call :class:`ParserElement.parseWithTabs`

    Example::

        wd = Word(alphas)
        for match in locatedExpr(wd).searchString("ljsdf123lksdjjf123lkkjj1222"):
            print(match)

    prints::

        [[0, 'ljsdf', 5]]
        [[8, 'lksdjjf', 15]]
        [[18, 'lkkjj', 23]]
    """
    locator = Empty().setParseAction(lambda s, l, t: l)
    return Group(locator("locn_start") + expr("value") + locator.copy().leaveWhitespace()("locn_end"))


# convenience constants for positional expressions
empty       = Empty().setName("empty")
lineStart   = LineStart().setName("lineStart")
lineEnd     = LineEnd().setName("lineEnd")
stringStart = StringStart().setName("stringStart")
stringEnd   = StringEnd().setName("stringEnd")

_escapedPunc = Word(_bslash, r"\[]-*.$+^?()~ ", exact=2).setParseAction(lambda s, l, t: t[0][1])
_escapedHexChar = Regex(r"\\0?[xX][0-9a-fA-F]+").setParseAction(lambda s, l, t: unichr(int(t[0].lstrip(r'\0x'), 16)))
_escapedOctChar = Regex(r"\\0[0-7]+").setParseAction(lambda s, l, t: unichr(int(t[0][1:], 8)))
_singleChar = _escapedPunc | _escapedHexChar | _escapedOctChar | CharsNotIn(r'\]', exact=1)
_charRange = Group(_singleChar + Suppress("-") + _singleChar)
_reBracketExpr = Literal("[") + Optional("^").setResultsName("negate") + Group(OneOrMore(_charRange | _singleChar)).setResultsName("body") + "]"

def srange(s):
    r"""Helper to easily define string ranges for use in Word
    construction. Borrows syntax from regexp '[]' string range
    definitions::

        srange("[0-9]")   -> "0123456789"
        srange("[a-z]")   -> "abcdefghijklmnopqrstuvwxyz"
        srange("[a-z$_]") -> "abcdefghijklmnopqrstuvwxyz$_"

    The input string must be enclosed in []'s, and the returned string
    is the expanded character set joined into a single string. The
    values enclosed in the []'s may be:

     - a single character
     - an escaped character with a leading backslash (such as ``\-``
       or ``\]``)
     - an escaped hex character with a leading ``'\x'``
       (``\x21``, which is a ``'!'`` character) (``\0x##``
       is also supported for backwards compatibility)
     - an escaped octal character with a leading ``'\0'``
       (``\041``, which is a ``'!'`` character)
     - a range of any of the above, separated by a dash (``'a-z'``,
       etc.)
     - any combination of the above (``'aeiouy'``,
       ``'a-zA-Z0-9_$'``, etc.)
    """
    _expanded = lambda p: p if not isinstance(p, ParseResults) else ''.join(unichr(c) for c in range(ord(p[0]), ord(p[1]) + 1))
    try:
        return "".join(_expanded(part) for part in _reBracketExpr.parseString(s).body)
    except Exception:
        return ""

def matchOnlyAtCol(n):
    """Helper method for defining parse actions that require matching at
    a specific column in the input text.
    """
    def verifyCol(strg, locn, toks):
        if col(locn, strg) != n:
            raise ParseException(strg, locn, "matched token not at column %d" % n)
    return verifyCol

def replaceWith(replStr):
    """Helper method for common parse actions that simply return
    a literal value.  Especially useful when used with
    :class:`transformString<ParserElement.transformString>` ().

    Example::

        num = Word(nums).setParseAction(lambda toks: int(toks[0]))
        na = oneOf("N/A NA").setParseAction(replaceWith(math.nan))
        term = na | num

        OneOrMore(term).parseString("324 234 N/A 234") # -> [324, 234, nan, 234]
    """
    return lambda s, l, t: [replStr]

def removeQuotes(s, l, t):
    """Helper parse action for removing quotation marks from parsed
    quoted strings.

    Example::

        # by default, quotation marks are included in parsed results
        quotedString.parseString("'Now is the Winter of our Discontent'") # -> ["'Now is the Winter of our Discontent'"]

        # use removeQuotes to strip quotation marks from parsed results
        quotedString.setParseAction(removeQuotes)
        quotedString.parseString("'Now is the Winter of our Discontent'") # -> ["Now is the Winter of our Discontent"]
    """
    return t[0][1:-1]

def tokenMap(func, *args):
    """Helper to define a parse action by mapping a function to all
    elements of a ParseResults list. If any additional args are passed,
    they are forwarded to the given function as additional arguments
    after the token, as in
    ``hex_integer = Word(hexnums).setParseAction(tokenMap(int, 16))``,
    which will convert the parsed data to an integer using base 16.

    Example (compare the last to example in :class:`ParserElement.transformString`::

        hex_ints = OneOrMore(Word(hexnums)).setParseAction(tokenMap(int, 16))
        hex_ints.runTests('''
            00 11 22 aa FF 0a 0d 1a
            ''')

        upperword = Word(alphas).setParseAction(tokenMap(str.upper))
        OneOrMore(upperword).runTests('''
            my kingdom for a horse
            ''')

        wd = Word(alphas).setParseAction(tokenMap(str.title))
        OneOrMore(wd).setParseAction(' '.join).runTests('''
            now is the winter of our discontent made glorious summer by this sun of york
            ''')

    prints::

        00 11 22 aa FF 0a 0d 1a
        [0, 17, 34, 170, 255, 10, 13, 26]

        my kingdom for a horse
        ['MY', 'KINGDOM', 'FOR', 'A', 'HORSE']

        now is the winter of our discontent made glorious summer by this sun of york
        ['Now Is The Winter Of Our Discontent Made Glorious Summer By This Sun Of York']
    """
    def pa(s, l, t):
        return [func(tokn, *args) for tokn in t]

    try:
        func_name = getattr(func, '__name__',
                            getattr(func, '__class__').__name__)
    except Exception:
        func_name = str(func)
    pa.__name__ = func_name

    return pa

upcaseTokens = tokenMap(lambda t: _ustr(t).upper())
"""(Deprecated) Helper parse action to convert tokens to upper case.
Deprecated in favor of :class:`pyparsing_common.upcaseTokens`"""

downcaseTokens = tokenMap(lambda t: _ustr(t).lower())
"""(Deprecated) Helper parse action to convert tokens to lower case.
Deprecated in favor of :class:`pyparsing_common.downcaseTokens`"""

def _makeTags(tagStr, xml,
              suppress_LT=Suppress("<"),
              suppress_GT=Suppress(">")):
    """Internal helper to construct opening and closing tag expressions, given a tag name"""
    if isinstance(tagStr, basestring):
        resname = tagStr
        tagStr = Keyword(tagStr, caseless=not xml)
    else:
        resname = tagStr.name

    tagAttrName = Word(alphas, alphanums + "_-:")
    if xml:
        tagAttrValue = dblQuotedString.copy().setParseAction(removeQuotes)
        openTag = (suppress_LT
                   + tagStr("tag")
                   + Dict(ZeroOrMore(Group(tagAttrName + Suppress("=") + tagAttrValue)))
                   + Optional("/", default=[False])("empty").setParseAction(lambda s, l, t: t[0] == '/')
                   + suppress_GT)
    else:
        tagAttrValue = quotedString.copy().setParseAction(removeQuotes) | Word(printables, excludeChars=">")
        openTag = (suppress_LT
                   + tagStr("tag")
                   + Dict(ZeroOrMore(Group(tagAttrName.setParseAction(downcaseTokens)
                                           + Optional(Suppress("=") + tagAttrValue))))
                   + Optional("/", default=[False])("empty").setParseAction(lambda s, l, t: t[0] == '/')
                   + suppress_GT)
    closeTag = Combine(_L("</") + tagStr + ">", adjacent=False)

    openTag.setName("<%s>" % resname)
    # add start<tagname> results name in parse action now that ungrouped names are not reported at two levels
    openTag.addParseAction(lambda t: t.__setitem__("start" + "".join(resname.replace(":", " ").title().split()), t.copy()))
    closeTag = closeTag("end" + "".join(resname.replace(":", " ").title().split())).setName("</%s>" % resname)
    openTag.tag = resname
    closeTag.tag = resname
    openTag.tag_body = SkipTo(closeTag())
    return openTag, closeTag

def makeHTMLTags(tagStr):
    """Helper to construct opening and closing tag expressions for HTML,
    given a tag name. Matches tags in either upper or lower case,
    attributes with namespaces and with quoted or unquoted values.

    Example::

        text = '<td>More info at the <a href="https://github.com/pyparsing/pyparsing/wiki">pyparsing</a> wiki page</td>'
        # makeHTMLTags returns pyparsing expressions for the opening and
        # closing tags as a 2-tuple
        a, a_end = makeHTMLTags("A")
        link_expr = a + SkipTo(a_end)("link_text") + a_end

        for link in link_expr.searchString(text):
            # attributes in the <A> tag (like "href" shown here) are
            # also accessible as named results
            print(link.link_text, '->', link.href)

    prints::

        pyparsing -> https://github.com/pyparsing/pyparsing/wiki
    """
    return _makeTags(tagStr, False)

def makeXMLTags(tagStr):
    """Helper to construct opening and closing tag expressions for XML,
    given a tag name. Matches tags only in the given upper/lower case.

    Example: similar to :class:`makeHTMLTags`
    """
    return _makeTags(tagStr, True)

def withAttribute(*args, **attrDict):
    """Helper to create a validating parse action to be used with start
    tags created with :class:`makeXMLTags` or
    :class:`makeHTMLTags`. Use ``withAttribute`` to qualify
    a starting tag with a required attribute value, to avoid false
    matches on common tags such as ``<TD>`` or ``<DIV>``.

    Call ``withAttribute`` with a series of attribute names and
    values. Specify the list of filter attributes names and values as:

     - keyword arguments, as in ``(align="right")``, or
     - as an explicit dict with ``**`` operator, when an attribute
       name is also a Python reserved word, as in ``**{"class":"Customer", "align":"right"}``
     - a list of name-value tuples, as in ``(("ns1:class", "Customer"), ("ns2:align", "right"))``

    For attribute names with a namespace prefix, you must use the second
    form.  Attribute names are matched insensitive to upper/lower case.

    If just testing for ``class`` (with or without a namespace), use
    :class:`withClass`.

    To verify that the attribute exists, but without specifying a value,
    pass ``withAttribute.ANY_VALUE`` as the value.

    Example::

        html = '''
            <div>
            Some text
            <div type="grid">1 4 0 1 0</div>
            <div type="graph">1,3 2,3 1,1</div>
            <div>this has no type</div>
            </div>

        '''
        div,div_end = makeHTMLTags("div")

        # only match div tag having a type attribute with value "grid"
        div_grid = div().setParseAction(withAttribute(type="grid"))
        grid_expr = div_grid + SkipTo(div | div_end)("body")
        for grid_header in grid_expr.searchString(html):
            print(grid_header.body)

        # construct a match with any div tag having a type attribute, regardless of the value
        div_any_type = div().setParseAction(withAttribute(type=withAttribute.ANY_VALUE))
        div_expr = div_any_type + SkipTo(div | div_end)("body")
        for div_header in div_expr.searchString(html):
            print(div_header.body)

    prints::

        1 4 0 1 0

        1 4 0 1 0
        1,3 2,3 1,1
    """
    if args:
        attrs = args[:]
    else:
        attrs = attrDict.items()
    attrs = [(k, v) for k, v in attrs]
    def pa(s, l, tokens):
        for attrName, attrValue in attrs:
            if attrName not in tokens:
                raise ParseException(s, l, "no matching attribute " + attrName)
            if attrValue != withAttribute.ANY_VALUE and tokens[attrName] != attrValue:
                raise ParseException(s, l, "attribute '%s' has value '%s', must be '%s'" %
                                            (attrName, tokens[attrName], attrValue))
    return pa
withAttribute.ANY_VALUE = object()

def withClass(classname, namespace=''):
    """Simplified version of :class:`withAttribute` when
    matching on a div class - made difficult because ``class`` is
    a reserved word in Python.

    Example::

        html = '''
            <div>
            Some text
            <div class="grid">1 4 0 1 0</div>
            <div class="graph">1,3 2,3 1,1</div>
            <div>this &lt;div&gt; has no class</div>
            </div>

        '''
        div,div_end = makeHTMLTags("div")
        div_grid = div().setParseAction(withClass("grid"))

        grid_expr = div_grid + SkipTo(div | div_end)("body")
        for grid_header in grid_expr.searchString(html):
            print(grid_header.body)

        div_any_type = div().setParseAction(withClass(withAttribute.ANY_VALUE))
        div_expr = div_any_type + SkipTo(div | div_end)("body")
        for div_header in div_expr.searchString(html):
            print(div_header.body)

    prints::

        1 4 0 1 0

        1 4 0 1 0
        1,3 2,3 1,1
    """
    classattr = "%s:class" % namespace if namespace else "class"
    return withAttribute(**{classattr: classname})

opAssoc = SimpleNamespace()
opAssoc.LEFT = object()
opAssoc.RIGHT = object()

def infixNotation(baseExpr, opList, lpar=Suppress('('), rpar=Suppress(')')):
    """Helper method for constructing grammars of expressions made up of
    operators working in a precedence hierarchy.  Operators may be unary
    or binary, left- or right-associative.  Parse actions can also be
    attached to operator expressions. The generated parser will also
    recognize the use of parentheses to override operator precedences
    (see example below).

    Note: if you define a deep operator list, you may see performance
    issues when using infixNotation. See
    :class:`ParserElement.enablePackrat` for a mechanism to potentially
    improve your parser performance.

    Parameters:
     - baseExpr - expression representing the most basic element for the
       nested
     - opList - list of tuples, one for each operator precedence level
       in the expression grammar; each tuple is of the form ``(opExpr,
       numTerms, rightLeftAssoc, parseAction)``, where:

       - opExpr is the pyparsing expression for the operator; may also
         be a string, which will be converted to a Literal; if numTerms
         is 3, opExpr is a tuple of two expressions, for the two
         operators separating the 3 terms
       - numTerms is the number of terms for this operator (must be 1,
         2, or 3)
       - rightLeftAssoc is the indicator whether the operator is right
         or left associative, using the pyparsing-defined constants
         ``opAssoc.RIGHT`` and ``opAssoc.LEFT``.
       - parseAction is the parse action to be associated with
         expressions matching this operator expression (the parse action
         tuple member may be omitted); if the parse action is passed
         a tuple or list of functions, this is equivalent to calling
         ``setParseAction(*fn)``
         (:class:`ParserElement.setParseAction`)
     - lpar - expression for matching left-parentheses
       (default= ``Suppress('(')``)
     - rpar - expression for matching right-parentheses
       (default= ``Suppress(')')``)

    Example::

        # simple example of four-function arithmetic with ints and
        # variable names
        integer = pyparsing_common.signed_integer
        varname = pyparsing_common.identifier

        arith_expr = infixNotation(integer | varname,
            [
            ('-', 1, opAssoc.RIGHT),
            (oneOf('* /'), 2, opAssoc.LEFT),
            (oneOf('+ -'), 2, opAssoc.LEFT),
            ])

        arith_expr.runTests('''
            5+3*6
            (5+3)*6
            -2--11
            ''', fullDump=False)

    prints::

        5+3*6
        [[5, '+', [3, '*', 6]]]

        (5+3)*6
        [[[5, '+', 3], '*', 6]]

        -2--11
        [[['-', 2], '-', ['-', 11]]]
    """
    # captive version of FollowedBy that does not do parse actions or capture results names
    class _FB(FollowedBy):
        def parseImpl(self, instring, loc, doActions=True):
            self.expr.tryParse(instring, loc)
            return loc, []

    ret = Forward()
    lastExpr = baseExpr | (lpar + ret + rpar)
    for i, operDef in enumerate(opList):
        opExpr, arity, rightLeftAssoc, pa = (operDef + (None, ))[:4]
        termName = "%s term" % opExpr if arity < 3 else "%s%s term" % opExpr
        if arity == 3:
            if opExpr is None or len(opExpr) != 2:
                raise ValueError(
                    "if numterms=3, opExpr must be a tuple or list of two expressions")
            opExpr1, opExpr2 = opExpr
        thisExpr = Forward().setName(termName)
        if rightLeftAssoc == opAssoc.LEFT:
            if arity == 1:
                matchExpr = _FB(lastExpr + opExpr) + Group(lastExpr + OneOrMore(opExpr))
            elif arity == 2:
                if opExpr is not None:
                    matchExpr = _FB(lastExpr + opExpr + lastExpr) + Group(lastExpr + OneOrMore(opExpr + lastExpr))
                else:
                    matchExpr = _FB(lastExpr + lastExpr) + Group(lastExpr + OneOrMore(lastExpr))
            elif arity == 3:
                matchExpr = (_FB(lastExpr + opExpr1 + lastExpr + opExpr2 + lastExpr)
                             + Group(lastExpr + opExpr1 + lastExpr + opExpr2 + lastExpr))
            else:
                raise ValueError("operator must be unary (1), binary (2), or ternary (3)")
        elif rightLeftAssoc == opAssoc.RIGHT:
            if arity == 1:
                # try to avoid LR with this extra test
                if not isinstance(opExpr, Optional):
                    opExpr = Optional(opExpr)
                matchExpr = _FB(opExpr.expr + thisExpr) + Group(opExpr + thisExpr)
            elif arity == 2:
                if opExpr is not None:
                    matchExpr = _FB(lastExpr + opExpr + thisExpr) + Group(lastExpr + OneOrMore(opExpr + thisExpr))
                else:
                    matchExpr = _FB(lastExpr + thisExpr) + Group(lastExpr + OneOrMore(thisExpr))
            elif arity == 3:
                matchExpr = (_FB(lastExpr + opExpr1 + thisExpr + opExpr2 + thisExpr)
                             + Group(lastExpr + opExpr1 + thisExpr + opExpr2 + thisExpr))
            else:
                raise ValueError("operator must be unary (1), binary (2), or ternary (3)")
        else:
            raise ValueError("operator must indicate right or left associativity")
        if pa:
            if isinstance(pa, (tuple, list)):
                matchExpr.setParseAction(*pa)
            else:
                matchExpr.setParseAction(pa)
        thisExpr <<= (matchExpr.setName(termName) | lastExpr)
        lastExpr = thisExpr
    ret <<= lastExpr
    return ret

operatorPrecedence = infixNotation
"""(Deprecated) Former name of :class:`infixNotation`, will be
dropped in a future release."""

dblQuotedString = Combine(Regex(r'"(?:[^"\n\r\\]|(?:"")|(?:\\(?:[^x]|x[0-9a-fA-F]+)))*') + '"').setName("string enclosed in double quotes")
sglQuotedString = Combine(Regex(r"'(?:[^'\n\r\\]|(?:'')|(?:\\(?:[^x]|x[0-9a-fA-F]+)))*") + "'").setName("string enclosed in single quotes")
quotedString = Combine(Regex(r'"(?:[^"\n\r\\]|(?:"")|(?:\\(?:[^x]|x[0-9a-fA-F]+)))*') + '"'
                       | Regex(r"'(?:[^'\n\r\\]|(?:'')|(?:\\(?:[^x]|x[0-9a-fA-F]+)))*") + "'").setName("quotedString using single or double quotes")
unicodeString = Combine(_L('u') + quotedString.copy()).setName("unicode string literal")

def nestedExpr(opener="(", closer=")", content=None, ignoreExpr=quotedString.copy()):
    """Helper method for defining nested lists enclosed in opening and
    closing delimiters ("(" and ")" are the default).

    Parameters:
     - opener - opening character for a nested list
       (default= ``"("``); can also be a pyparsing expression
     - closer - closing character for a nested list
       (default= ``")"``); can also be a pyparsing expression
     - content - expression for items within the nested lists
       (default= ``None``)
     - ignoreExpr - expression for ignoring opening and closing
       delimiters (default= :class:`quotedString`)

    If an expression is not provided for the content argument, the
    nested expression will capture all whitespace-delimited content
    between delimiters as a list of separate values.

    Use the ``ignoreExpr`` argument to define expressions that may
    contain opening or closing characters that should not be treated as
    opening or closing characters for nesting, such as quotedString or
    a comment expression.  Specify multiple expressions using an
    :class:`Or` or :class:`MatchFirst`. The default is
    :class:`quotedString`, but if no expressions are to be ignored, then
    pass ``None`` for this argument.

    Example::

        data_type = oneOf("void int short long char float double")
        decl_data_type = Combine(data_type + Optional(Word('*')))
        ident = Word(alphas+'_', alphanums+'_')
        number = pyparsing_common.number
        arg = Group(decl_data_type + ident)
        LPAR, RPAR = map(Suppress, "()")

        code_body = nestedExpr('{', '}', ignoreExpr=(quotedString | cStyleComment))

        c_function = (decl_data_type("type")
                      + ident("name")
                      + LPAR + Optional(delimitedList(arg), [])("args") + RPAR
                      + code_body("body"))
        c_function.ignore(cStyleComment)

        source_code = '''
            int is_odd(int x) {
                return (x%2);
            }

            int dec_to_hex(char hchar) {
                if (hchar >= '0' && hchar <= '9') {
                    return (ord(hchar)-ord('0'));
                } else {
                    return (10+ord(hchar)-ord('A'));
                }
            }
        '''
        for func in c_function.searchString(source_code):
            print("%(name)s (%(type)s) args: %(args)s" % func)


    prints::

        is_odd (int) args: [['int', 'x']]
        dec_to_hex (int) args: [['char', 'hchar']]
    """
    if opener == closer:
        raise ValueError("opening and closing strings cannot be the same")
    if content is None:
        if isinstance(opener, basestring) and isinstance(closer, basestring):
            if len(opener) == 1 and len(closer) == 1:
                if ignoreExpr is not None:
                    content = (Combine(OneOrMore(~ignoreExpr
                                                 + CharsNotIn(opener
                                                              + closer
                                                              + ParserElement.DEFAULT_WHITE_CHARS, exact=1)
                                                 )
                                       ).setParseAction(lambda t: t[0].strip()))
                else:
                    content = (empty.copy() + CharsNotIn(opener
                                                         + closer
                                                         + ParserElement.DEFAULT_WHITE_CHARS
                                                         ).setParseAction(lambda t: t[0].strip()))
            else:
                if ignoreExpr is not None:
                    content = (Combine(OneOrMore(~ignoreExpr
                                                 + ~Literal(opener)
                                                 + ~Literal(closer)
                                                 + CharsNotIn(ParserElement.DEFAULT_WHITE_CHARS, exact=1))
                                       ).setParseAction(lambda t: t[0].strip()))
                else:
                    content = (Combine(OneOrMore(~Literal(opener)
                                                 + ~Literal(closer)
                                                 + CharsNotIn(ParserElement.DEFAULT_WHITE_CHARS, exact=1))
                                       ).setParseAction(lambda t: t[0].strip()))
        else:
            raise ValueError("opening and closing arguments must be strings if no content expression is given")
    ret = Forward()
    if ignoreExpr is not None:
        ret <<= Group(Suppress(opener) + ZeroOrMore(ignoreExpr | ret | content) + Suppress(closer))
    else:
        ret <<= Group(Suppress(opener) + ZeroOrMore(ret | content)  + Suppress(closer))
    ret.setName('nested %s%s expression' % (opener, closer))
    return ret

def indentedBlock(blockStatementExpr, indentStack, indent=True):
    """Helper method for defining space-delimited indentation blocks,
    such as those used to define block statements in Python source code.

    Parameters:

     - blockStatementExpr - expression defining syntax of statement that
       is repeated within the indented block
     - indentStack - list created by caller to manage indentation stack
       (multiple statementWithIndentedBlock expressions within a single
       grammar should share a common indentStack)
     - indent - boolean indicating whether block must be indented beyond
       the current level; set to False for block of left-most
       statements (default= ``True``)

    A valid block must contain at least one ``blockStatement``.

    Example::

        data = '''
        def A(z):
          A1
          B = 100
          G = A2
          A2
          A3
        B
        def BB(a,b,c):
          BB1
          def BBA():
            bba1
            bba2
            bba3
        C
        D
        def spam(x,y):
             def eggs(z):
                 pass
        '''


        indentStack = [1]
        stmt = Forward()

        identifier = Word(alphas, alphanums)
        funcDecl = ("def" + identifier + Group("(" + Optional(delimitedList(identifier)) + ")") + ":")
        func_body = indentedBlock(stmt, indentStack)
        funcDef = Group(funcDecl + func_body)

        rvalue = Forward()
        funcCall = Group(identifier + "(" + Optional(delimitedList(rvalue)) + ")")
        rvalue << (funcCall | identifier | Word(nums))
        assignment = Group(identifier + "=" + rvalue)
        stmt << (funcDef | assignment | identifier)

        module_body = OneOrMore(stmt)

        parseTree = module_body.parseString(data)
        parseTree.pprint()

    prints::

        [['def',
          'A',
          ['(', 'z', ')'],
          ':',
          [['A1'], [['B', '=', '100']], [['G', '=', 'A2']], ['A2'], ['A3']]],
         'B',
         ['def',
          'BB',
          ['(', 'a', 'b', 'c', ')'],
          ':',
          [['BB1'], [['def', 'BBA', ['(', ')'], ':', [['bba1'], ['bba2'], ['bba3']]]]]],
         'C',
         'D',
         ['def',
          'spam',
          ['(', 'x', 'y', ')'],
          ':',
          [[['def', 'eggs', ['(', 'z', ')'], ':', [['pass']]]]]]]
    """
    backup_stack = indentStack[:]

    def reset_stack():
        indentStack[:] = backup_stack

    def checkPeerIndent(s, l, t):
        if l >= len(s): return
        curCol = col(l, s)
        if curCol != indentStack[-1]:
            if curCol > indentStack[-1]:
                raise ParseException(s, l, "illegal nesting")
            raise ParseException(s, l, "not a peer entry")

    def checkSubIndent(s, l, t):
        curCol = col(l, s)
        if curCol > indentStack[-1]:
            indentStack.append(curCol)
        else:
            raise ParseException(s, l, "not a subentry")

    def checkUnindent(s, l, t):
        if l >= len(s): return
        curCol = col(l, s)
        if not(indentStack and curCol in indentStack):
            raise ParseException(s, l, "not an unindent")
        if curCol < indentStack[-1]:
            indentStack.pop()

    NL = OneOrMore(LineEnd().setWhitespaceChars("\t ").suppress())
    INDENT = (Empty() + Empty().setParseAction(checkSubIndent)).setName('INDENT')
    PEER   = Empty().setParseAction(checkPeerIndent).setName('')
    UNDENT = Empty().setParseAction(checkUnindent).setName('UNINDENT')
    if indent:
        smExpr = Group(Optional(NL)
                       + INDENT
                       + OneOrMore(PEER + Group(blockStatementExpr) + Optional(NL))
                       + UNDENT)
    else:
        smExpr = Group(Optional(NL)
                       + OneOrMore(PEER + Group(blockStatementExpr) + Optional(NL))
                       + UNDENT)
    smExpr.setFailAction(lambda a, b, c, d: reset_stack())
    blockStatementExpr.ignore(_bslash + LineEnd())
    return smExpr.setName('indented block')

alphas8bit = srange(r"[\0xc0-\0xd6\0xd8-\0xf6\0xf8-\0xff]")
punc8bit = srange(r"[\0xa1-\0xbf\0xd7\0xf7]")

anyOpenTag, anyCloseTag = makeHTMLTags(Word(alphas, alphanums + "_:").setName('any tag'))
_htmlEntityMap = dict(zip("gt lt amp nbsp quot apos".split(), '><& "\''))
commonHTMLEntity = Regex('&(?P<entity>' + '|'.join(_htmlEntityMap.keys()) +");").setName("common HTML entity")
def replaceHTMLEntity(t):
    """Helper parser action to replace common HTML entities with their special characters"""
    return _htmlEntityMap.get(t.entity)

# it's easy to get these comment structures wrong - they're very common, so may as well make them available
cStyleComment = Combine(Regex(r"/\*(?:[^*]|\*(?!/))*") + '*/').setName("C style comment")
"Comment of the form ``/* ... */``"

htmlComment = Regex(r"<!--[\s\S]*?-->").setName("HTML comment")
"Comment of the form ``<!-- ... -->``"

restOfLine = Regex(r".*").leaveWhitespace().setName("rest of line")
dblSlashComment = Regex(r"//(?:\\\n|[^\n])*").setName("// comment")
"Comment of the form ``// ... (to end of line)``"

cppStyleComment = Combine(Regex(r"/\*(?:[^*]|\*(?!/))*") + '*/' | dblSlashComment).setName("C++ style comment")
"Comment of either form :class:`cStyleComment` or :class:`dblSlashComment`"

javaStyleComment = cppStyleComment
"Same as :class:`cppStyleComment`"

pythonStyleComment = Regex(r"#.*").setName("Python style comment")
"Comment of the form ``# ... (to end of line)``"

_commasepitem = Combine(OneOrMore(Word(printables, excludeChars=',')
                                  + Optional(Word(" \t")
                                             + ~Literal(",") + ~LineEnd()))).streamline().setName("commaItem")
commaSeparatedList = delimitedList(Optional(quotedString.copy() | _commasepitem, default="")).setName("commaSeparatedList")
"""(Deprecated) Predefined expression of 1 or more printable words or
quoted strings, separated by commas.

This expression is deprecated in favor of :class:`pyparsing_common.comma_separated_list`.
"""

# some other useful expressions - using lower-case class name since we are really using this as a namespace
class pyparsing_common:
    """Here are some common low-level expressions that may be useful in
    jump-starting parser development:

     - numeric forms (:class:`integers<integer>`, :class:`reals<real>`,
       :class:`scientific notation<sci_real>`)
     - common :class:`programming identifiers<identifier>`
     - network addresses (:class:`MAC<mac_address>`,
       :class:`IPv4<ipv4_address>`, :class:`IPv6<ipv6_address>`)
     - ISO8601 :class:`dates<iso8601_date>` and
       :class:`datetime<iso8601_datetime>`
     - :class:`UUID<uuid>`
     - :class:`comma-separated list<comma_separated_list>`

    Parse actions:

     - :class:`convertToInteger`
     - :class:`convertToFloat`
     - :class:`convertToDate`
     - :class:`convertToDatetime`
     - :class:`stripHTMLTags`
     - :class:`upcaseTokens`
     - :class:`downcaseTokens`

    Example::

        pyparsing_common.number.runTests('''
            # any int or real number, returned as the appropriate type
            100
            -100
            +100
            3.14159
            6.02e23
            1e-12
            ''')

        pyparsing_common.fnumber.runTests('''
            # any int or real number, returned as float
            100
            -100
            +100
            3.14159
            6.02e23
            1e-12
            ''')

        pyparsing_common.hex_integer.runTests('''
            # hex numbers
            100
            FF
            ''')

        pyparsing_common.fraction.runTests('''
            # fractions
            1/2
            -3/4
            ''')

        pyparsing_common.mixed_integer.runTests('''
            # mixed fractions
            1
            1/2
            -3/4
            1-3/4
            ''')

        import uuid
        pyparsing_common.uuid.setParseAction(tokenMap(uuid.UUID))
        pyparsing_common.uuid.runTests('''
            # uuid
            12345678-1234-5678-1234-567812345678
            ''')

    prints::

        # any int or real number, returned as the appropriate type
        100
        [100]

        -100
        [-100]

        +100
        [100]

        3.14159
        [3.14159]

        6.02e23
        [6.02e+23]

        1e-12
        [1e-12]

        # any int or real number, returned as float
        100
        [100.0]

        -100
        [-100.0]

        +100
        [100.0]

        3.14159
        [3.14159]

        6.02e23
        [6.02e+23]

        1e-12
        [1e-12]

        # hex numbers
        100
        [256]

        FF
        [255]

        # fractions
        1/2
        [0.5]

        -3/4
        [-0.75]

        # mixed fractions
        1
        [1]

        1/2
        [0.5]

        -3/4
        [-0.75]

        1-3/4
        [1.75]

        # uuid
        12345678-1234-5678-1234-567812345678
        [UUID('12345678-1234-5678-1234-567812345678')]
    """

    convertToInteger = tokenMap(int)
    """
    Parse action for converting parsed integers to Python int
    """

    convertToFloat = tokenMap(float)
    """
    Parse action for converting parsed numbers to Python float
    """

    integer = Word(nums).setName("integer").setParseAction(convertToInteger)
    """expression that parses an unsigned integer, returns an int"""

    hex_integer = Word(hexnums).setName("hex integer").setParseAction(tokenMap(int, 16))
    """expression that parses a hexadecimal integer, returns an int"""

    signed_integer = Regex(r'[+-]?\d+').setName("signed integer").setParseAction(convertToInteger)
    """expression that parses an integer with optional leading sign, returns an int"""

    fraction = (signed_integer().setParseAction(convertToFloat) + '/' + signed_integer().setParseAction(convertToFloat)).setName("fraction")
    """fractional expression of an integer divided by an integer, returns a float"""
    fraction.addParseAction(lambda t: t[0]/t[-1])

    mixed_integer = (fraction | signed_integer + Optional(Optional('-').suppress() + fraction)).setName("fraction or mixed integer-fraction")
    """mixed integer of the form 'integer - fraction', with optional leading integer, returns float"""
    mixed_integer.addParseAction(sum)

    real = Regex(r'[+-]?(:?\d+\.\d*|\.\d+)').setName("real number").setParseAction(convertToFloat)
    """expression that parses a floating point number and returns a float"""

    sci_real = Regex(r'[+-]?(:?\d+(:?[eE][+-]?\d+)|(:?\d+\.\d*|\.\d+)(:?[eE][+-]?\d+)?)').setName("real number with scientific notation").setParseAction(convertToFloat)
    """expression that parses a floating point number with optional
    scientific notation and returns a float"""

    # streamlining this expression makes the docs nicer-looking
    number = (sci_real | real | signed_integer).streamline()
    """any numeric expression, returns the corresponding Python type"""

    fnumber = Regex(r'[+-]?\d+\.?\d*([eE][+-]?\d+)?').setName("fnumber").setParseAction(convertToFloat)
    """any int or real number, returned as float"""

    identifier = Word(alphas + '_', alphanums + '_').setName("identifier")
    """typical code identifier (leading alpha or '_', followed by 0 or more alphas, nums, or '_')"""

    ipv4_address = Regex(r'(25[0-5]|2[0-4][0-9]|1?[0-9]{1,2})(\.(25[0-5]|2[0-4][0-9]|1?[0-9]{1,2})){3}').setName("IPv4 address")
    "IPv4 address (``0.0.0.0 - 255.255.255.255``)"

    _ipv6_part = Regex(r'[0-9a-fA-F]{1,4}').setName("hex_integer")
    _full_ipv6_address = (_ipv6_part + (':' + _ipv6_part) * 7).setName("full IPv6 address")
    _short_ipv6_address = (Optional(_ipv6_part + (':' + _ipv6_part) * (0, 6))
                           + "::"
                           + Optional(_ipv6_part + (':' + _ipv6_part) * (0, 6))
                           ).setName("short IPv6 address")
    _short_ipv6_address.addCondition(lambda t: sum(1 for tt in t if pyparsing_common._ipv6_part.matches(tt)) < 8)
    _mixed_ipv6_address = ("::ffff:" + ipv4_address).setName("mixed IPv6 address")
    ipv6_address = Combine((_full_ipv6_address | _mixed_ipv6_address | _short_ipv6_address).setName("IPv6 address")).setName("IPv6 address")
    "IPv6 address (long, short, or mixed form)"

    mac_address = Regex(r'[0-9a-fA-F]{2}([:.-])[0-9a-fA-F]{2}(?:\1[0-9a-fA-F]{2}){4}').setName("MAC address")
    "MAC address xx:xx:xx:xx:xx (may also have '-' or '.' delimiters)"

    @staticmethod
    def convertToDate(fmt="%Y-%m-%d"):
        """
        Helper to create a parse action for converting parsed date string to Python datetime.date

        Params -
         - fmt - format to be passed to datetime.strptime (default= ``"%Y-%m-%d"``)

        Example::

            date_expr = pyparsing_common.iso8601_date.copy()
            date_expr.setParseAction(pyparsing_common.convertToDate())
            print(date_expr.parseString("1999-12-31"))

        prints::

            [datetime.date(1999, 12, 31)]
        """
        def cvt_fn(s, l, t):
            try:
                return datetime.strptime(t[0], fmt).date()
            except ValueError as ve:
                raise ParseException(s, l, str(ve))
        return cvt_fn

    @staticmethod
    def convertToDatetime(fmt="%Y-%m-%dT%H:%M:%S.%f"):
        """Helper to create a parse action for converting parsed
        datetime string to Python datetime.datetime

        Params -
         - fmt - format to be passed to datetime.strptime (default= ``"%Y-%m-%dT%H:%M:%S.%f"``)

        Example::

            dt_expr = pyparsing_common.iso8601_datetime.copy()
            dt_expr.setParseAction(pyparsing_common.convertToDatetime())
            print(dt_expr.parseString("1999-12-31T23:59:59.999"))

        prints::

            [datetime.datetime(1999, 12, 31, 23, 59, 59, 999000)]
        """
        def cvt_fn(s, l, t):
            try:
                return datetime.strptime(t[0], fmt)
            except ValueError as ve:
                raise ParseException(s, l, str(ve))
        return cvt_fn

    iso8601_date = Regex(r'(?P<year>\d{4})(?:-(?P<month>\d\d)(?:-(?P<day>\d\d))?)?').setName("ISO8601 date")
    "ISO8601 date (``yyyy-mm-dd``)"

    iso8601_datetime = Regex(r'(?P<year>\d{4})-(?P<month>\d\d)-(?P<day>\d\d)[T ](?P<hour>\d\d):(?P<minute>\d\d)(:(?P<second>\d\d(\.\d*)?)?)?(?P<tz>Z|[+-]\d\d:?\d\d)?').setName("ISO8601 datetime")
    "ISO8601 datetime (``yyyy-mm-ddThh:mm:ss.s(Z|+-00:00)``) - trailing seconds, milliseconds, and timezone optional; accepts separating ``'T'`` or ``' '``"

    uuid = Regex(r'[0-9a-fA-F]{8}(-[0-9a-fA-F]{4}){3}-[0-9a-fA-F]{12}').setName("UUID")
    "UUID (``xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx``)"

    _html_stripper = anyOpenTag.suppress() | anyCloseTag.suppress()
    @staticmethod
    def stripHTMLTags(s, l, tokens):
        """Parse action to remove HTML tags from web page HTML source

        Example::

            # strip HTML links from normal text
            text = '<td>More info at the <a href="https://github.com/pyparsing/pyparsing/wiki">pyparsing</a> wiki page</td>'
            td, td_end = makeHTMLTags("TD")
            table_text = td + SkipTo(td_end).setParseAction(pyparsing_common.stripHTMLTags)("body") + td_end
            print(table_text.parseString(text).body)

        Prints::

            More info at the pyparsing wiki page
        """
        return pyparsing_common._html_stripper.transformString(tokens[0])

    _commasepitem = Combine(OneOrMore(~Literal(",")
                                      + ~LineEnd()
                                      + Word(printables, excludeChars=',')
                                      + Optional(White(" \t")))).streamline().setName("commaItem")
    comma_separated_list = delimitedList(Optional(quotedString.copy()
                                                  | _commasepitem, default='')
                                         ).setName("comma separated list")
    """Predefined expression of 1 or more printable words or quoted strings, separated by commas."""

    upcaseTokens = staticmethod(tokenMap(lambda t: _ustr(t).upper()))
    """Parse action to convert tokens to upper case."""

    downcaseTokens = staticmethod(tokenMap(lambda t: _ustr(t).lower()))
    """Parse action to convert tokens to lower case."""


class _lazyclassproperty(object):
    def __init__(self, fn):
        self.fn = fn
        self.__doc__ = fn.__doc__
        self.__name__ = fn.__name__

    def __get__(self, obj, cls):
        if cls is None:
            cls = type(obj)
        if not hasattr(cls, '_intern') or any(cls._intern is getattr(superclass, '_intern', [])
                                              for superclass in cls.__mro__[1:]):
            cls._intern = {}
        attrname = self.fn.__name__
        if attrname not in cls._intern:
            cls._intern[attrname] = self.fn(cls)
        return cls._intern[attrname]


class unicode_set(object):
    """
    A set of Unicode characters, for language-specific strings for
    ``alphas``, ``nums``, ``alphanums``, and ``printables``.
    A unicode_set is defined by a list of ranges in the Unicode character
    set, in a class attribute ``_ranges``, such as::

        _ranges = [(0x0020, 0x007e), (0x00a0, 0x00ff),]

    A unicode set can also be defined using multiple inheritance of other unicode sets::

        class CJK(Chinese, Japanese, Korean):
            pass
    """
    _ranges = []

    @classmethod
    def _get_chars_for_ranges(cls):
        ret = []
        for cc in cls.__mro__:
            if cc is unicode_set:
                break
            for rr in cc._ranges:
                ret.extend(range(rr[0], rr[-1] + 1))
        return [unichr(c) for c in sorted(set(ret))]

    @_lazyclassproperty
    def printables(cls):
        "all non-whitespace characters in this range"
        return u''.join(filterfalse(unicode.isspace, cls._get_chars_for_ranges()))

    @_lazyclassproperty
    def alphas(cls):
        "all alphabetic characters in this range"
        return u''.join(filter(unicode.isalpha, cls._get_chars_for_ranges()))

    @_lazyclassproperty
    def nums(cls):
        "all numeric digit characters in this range"
        return u''.join(filter(unicode.isdigit, cls._get_chars_for_ranges()))

    @_lazyclassproperty
    def alphanums(cls):
        "all alphanumeric characters in this range"
        return cls.alphas + cls.nums


class pyparsing_unicode(unicode_set):
    """
    A namespace class for defining common language unicode_sets.
    """
    _ranges = [(32, sys.maxunicode)]

    class Latin1(unicode_set):
        "Unicode set for Latin-1 Unicode Character Range"
        _ranges = [(0x0020, 0x007e), (0x00a0, 0x00ff),]

    class LatinA(unicode_set):
        "Unicode set for Latin-A Unicode Character Range"
        _ranges = [(0x0100, 0x017f),]

    class LatinB(unicode_set):
        "Unicode set for Latin-B Unicode Character Range"
        _ranges = [(0x0180, 0x024f),]

    class Greek(unicode_set):
        "Unicode set for Greek Unicode Character Ranges"
        _ranges = [
            (0x0370, 0x03ff), (0x1f00, 0x1f15), (0x1f18, 0x1f1d), (0x1f20, 0x1f45), (0x1f48, 0x1f4d),
            (0x1f50, 0x1f57), (0x1f59,), (0x1f5b,), (0x1f5d,), (0x1f5f, 0x1f7d), (0x1f80, 0x1fb4), (0x1fb6, 0x1fc4),
            (0x1fc6, 0x1fd3), (0x1fd6, 0x1fdb), (0x1fdd, 0x1fef), (0x1ff2, 0x1ff4), (0x1ff6, 0x1ffe),
        ]

    class Cyrillic(unicode_set):
        "Unicode set for Cyrillic Unicode Character Range"
        _ranges = [(0x0400, 0x04ff)]

    class Chinese(unicode_set):
        "Unicode set for Chinese Unicode Character Range"
        _ranges = [(0x4e00, 0x9fff), (0x3000, 0x303f),]

    class Japanese(unicode_set):
        "Unicode set for Japanese Unicode Character Range, combining Kanji, Hiragana, and Katakana ranges"
        _ranges = []

        class Kanji(unicode_set):
            "Unicode set for Kanji Unicode Character Range"
            _ranges = [(0x4E00, 0x9Fbf), (0x3000, 0x303f),]

        class Hiragana(unicode_set):
            "Unicode set for Hiragana Unicode Character Range"
            _ranges = [(0x3040, 0x309f),]

        class Katakana(unicode_set):
            "Unicode set for Katakana  Unicode Character Range"
            _ranges = [(0x30a0, 0x30ff),]

    class Korean(unicode_set):
        "Unicode set for Korean Unicode Character Range"
        _ranges = [(0xac00, 0xd7af), (0x1100, 0x11ff), (0x3130, 0x318f), (0xa960, 0xa97f), (0xd7b0, 0xd7ff), (0x3000, 0x303f),]

    class CJK(Chinese, Japanese, Korean):
        "Unicode set for combined Chinese, Japanese, and Korean (CJK) Unicode Character Range"
        pass

    class Thai(unicode_set):
        "Unicode set for Thai Unicode Character Range"
        _ranges = [(0x0e01, 0x0e3a), (0x0e3f, 0x0e5b),]

    class Arabic(unicode_set):
        "Unicode set for Arabic Unicode Character Range"
        _ranges = [(0x0600, 0x061b), (0x061e, 0x06ff), (0x0700, 0x077f),]

    class Hebrew(unicode_set):
        "Unicode set for Hebrew Unicode Character Range"
        _ranges = [(0x0590, 0x05ff),]

    class Devanagari(unicode_set):
        "Unicode set for Devanagari Unicode Character Range"
        _ranges = [(0x0900, 0x097f), (0xa8e0, 0xa8ff)]

pyparsing_unicode.Japanese._ranges = (pyparsing_unicode.Japanese.Kanji._ranges
                                      + pyparsing_unicode.Japanese.Hiragana._ranges
                                      + pyparsing_unicode.Japanese.Katakana._ranges)

# define ranges in language character sets
if PY_3:
    setattr(pyparsing_unicode, u"العربية", pyparsing_unicode.Arabic)
    setattr(pyparsing_unicode, u"中文", pyparsing_unicode.Chinese)
    setattr(pyparsing_unicode, u"кириллица", pyparsing_unicode.Cyrillic)
    setattr(pyparsing_unicode, u"Ελληνικά", pyparsing_unicode.Greek)
    setattr(pyparsing_unicode, u"עִברִית", pyparsing_unicode.Hebrew)
    setattr(pyparsing_unicode, u"日本語", pyparsing_unicode.Japanese)
    setattr(pyparsing_unicode.Japanese, u"漢字", pyparsing_unicode.Japanese.Kanji)
    setattr(pyparsing_unicode.Japanese, u"カタカナ", pyparsing_unicode.Japanese.Katakana)
    setattr(pyparsing_unicode.Japanese, u"ひらがな", pyparsing_unicode.Japanese.Hiragana)
    setattr(pyparsing_unicode, u"한국어", pyparsing_unicode.Korean)
    setattr(pyparsing_unicode, u"ไทย", pyparsing_unicode.Thai)
    setattr(pyparsing_unicode, u"देवनागरी", pyparsing_unicode.Devanagari)


if __name__ == "__main__":

    selectToken    = CaselessLiteral("select")
    fromToken      = CaselessLiteral("from")

    ident          = Word(alphas, alphanums + "_$")

    columnName     = delimitedList(ident, ".", combine=True).setParseAction(upcaseTokens)
    columnNameList = Group(delimitedList(columnName)).setName("columns")
    columnSpec     = ('*' | columnNameList)

    tableName      = delimitedList(ident, ".", combine=True).setParseAction(upcaseTokens)
    tableNameList  = Group(delimitedList(tableName)).setName("tables")

    simpleSQL      = selectToken("command") + columnSpec("columns") + fromToken + tableNameList("tables")

    # demo runTests method, including embedded comments in test string
    simpleSQL.runTests("""
        # '*' as column list and dotted table name
        select * from SYS.XYZZY

        # caseless match on "SELECT", and casts back to "select"
        SELECT * from XYZZY, ABC

        # list of column names, and mixed case SELECT keyword
        Select AA,BB,CC from Sys.dual

        # multiple tables
        Select A, B, C from Sys.dual, Table2

        # invalid SELECT keyword - should fail
        Xelect A, B, C from Sys.dual

        # incomplete command - should fail
        Select

        # invalid column name - should fail
        Select ^^^ frox Sys.dual

        """)

    pyparsing_common.number.runTests("""
        100
        -100
        +100
        3.14159
        6.02e23
        1e-12
        """)

    # any int or real number, returned as float
    pyparsing_common.fnumber.runTests("""
        100
        -100
        +100
        3.14159
        6.02e23
        1e-12
        """)

    pyparsing_common.hex_integer.runTests("""
        100
        FF
        """)

    import uuid
    pyparsing_common.uuid.setParseAction(tokenMap(uuid.UUID))
    pyparsing_common.uuid.runTests("""
        12345678-1234-5678-1234-567812345678
        """)