577 lines
16 KiB
Python
577 lines
16 KiB
Python
#=======================================================================
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#
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# Python Lexical Analyser
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#
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# Regular Expressions
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#
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#=======================================================================
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from __future__ import absolute_import
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import types
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try:
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from sys import maxsize as maxint
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except ImportError:
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from sys import maxint
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from . import Errors
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#
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# Constants
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#
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BOL = 'bol'
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EOL = 'eol'
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EOF = 'eof'
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nl_code = ord('\n')
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#
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# Helper functions
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#
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def chars_to_ranges(s):
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"""
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Return a list of character codes consisting of pairs
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[code1a, code1b, code2a, code2b,...] which cover all
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the characters in |s|.
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"""
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char_list = list(s)
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char_list.sort()
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i = 0
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n = len(char_list)
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result = []
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while i < n:
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code1 = ord(char_list[i])
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code2 = code1 + 1
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i += 1
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while i < n and code2 >= ord(char_list[i]):
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code2 += 1
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i += 1
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result.append(code1)
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result.append(code2)
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return result
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def uppercase_range(code1, code2):
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"""
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If the range of characters from code1 to code2-1 includes any
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lower case letters, return the corresponding upper case range.
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"""
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code3 = max(code1, ord('a'))
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code4 = min(code2, ord('z') + 1)
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if code3 < code4:
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d = ord('A') - ord('a')
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return (code3 + d, code4 + d)
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else:
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return None
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def lowercase_range(code1, code2):
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"""
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If the range of characters from code1 to code2-1 includes any
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upper case letters, return the corresponding lower case range.
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"""
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code3 = max(code1, ord('A'))
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code4 = min(code2, ord('Z') + 1)
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if code3 < code4:
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d = ord('a') - ord('A')
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return (code3 + d, code4 + d)
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else:
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return None
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def CodeRanges(code_list):
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"""
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Given a list of codes as returned by chars_to_ranges, return
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an RE which will match a character in any of the ranges.
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"""
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re_list = [CodeRange(code_list[i], code_list[i + 1]) for i in range(0, len(code_list), 2)]
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return Alt(*re_list)
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def CodeRange(code1, code2):
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"""
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CodeRange(code1, code2) is an RE which matches any character
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with a code |c| in the range |code1| <= |c| < |code2|.
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"""
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if code1 <= nl_code < code2:
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return Alt(RawCodeRange(code1, nl_code),
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RawNewline,
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RawCodeRange(nl_code + 1, code2))
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else:
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return RawCodeRange(code1, code2)
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#
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# Abstract classes
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#
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class RE(object):
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"""RE is the base class for regular expression constructors.
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The following operators are defined on REs:
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re1 + re2 is an RE which matches |re1| followed by |re2|
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re1 | re2 is an RE which matches either |re1| or |re2|
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"""
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nullable = 1 # True if this RE can match 0 input symbols
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match_nl = 1 # True if this RE can match a string ending with '\n'
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str = None # Set to a string to override the class's __str__ result
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def build_machine(self, machine, initial_state, final_state,
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match_bol, nocase):
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"""
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This method should add states to |machine| to implement this
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RE, starting at |initial_state| and ending at |final_state|.
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If |match_bol| is true, the RE must be able to match at the
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beginning of a line. If nocase is true, upper and lower case
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letters should be treated as equivalent.
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"""
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raise NotImplementedError("%s.build_machine not implemented" %
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self.__class__.__name__)
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def build_opt(self, m, initial_state, c):
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"""
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Given a state |s| of machine |m|, return a new state
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reachable from |s| on character |c| or epsilon.
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"""
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s = m.new_state()
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initial_state.link_to(s)
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initial_state.add_transition(c, s)
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return s
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def __add__(self, other):
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return Seq(self, other)
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def __or__(self, other):
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return Alt(self, other)
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def __str__(self):
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if self.str:
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return self.str
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else:
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return self.calc_str()
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def check_re(self, num, value):
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if not isinstance(value, RE):
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self.wrong_type(num, value, "Plex.RE instance")
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def check_string(self, num, value):
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if type(value) != type(''):
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self.wrong_type(num, value, "string")
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def check_char(self, num, value):
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self.check_string(num, value)
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if len(value) != 1:
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raise Errors.PlexValueError("Invalid value for argument %d of Plex.%s."
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"Expected a string of length 1, got: %s" % (
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num, self.__class__.__name__, repr(value)))
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def wrong_type(self, num, value, expected):
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if type(value) == types.InstanceType:
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got = "%s.%s instance" % (
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value.__class__.__module__, value.__class__.__name__)
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else:
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got = type(value).__name__
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raise Errors.PlexTypeError("Invalid type for argument %d of Plex.%s "
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"(expected %s, got %s" % (
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num, self.__class__.__name__, expected, got))
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#
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# Primitive RE constructors
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# -------------------------
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#
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# These are the basic REs from which all others are built.
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#
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## class Char(RE):
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## """
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## Char(c) is an RE which matches the character |c|.
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## """
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## nullable = 0
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## def __init__(self, char):
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## self.char = char
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## self.match_nl = char == '\n'
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## def build_machine(self, m, initial_state, final_state, match_bol, nocase):
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## c = self.char
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## if match_bol and c != BOL:
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## s1 = self.build_opt(m, initial_state, BOL)
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## else:
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## s1 = initial_state
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## if c == '\n' or c == EOF:
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## s1 = self.build_opt(m, s1, EOL)
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## if len(c) == 1:
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## code = ord(self.char)
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## s1.add_transition((code, code+1), final_state)
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## if nocase and is_letter_code(code):
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## code2 = other_case_code(code)
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## s1.add_transition((code2, code2+1), final_state)
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## else:
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## s1.add_transition(c, final_state)
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## def calc_str(self):
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## return "Char(%s)" % repr(self.char)
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def Char(c):
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"""
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Char(c) is an RE which matches the character |c|.
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"""
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if len(c) == 1:
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result = CodeRange(ord(c), ord(c) + 1)
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else:
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result = SpecialSymbol(c)
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result.str = "Char(%s)" % repr(c)
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return result
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class RawCodeRange(RE):
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"""
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RawCodeRange(code1, code2) is a low-level RE which matches any character
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with a code |c| in the range |code1| <= |c| < |code2|, where the range
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does not include newline. For internal use only.
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"""
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nullable = 0
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match_nl = 0
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range = None # (code, code)
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uppercase_range = None # (code, code) or None
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lowercase_range = None # (code, code) or None
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def __init__(self, code1, code2):
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self.range = (code1, code2)
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self.uppercase_range = uppercase_range(code1, code2)
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self.lowercase_range = lowercase_range(code1, code2)
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def build_machine(self, m, initial_state, final_state, match_bol, nocase):
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if match_bol:
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initial_state = self.build_opt(m, initial_state, BOL)
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initial_state.add_transition(self.range, final_state)
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if nocase:
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if self.uppercase_range:
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initial_state.add_transition(self.uppercase_range, final_state)
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if self.lowercase_range:
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initial_state.add_transition(self.lowercase_range, final_state)
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def calc_str(self):
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return "CodeRange(%d,%d)" % (self.code1, self.code2)
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class _RawNewline(RE):
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"""
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RawNewline is a low-level RE which matches a newline character.
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For internal use only.
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"""
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nullable = 0
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match_nl = 1
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def build_machine(self, m, initial_state, final_state, match_bol, nocase):
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if match_bol:
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initial_state = self.build_opt(m, initial_state, BOL)
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s = self.build_opt(m, initial_state, EOL)
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s.add_transition((nl_code, nl_code + 1), final_state)
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RawNewline = _RawNewline()
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class SpecialSymbol(RE):
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"""
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SpecialSymbol(sym) is an RE which matches the special input
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symbol |sym|, which is one of BOL, EOL or EOF.
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"""
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nullable = 0
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match_nl = 0
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sym = None
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def __init__(self, sym):
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self.sym = sym
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def build_machine(self, m, initial_state, final_state, match_bol, nocase):
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# Sequences 'bol bol' and 'bol eof' are impossible, so only need
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# to allow for bol if sym is eol
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if match_bol and self.sym == EOL:
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initial_state = self.build_opt(m, initial_state, BOL)
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initial_state.add_transition(self.sym, final_state)
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class Seq(RE):
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"""Seq(re1, re2, re3...) is an RE which matches |re1| followed by
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|re2| followed by |re3|..."""
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def __init__(self, *re_list):
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nullable = 1
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for i, re in enumerate(re_list):
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self.check_re(i, re)
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nullable = nullable and re.nullable
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self.re_list = re_list
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self.nullable = nullable
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i = len(re_list)
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match_nl = 0
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while i:
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i -= 1
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re = re_list[i]
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if re.match_nl:
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match_nl = 1
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break
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if not re.nullable:
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break
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self.match_nl = match_nl
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def build_machine(self, m, initial_state, final_state, match_bol, nocase):
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re_list = self.re_list
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if len(re_list) == 0:
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initial_state.link_to(final_state)
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else:
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s1 = initial_state
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n = len(re_list)
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for i, re in enumerate(re_list):
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if i < n - 1:
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s2 = m.new_state()
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else:
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s2 = final_state
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re.build_machine(m, s1, s2, match_bol, nocase)
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s1 = s2
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match_bol = re.match_nl or (match_bol and re.nullable)
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def calc_str(self):
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return "Seq(%s)" % ','.join(map(str, self.re_list))
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class Alt(RE):
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"""Alt(re1, re2, re3...) is an RE which matches either |re1| or
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|re2| or |re3|..."""
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def __init__(self, *re_list):
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self.re_list = re_list
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nullable = 0
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match_nl = 0
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nullable_res = []
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non_nullable_res = []
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i = 1
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for re in re_list:
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self.check_re(i, re)
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if re.nullable:
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nullable_res.append(re)
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nullable = 1
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else:
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non_nullable_res.append(re)
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if re.match_nl:
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match_nl = 1
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i += 1
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self.nullable_res = nullable_res
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self.non_nullable_res = non_nullable_res
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self.nullable = nullable
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self.match_nl = match_nl
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def build_machine(self, m, initial_state, final_state, match_bol, nocase):
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for re in self.nullable_res:
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re.build_machine(m, initial_state, final_state, match_bol, nocase)
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if self.non_nullable_res:
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if match_bol:
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initial_state = self.build_opt(m, initial_state, BOL)
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for re in self.non_nullable_res:
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re.build_machine(m, initial_state, final_state, 0, nocase)
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def calc_str(self):
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return "Alt(%s)" % ','.join(map(str, self.re_list))
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class Rep1(RE):
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"""Rep1(re) is an RE which matches one or more repetitions of |re|."""
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def __init__(self, re):
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self.check_re(1, re)
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self.re = re
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self.nullable = re.nullable
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self.match_nl = re.match_nl
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def build_machine(self, m, initial_state, final_state, match_bol, nocase):
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s1 = m.new_state()
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s2 = m.new_state()
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initial_state.link_to(s1)
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self.re.build_machine(m, s1, s2, match_bol or self.re.match_nl, nocase)
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s2.link_to(s1)
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s2.link_to(final_state)
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def calc_str(self):
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return "Rep1(%s)" % self.re
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class SwitchCase(RE):
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"""
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SwitchCase(re, nocase) is an RE which matches the same strings as RE,
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but treating upper and lower case letters according to |nocase|. If
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|nocase| is true, case is ignored, otherwise it is not.
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"""
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re = None
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nocase = None
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def __init__(self, re, nocase):
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self.re = re
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self.nocase = nocase
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self.nullable = re.nullable
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self.match_nl = re.match_nl
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def build_machine(self, m, initial_state, final_state, match_bol, nocase):
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self.re.build_machine(m, initial_state, final_state, match_bol,
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self.nocase)
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def calc_str(self):
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if self.nocase:
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name = "NoCase"
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else:
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name = "Case"
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return "%s(%s)" % (name, self.re)
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#
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# Composite RE constructors
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# -------------------------
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#
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# These REs are defined in terms of the primitive REs.
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#
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Empty = Seq()
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Empty.__doc__ = \
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"""
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Empty is an RE which matches the empty string.
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"""
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Empty.str = "Empty"
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def Str1(s):
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"""
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Str1(s) is an RE which matches the literal string |s|.
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"""
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result = Seq(*tuple(map(Char, s)))
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result.str = "Str(%s)" % repr(s)
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return result
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def Str(*strs):
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"""
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Str(s) is an RE which matches the literal string |s|.
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Str(s1, s2, s3, ...) is an RE which matches any of |s1| or |s2| or |s3|...
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"""
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if len(strs) == 1:
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return Str1(strs[0])
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else:
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result = Alt(*tuple(map(Str1, strs)))
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result.str = "Str(%s)" % ','.join(map(repr, strs))
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return result
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def Any(s):
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"""
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Any(s) is an RE which matches any character in the string |s|.
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"""
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#result = apply(Alt, tuple(map(Char, s)))
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result = CodeRanges(chars_to_ranges(s))
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result.str = "Any(%s)" % repr(s)
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return result
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def AnyBut(s):
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"""
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AnyBut(s) is an RE which matches any character (including
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newline) which is not in the string |s|.
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"""
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ranges = chars_to_ranges(s)
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ranges.insert(0, -maxint)
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ranges.append(maxint)
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result = CodeRanges(ranges)
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result.str = "AnyBut(%s)" % repr(s)
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return result
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AnyChar = AnyBut("")
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AnyChar.__doc__ = \
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"""
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AnyChar is an RE which matches any single character (including a newline).
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"""
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AnyChar.str = "AnyChar"
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def Range(s1, s2=None):
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"""
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Range(c1, c2) is an RE which matches any single character in the range
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|c1| to |c2| inclusive.
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Range(s) where |s| is a string of even length is an RE which matches
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any single character in the ranges |s[0]| to |s[1]|, |s[2]| to |s[3]|,...
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"""
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if s2:
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result = CodeRange(ord(s1), ord(s2) + 1)
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result.str = "Range(%s,%s)" % (s1, s2)
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else:
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ranges = []
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for i in range(0, len(s1), 2):
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ranges.append(CodeRange(ord(s1[i]), ord(s1[i + 1]) + 1))
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result = Alt(*ranges)
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result.str = "Range(%s)" % repr(s1)
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return result
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def Opt(re):
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"""
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Opt(re) is an RE which matches either |re| or the empty string.
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"""
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result = Alt(re, Empty)
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result.str = "Opt(%s)" % re
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return result
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def Rep(re):
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"""
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Rep(re) is an RE which matches zero or more repetitions of |re|.
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"""
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result = Opt(Rep1(re))
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result.str = "Rep(%s)" % re
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return result
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def NoCase(re):
|
|
"""
|
|
NoCase(re) is an RE which matches the same strings as RE, but treating
|
|
upper and lower case letters as equivalent.
|
|
"""
|
|
return SwitchCase(re, nocase=1)
|
|
|
|
|
|
def Case(re):
|
|
"""
|
|
Case(re) is an RE which matches the same strings as RE, but treating
|
|
upper and lower case letters as distinct, i.e. it cancels the effect
|
|
of any enclosing NoCase().
|
|
"""
|
|
return SwitchCase(re, nocase=0)
|
|
|
|
#
|
|
# RE Constants
|
|
#
|
|
|
|
Bol = Char(BOL)
|
|
Bol.__doc__ = \
|
|
"""
|
|
Bol is an RE which matches the beginning of a line.
|
|
"""
|
|
Bol.str = "Bol"
|
|
|
|
Eol = Char(EOL)
|
|
Eol.__doc__ = \
|
|
"""
|
|
Eol is an RE which matches the end of a line.
|
|
"""
|
|
Eol.str = "Eol"
|
|
|
|
Eof = Char(EOF)
|
|
Eof.__doc__ = \
|
|
"""
|
|
Eof is an RE which matches the end of the file.
|
|
"""
|
|
Eof.str = "Eof"
|
|
|