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