mirror of
https://github.com/python/cpython.git
synced 2025-10-31 21:51:50 +00:00
ebc37b28fa
-- fixed negative lookbehind to work correctly at the beginning of the target string (bug #117242) -- improved syntax check; you can no longer refer to a group inside itself (bug #110866)
692 lines
22 KiB
Python
692 lines
22 KiB
Python
#
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# Secret Labs' Regular Expression Engine
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#
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# convert re-style regular expression to sre pattern
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#
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# Copyright (c) 1998-2000 by Secret Labs AB. All rights reserved.
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#
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# See the sre.py file for information on usage and redistribution.
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#
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import string, sys
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from sre_constants import *
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SPECIAL_CHARS = ".\\[{()*+?^$|"
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REPEAT_CHARS = "*+?{"
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DIGITS = tuple("0123456789")
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OCTDIGITS = tuple("01234567")
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HEXDIGITS = tuple("0123456789abcdefABCDEF")
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WHITESPACE = tuple(" \t\n\r\v\f")
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ESCAPES = {
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r"\a": (LITERAL, 7),
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r"\b": (LITERAL, 8),
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r"\f": (LITERAL, 12),
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r"\n": (LITERAL, 10),
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r"\r": (LITERAL, 13),
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r"\t": (LITERAL, 9),
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r"\v": (LITERAL, 11),
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r"\\": (LITERAL, ord("\\"))
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}
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CATEGORIES = {
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r"\A": (AT, AT_BEGINNING), # start of string
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r"\b": (AT, AT_BOUNDARY),
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r"\B": (AT, AT_NON_BOUNDARY),
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r"\d": (IN, [(CATEGORY, CATEGORY_DIGIT)]),
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r"\D": (IN, [(CATEGORY, CATEGORY_NOT_DIGIT)]),
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r"\s": (IN, [(CATEGORY, CATEGORY_SPACE)]),
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r"\S": (IN, [(CATEGORY, CATEGORY_NOT_SPACE)]),
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r"\w": (IN, [(CATEGORY, CATEGORY_WORD)]),
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r"\W": (IN, [(CATEGORY, CATEGORY_NOT_WORD)]),
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r"\Z": (AT, AT_END), # end of string
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}
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FLAGS = {
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# standard flags
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"i": SRE_FLAG_IGNORECASE,
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"L": SRE_FLAG_LOCALE,
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"m": SRE_FLAG_MULTILINE,
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"s": SRE_FLAG_DOTALL,
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"x": SRE_FLAG_VERBOSE,
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# extensions
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"t": SRE_FLAG_TEMPLATE,
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"u": SRE_FLAG_UNICODE,
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}
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class Pattern:
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# master pattern object. keeps track of global attributes
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def __init__(self):
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self.flags = 0
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self.open = []
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self.groups = 1
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self.groupdict = {}
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def opengroup(self, name=None):
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gid = self.groups
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self.groups = gid + 1
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if name:
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self.groupdict[name] = gid
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self.open.append(gid)
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return gid
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def closegroup(self, gid):
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self.open.remove(gid)
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def checkgroup(self, gid):
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return gid < self.groups and gid not in self.open
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class SubPattern:
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# a subpattern, in intermediate form
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def __init__(self, pattern, data=None):
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self.pattern = pattern
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if not data:
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data = []
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self.data = data
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self.width = None
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def dump(self, level=0):
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nl = 1
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for op, av in self.data:
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print level*" " + op,; nl = 0
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if op == "in":
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# member sublanguage
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print; nl = 1
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for op, a in av:
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print (level+1)*" " + op, a
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elif op == "branch":
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print; nl = 1
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i = 0
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for a in av[1]:
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if i > 0:
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print level*" " + "or"
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a.dump(level+1); nl = 1
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i = i + 1
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elif type(av) in (type(()), type([])):
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for a in av:
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if isinstance(a, SubPattern):
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if not nl: print
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a.dump(level+1); nl = 1
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else:
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print a, ; nl = 0
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else:
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print av, ; nl = 0
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if not nl: print
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def __repr__(self):
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return repr(self.data)
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def __len__(self):
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return len(self.data)
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def __delitem__(self, index):
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del self.data[index]
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def __getitem__(self, index):
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return self.data[index]
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def __setitem__(self, index, code):
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self.data[index] = code
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def __getslice__(self, start, stop):
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return SubPattern(self.pattern, self.data[start:stop])
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def insert(self, index, code):
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self.data.insert(index, code)
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def append(self, code):
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self.data.append(code)
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def getwidth(self):
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# determine the width (min, max) for this subpattern
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if self.width:
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return self.width
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lo = hi = 0L
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for op, av in self.data:
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if op is BRANCH:
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i = sys.maxint
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j = 0
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for av in av[1]:
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l, h = av.getwidth()
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i = min(i, l)
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j = max(j, h)
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lo = lo + i
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hi = hi + j
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elif op is CALL:
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i, j = av.getwidth()
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lo = lo + i
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hi = hi + j
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elif op is SUBPATTERN:
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i, j = av[1].getwidth()
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lo = lo + i
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hi = hi + j
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elif op in (MIN_REPEAT, MAX_REPEAT):
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i, j = av[2].getwidth()
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lo = lo + long(i) * av[0]
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hi = hi + long(j) * av[1]
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elif op in (ANY, RANGE, IN, LITERAL, NOT_LITERAL, CATEGORY):
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lo = lo + 1
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hi = hi + 1
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elif op == SUCCESS:
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break
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self.width = int(min(lo, sys.maxint)), int(min(hi, sys.maxint))
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return self.width
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class Tokenizer:
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def __init__(self, string):
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self.string = string
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self.index = 0
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self.__next()
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def __next(self):
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if self.index >= len(self.string):
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self.next = None
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return
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char = self.string[self.index]
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if char[0] == "\\":
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try:
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c = self.string[self.index + 1]
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except IndexError:
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raise error, "bogus escape"
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char = char + c
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self.index = self.index + len(char)
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self.next = char
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def match(self, char, skip=1):
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if char == self.next:
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if skip:
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self.__next()
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return 1
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return 0
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def get(self):
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this = self.next
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self.__next()
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return this
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def tell(self):
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return self.index, self.next
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def seek(self, index):
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self.index, self.next = index
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def isident(char):
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return "a" <= char <= "z" or "A" <= char <= "Z" or char == "_"
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def isdigit(char):
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return "0" <= char <= "9"
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def isname(name):
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# check that group name is a valid string
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if not isident(name[0]):
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return 0
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for char in name:
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if not isident(char) and not isdigit(char):
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return 0
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return 1
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def _group(escape, groups):
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# check if the escape string represents a valid group
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try:
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gid = int(escape[1:])
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if gid and gid < groups:
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return gid
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except ValueError:
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pass
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return None # not a valid group
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def _class_escape(source, escape):
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# handle escape code inside character class
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code = ESCAPES.get(escape)
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if code:
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return code
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code = CATEGORIES.get(escape)
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if code:
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return code
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try:
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if escape[1:2] == "x":
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# hexadecimal escape (exactly two digits)
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while source.next in HEXDIGITS and len(escape) < 4:
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escape = escape + source.get()
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escape = escape[2:]
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if len(escape) != 2:
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raise error, "bogus escape: %s" % repr("\\" + escape)
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return LITERAL, int(escape, 16) & 0xff
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elif str(escape[1:2]) in OCTDIGITS:
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# octal escape (up to three digits)
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while source.next in OCTDIGITS and len(escape) < 5:
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escape = escape + source.get()
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escape = escape[1:]
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return LITERAL, int(escape, 8) & 0xff
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if len(escape) == 2:
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return LITERAL, ord(escape[1])
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except ValueError:
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pass
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raise error, "bogus escape: %s" % repr(escape)
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def _escape(source, escape, state):
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# handle escape code in expression
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code = CATEGORIES.get(escape)
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if code:
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return code
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code = ESCAPES.get(escape)
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if code:
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return code
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try:
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if escape[1:2] == "x":
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# hexadecimal escape
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while source.next in HEXDIGITS and len(escape) < 4:
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escape = escape + source.get()
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if len(escape) != 4:
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raise ValueError
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return LITERAL, int(escape[2:], 16) & 0xff
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elif escape[1:2] == "0":
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# octal escape
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while source.next in OCTDIGITS and len(escape) < 4:
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escape = escape + source.get()
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return LITERAL, int(escape[1:], 8) & 0xff
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elif escape[1:2] in DIGITS:
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# octal escape *or* decimal group reference (sigh)
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here = source.tell()
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if source.next in DIGITS:
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escape = escape + source.get()
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if (escape[1] in OCTDIGITS and escape[2] in OCTDIGITS and
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source.next in OCTDIGITS):
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# got three octal digits; this is an octal escape
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escape = escape + source.get()
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return LITERAL, int(escape[1:], 8) & 0xff
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# got at least one decimal digit; this is a group reference
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group = _group(escape, state.groups)
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if group:
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if not state.checkgroup(group):
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raise error, "cannot refer to open group"
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return GROUPREF, group
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raise ValueError
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if len(escape) == 2:
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return LITERAL, ord(escape[1])
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except ValueError:
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pass
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raise error, "bogus escape: %s" % repr(escape)
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def _parse_sub(source, state, nested=1):
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# parse an alternation: a|b|c
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items = []
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while 1:
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items.append(_parse(source, state))
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if source.match("|"):
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continue
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if not nested:
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break
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if not source.next or source.match(")", 0):
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break
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else:
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raise error, "pattern not properly closed"
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if len(items) == 1:
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return items[0]
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subpattern = SubPattern(state)
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# check if all items share a common prefix
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while 1:
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prefix = None
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for item in items:
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if not item:
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break
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if prefix is None:
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prefix = item[0]
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elif item[0] != prefix:
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break
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else:
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# all subitems start with a common "prefix".
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# move it out of the branch
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for item in items:
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del item[0]
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subpattern.append(prefix)
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continue # check next one
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break
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# check if the branch can be replaced by a character set
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for item in items:
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if len(item) != 1 or item[0][0] != LITERAL:
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break
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else:
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# we can store this as a character set instead of a
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# branch (the compiler may optimize this even more)
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set = []
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for item in items:
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set.append(item[0])
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subpattern.append((IN, set))
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return subpattern
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subpattern.append((BRANCH, (None, items)))
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return subpattern
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def _parse(source, state):
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# parse a simple pattern
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subpattern = SubPattern(state)
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while 1:
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if source.next in ("|", ")"):
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break # end of subpattern
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this = source.get()
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if this is None:
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break # end of pattern
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if state.flags & SRE_FLAG_VERBOSE:
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# skip whitespace and comments
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if this in WHITESPACE:
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continue
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if this == "#":
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while 1:
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this = source.get()
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if this in (None, "\n"):
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break
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continue
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if this and this[0] not in SPECIAL_CHARS:
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subpattern.append((LITERAL, ord(this)))
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elif this == "[":
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# character set
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set = []
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## if source.match(":"):
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## pass # handle character classes
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if source.match("^"):
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set.append((NEGATE, None))
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# check remaining characters
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start = set[:]
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while 1:
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this = source.get()
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if this == "]" and set != start:
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break
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elif this and this[0] == "\\":
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code1 = _class_escape(source, this)
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elif this:
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code1 = LITERAL, ord(this)
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else:
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raise error, "unexpected end of regular expression"
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if source.match("-"):
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# potential range
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this = source.get()
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if this == "]":
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if code1[0] is IN:
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code1 = code1[1][0]
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set.append(code1)
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set.append((LITERAL, ord("-")))
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break
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else:
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if this[0] == "\\":
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code2 = _class_escape(source, this)
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else:
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code2 = LITERAL, ord(this)
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if code1[0] != LITERAL or code2[0] != LITERAL:
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raise error, "illegal range"
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lo = code1[1]
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hi = code2[1]
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if hi < lo:
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raise error, "illegal range"
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set.append((RANGE, (lo, hi)))
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else:
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if code1[0] is IN:
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code1 = code1[1][0]
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set.append(code1)
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# FIXME: <fl> move set optimization to compiler!
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if len(set)==1 and set[0][0] is LITERAL:
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subpattern.append(set[0]) # optimization
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elif len(set)==2 and set[0][0] is NEGATE and set[1][0] is LITERAL:
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subpattern.append((NOT_LITERAL, set[1][1])) # optimization
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else:
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# FIXME: <fl> add charmap optimization
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subpattern.append((IN, set))
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elif this and this[0] in REPEAT_CHARS:
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# repeat previous item
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if this == "?":
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min, max = 0, 1
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elif this == "*":
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min, max = 0, MAXREPEAT
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elif this == "+":
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min, max = 1, MAXREPEAT
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elif this == "{":
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here = source.tell()
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min, max = 0, MAXREPEAT
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lo = hi = ""
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while source.next in DIGITS:
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lo = lo + source.get()
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if source.match(","):
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while source.next in DIGITS:
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hi = hi + source.get()
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else:
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hi = lo
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if not source.match("}"):
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subpattern.append((LITERAL, ord(this)))
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source.seek(here)
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continue
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if lo:
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min = int(lo)
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if hi:
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max = int(hi)
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# FIXME: <fl> check that hi >= lo!
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else:
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raise error, "not supported"
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# figure out which item to repeat
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if subpattern:
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item = subpattern[-1:]
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else:
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raise error, "nothing to repeat"
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if source.match("?"):
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subpattern[-1] = (MIN_REPEAT, (min, max, item))
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else:
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subpattern[-1] = (MAX_REPEAT, (min, max, item))
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elif this == ".":
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subpattern.append((ANY, None))
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elif this == "(":
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group = 1
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name = None
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if source.match("?"):
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group = 0
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# options
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if source.match("P"):
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# python extensions
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if source.match("<"):
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# named group: skip forward to end of name
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name = ""
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while 1:
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char = source.get()
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if char is None:
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raise error, "unterminated name"
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if char == ">":
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break
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name = name + char
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group = 1
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if not isname(name):
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raise error, "illegal character in group name"
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elif source.match("="):
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# named backreference
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name = ""
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while 1:
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char = source.get()
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if char is None:
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raise error, "unterminated name"
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if char == ")":
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break
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name = name + char
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if not isname(name):
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raise error, "illegal character in group name"
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gid = state.groupdict.get(name)
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if gid is None:
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raise error, "unknown group name"
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subpattern.append((GROUPREF, gid))
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continue
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else:
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char = source.get()
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if char is None:
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raise error, "unexpected end of pattern"
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raise error, "unknown specifier: ?P%s" % char
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elif source.match(":"):
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# non-capturing group
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group = 2
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elif source.match("#"):
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# comment
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while 1:
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if source.next is None or source.next == ")":
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break
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source.get()
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if not source.match(")"):
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raise error, "unbalanced parenthesis"
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continue
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elif source.next in ("=", "!", "<"):
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# lookahead assertions
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char = source.get()
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dir = 1
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if char == "<":
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if source.next not in ("=", "!"):
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raise error, "syntax error"
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dir = -1 # lookbehind
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|
char = source.get()
|
|
p = _parse_sub(source, state)
|
|
if not source.match(")"):
|
|
raise error, "unbalanced parenthesis"
|
|
if char == "=":
|
|
subpattern.append((ASSERT, (dir, p)))
|
|
else:
|
|
subpattern.append((ASSERT_NOT, (dir, p)))
|
|
continue
|
|
else:
|
|
# flags
|
|
while FLAGS.has_key(source.next):
|
|
state.flags = state.flags | FLAGS[source.get()]
|
|
if group:
|
|
# parse group contents
|
|
if group == 2:
|
|
# anonymous group
|
|
group = None
|
|
else:
|
|
group = state.opengroup(name)
|
|
p = _parse_sub(source, state)
|
|
if not source.match(")"):
|
|
raise error, "unbalanced parenthesis"
|
|
if group is not None:
|
|
state.closegroup(group)
|
|
subpattern.append((SUBPATTERN, (group, p)))
|
|
else:
|
|
while 1:
|
|
char = source.get()
|
|
if char is None or char == ")":
|
|
break
|
|
raise error, "unknown extension"
|
|
|
|
elif this == "^":
|
|
subpattern.append((AT, AT_BEGINNING))
|
|
|
|
elif this == "$":
|
|
subpattern.append((AT, AT_END))
|
|
|
|
elif this and this[0] == "\\":
|
|
code = _escape(source, this, state)
|
|
subpattern.append(code)
|
|
|
|
else:
|
|
raise error, "parser error"
|
|
|
|
return subpattern
|
|
|
|
def parse(str, flags=0, pattern=None):
|
|
# parse 're' pattern into list of (opcode, argument) tuples
|
|
|
|
source = Tokenizer(str)
|
|
|
|
if pattern is None:
|
|
pattern = Pattern()
|
|
pattern.flags = flags
|
|
|
|
p = _parse_sub(source, pattern, 0)
|
|
|
|
tail = source.get()
|
|
if tail == ")":
|
|
raise error, "unbalanced parenthesis"
|
|
elif tail:
|
|
raise error, "bogus characters at end of regular expression"
|
|
|
|
# p.dump()
|
|
|
|
if not (flags & SRE_FLAG_VERBOSE) and p.pattern.flags & SRE_FLAG_VERBOSE:
|
|
# the VERBOSE flag was switched on inside the pattern. to be
|
|
# on the safe side, we'll parse the whole thing again...
|
|
return parse(str, p.pattern.flags)
|
|
|
|
return p
|
|
|
|
def parse_template(source, pattern):
|
|
# parse 're' replacement string into list of literals and
|
|
# group references
|
|
s = Tokenizer(source)
|
|
p = []
|
|
a = p.append
|
|
while 1:
|
|
this = s.get()
|
|
if this is None:
|
|
break # end of replacement string
|
|
if this and this[0] == "\\":
|
|
# group
|
|
if this == "\\g":
|
|
name = ""
|
|
if s.match("<"):
|
|
while 1:
|
|
char = s.get()
|
|
if char is None:
|
|
raise error, "unterminated group name"
|
|
if char == ">":
|
|
break
|
|
name = name + char
|
|
if not name:
|
|
raise error, "bad group name"
|
|
try:
|
|
index = int(name)
|
|
except ValueError:
|
|
if not isname(name):
|
|
raise error, "illegal character in group name"
|
|
try:
|
|
index = pattern.groupindex[name]
|
|
except KeyError:
|
|
raise IndexError, "unknown group name"
|
|
a((MARK, index))
|
|
elif len(this) > 1 and this[1] in DIGITS:
|
|
code = None
|
|
while 1:
|
|
group = _group(this, pattern.groups+1)
|
|
if group:
|
|
if (s.next not in DIGITS or
|
|
not _group(this + s.next, pattern.groups+1)):
|
|
code = MARK, int(group)
|
|
break
|
|
elif s.next in OCTDIGITS:
|
|
this = this + s.get()
|
|
else:
|
|
break
|
|
if not code:
|
|
this = this[1:]
|
|
code = LITERAL, int(this[-6:], 8) & 0xff
|
|
a(code)
|
|
else:
|
|
try:
|
|
a(ESCAPES[this])
|
|
except KeyError:
|
|
for c in this:
|
|
a((LITERAL, ord(c)))
|
|
else:
|
|
a((LITERAL, ord(this)))
|
|
return p
|
|
|
|
def expand_template(template, match):
|
|
# FIXME: <fl> this is sooooo slow. drop in the slicelist
|
|
# code instead
|
|
p = []
|
|
a = p.append
|
|
sep = match.string[:0]
|
|
if type(sep) is type(""):
|
|
char = chr
|
|
else:
|
|
char = unichr
|
|
for c, s in template:
|
|
if c is LITERAL:
|
|
a(char(s))
|
|
elif c is MARK:
|
|
s = match.group(s)
|
|
if s is None:
|
|
raise error, "empty group"
|
|
a(s)
|
|
return string.join(p, sep)
|