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739 lines
24 KiB
739 lines
24 KiB
# |
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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) 1998-2001 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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|
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"""Internal support module for sre""" |
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|
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# XXX: show string offset and offending character for all errors |
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|
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# this module works under 1.5.2 and later. don't use string methods |
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import string, sys |
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|
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from sre_constants import * |
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|
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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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|
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ESCAPES = { |
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r"\a": (LITERAL, ord("\a")), |
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r"\b": (LITERAL, ord("\b")), |
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r"\f": (LITERAL, ord("\f")), |
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r"\n": (LITERAL, ord("\n")), |
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r"\r": (LITERAL, ord("\r")), |
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r"\t": (LITERAL, ord("\t")), |
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r"\v": (LITERAL, ord("\v")), |
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r"\\": (LITERAL, ord("\\")) |
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} |
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|
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CATEGORIES = { |
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r"\A": (AT, AT_BEGINNING_STRING), # 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_STRING), # 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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# figure out best way to convert hex/octal numbers to integers |
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try: |
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int("10", 8) |
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atoi = int # 2.0 and later |
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except TypeError: |
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atoi = string.atoi # 1.5.2 |
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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 is not None: |
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ogid = self.groupdict.get(name, None) |
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if ogid is not None: |
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raise error, ("redefinition of group name %s as group %d; " |
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"was group %d" % (repr(name), gid, ogid)) |
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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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|
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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 data is None: |
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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 (end of line)" |
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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 False |
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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 False |
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return True |
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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 = atoi(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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|
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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, atoi(escape, 16) & 0xff |
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elif 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, atoi(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, atoi(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, atoi(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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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, atoi(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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|
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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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|
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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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|
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if len(items) == 1: |
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return items[0] |
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|
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subpattern = SubPattern(state) |
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|
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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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|
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subpattern.append((BRANCH, (None, items))) |
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return subpattern |
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|
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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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|
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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() |
|
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))) |
|
|
|
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 |
|
if source.match("^"): |
|
set.append((NEGATE, None)) |
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# check remaining characters |
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start = set[:] |
|
while 1: |
|
this = source.get() |
|
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) |
|
elif this: |
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code1 = LITERAL, ord(this) |
|
else: |
|
raise error, "unexpected end of regular expression" |
|
if source.match("-"): |
|
# potential range |
|
this = source.get() |
|
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("-"))) |
|
break |
|
elif this: |
|
if this[0] == "\\": |
|
code2 = _class_escape(source, this) |
|
else: |
|
code2 = LITERAL, ord(this) |
|
if code1[0] != LITERAL or code2[0] != LITERAL: |
|
raise error, "bad character range" |
|
lo = code1[1] |
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hi = code2[1] |
|
if hi < lo: |
|
raise error, "bad character range" |
|
set.append((RANGE, (lo, hi))) |
|
else: |
|
raise error, "unexpected end of regular expression" |
|
else: |
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if code1[0] is IN: |
|
code1 = code1[1][0] |
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set.append(code1) |
|
|
|
# XXX: <fl> should move set optimization to compiler! |
|
if len(set)==1 and set[0][0] is LITERAL: |
|
subpattern.append(set[0]) # optimization |
|
elif len(set)==2 and set[0][0] is NEGATE and set[1][0] is LITERAL: |
|
subpattern.append((NOT_LITERAL, set[1][1])) # optimization |
|
else: |
|
# XXX: <fl> should add charmap optimization here |
|
subpattern.append((IN, set)) |
|
|
|
elif this and this[0] in REPEAT_CHARS: |
|
# repeat previous item |
|
if this == "?": |
|
min, max = 0, 1 |
|
elif this == "*": |
|
min, max = 0, MAXREPEAT |
|
|
|
elif this == "+": |
|
min, max = 1, MAXREPEAT |
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elif this == "{": |
|
here = source.tell() |
|
min, max = 0, MAXREPEAT |
|
lo = hi = "" |
|
while source.next in DIGITS: |
|
lo = lo + source.get() |
|
if source.match(","): |
|
while source.next in DIGITS: |
|
hi = hi + source.get() |
|
else: |
|
hi = lo |
|
if not source.match("}"): |
|
subpattern.append((LITERAL, ord(this))) |
|
source.seek(here) |
|
continue |
|
if lo: |
|
min = atoi(lo) |
|
if hi: |
|
max = atoi(hi) |
|
if max < min: |
|
raise error, "bad repeat interval" |
|
else: |
|
raise error, "not supported" |
|
# figure out which item to repeat |
|
if subpattern: |
|
item = subpattern[-1:] |
|
else: |
|
item = None |
|
if not item or (len(item) == 1 and item[0][0] == AT): |
|
raise error, "nothing to repeat" |
|
if item[0][0] in (MIN_REPEAT, MAX_REPEAT): |
|
raise error, "multiple repeat" |
|
if source.match("?"): |
|
subpattern[-1] = (MIN_REPEAT, (min, max, item)) |
|
else: |
|
subpattern[-1] = (MAX_REPEAT, (min, max, item)) |
|
|
|
elif this == ".": |
|
subpattern.append((ANY, None)) |
|
|
|
elif this == "(": |
|
group = 1 |
|
name = None |
|
if source.match("?"): |
|
group = 0 |
|
# options |
|
if source.match("P"): |
|
# python extensions |
|
if source.match("<"): |
|
# named group: skip forward to end of name |
|
name = "" |
|
while 1: |
|
char = source.get() |
|
if char is None: |
|
raise error, "unterminated name" |
|
if char == ">": |
|
break |
|
name = name + char |
|
group = 1 |
|
if not isname(name): |
|
raise error, "bad character in group name" |
|
elif source.match("="): |
|
# named backreference |
|
name = "" |
|
while 1: |
|
char = source.get() |
|
if char is None: |
|
raise error, "unterminated name" |
|
if char == ")": |
|
break |
|
name = name + char |
|
if not isname(name): |
|
raise error, "bad character in group name" |
|
gid = state.groupdict.get(name) |
|
if gid is None: |
|
raise error, "unknown group name" |
|
subpattern.append((GROUPREF, gid)) |
|
continue |
|
else: |
|
char = source.get() |
|
if char is None: |
|
raise error, "unexpected end of pattern" |
|
raise error, "unknown specifier: ?P%s" % char |
|
elif source.match(":"): |
|
# non-capturing group |
|
group = 2 |
|
elif source.match("#"): |
|
# comment |
|
while 1: |
|
if source.next is None or source.next == ")": |
|
break |
|
source.get() |
|
if not source.match(")"): |
|
raise error, "unbalanced parenthesis" |
|
continue |
|
elif source.next in ("=", "!", "<"): |
|
# lookahead assertions |
|
char = source.get() |
|
dir = 1 |
|
if char == "<": |
|
if source.next not in ("=", "!"): |
|
raise error, "syntax error" |
|
dir = -1 # lookbehind |
|
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 |
|
if not source.next in FLAGS: |
|
raise error, "unexpected end of pattern" |
|
while source.next in FLAGS: |
|
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: |
|
raise error, "unexpected end of pattern" |
|
if 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 |
|
pattern.str = str |
|
|
|
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" |
|
|
|
if flags & SRE_FLAG_DEBUG: |
|
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 |
|
def literal(literal, p=p): |
|
if p and p[-1][0] is LITERAL: |
|
p[-1] = LITERAL, p[-1][1] + literal |
|
else: |
|
p.append((LITERAL, literal)) |
|
sep = source[:0] |
|
if type(sep) is type(""): |
|
makechar = chr |
|
else: |
|
makechar = unichr |
|
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 = atoi(name) |
|
except ValueError: |
|
if not isname(name): |
|
raise error, "bad 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, group |
|
break |
|
elif s.next in OCTDIGITS: |
|
this = this + s.get() |
|
else: |
|
break |
|
if not code: |
|
this = this[1:] |
|
code = LITERAL, makechar(atoi(this[-6:], 8) & 0xff) |
|
if code[0] is LITERAL: |
|
literal(code[1]) |
|
else: |
|
a(code) |
|
else: |
|
try: |
|
this = makechar(ESCAPES[this][1]) |
|
except KeyError: |
|
pass |
|
literal(this) |
|
else: |
|
literal(this) |
|
# convert template to groups and literals lists |
|
i = 0 |
|
groups = [] |
|
literals = [] |
|
for c, s in p: |
|
if c is MARK: |
|
groups.append((i, s)) |
|
literals.append(None) |
|
else: |
|
literals.append(s) |
|
i = i + 1 |
|
return groups, literals |
|
|
|
def expand_template(template, match): |
|
g = match.group |
|
sep = match.string[:0] |
|
groups, literals = template |
|
literals = literals[:] |
|
try: |
|
for index, group in groups: |
|
literals[index] = s = g(group) |
|
if s is None: |
|
raise IndexError |
|
except IndexError: |
|
raise error, "empty group" |
|
return string.join(literals, sep)
|
|
|