# # Secret Labs' Regular Expression Engine # # convert re-style regular expression to sre pattern # # Copyright (c) 1998-2000 by Secret Labs AB. All rights reserved. # # See the sre.py file for information on usage and redistribution. # import string, sys from sre_constants import * SPECIAL_CHARS = ".\\[{()*+?^$|" REPEAT_CHARS = "*+?{" DIGITS = tuple("0123456789") OCTDIGITS = tuple("01234567") HEXDIGITS = tuple("0123456789abcdefABCDEF") WHITESPACE = tuple(" \t\n\r\v\f") ESCAPES = { r"\a": (LITERAL, 7), r"\b": (LITERAL, 8), r"\f": (LITERAL, 12), r"\n": (LITERAL, 10), r"\r": (LITERAL, 13), r"\t": (LITERAL, 9), r"\v": (LITERAL, 11), r"\\": (LITERAL, ord("\\")) } CATEGORIES = { r"\A": (AT, AT_BEGINNING), # start of string r"\b": (AT, AT_BOUNDARY), r"\B": (AT, AT_NON_BOUNDARY), r"\d": (IN, [(CATEGORY, CATEGORY_DIGIT)]), r"\D": (IN, [(CATEGORY, CATEGORY_NOT_DIGIT)]), r"\s": (IN, [(CATEGORY, CATEGORY_SPACE)]), r"\S": (IN, [(CATEGORY, CATEGORY_NOT_SPACE)]), r"\w": (IN, [(CATEGORY, CATEGORY_WORD)]), r"\W": (IN, [(CATEGORY, CATEGORY_NOT_WORD)]), r"\Z": (AT, AT_END), # end of string } FLAGS = { # standard flags "i": SRE_FLAG_IGNORECASE, "L": SRE_FLAG_LOCALE, "m": SRE_FLAG_MULTILINE, "s": SRE_FLAG_DOTALL, "x": SRE_FLAG_VERBOSE, # extensions "t": SRE_FLAG_TEMPLATE, "u": SRE_FLAG_UNICODE, } class Pattern: # master pattern object. keeps track of global attributes def __init__(self): self.flags = 0 self.groups = 1 self.groupdict = {} def getgroup(self, name=None): gid = self.groups self.groups = gid + 1 if name: self.groupdict[name] = gid return gid class SubPattern: # a subpattern, in intermediate form def __init__(self, pattern, data=None): self.pattern = pattern if not data: data = [] self.data = data self.width = None def dump(self, level=0): nl = 1 for op, av in self.data: print level*" " + op,; nl = 0 if op == "in": # member sublanguage print; nl = 1 for op, a in av: print (level+1)*" " + op, a elif op == "branch": print; nl = 1 i = 0 for a in av[1]: if i > 0: print level*" " + "or" a.dump(level+1); nl = 1 i = i + 1 elif type(av) in (type(()), type([])): for a in av: if isinstance(a, SubPattern): if not nl: print a.dump(level+1); nl = 1 else: print a, ; nl = 0 else: print av, ; nl = 0 if not nl: print def __repr__(self): return repr(self.data) def __len__(self): return len(self.data) def __delitem__(self, index): del self.data[index] def __getitem__(self, index): return self.data[index] def __setitem__(self, index, code): self.data[index] = code def __getslice__(self, start, stop): return SubPattern(self.pattern, self.data[start:stop]) def insert(self, index, code): self.data.insert(index, code) def append(self, code): self.data.append(code) def getwidth(self): # determine the width (min, max) for this subpattern if self.width: return self.width lo = hi = 0L for op, av in self.data: if op is BRANCH: i = sys.maxint j = 0 for av in av[1]: l, h = av.getwidth() i = min(i, l) j = max(j, h) lo = lo + i hi = hi + j elif op is CALL: i, j = av.getwidth() lo = lo + i hi = hi + j elif op is SUBPATTERN: i, j = av[1].getwidth() lo = lo + i hi = hi + j elif op in (MIN_REPEAT, MAX_REPEAT): i, j = av[2].getwidth() lo = lo + long(i) * av[0] hi = hi + long(j) * av[1] elif op in (ANY, RANGE, IN, LITERAL, NOT_LITERAL, CATEGORY): lo = lo + 1 hi = hi + 1 elif op == SUCCESS: break self.width = int(min(lo, sys.maxint)), int(min(hi, sys.maxint)) return self.width class Tokenizer: def __init__(self, string): self.string = string self.index = 0 self.__next() def __next(self): if self.index >= len(self.string): self.next = None return char = self.string[self.index] if char[0] == "\\": try: c = self.string[self.index + 1] except IndexError: raise error, "bogus escape" char = char + c self.index = self.index + len(char) self.next = char def match(self, char, skip=1): if char == self.next: if skip: self.__next() return 1 return 0 def get(self): this = self.next self.__next() return this def tell(self): return self.index, self.next def seek(self, index): self.index, self.next = index def isident(char): return "a" <= char <= "z" or "A" <= char <= "Z" or char == "_" def isdigit(char): return "0" <= char <= "9" def isname(name): # check that group name is a valid string if not isident(name[0]): return 0 for char in name: if not isident(char) and not isdigit(char): return 0 return 1 def _group(escape, groups): # check if the escape string represents a valid group try: gid = int(escape[1:]) if gid and gid < groups: return gid except ValueError: pass return None # not a valid group def _class_escape(source, escape): # handle escape code inside character class code = ESCAPES.get(escape) if code: return code code = CATEGORIES.get(escape) if code: return code try: if escape[1:2] == "x": # hexadecimal escape (exactly two digits) while source.next in HEXDIGITS and len(escape) < 4: escape = escape + source.get() escape = escape[2:] if len(escape) != 2: raise error, "bogus escape: %s" % repr("\\" + escape) return LITERAL, int(escape, 16) & 0xff elif str(escape[1:2]) in OCTDIGITS: # octal escape (up to three digits) while source.next in OCTDIGITS and len(escape) < 5: escape = escape + source.get() escape = escape[1:] return LITERAL, int(escape, 8) & 0xff if len(escape) == 2: return LITERAL, ord(escape[1]) except ValueError: pass raise error, "bogus escape: %s" % repr(escape) def _escape(source, escape, state): # handle escape code in expression code = CATEGORIES.get(escape) if code: return code code = ESCAPES.get(escape) if code: return code try: if escape[1:2] == "x": # hexadecimal escape while source.next in HEXDIGITS and len(escape) < 4: escape = escape + source.get() if len(escape) != 4: raise ValueError return LITERAL, int(escape[2:], 16) & 0xff elif escape[1:2] == "0": # octal escape while source.next in OCTDIGITS and len(escape) < 4: escape = escape + source.get() return LITERAL, int(escape[1:], 8) & 0xff elif escape[1:2] in DIGITS: # octal escape *or* decimal group reference (sigh) here = source.tell() if source.next in DIGITS: escape = escape + source.get() if (escape[1] in OCTDIGITS and escape[2] in OCTDIGITS and source.next in OCTDIGITS): # got three octal digits; this is an octal escape escape = escape + source.get() return LITERAL, int(escape[1:], 8) & 0xff # got at least one decimal digit; this is a group reference group = _group(escape, state.groups) if group: return GROUPREF, group raise ValueError if len(escape) == 2: return LITERAL, ord(escape[1]) except ValueError: pass raise error, "bogus escape: %s" % repr(escape) def _parse_sub(source, state, nested=1): # parse an alternation: a|b|c items = [] while 1: items.append(_parse(source, state)) if source.match("|"): continue if not nested: break if not source.next or source.match(")", 0): break else: raise error, "pattern not properly closed" if len(items) == 1: return items[0] subpattern = SubPattern(state) # check if all items share a common prefix while 1: prefix = None for item in items: if not item: break if prefix is None: prefix = item[0] elif item[0] != prefix: break else: # all subitems start with a common "prefix". # move it out of the branch for item in items: del item[0] subpattern.append(prefix) continue # check next one break # check if the branch can be replaced by a character set for item in items: if len(item) != 1 or item[0][0] != LITERAL: break else: # we can store this as a character set instead of a # branch (the compiler may optimize this even more) set = [] for item in items: set.append(item[0]) subpattern.append((IN, set)) return subpattern subpattern.append((BRANCH, (None, items))) return subpattern def _parse(source, state): # parse a simple pattern subpattern = SubPattern(state) while 1: if source.next in ("|", ")"): break # end of subpattern this = source.get() if this is None: break # end of pattern if state.flags & SRE_FLAG_VERBOSE: # skip whitespace and comments if this in WHITESPACE: continue if this == "#": while 1: this = source.get() if this in (None, "\n"): break continue if this and this[0] not in SPECIAL_CHARS: subpattern.append((LITERAL, ord(this))) elif this == "[": # character set set = [] ## if source.match(":"): ## pass # handle character classes if source.match("^"): set.append((NEGATE, None)) # check remaining characters start = set[:] while 1: this = source.get() if this == "]" and set != start: break elif this and this[0] == "\\": code1 = _class_escape(source, this) elif this: code1 = LITERAL, ord(this) else: raise error, "unexpected end of regular expression" if source.match("-"): # potential range this = source.get() if this == "]": if code1[0] is IN: code1 = code1[1][0] set.append(code1) set.append((LITERAL, ord("-"))) break else: if this[0] == "\\": code2 = _class_escape(source, this) else: code2 = LITERAL, ord(this) if code1[0] != LITERAL or code2[0] != LITERAL: raise error, "illegal range" lo = code1[1] hi = code2[1] if hi < lo: raise error, "illegal range" set.append((RANGE, (lo, hi))) else: if code1[0] is IN: code1 = code1[1][0] set.append(code1) # FIXME: 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: # FIXME: add charmap optimization 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 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 = int(lo) if hi: max = int(hi) # FIXME: check that hi >= lo! else: raise error, "not supported" # figure out which item to repeat if subpattern: item = subpattern[-1:] else: raise error, "nothing to 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, "illegal 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, "illegal 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 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.getgroup(name) p = _parse_sub(source, state) if not source.match(")"): raise error, "unbalanced parenthesis" 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: 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)