| # |
| # Secret Labs' Regular Expression Engine |
| # |
| # convert re-style regular expression to sre pattern |
| # |
| # Copyright (c) 1998-2001 by Secret Labs AB. All rights reserved. |
| # |
| # See the sre.py file for information on usage and redistribution. |
| # |
| |
| """Internal support module for sre""" |
| |
| # XXX: show string offset and offending character for all errors |
| |
| import sys |
| |
| from sre_constants import * |
| |
| def set(seq): |
| s = {} |
| for elem in seq: |
| s[elem] = 1 |
| return s |
| |
| SPECIAL_CHARS = ".\\[{()*+?^$|" |
| REPEAT_CHARS = "*+?{" |
| |
| DIGITS = set("0123456789") |
| |
| OCTDIGITS = set("01234567") |
| HEXDIGITS = set("0123456789abcdefABCDEF") |
| |
| WHITESPACE = set(" \t\n\r\v\f") |
| |
| ESCAPES = { |
| r"\a": (LITERAL, ord("\a")), |
| r"\b": (LITERAL, ord("\b")), |
| r"\f": (LITERAL, ord("\f")), |
| r"\n": (LITERAL, ord("\n")), |
| r"\r": (LITERAL, ord("\r")), |
| r"\t": (LITERAL, ord("\t")), |
| r"\v": (LITERAL, ord("\v")), |
| r"\\": (LITERAL, ord("\\")) |
| } |
| |
| CATEGORIES = { |
| r"\A": (AT, AT_BEGINNING_STRING), # 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_STRING), # 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.open = [] |
| self.groups = 1 |
| self.groupdict = {} |
| def opengroup(self, name=None): |
| gid = self.groups |
| self.groups = gid + 1 |
| if name is not None: |
| ogid = self.groupdict.get(name, None) |
| if ogid is not None: |
| raise error, ("redefinition of group name %s as group %d; " |
| "was group %d" % (repr(name), gid, ogid)) |
| self.groupdict[name] = gid |
| self.open.append(gid) |
| return gid |
| def closegroup(self, gid): |
| self.open.remove(gid) |
| def checkgroup(self, gid): |
| return gid < self.groups and gid not in self.open |
| |
| class SubPattern: |
| # a subpattern, in intermediate form |
| def __init__(self, pattern, data=None): |
| self.pattern = pattern |
| if data is None: |
| data = [] |
| self.data = data |
| self.width = None |
| def dump(self, level=0): |
| nl = 1 |
| seqtypes = (tuple, list) |
| for op, av in self.data: |
| print(level*" " + op, end=' '); 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 isinstance(av, seqtypes): |
| for a in av: |
| if isinstance(a, SubPattern): |
| if not nl: print() |
| a.dump(level+1); nl = 1 |
| else: |
| print(a, end=' ') ; nl = 0 |
| else: |
| print(av, end=' ') ; 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): |
| if isinstance(index, slice): |
| return SubPattern(self.pattern, self.data[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 = 0 |
| UNITCODES = (ANY, RANGE, IN, LITERAL, NOT_LITERAL, CATEGORY) |
| REPEATCODES = (MIN_REPEAT, MAX_REPEAT) |
| 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 REPEATCODES: |
| i, j = av[2].getwidth() |
| lo = lo + int(i) * av[0] |
| hi = hi + int(j) * av[1] |
| elif op in UNITCODES: |
| 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 (end of line)" |
| 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 False |
| for char in name[1:]: |
| if not isident(char) and not isdigit(char): |
| return False |
| return True |
| |
| 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: |
| c = escape[1:2] |
| if c == "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 c in OCTDIGITS: |
| # octal escape (up to three digits) |
| while source.next in OCTDIGITS and len(escape) < 4: |
| escape = escape + source.get() |
| escape = escape[1:] |
| return LITERAL, int(escape, 8) & 0xff |
| elif c in DIGITS: |
| raise error, "bogus escape: %s" % repr(escape) |
| 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: |
| c = escape[1:2] |
| if c == "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 c == "0": |
| # octal escape |
| while source.next in OCTDIGITS and len(escape) < 4: |
| escape = escape + source.get() |
| return LITERAL, int(escape[1:], 8) & 0xff |
| elif c in DIGITS: |
| # octal escape *or* decimal group reference (sigh) |
| 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 |
| # not an octal escape, so this is a group reference |
| group = int(escape[1:]) |
| if group < state.groups: |
| if not state.checkgroup(group): |
| raise error, "cannot refer to open 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 = [] |
| itemsappend = items.append |
| sourcematch = source.match |
| while 1: |
| itemsappend(_parse(source, state)) |
| if sourcematch("|"): |
| continue |
| if not nested: |
| break |
| if not source.next or sourcematch(")", 0): |
| break |
| else: |
| raise error, "pattern not properly closed" |
| |
| if len(items) == 1: |
| return items[0] |
| |
| subpattern = SubPattern(state) |
| subpatternappend = subpattern.append |
| |
| # 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] |
| subpatternappend(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 = [] |
| setappend = set.append |
| for item in items: |
| setappend(item[0]) |
| subpatternappend((IN, set)) |
| return subpattern |
| |
| subpattern.append((BRANCH, (None, items))) |
| return subpattern |
| |
| def _parse_sub_cond(source, state, condgroup): |
| item_yes = _parse(source, state) |
| if source.match("|"): |
| item_no = _parse(source, state) |
| if source.match("|"): |
| raise error, "conditional backref with more than two branches" |
| else: |
| item_no = None |
| if source.next and not source.match(")", 0): |
| raise error, "pattern not properly closed" |
| subpattern = SubPattern(state) |
| subpattern.append((GROUPREF_EXISTS, (condgroup, item_yes, item_no))) |
| return subpattern |
| |
| _PATTERNENDERS = set("|)") |
| _ASSERTCHARS = set("=!<") |
| _LOOKBEHINDASSERTCHARS = set("=!") |
| _REPEATCODES = set([MIN_REPEAT, MAX_REPEAT]) |
| |
| def _parse(source, state): |
| # parse a simple pattern |
| subpattern = SubPattern(state) |
| |
| # precompute constants into local variables |
| subpatternappend = subpattern.append |
| sourceget = source.get |
| sourcematch = source.match |
| _len = len |
| PATTERNENDERS = _PATTERNENDERS |
| ASSERTCHARS = _ASSERTCHARS |
| LOOKBEHINDASSERTCHARS = _LOOKBEHINDASSERTCHARS |
| REPEATCODES = _REPEATCODES |
| |
| while 1: |
| |
| if source.next in PATTERNENDERS: |
| break # end of subpattern |
| this = sourceget() |
| 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 = sourceget() |
| if this in (None, "\n"): |
| break |
| continue |
| |
| if this and this[0] not in SPECIAL_CHARS: |
| subpatternappend((LITERAL, ord(this))) |
| |
| elif this == "[": |
| # character set |
| set = [] |
| setappend = set.append |
| ## if sourcematch(":"): |
| ## pass # handle character classes |
| if sourcematch("^"): |
| setappend((NEGATE, None)) |
| # check remaining characters |
| start = set[:] |
| while 1: |
| this = sourceget() |
| 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 sourcematch("-"): |
| # potential range |
| this = sourceget() |
| if this == "]": |
| if code1[0] is IN: |
| code1 = code1[1][0] |
| setappend(code1) |
| setappend((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] |
| hi = code2[1] |
| if hi < lo: |
| raise error, "bad character range" |
| setappend((RANGE, (lo, hi))) |
| else: |
| raise error, "unexpected end of regular expression" |
| else: |
| if code1[0] is IN: |
| code1 = code1[1][0] |
| setappend(code1) |
| |
| # XXX: <fl> should move set optimization to compiler! |
| if _len(set)==1 and set[0][0] is LITERAL: |
| subpatternappend(set[0]) # optimization |
| elif _len(set)==2 and set[0][0] is NEGATE and set[1][0] is LITERAL: |
| subpatternappend((NOT_LITERAL, set[1][1])) # optimization |
| else: |
| # XXX: <fl> should add charmap optimization here |
| subpatternappend((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 == "{": |
| if source.next == "}": |
| subpatternappend((LITERAL, ord(this))) |
| continue |
| here = source.tell() |
| min, max = 0, MAXREPEAT |
| lo = hi = "" |
| while source.next in DIGITS: |
| lo = lo + source.get() |
| if sourcematch(","): |
| while source.next in DIGITS: |
| hi = hi + sourceget() |
| else: |
| hi = lo |
| if not sourcematch("}"): |
| subpatternappend((LITERAL, ord(this))) |
| source.seek(here) |
| continue |
| if lo: |
| min = int(lo) |
| if hi: |
| max = int(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 REPEATCODES: |
| raise error, "multiple repeat" |
| if sourcematch("?"): |
| subpattern[-1] = (MIN_REPEAT, (min, max, item)) |
| else: |
| subpattern[-1] = (MAX_REPEAT, (min, max, item)) |
| |
| elif this == ".": |
| subpatternappend((ANY, None)) |
| |
| elif this == "(": |
| group = 1 |
| name = None |
| condgroup = None |
| if sourcematch("?"): |
| group = 0 |
| # options |
| if sourcematch("P"): |
| # python extensions |
| if sourcematch("<"): |
| # named group: skip forward to end of name |
| name = "" |
| while 1: |
| char = sourceget() |
| 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 sourcematch("="): |
| # named backreference |
| name = "" |
| while 1: |
| char = sourceget() |
| 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" |
| subpatternappend((GROUPREF, gid)) |
| continue |
| else: |
| char = sourceget() |
| if char is None: |
| raise error, "unexpected end of pattern" |
| raise error, "unknown specifier: ?P%s" % char |
| elif sourcematch(":"): |
| # non-capturing group |
| group = 2 |
| elif sourcematch("#"): |
| # comment |
| while 1: |
| if source.next is None or source.next == ")": |
| break |
| sourceget() |
| if not sourcematch(")"): |
| raise error, "unbalanced parenthesis" |
| continue |
| elif source.next in ASSERTCHARS: |
| # lookahead assertions |
| char = sourceget() |
| dir = 1 |
| if char == "<": |
| if source.next not in LOOKBEHINDASSERTCHARS: |
| raise error, "syntax error" |
| dir = -1 # lookbehind |
| char = sourceget() |
| p = _parse_sub(source, state) |
| if not sourcematch(")"): |
| raise error, "unbalanced parenthesis" |
| if char == "=": |
| subpatternappend((ASSERT, (dir, p))) |
| else: |
| subpatternappend((ASSERT_NOT, (dir, p))) |
| continue |
| elif sourcematch("("): |
| # conditional backreference group |
| condname = "" |
| while 1: |
| char = sourceget() |
| if char is None: |
| raise error, "unterminated name" |
| if char == ")": |
| break |
| condname = condname + char |
| group = 2 |
| if isname(condname): |
| condgroup = state.groupdict.get(condname) |
| if condgroup is None: |
| raise error, "unknown group name" |
| else: |
| try: |
| condgroup = int(condname) |
| except ValueError: |
| raise error, "bad character in group name" |
| else: |
| # flags |
| if not source.next in FLAGS: |
| raise error, "unexpected end of pattern" |
| while source.next in FLAGS: |
| state.flags = state.flags | FLAGS[sourceget()] |
| if group: |
| # parse group contents |
| if group == 2: |
| # anonymous group |
| group = None |
| else: |
| group = state.opengroup(name) |
| if condgroup: |
| p = _parse_sub_cond(source, state, condgroup) |
| else: |
| p = _parse_sub(source, state) |
| if not sourcematch(")"): |
| raise error, "unbalanced parenthesis" |
| if group is not None: |
| state.closegroup(group) |
| subpatternappend((SUBPATTERN, (group, p))) |
| else: |
| while 1: |
| char = sourceget() |
| if char is None: |
| raise error, "unexpected end of pattern" |
| if char == ")": |
| break |
| raise error, "unknown extension" |
| |
| elif this == "^": |
| subpatternappend((AT, AT_BEGINNING)) |
| |
| elif this == "$": |
| subpattern.append((AT, AT_END)) |
| |
| elif this and this[0] == "\\": |
| code = _escape(source, this, state) |
| subpatternappend(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) |
| sget = s.get |
| p = [] |
| a = p.append |
| def literal(literal, p=p, pappend=a): |
| if p and p[-1][0] is LITERAL: |
| p[-1] = LITERAL, p[-1][1] + literal |
| else: |
| pappend((LITERAL, literal)) |
| sep = source[:0] |
| if isinstance(sep, str): |
| makechar = chr |
| else: |
| makechar = chr |
| while 1: |
| this = sget() |
| if this is None: |
| break # end of replacement string |
| if this and this[0] == "\\": |
| # group |
| c = this[1:2] |
| if c == "g": |
| name = "" |
| if s.match("<"): |
| while 1: |
| char = sget() |
| 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) |
| if index < 0: |
| raise error, "negative group number" |
| 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 c == "0": |
| if s.next in OCTDIGITS: |
| this = this + sget() |
| if s.next in OCTDIGITS: |
| this = this + sget() |
| literal(makechar(int(this[1:], 8) & 0xff)) |
| elif c in DIGITS: |
| isoctal = False |
| if s.next in DIGITS: |
| this = this + sget() |
| if (c in OCTDIGITS and this[2] in OCTDIGITS and |
| s.next in OCTDIGITS): |
| this = this + sget() |
| isoctal = True |
| literal(makechar(int(this[1:], 8) & 0xff)) |
| if not isoctal: |
| a((MARK, int(this[1:]))) |
| 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 = [] |
| groupsappend = groups.append |
| literals = [None] * len(p) |
| for c, s in p: |
| if c is MARK: |
| groupsappend((i, s)) |
| # literal[i] is already None |
| else: |
| literals[i] = 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 error, "unmatched group" |
| except IndexError: |
| raise error, "invalid group reference" |
| return sep.join(literals) |