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sre_parse.py39.8 KB · 1077 lines
## 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 from sre_constants import * SPECIAL_CHARS = ".\\[{()*+?^$|"REPEAT_CHARS = "*+?{" DIGITS = frozenset("0123456789") OCTDIGITS = frozenset("01234567")HEXDIGITS = frozenset("0123456789abcdefABCDEF")ASCIILETTERS = frozenset("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ") WHITESPACE = frozenset(" \t\n\r\v\f") _REPEATCODES = frozenset({MIN_REPEAT, MAX_REPEAT})_UNITCODES = frozenset({ANY, RANGE, IN, LITERAL, NOT_LITERAL, CATEGORY}) 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    "a": SRE_FLAG_ASCII,    "t": SRE_FLAG_TEMPLATE,    "u": SRE_FLAG_UNICODE,} TYPE_FLAGS = SRE_FLAG_ASCII | SRE_FLAG_LOCALE | SRE_FLAG_UNICODEGLOBAL_FLAGS = SRE_FLAG_DEBUG | SRE_FLAG_TEMPLATE class Verbose(Exception):    pass class State:    # keeps track of state for parsing    def __init__(self):        self.flags = 0        self.groupdict = {}        self.groupwidths = [None]  # group 0        self.lookbehindgroups = None        self.grouprefpos = {}    @property    def groups(self):        return len(self.groupwidths)    def opengroup(self, name=None):        gid = self.groups        self.groupwidths.append(None)        if self.groups > MAXGROUPS:            raise error("too many groups")        if name is not None:            ogid = self.groupdict.get(name, None)            if ogid is not None:                raise error("redefinition of group name %r as group %d; "                            "was group %d" % (name, gid,  ogid))            self.groupdict[name] = gid        return gid    def closegroup(self, gid, p):        self.groupwidths[gid] = p.getwidth()    def checkgroup(self, gid):        return gid < self.groups and self.groupwidths[gid] is not None     def checklookbehindgroup(self, gid, source):        if self.lookbehindgroups is not None:            if not self.checkgroup(gid):                raise source.error('cannot refer to an open group')            if gid >= self.lookbehindgroups:                raise source.error('cannot refer to group defined in the same '                                   'lookbehind subpattern') class SubPattern:    # a subpattern, in intermediate form    def __init__(self, state, data=None):        self.state = state        if data is None:            data = []        self.data = data        self.width = None     def dump(self, level=0):        nl = True        seqtypes = (tuple, list)        for op, av in self.data:            print(level*"  " + str(op), end='')            if op is IN:                # member sublanguage                print()                for op, a in av:                    print((level+1)*"  " + str(op), a)            elif op is BRANCH:                print()                for i, a in enumerate(av[1]):                    if i:                        print(level*"  " + "OR")                    a.dump(level+1)            elif op is GROUPREF_EXISTS:                condgroup, item_yes, item_no = av                print('', condgroup)                item_yes.dump(level+1)                if item_no:                    print(level*"  " + "ELSE")                    item_no.dump(level+1)            elif isinstance(av, seqtypes):                nl = False                for a in av:                    if isinstance(a, SubPattern):                        if not nl:                            print()                        a.dump(level+1)                        nl = True                    else:                        if not nl:                            print(' ', end='')                        print(a, end='')                        nl = False                if not nl:                    print()            else:                print('', av)    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.state, self.data[index])        return self.data[index]    def __setitem__(self, index, code):        self.data[index] = code    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 is not None:            return self.width        lo = hi = 0        for op, av in self.data:            if op is BRANCH:                i = MAXREPEAT - 1                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 + i * av[0]                hi = hi + j * av[1]            elif op in _UNITCODES:                lo = lo + 1                hi = hi + 1            elif op is GROUPREF:                i, j = self.state.groupwidths[av]                lo = lo + i                hi = hi + j            elif op is GROUPREF_EXISTS:                i, j = av[1].getwidth()                if av[2] is not None:                    l, h = av[2].getwidth()                    i = min(i, l)                    j = max(j, h)                else:                    i = 0                lo = lo + i                hi = hi + j            elif op is SUCCESS:                break        self.width = min(lo, MAXREPEAT - 1), min(hi, MAXREPEAT)        return self.width class Tokenizer:    def __init__(self, string):        self.istext = isinstance(string, str)        self.string = string        if not self.istext:            string = str(string, 'latin1')        self.decoded_string = string        self.index = 0        self.next = None        self.__next()    def __next(self):        index = self.index        try:            char = self.decoded_string[index]        except IndexError:            self.next = None            return        if char == "\\":            index += 1            try:                char += self.decoded_string[index]            except IndexError:                raise error("bad escape (end of pattern)",                            self.string, len(self.string) - 1) from None        self.index = index + 1        self.next = char    def match(self, char):        if char == self.next:            self.__next()            return True        return False    def get(self):        this = self.next        self.__next()        return this    def getwhile(self, n, charset):        result = ''        for _ in range(n):            c = self.next            if c not in charset:                break            result += c            self.__next()        return result    def getuntil(self, terminator, name):        result = ''        while True:            c = self.next            self.__next()            if c is None:                if not result:                    raise self.error("missing " + name)                raise self.error("missing %s, unterminated name" % terminator,                                 len(result))            if c == terminator:                if not result:                    raise self.error("missing " + name, 1)                break            result += c        return result    @property    def pos(self):        return self.index - len(self.next or '')    def tell(self):        return self.index - len(self.next or '')    def seek(self, index):        self.index = index        self.__next()     def error(self, msg, offset=0):        return error(msg, self.string, self.tell() - offset) 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 and code[0] is IN:        return code    try:        c = escape[1:2]        if c == "x":            # hexadecimal escape (exactly two digits)            escape += source.getwhile(2, HEXDIGITS)            if len(escape) != 4:                raise source.error("incomplete escape %s" % escape, len(escape))            return LITERAL, int(escape[2:], 16)        elif c == "u" and source.istext:            # unicode escape (exactly four digits)            escape += source.getwhile(4, HEXDIGITS)            if len(escape) != 6:                raise source.error("incomplete escape %s" % escape, len(escape))            return LITERAL, int(escape[2:], 16)        elif c == "U" and source.istext:            # unicode escape (exactly eight digits)            escape += source.getwhile(8, HEXDIGITS)            if len(escape) != 10:                raise source.error("incomplete escape %s" % escape, len(escape))            c = int(escape[2:], 16)            chr(c) # raise ValueError for invalid code            return LITERAL, c        elif c == "N" and source.istext:            import unicodedata            # named unicode escape e.g. \N{EM DASH}            if not source.match('{'):                raise source.error("missing {")            charname = source.getuntil('}', 'character name')            try:                c = ord(unicodedata.lookup(charname))            except (KeyError, TypeError):                raise source.error("undefined character name %r" % charname,                                   len(charname) + len(r'\N{}'))            return LITERAL, c        elif c in OCTDIGITS:            # octal escape (up to three digits)            escape += source.getwhile(2, OCTDIGITS)            c = int(escape[1:], 8)            if c > 0o377:                raise source.error('octal escape value %s outside of '                                   'range 0-0o377' % escape, len(escape))            return LITERAL, c        elif c in DIGITS:            raise ValueError        if len(escape) == 2:            if c in ASCIILETTERS:                raise source.error('bad escape %s' % escape, len(escape))            return LITERAL, ord(escape[1])    except ValueError:        pass    raise source.error("bad escape %s" % escape, len(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            escape += source.getwhile(2, HEXDIGITS)            if len(escape) != 4:                raise source.error("incomplete escape %s" % escape, len(escape))            return LITERAL, int(escape[2:], 16)        elif c == "u" and source.istext:            # unicode escape (exactly four digits)            escape += source.getwhile(4, HEXDIGITS)            if len(escape) != 6:                raise source.error("incomplete escape %s" % escape, len(escape))            return LITERAL, int(escape[2:], 16)        elif c == "U" and source.istext:            # unicode escape (exactly eight digits)            escape += source.getwhile(8, HEXDIGITS)            if len(escape) != 10:                raise source.error("incomplete escape %s" % escape, len(escape))            c = int(escape[2:], 16)            chr(c) # raise ValueError for invalid code            return LITERAL, c        elif c == "N" and source.istext:            import unicodedata            # named unicode escape e.g. \N{EM DASH}            if not source.match('{'):                raise source.error("missing {")            charname = source.getuntil('}', 'character name')            try:                c = ord(unicodedata.lookup(charname))            except (KeyError, TypeError):                raise source.error("undefined character name %r" % charname,                                   len(charname) + len(r'\N{}'))            return LITERAL, c        elif c == "0":            # octal escape            escape += source.getwhile(2, OCTDIGITS)            return LITERAL, int(escape[1:], 8)        elif c in DIGITS:            # octal escape *or* decimal group reference (sigh)            if source.next in DIGITS:                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 += source.get()                    c = int(escape[1:], 8)                    if c > 0o377:                        raise source.error('octal escape value %s outside of '                                           'range 0-0o377' % escape,                                           len(escape))                    return LITERAL, c            # not an octal escape, so this is a group reference            group = int(escape[1:])            if group < state.groups:                if not state.checkgroup(group):                    raise source.error("cannot refer to an open group",                                       len(escape))                state.checklookbehindgroup(group, source)                return GROUPREF, group            raise source.error("invalid group reference %d" % group, len(escape) - 1)        if len(escape) == 2:            if c in ASCIILETTERS:                raise source.error("bad escape %s" % escape, len(escape))            return LITERAL, ord(escape[1])    except ValueError:        pass    raise source.error("bad escape %s" % escape, len(escape)) def _uniq(items):    return list(dict.fromkeys(items)) def _parse_sub(source, state, verbose, nested):    # parse an alternation: a|b|c     items = []    itemsappend = items.append    sourcematch = source.match    start = source.tell()    while True:        itemsappend(_parse(source, state, verbose, nested + 1,                           not nested and not items))        if not sourcematch("|"):            break     if len(items) == 1:        return items[0]     subpattern = SubPattern(state)     # check if all items share a common prefix    while True:        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    set = []    for item in items:        if len(item) != 1:            break        op, av = item[0]        if op is LITERAL:            set.append((op, av))        elif op is IN and av[0][0] is not NEGATE:            set.extend(av)        else:            break    else:        # we can store this as a character set instead of a        # branch (the compiler may optimize this even more)        subpattern.append((IN, _uniq(set)))        return subpattern     subpattern.append((BRANCH, (None, items)))    return subpattern def _parse(source, state, verbose, nested, first=False):    # parse a simple pattern    subpattern = SubPattern(state)     # precompute constants into local variables    subpatternappend = subpattern.append    sourceget = source.get    sourcematch = source.match    _len = len    _ord = ord     while True:         this = source.next        if this is None:            break # end of pattern        if this in "|)":            break # end of subpattern        sourceget()         if verbose:            # skip whitespace and comments            if this in WHITESPACE:                continue            if this == "#":                while True:                    this = sourceget()                    if this is None or this == "\n":                        break                continue         if this[0] == "\\":            code = _escape(source, this, state)            subpatternappend(code)         elif this not in SPECIAL_CHARS:            subpatternappend((LITERAL, _ord(this)))         elif this == "[":            here = source.tell() - 1            # character set            set = []            setappend = set.append##          if sourcematch(":"):##              pass # handle character classes            if source.next == '[':                import warnings                warnings.warn(                    'Possible nested set at position %d' % source.tell(),                    FutureWarning, stacklevel=nested + 6                )            negate = sourcematch("^")            # check remaining characters            while True:                this = sourceget()                if this is None:                    raise source.error("unterminated character set",                                       source.tell() - here)                if this == "]" and set:                    break                elif this[0] == "\\":                    code1 = _class_escape(source, this)                else:                    if set and this in '-&~|' and source.next == this:                        import warnings                        warnings.warn(                            'Possible set %s at position %d' % (                                'difference' if this == '-' else                                'intersection' if this == '&' else                                'symmetric difference' if this == '~' else                                'union',                                source.tell() - 1),                            FutureWarning, stacklevel=nested + 6                        )                    code1 = LITERAL, _ord(this)                if sourcematch("-"):                    # potential range                    that = sourceget()                    if that is None:                        raise source.error("unterminated character set",                                           source.tell() - here)                    if that == "]":                        if code1[0] is IN:                            code1 = code1[1][0]                        setappend(code1)                        setappend((LITERAL, _ord("-")))                        break                    if that[0] == "\\":                        code2 = _class_escape(source, that)                    else:                        if that == '-':                            import warnings                            warnings.warn(                                'Possible set difference at position %d' % (                                    source.tell() - 2),                                FutureWarning, stacklevel=nested + 6                            )                        code2 = LITERAL, _ord(that)                    if code1[0] != LITERAL or code2[0] != LITERAL:                        msg = "bad character range %s-%s" % (this, that)                        raise source.error(msg, len(this) + 1 + len(that))                    lo = code1[1]                    hi = code2[1]                    if hi < lo:                        msg = "bad character range %s-%s" % (this, that)                        raise source.error(msg, len(this) + 1 + len(that))                    setappend((RANGE, (lo, hi)))                else:                    if code1[0] is IN:                        code1 = code1[1][0]                    setappend(code1)             set = _uniq(set)            # XXX: <fl> should move set optimization to compiler!            if _len(set) == 1 and set[0][0] is LITERAL:                # optimization                if negate:                    subpatternappend((NOT_LITERAL, set[0][1]))                else:                    subpatternappend(set[0])            else:                if negate:                    set.insert(0, (NEGATE, None))                # charmap optimization can't be added here because                # global flags still are not known                subpatternappend((IN, set))         elif this in REPEAT_CHARS:            # repeat previous item            here = source.tell()            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                 min, max = 0, MAXREPEAT                lo = hi = ""                while source.next in DIGITS:                    lo += sourceget()                if sourcematch(","):                    while source.next in DIGITS:                        hi += sourceget()                else:                    hi = lo                if not sourcematch("}"):                    subpatternappend((LITERAL, _ord(this)))                    source.seek(here)                    continue                 if lo:                    min = int(lo)                    if min >= MAXREPEAT:                        raise OverflowError("the repetition number is too large")                if hi:                    max = int(hi)                    if max >= MAXREPEAT:                        raise OverflowError("the repetition number is too large")                    if max < min:                        raise source.error("min repeat greater than max repeat",                                           source.tell() - here)            else:                raise AssertionError("unsupported quantifier %r" % (char,))            # figure out which item to repeat            if subpattern:                item = subpattern[-1:]            else:                item = None            if not item or item[0][0] is AT:                raise source.error("nothing to repeat",                                   source.tell() - here + len(this))            if item[0][0] in _REPEATCODES:                raise source.error("multiple repeat",                                   source.tell() - here + len(this))            if item[0][0] is SUBPATTERN:                group, add_flags, del_flags, p = item[0][1]                if group is None and not add_flags and not del_flags:                    item = p            if sourcematch("?"):                subpattern[-1] = (MIN_REPEAT, (min, max, item))            else:                subpattern[-1] = (MAX_REPEAT, (min, max, item))         elif this == ".":            subpatternappend((ANY, None))         elif this == "(":            start = source.tell() - 1            group = True            name = None            add_flags = 0            del_flags = 0            if sourcematch("?"):                # options                char = sourceget()                if char is None:                    raise source.error("unexpected end of pattern")                if char == "P":                    # python extensions                    if sourcematch("<"):                        # named group: skip forward to end of name                        name = source.getuntil(">", "group name")                        if not name.isidentifier():                            msg = "bad character in group name %r" % name                            raise source.error(msg, len(name) + 1)                    elif sourcematch("="):                        # named backreference                        name = source.getuntil(")", "group name")                        if not name.isidentifier():                            msg = "bad character in group name %r" % name                            raise source.error(msg, len(name) + 1)                        gid = state.groupdict.get(name)                        if gid is None:                            msg = "unknown group name %r" % name                            raise source.error(msg, len(name) + 1)                        if not state.checkgroup(gid):                            raise source.error("cannot refer to an open group",                                               len(name) + 1)                        state.checklookbehindgroup(gid, source)                        subpatternappend((GROUPREF, gid))                        continue                     else:                        char = sourceget()                        if char is None:                            raise source.error("unexpected end of pattern")                        raise source.error("unknown extension ?P" + char,                                           len(char) + 2)                elif char == ":":                    # non-capturing group                    group = None                elif char == "#":                    # comment                    while True:                        if source.next is None:                            raise source.error("missing ), unterminated comment",                                               source.tell() - start)                        if sourceget() == ")":                            break                    continue                 elif char in "=!<":                    # lookahead assertions                    dir = 1                    if char == "<":                        char = sourceget()                        if char is None:                            raise source.error("unexpected end of pattern")                        if char not in "=!":                            raise source.error("unknown extension ?<" + char,                                               len(char) + 2)                        dir = -1 # lookbehind                        lookbehindgroups = state.lookbehindgroups                        if lookbehindgroups is None:                            state.lookbehindgroups = state.groups                    p = _parse_sub(source, state, verbose, nested + 1)                    if dir < 0:                        if lookbehindgroups is None:                            state.lookbehindgroups = None                    if not sourcematch(")"):                        raise source.error("missing ), unterminated subpattern",                                           source.tell() - start)                    if char == "=":                        subpatternappend((ASSERT, (dir, p)))                    else:                        subpatternappend((ASSERT_NOT, (dir, p)))                    continue                 elif char == "(":                    # conditional backreference group                    condname = source.getuntil(")", "group name")                    if condname.isidentifier():                        condgroup = state.groupdict.get(condname)                        if condgroup is None:                            msg = "unknown group name %r" % condname                            raise source.error(msg, len(condname) + 1)                    else:                        try:                            condgroup = int(condname)                            if condgroup < 0:                                raise ValueError                        except ValueError:                            msg = "bad character in group name %r" % condname                            raise source.error(msg, len(condname) + 1) from None                        if not condgroup:                            raise source.error("bad group number",                                               len(condname) + 1)                        if condgroup >= MAXGROUPS:                            msg = "invalid group reference %d" % condgroup                            raise source.error(msg, len(condname) + 1)                        if condgroup not in state.grouprefpos:                            state.grouprefpos[condgroup] = (                                source.tell() - len(condname) - 1                            )                    state.checklookbehindgroup(condgroup, source)                    item_yes = _parse(source, state, verbose, nested + 1)                    if source.match("|"):                        item_no = _parse(source, state, verbose, nested + 1)                        if source.next == "|":                            raise source.error("conditional backref with more than two branches")                    else:                        item_no = None                    if not source.match(")"):                        raise source.error("missing ), unterminated subpattern",                                           source.tell() - start)                    subpatternappend((GROUPREF_EXISTS, (condgroup, item_yes, item_no)))                    continue                 elif char in FLAGS or char == "-":                    # flags                    flags = _parse_flags(source, state, char)                    if flags is None:  # global flags                        if not first or subpattern:                            import warnings                            warnings.warn(                                'Flags not at the start of the expression %r%s'                                ' but at position %d' % (                                    source.string[:20],  # truncate long regexes                                    ' (truncated)' if len(source.string) > 20 else '',                                    start,                                ),                                DeprecationWarning, stacklevel=nested + 6                            )                        if (state.flags & SRE_FLAG_VERBOSE) and not verbose:                            raise Verbose                        continue                     add_flags, del_flags = flags                    group = None                else:                    raise source.error("unknown extension ?" + char,                                       len(char) + 1)             # parse group contents            if group is not None:                try:                    group = state.opengroup(name)                except error as err:                    raise source.error(err.msg, len(name) + 1) from None            sub_verbose = ((verbose or (add_flags & SRE_FLAG_VERBOSE)) and                           not (del_flags & SRE_FLAG_VERBOSE))            p = _parse_sub(source, state, sub_verbose, nested + 1)            if not source.match(")"):                raise source.error("missing ), unterminated subpattern",                                   source.tell() - start)            if group is not None:                state.closegroup(group, p)            subpatternappend((SUBPATTERN, (group, add_flags, del_flags, p)))         elif this == "^":            subpatternappend((AT, AT_BEGINNING))         elif this == "$":            subpatternappend((AT, AT_END))         else:            raise AssertionError("unsupported special character %r" % (char,))     # unpack non-capturing groups    for i in range(len(subpattern))[::-1]:        op, av = subpattern[i]        if op is SUBPATTERN:            group, add_flags, del_flags, p = av            if group is None and not add_flags and not del_flags:                subpattern[i: i+1] = p     return subpattern def _parse_flags(source, state, char):    sourceget = source.get    add_flags = 0    del_flags = 0    if char != "-":        while True:            flag = FLAGS[char]            if source.istext:                if char == 'L':                    msg = "bad inline flags: cannot use 'L' flag with a str pattern"                    raise source.error(msg)            else:                if char == 'u':                    msg = "bad inline flags: cannot use 'u' flag with a bytes pattern"                    raise source.error(msg)            add_flags |= flag            if (flag & TYPE_FLAGS) and (add_flags & TYPE_FLAGS) != flag:                msg = "bad inline flags: flags 'a', 'u' and 'L' are incompatible"                raise source.error(msg)            char = sourceget()            if char is None:                raise source.error("missing -, : or )")            if char in ")-:":                break            if char not in FLAGS:                msg = "unknown flag" if char.isalpha() else "missing -, : or )"                raise source.error(msg, len(char))    if char == ")":        state.flags |= add_flags        return None    if add_flags & GLOBAL_FLAGS:        raise source.error("bad inline flags: cannot turn on global flag", 1)    if char == "-":        char = sourceget()        if char is None:            raise source.error("missing flag")        if char not in FLAGS:            msg = "unknown flag" if char.isalpha() else "missing flag"            raise source.error(msg, len(char))        while True:            flag = FLAGS[char]            if flag & TYPE_FLAGS:                msg = "bad inline flags: cannot turn off flags 'a', 'u' and 'L'"                raise source.error(msg)            del_flags |= flag            char = sourceget()            if char is None:                raise source.error("missing :")            if char == ":":                break            if char not in FLAGS:                msg = "unknown flag" if char.isalpha() else "missing :"                raise source.error(msg, len(char))    assert char == ":"    if del_flags & GLOBAL_FLAGS:        raise source.error("bad inline flags: cannot turn off global flag", 1)    if add_flags & del_flags:        raise source.error("bad inline flags: flag turned on and off", 1)    return add_flags, del_flags def fix_flags(src, flags):    # Check and fix flags according to the type of pattern (str or bytes)    if isinstance(src, str):        if flags & SRE_FLAG_LOCALE:            raise ValueError("cannot use LOCALE flag with a str pattern")        if not flags & SRE_FLAG_ASCII:            flags |= SRE_FLAG_UNICODE        elif flags & SRE_FLAG_UNICODE:            raise ValueError("ASCII and UNICODE flags are incompatible")    else:        if flags & SRE_FLAG_UNICODE:            raise ValueError("cannot use UNICODE flag with a bytes pattern")        if flags & SRE_FLAG_LOCALE and flags & SRE_FLAG_ASCII:            raise ValueError("ASCII and LOCALE flags are incompatible")    return flags def parse(str, flags=0, state=None):    # parse 're' pattern into list of (opcode, argument) tuples     source = Tokenizer(str)     if state is None:        state = State()    state.flags = flags    state.str = str     try:        p = _parse_sub(source, state, flags & SRE_FLAG_VERBOSE, 0)    except Verbose:        # the VERBOSE flag was switched on inside the pattern.  to be        # on the safe side, we'll parse the whole thing again...        state = State()        state.flags = flags | SRE_FLAG_VERBOSE        state.str = str        source.seek(0)        p = _parse_sub(source, state, True, 0)     p.state.flags = fix_flags(str, p.state.flags)     if source.next is not None:        assert source.next == ")"        raise source.error("unbalanced parenthesis")     for g in p.state.grouprefpos:        if g >= p.state.groups:            msg = "invalid group reference %d" % g            raise error(msg, str, p.state.grouprefpos[g])     if flags & SRE_FLAG_DEBUG:        p.dump()     return p def parse_template(source, state):    # parse 're' replacement string into list of literals and    # group references    s = Tokenizer(source)    sget = s.get    groups = []    literals = []    literal = []    lappend = literal.append    def addgroup(index, pos):        if index > state.groups:            raise s.error("invalid group reference %d" % index, pos)        if literal:            literals.append(''.join(literal))            del literal[:]        groups.append((len(literals), index))        literals.append(None)    groupindex = state.groupindex    while True:        this = sget()        if this is None:            break # end of replacement string        if this[0] == "\\":            # group            c = this[1]            if c == "g":                name = ""                if not s.match("<"):                    raise s.error("missing <")                name = s.getuntil(">", "group name")                if name.isidentifier():                    try:                        index = groupindex[name]                    except KeyError:                        raise IndexError("unknown group name %r" % name)                else:                    try:                        index = int(name)                        if index < 0:                            raise ValueError                    except ValueError:                        raise s.error("bad character in group name %r" % name,                                      len(name) + 1) from None                    if index >= MAXGROUPS:                        raise s.error("invalid group reference %d" % index,                                      len(name) + 1)                addgroup(index, len(name) + 1)            elif c == "0":                if s.next in OCTDIGITS:                    this += sget()                    if s.next in OCTDIGITS:                        this += sget()                lappend(chr(int(this[1:], 8) & 0xff))            elif c in DIGITS:                isoctal = False                if s.next in DIGITS:                    this += sget()                    if (c in OCTDIGITS and this[2] in OCTDIGITS and                        s.next in OCTDIGITS):                        this += sget()                        isoctal = True                        c = int(this[1:], 8)                        if c > 0o377:                            raise s.error('octal escape value %s outside of '                                          'range 0-0o377' % this, len(this))                        lappend(chr(c))                if not isoctal:                    addgroup(int(this[1:]), len(this) - 1)            else:                try:                    this = chr(ESCAPES[this][1])                except KeyError:                    if c in ASCIILETTERS:                        raise s.error('bad escape %s' % this, len(this))                lappend(this)        else:            lappend(this)    if literal:        literals.append(''.join(literal))    if not isinstance(source, str):        # The tokenizer implicitly decodes bytes objects as latin-1, we must        # therefore re-encode the final representation.        literals = [None if s is None else s.encode('latin-1') for s in literals]    return groups, literals def expand_template(template, match):    g = match.group    empty = match.string[:0]    groups, literals = template    literals = literals[:]    try:        for index, group in groups:            literals[index] = g(group) or empty    except IndexError:        raise error("invalid group reference %d" % index)    return empty.join(literals)