Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 1 | # |
| 2 | # Secret Labs' Regular Expression Engine |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 3 | # |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 4 | # convert re-style regular expression to sre pattern |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 5 | # |
| 6 | # Copyright (c) 1998-2000 by Secret Labs AB. All rights reserved. |
| 7 | # |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 8 | # Portions of this engine have been developed in cooperation with |
| 9 | # CNRI. Hewlett-Packard provided funding for 1.6 integration and |
| 10 | # other compatibility work. |
| 11 | # |
| 12 | |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 13 | import string, sys |
| 14 | |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 15 | import _sre |
| 16 | |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 17 | from sre_constants import * |
| 18 | |
Fredrik Lundh | 6c68dc7 | 2000-06-29 10:34:56 +0000 | [diff] [blame] | 19 | # FIXME: should be 65535, but the arraymodule is still broken |
| 20 | MAXREPEAT = 32767 |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 21 | |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 22 | SPECIAL_CHARS = ".\\[{()*+?^$|" |
| 23 | REPEAT_CHARS = "*+?{" |
| 24 | |
Fredrik Lundh | 75f2d67 | 2000-06-29 11:34:28 +0000 | [diff] [blame] | 25 | DIGITS = tuple(string.digits) |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 26 | |
Fredrik Lundh | 75f2d67 | 2000-06-29 11:34:28 +0000 | [diff] [blame] | 27 | OCTDIGITS = tuple("01234567") |
| 28 | HEXDIGITS = tuple("0123456789abcdefABCDEF") |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 29 | |
Fredrik Lundh | 6c68dc7 | 2000-06-29 10:34:56 +0000 | [diff] [blame] | 30 | WHITESPACE = string.whitespace |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 31 | |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 32 | ESCAPES = { |
Fredrik Lundh | 01016fe | 2000-06-30 00:27:46 +0000 | [diff] [blame^] | 33 | r"\a": (LITERAL, chr(7)), |
| 34 | r"\b": (LITERAL, chr(8)), |
| 35 | r"\f": (LITERAL, chr(12)), |
| 36 | r"\n": (LITERAL, chr(10)), |
| 37 | r"\r": (LITERAL, chr(13)), |
| 38 | r"\t": (LITERAL, chr(9)), |
| 39 | r"\v": (LITERAL, chr(11)), |
| 40 | r"\\": (LITERAL, "\\") |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 41 | } |
| 42 | |
| 43 | CATEGORIES = { |
Fredrik Lundh | 01016fe | 2000-06-30 00:27:46 +0000 | [diff] [blame^] | 44 | r"\A": (AT, AT_BEGINNING), # start of string |
| 45 | r"\b": (AT, AT_BOUNDARY), |
| 46 | r"\B": (AT, AT_NON_BOUNDARY), |
| 47 | r"\d": (IN, [(CATEGORY, CATEGORY_DIGIT)]), |
| 48 | r"\D": (IN, [(CATEGORY, CATEGORY_NOT_DIGIT)]), |
| 49 | r"\s": (IN, [(CATEGORY, CATEGORY_SPACE)]), |
| 50 | r"\S": (IN, [(CATEGORY, CATEGORY_NOT_SPACE)]), |
| 51 | r"\w": (IN, [(CATEGORY, CATEGORY_WORD)]), |
| 52 | r"\W": (IN, [(CATEGORY, CATEGORY_NOT_WORD)]), |
| 53 | r"\Z": (AT, AT_END), # end of string |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 54 | } |
| 55 | |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 56 | FLAGS = { |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 57 | # standard flags |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 58 | "i": SRE_FLAG_IGNORECASE, |
| 59 | "L": SRE_FLAG_LOCALE, |
| 60 | "m": SRE_FLAG_MULTILINE, |
| 61 | "s": SRE_FLAG_DOTALL, |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 62 | "x": SRE_FLAG_VERBOSE, |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 63 | # extensions |
| 64 | "t": SRE_FLAG_TEMPLATE, |
| 65 | "u": SRE_FLAG_UNICODE, |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 66 | } |
| 67 | |
| 68 | class State: |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 69 | def __init__(self): |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 70 | self.flags = 0 |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 71 | self.groups = 1 |
| 72 | self.groupdict = {} |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 73 | def getgroup(self, name=None): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 74 | gid = self.groups |
| 75 | self.groups = gid + 1 |
| 76 | if name: |
| 77 | self.groupdict[name] = gid |
| 78 | return gid |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 79 | |
| 80 | class SubPattern: |
| 81 | # a subpattern, in intermediate form |
| 82 | def __init__(self, pattern, data=None): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 83 | self.pattern = pattern |
| 84 | if not data: |
| 85 | data = [] |
| 86 | self.data = data |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 87 | self.width = None |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 88 | def __repr__(self): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 89 | return repr(self.data) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 90 | def __len__(self): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 91 | return len(self.data) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 92 | def __delitem__(self, index): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 93 | del self.data[index] |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 94 | def __getitem__(self, index): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 95 | return self.data[index] |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 96 | def __setitem__(self, index, code): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 97 | self.data[index] = code |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 98 | def __getslice__(self, start, stop): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 99 | return SubPattern(self.pattern, self.data[start:stop]) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 100 | def insert(self, index, code): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 101 | self.data.insert(index, code) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 102 | def append(self, code): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 103 | self.data.append(code) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 104 | def getwidth(self): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 105 | # determine the width (min, max) for this subpattern |
| 106 | if self.width: |
| 107 | return self.width |
| 108 | lo = hi = 0L |
| 109 | for op, av in self.data: |
| 110 | if op is BRANCH: |
| 111 | l = sys.maxint |
| 112 | h = 0 |
| 113 | for av in av[1]: |
| 114 | i, j = av.getwidth() |
| 115 | l = min(l, i) |
| 116 | h = min(h, j) |
| 117 | lo = lo + i |
| 118 | hi = hi + j |
| 119 | elif op is CALL: |
| 120 | i, j = av.getwidth() |
| 121 | lo = lo + i |
| 122 | hi = hi + j |
| 123 | elif op is SUBPATTERN: |
| 124 | i, j = av[1].getwidth() |
| 125 | lo = lo + i |
| 126 | hi = hi + j |
| 127 | elif op in (MIN_REPEAT, MAX_REPEAT): |
| 128 | i, j = av[2].getwidth() |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 129 | lo = lo + long(i) * av[0] |
| 130 | hi = hi + long(j) * av[1] |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 131 | elif op in (ANY, RANGE, IN, LITERAL, NOT_LITERAL, CATEGORY): |
| 132 | lo = lo + 1 |
| 133 | hi = hi + 1 |
| 134 | elif op == SUCCESS: |
| 135 | break |
| 136 | self.width = int(min(lo, sys.maxint)), int(min(hi, sys.maxint)) |
| 137 | return self.width |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 138 | |
| 139 | class Tokenizer: |
| 140 | def __init__(self, string): |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 141 | self.index = 0 |
| 142 | self.string = string |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 143 | self.next = self.__next() |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 144 | def __next(self): |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 145 | if self.index >= len(self.string): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 146 | return None |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 147 | char = self.string[self.index] |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 148 | if char[0] == "\\": |
| 149 | try: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 150 | c = self.string[self.index + 1] |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 151 | except IndexError: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 152 | raise error, "bogus escape" |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 153 | char = char + c |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 154 | self.index = self.index + len(char) |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 155 | return char |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 156 | def match(self, char): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 157 | if char == self.next: |
| 158 | self.next = self.__next() |
| 159 | return 1 |
| 160 | return 0 |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 161 | def match_set(self, set): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 162 | if self.next and self.next in set: |
| 163 | self.next = self.__next() |
| 164 | return 1 |
| 165 | return 0 |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 166 | def get(self): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 167 | this = self.next |
| 168 | self.next = self.__next() |
| 169 | return this |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 170 | |
Fredrik Lundh | 4781b07 | 2000-06-29 12:38:45 +0000 | [diff] [blame] | 171 | def isident(char): |
| 172 | return "a" <= char <= "z" or "A" <= char <= "Z" or char == "_" |
| 173 | |
| 174 | def isdigit(char): |
| 175 | return "0" <= char <= "9" |
| 176 | |
| 177 | def isname(name): |
| 178 | # check that group name is a valid string |
| 179 | # FIXME: <fl> this code is really lame. should use a regular |
| 180 | # expression instead, but I seem to have certain bootstrapping |
| 181 | # problems here ;-) |
| 182 | if not isident(name[0]): |
| 183 | return 0 |
| 184 | for char in name: |
| 185 | if not isident(char) and not isdigit(char): |
| 186 | return 0 |
| 187 | return 1 |
| 188 | |
Fredrik Lundh | 01016fe | 2000-06-30 00:27:46 +0000 | [diff] [blame^] | 189 | def _group(escape, groups): |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 190 | # check if the escape string represents a valid group |
| 191 | try: |
| 192 | group = int(escape[1:]) |
Fredrik Lundh | 01016fe | 2000-06-30 00:27:46 +0000 | [diff] [blame^] | 193 | if group and group < groups: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 194 | return group |
| 195 | except ValueError: |
| 196 | pass |
| 197 | return None # not a valid group |
| 198 | |
| 199 | def _class_escape(source, escape): |
| 200 | # handle escape code inside character class |
| 201 | code = ESCAPES.get(escape) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 202 | if code: |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 203 | return code |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 204 | code = CATEGORIES.get(escape) |
| 205 | if code: |
| 206 | return code |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 207 | try: |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 208 | if escape[1:2] == "x": |
Fredrik Lundh | 75f2d67 | 2000-06-29 11:34:28 +0000 | [diff] [blame] | 209 | while source.next in HEXDIGITS: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 210 | escape = escape + source.get() |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 211 | escape = escape[2:] |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 212 | # FIXME: support unicode characters! |
| 213 | return LITERAL, chr(int(escape[-4:], 16) & 0xff) |
| 214 | elif str(escape[1:2]) in OCTDIGITS: |
Fredrik Lundh | 75f2d67 | 2000-06-29 11:34:28 +0000 | [diff] [blame] | 215 | while source.next in OCTDIGITS: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 216 | escape = escape + source.get() |
| 217 | escape = escape[1:] |
| 218 | # FIXME: support unicode characters! |
| 219 | return LITERAL, chr(int(escape[-6:], 8) & 0xff) |
| 220 | if len(escape) == 2: |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 221 | return LITERAL, escape[1] |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 222 | except ValueError: |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 223 | pass |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 224 | raise error, "bogus escape: %s" % repr(escape) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 225 | |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 226 | def _escape(source, escape, state): |
| 227 | # handle escape code in expression |
| 228 | code = CATEGORIES.get(escape) |
| 229 | if code: |
| 230 | return code |
| 231 | code = ESCAPES.get(escape) |
| 232 | if code: |
| 233 | return code |
| 234 | try: |
| 235 | if escape[1:2] == "x": |
Fredrik Lundh | 75f2d67 | 2000-06-29 11:34:28 +0000 | [diff] [blame] | 236 | while source.next in HEXDIGITS: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 237 | escape = escape + source.get() |
| 238 | escape = escape[2:] |
| 239 | # FIXME: support unicode characters! |
| 240 | return LITERAL, chr(int(escape[-4:], 16) & 0xff) |
Fredrik Lundh | 75f2d67 | 2000-06-29 11:34:28 +0000 | [diff] [blame] | 241 | elif escape[1:2] in DIGITS: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 242 | while 1: |
Fredrik Lundh | 01016fe | 2000-06-30 00:27:46 +0000 | [diff] [blame^] | 243 | group = _group(escape, state.groups) |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 244 | if group: |
| 245 | if (not source.next or |
Fredrik Lundh | 01016fe | 2000-06-30 00:27:46 +0000 | [diff] [blame^] | 246 | not _group(escape + source.next, state.groups)): |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 247 | return GROUP, group |
| 248 | escape = escape + source.get() |
Fredrik Lundh | 75f2d67 | 2000-06-29 11:34:28 +0000 | [diff] [blame] | 249 | elif source.next in OCTDIGITS: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 250 | escape = escape + source.get() |
| 251 | else: |
| 252 | break |
| 253 | escape = escape[1:] |
| 254 | # FIXME: support unicode characters! |
| 255 | return LITERAL, chr(int(escape[-6:], 8) & 0xff) |
| 256 | if len(escape) == 2: |
| 257 | return LITERAL, escape[1] |
| 258 | except ValueError: |
| 259 | pass |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 260 | raise error, "bogus escape: %s" % repr(escape) |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 261 | |
| 262 | |
| 263 | def _branch(pattern, items): |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 264 | |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 265 | # form a branch operator from a set of items |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 266 | |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 267 | subpattern = SubPattern(pattern) |
| 268 | |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 269 | # check if all items share a common prefix |
| 270 | while 1: |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 271 | prefix = None |
| 272 | for item in items: |
| 273 | if not item: |
| 274 | break |
| 275 | if prefix is None: |
| 276 | prefix = item[0] |
| 277 | elif item[0] != prefix: |
| 278 | break |
| 279 | else: |
| 280 | # all subitems start with a common "prefix". |
| 281 | # move it out of the branch |
| 282 | for item in items: |
| 283 | del item[0] |
| 284 | subpattern.append(prefix) |
| 285 | continue # check next one |
| 286 | break |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 287 | |
| 288 | # check if the branch can be replaced by a character set |
| 289 | for item in items: |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 290 | if len(item) != 1 or item[0][0] != LITERAL: |
| 291 | break |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 292 | else: |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 293 | # we can store this as a character set instead of a |
| 294 | # branch (FIXME: use a range if possible) |
| 295 | set = [] |
| 296 | for item in items: |
| 297 | set.append(item[0]) |
| 298 | subpattern.append((IN, set)) |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 299 | return subpattern |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 300 | |
| 301 | subpattern.append((BRANCH, (None, items))) |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 302 | return subpattern |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 303 | |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 304 | def _parse(source, state, flags=0): |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 305 | |
| 306 | # parse regular expression pattern into an operator list. |
| 307 | |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 308 | subpattern = SubPattern(state) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 309 | |
| 310 | while 1: |
| 311 | |
Fredrik Lundh | 6c68dc7 | 2000-06-29 10:34:56 +0000 | [diff] [blame] | 312 | if source.next in ("|", ")"): |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 313 | break # end of subpattern |
| 314 | this = source.get() |
| 315 | if this is None: |
| 316 | break # end of pattern |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 317 | |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 318 | if state.flags & SRE_FLAG_VERBOSE: |
| 319 | # skip whitespace and comments |
| 320 | if this in WHITESPACE: |
| 321 | continue |
| 322 | if this == "#": |
| 323 | while 1: |
| 324 | this = source.get() |
| 325 | if this in (None, "\n"): |
| 326 | break |
| 327 | continue |
| 328 | |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 329 | if this and this[0] not in SPECIAL_CHARS: |
| 330 | subpattern.append((LITERAL, this)) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 331 | |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 332 | elif this == "[": |
| 333 | # character set |
| 334 | set = [] |
| 335 | ## if source.match(":"): |
| 336 | ## pass # handle character classes |
| 337 | if source.match("^"): |
| 338 | set.append((NEGATE, None)) |
| 339 | # check remaining characters |
| 340 | start = set[:] |
| 341 | while 1: |
| 342 | this = source.get() |
| 343 | if this == "]" and set != start: |
| 344 | break |
| 345 | elif this and this[0] == "\\": |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 346 | code1 = _class_escape(source, this) |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 347 | elif this: |
| 348 | code1 = LITERAL, this |
| 349 | else: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 350 | raise error, "unexpected end of regular expression" |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 351 | if source.match("-"): |
| 352 | # potential range |
| 353 | this = source.get() |
| 354 | if this == "]": |
| 355 | set.append(code1) |
| 356 | set.append((LITERAL, "-")) |
| 357 | break |
| 358 | else: |
| 359 | if this[0] == "\\": |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 360 | code2 = _class_escape(source, this) |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 361 | else: |
| 362 | code2 = LITERAL, this |
| 363 | if code1[0] != LITERAL or code2[0] != LITERAL: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 364 | raise error, "illegal range" |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 365 | if len(code1[1]) != 1 or len(code2[1]) != 1: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 366 | raise error, "illegal range" |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 367 | set.append((RANGE, (code1[1], code2[1]))) |
| 368 | else: |
| 369 | if code1[0] is IN: |
| 370 | code1 = code1[1][0] |
| 371 | set.append(code1) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 372 | |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 373 | # FIXME: <fl> move set optimization to compiler! |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 374 | if len(set)==1 and set[0][0] is LITERAL: |
| 375 | subpattern.append(set[0]) # optimization |
| 376 | elif len(set)==2 and set[0][0] is NEGATE and set[1][0] is LITERAL: |
| 377 | subpattern.append((NOT_LITERAL, set[1][1])) # optimization |
| 378 | else: |
| 379 | # FIXME: <fl> add charmap optimization |
| 380 | subpattern.append((IN, set)) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 381 | |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 382 | elif this and this[0] in REPEAT_CHARS: |
| 383 | # repeat previous item |
| 384 | if this == "?": |
| 385 | min, max = 0, 1 |
| 386 | elif this == "*": |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 387 | min, max = 0, MAXREPEAT |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 388 | elif this == "+": |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 389 | min, max = 1, MAXREPEAT |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 390 | elif this == "{": |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 391 | min, max = 0, MAXREPEAT |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 392 | lo = hi = "" |
Fredrik Lundh | 75f2d67 | 2000-06-29 11:34:28 +0000 | [diff] [blame] | 393 | while source.next in DIGITS: |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 394 | lo = lo + source.get() |
| 395 | if source.match(","): |
Fredrik Lundh | 75f2d67 | 2000-06-29 11:34:28 +0000 | [diff] [blame] | 396 | while source.next in DIGITS: |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 397 | hi = hi + source.get() |
| 398 | else: |
| 399 | hi = lo |
| 400 | if not source.match("}"): |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 401 | raise error, "bogus range" |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 402 | if lo: |
| 403 | min = int(lo) |
| 404 | if hi: |
| 405 | max = int(hi) |
| 406 | # FIXME: <fl> check that hi >= lo! |
| 407 | else: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 408 | raise error, "not supported" |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 409 | # figure out which item to repeat |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 410 | if subpattern: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 411 | item = subpattern[-1:] |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 412 | else: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 413 | raise error, "nothing to repeat" |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 414 | if source.match("?"): |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 415 | subpattern[-1] = (MIN_REPEAT, (min, max, item)) |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 416 | else: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 417 | subpattern[-1] = (MAX_REPEAT, (min, max, item)) |
| 418 | |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 419 | elif this == ".": |
| 420 | subpattern.append((ANY, None)) |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 421 | |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 422 | elif this == "(": |
| 423 | group = 1 |
| 424 | name = None |
| 425 | if source.match("?"): |
| 426 | group = 0 |
| 427 | # options |
| 428 | if source.match("P"): |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 429 | # python extensions |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 430 | if source.match("<"): |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 431 | # named group: skip forward to end of name |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 432 | name = "" |
| 433 | while 1: |
| 434 | char = source.get() |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 435 | if char is None: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 436 | raise error, "unterminated name" |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 437 | if char == ">": |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 438 | break |
| 439 | name = name + char |
| 440 | group = 1 |
Fredrik Lundh | 4781b07 | 2000-06-29 12:38:45 +0000 | [diff] [blame] | 441 | if not isname(name): |
| 442 | raise error, "illegal character in group name" |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 443 | elif source.match("="): |
| 444 | # named backreference |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 445 | raise error, "not yet implemented" |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 446 | else: |
| 447 | char = source.get() |
| 448 | if char is None: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 449 | raise error, "unexpected end of pattern" |
| 450 | raise error, "unknown specifier: ?P%s" % char |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 451 | elif source.match(":"): |
| 452 | # non-capturing group |
| 453 | group = 2 |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 454 | elif source.match("#"): |
| 455 | # comment |
| 456 | while 1: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 457 | if source.next is None or source.next == ")": |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 458 | break |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 459 | source.get() |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 460 | else: |
| 461 | # flags |
| 462 | while FLAGS.has_key(source.next): |
| 463 | state.flags = state.flags | FLAGS[source.get()] |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 464 | if group: |
| 465 | # parse group contents |
| 466 | b = [] |
| 467 | if group == 2: |
| 468 | # anonymous group |
| 469 | group = None |
| 470 | else: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 471 | group = state.getgroup(name) |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 472 | while 1: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 473 | p = _parse(source, state, flags) |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 474 | if source.match(")"): |
| 475 | if b: |
| 476 | b.append(p) |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 477 | p = _branch(state, b) |
| 478 | subpattern.append((SUBPATTERN, (group, p))) |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 479 | break |
| 480 | elif source.match("|"): |
| 481 | b.append(p) |
| 482 | else: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 483 | raise error, "group not properly closed" |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 484 | else: |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 485 | while 1: |
| 486 | char = source.get() |
| 487 | if char is None or char == ")": |
| 488 | break |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 489 | raise error, "unknown extension" |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 490 | |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 491 | elif this == "^": |
| 492 | subpattern.append((AT, AT_BEGINNING)) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 493 | |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 494 | elif this == "$": |
| 495 | subpattern.append((AT, AT_END)) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 496 | |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 497 | elif this and this[0] == "\\": |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 498 | code = _escape(source, this, state) |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 499 | subpattern.append(code) |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 500 | |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 501 | else: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 502 | raise error, "parser error" |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 503 | |
| 504 | return subpattern |
| 505 | |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 506 | def parse(pattern, flags=0): |
| 507 | # parse 're' pattern into list of (opcode, argument) tuples |
| 508 | source = Tokenizer(pattern) |
| 509 | state = State() |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 510 | b = [] |
| 511 | while 1: |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 512 | p = _parse(source, state, flags) |
| 513 | tail = source.get() |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 514 | if tail == "|": |
| 515 | b.append(p) |
| 516 | elif tail == ")": |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 517 | raise error, "unbalanced parenthesis" |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 518 | elif tail is None: |
| 519 | if b: |
| 520 | b.append(p) |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 521 | p = _branch(state, b) |
Guido van Rossum | b81e70e | 2000-04-10 17:10:48 +0000 | [diff] [blame] | 522 | break |
| 523 | else: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 524 | raise error, "bogus characters at end of regular expression" |
Guido van Rossum | 7627c0d | 2000-03-31 14:58:54 +0000 | [diff] [blame] | 525 | return p |
| 526 | |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 527 | def parse_template(source, pattern): |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 528 | # parse 're' replacement string into list of literals and |
| 529 | # group references |
| 530 | s = Tokenizer(source) |
| 531 | p = [] |
| 532 | a = p.append |
| 533 | while 1: |
| 534 | this = s.get() |
| 535 | if this is None: |
| 536 | break # end of replacement string |
| 537 | if this and this[0] == "\\": |
Fredrik Lundh | 01016fe | 2000-06-30 00:27:46 +0000 | [diff] [blame^] | 538 | # group |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 539 | if this == "\\g": |
| 540 | name = "" |
| 541 | if s.match("<"): |
| 542 | while 1: |
| 543 | char = s.get() |
| 544 | if char is None: |
Fredrik Lundh | 4781b07 | 2000-06-29 12:38:45 +0000 | [diff] [blame] | 545 | raise error, "unterminated group name" |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 546 | if char == ">": |
| 547 | break |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 548 | name = name + char |
| 549 | if not name: |
Fredrik Lundh | 4781b07 | 2000-06-29 12:38:45 +0000 | [diff] [blame] | 550 | raise error, "bad group name" |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 551 | try: |
| 552 | index = int(name) |
| 553 | except ValueError: |
Fredrik Lundh | 4781b07 | 2000-06-29 12:38:45 +0000 | [diff] [blame] | 554 | if not isname(name): |
| 555 | raise error, "illegal character in group name" |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 556 | try: |
| 557 | index = pattern.groupindex[name] |
| 558 | except KeyError: |
Fredrik Lundh | 4781b07 | 2000-06-29 12:38:45 +0000 | [diff] [blame] | 559 | raise IndexError, "unknown group name" |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 560 | a((MARK, index)) |
| 561 | elif len(this) > 1 and this[1] in DIGITS: |
Fredrik Lundh | 01016fe | 2000-06-30 00:27:46 +0000 | [diff] [blame^] | 562 | code = None |
| 563 | while 1: |
| 564 | group = _group(this, pattern.groups+1) |
| 565 | if group: |
| 566 | if (not s.next or |
| 567 | not _group(this + s.next, pattern.groups+1)): |
| 568 | code = MARK, int(group) |
| 569 | break |
| 570 | elif s.next in OCTDIGITS: |
| 571 | this = this + s.get() |
| 572 | else: |
| 573 | break |
| 574 | if not code: |
| 575 | this = this[1:] |
| 576 | # FIXME: support unicode characters! |
| 577 | code = LITERAL, chr(int(this[-6:], 8) & 0xff) |
| 578 | a(code) |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 579 | else: |
| 580 | try: |
| 581 | a(ESCAPES[this]) |
| 582 | except KeyError: |
Fredrik Lundh | 01016fe | 2000-06-30 00:27:46 +0000 | [diff] [blame^] | 583 | for c in this: |
| 584 | a((LITERAL, c)) |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 585 | else: |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 586 | a((LITERAL, this)) |
Andrew M. Kuchling | 815d5b9 | 2000-06-09 14:08:07 +0000 | [diff] [blame] | 587 | return p |
| 588 | |
Fredrik Lundh | 436c3d58 | 2000-06-29 08:58:44 +0000 | [diff] [blame] | 589 | def expand_template(template, match): |
| 590 | # FIXME: <fl> this is sooooo slow. drop in the slicelist |
| 591 | # code instead |
| 592 | p = [] |
| 593 | a = p.append |
| 594 | for c, s in template: |
| 595 | if c is LITERAL: |
| 596 | a(s) |
| 597 | elif c is MARK: |
| 598 | s = match.group(s) |
| 599 | if s is None: |
| 600 | raise error, "empty group" |
| 601 | a(s) |
| 602 | return match.string[:0].join(p) |