Lib/sre_compile.py

   1 #
   2 # Secret Labs' Regular Expression Engine
   3 #
   4 # convert template to internal format
   5 #
   6 # Copyright (c) 1997-2001 by Secret Labs AB.  All rights reserved.
   7 #
   8 # See the sre.py file for information on usage and redistribution.
   9 #
  10
  11 """Internal support module for sre"""
  12
  13 import _sre, sys
  14 import sre_parse
  15 from sre_constants import *
  16
  17 assert _sre.MAGIC == MAGIC, "SRE module mismatch"
  18
  19 if _sre.CODESIZE == 2:
  20     MAXCODE = 65535
  21 else:
  22     MAXCODE = 0xFFFFFFFFL
  23
  24 def _identityfunction(x):
  25     return x
  26
  27 def set(seq):
  28     s = {}
  29     for elem in seq:
  30         s[elem] = 1
  31     return s
  32
  33 _LITERAL_CODES = set([LITERAL, NOT_LITERAL])
  34 _REPEATING_CODES = set([REPEAT, MIN_REPEAT, MAX_REPEAT])
  35 _SUCCESS_CODES = set([SUCCESS, FAILURE])
  36 _ASSERT_CODES = set([ASSERT, ASSERT_NOT])
  37
  38 def _compile(code, pattern, flags):
  39     # internal: compile a (sub)pattern
  40     emit = code.append
  41     _len = len
  42     LITERAL_CODES = _LITERAL_CODES
  43     REPEATING_CODES = _REPEATING_CODES
  44     SUCCESS_CODES = _SUCCESS_CODES
  45     ASSERT_CODES = _ASSERT_CODES
  46     for op, av in pattern:
  47         if op in LITERAL_CODES:
  48             if flags & SRE_FLAG_IGNORECASE:
  49                 emit(OPCODES[OP_IGNORE[op]])
  50                 emit(_sre.getlower(av, flags))
  51             else:
  52                 emit(OPCODES[op])
  53                 emit(av)
  54         elif op is IN:
  55             if flags & SRE_FLAG_IGNORECASE:
  56                 emit(OPCODES[OP_IGNORE[op]])
  57                 def fixup(literal, flags=flags):
  58                     return _sre.getlower(literal, flags)
  59             else:
  60                 emit(OPCODES[op])
  61                 fixup = _identityfunction
  62             skip = _len(code); emit(0)
  63             _compile_charset(av, flags, code, fixup)
  64             code[skip] = _len(code) - skip
  65         elif op is ANY:
  66             if flags & SRE_FLAG_DOTALL:
  67                 emit(OPCODES[ANY_ALL])
  68             else:
  69                 emit(OPCODES[ANY])
  70         elif op in REPEATING_CODES:
  71             if flags & SRE_FLAG_TEMPLATE:
  72                 raise error, "internal: unsupported template operator"
  73                 emit(OPCODES[REPEAT])
  74                 skip = _len(code); emit(0)
  75                 emit(av[0])
  76                 emit(av[1])
  77                 _compile(code, av[2], flags)
  78                 emit(OPCODES[SUCCESS])
  79                 code[skip] = _len(code) - skip
  80             elif _simple(av) and op is not REPEAT:
  81                 if op is MAX_REPEAT:
  82                     emit(OPCODES[REPEAT_ONE])
  83                 else:
  84                     emit(OPCODES[MIN_REPEAT_ONE])
  85                 skip = _len(code); emit(0)
  86                 emit(av[0])
  87                 emit(av[1])
  88                 _compile(code, av[2], flags)
  89                 emit(OPCODES[SUCCESS])
  90                 code[skip] = _len(code) - skip
  91             else:
  92                 emit(OPCODES[REPEAT])
  93                 skip = _len(code); emit(0)
  94                 emit(av[0])
  95                 emit(av[1])
  96                 _compile(code, av[2], flags)
  97                 code[skip] = _len(code) - skip
  98                 if op is MAX_REPEAT:
  99                     emit(OPCODES[MAX_UNTIL])
 100                 else:
 101                     emit(OPCODES[MIN_UNTIL])
 102         elif op is SUBPATTERN:
 103             if av[0]:
 104                 emit(OPCODES[MARK])
 105                 emit((av[0]-1)*2)
 106             # _compile_info(code, av[1], flags)
 107             _compile(code, av[1], flags)
 108             if av[0]:
 109                 emit(OPCODES[MARK])
 110                 emit((av[0]-1)*2+1)
 111         elif op in SUCCESS_CODES:
 112             emit(OPCODES[op])
 113         elif op in ASSERT_CODES:
 114             emit(OPCODES[op])
 115             skip = _len(code); emit(0)
 116             if av[0] >= 0:
 117                 emit(0) # look ahead
 118             else:
 119                 lo, hi = av[1].getwidth()
 120                 if lo != hi:
 121                     raise error, "look-behind requires fixed-width pattern"
 122                 emit(lo) # look behind
 123             _compile(code, av[1], flags)
 124             emit(OPCODES[SUCCESS])
 125             code[skip] = _len(code) - skip
 126         elif op is CALL:
 127             emit(OPCODES[op])
 128             skip = _len(code); emit(0)
 129             _compile(code, av, flags)
 130             emit(OPCODES[SUCCESS])
 131             code[skip] = _len(code) - skip
 132         elif op is AT:
 133             emit(OPCODES[op])
 134             if flags & SRE_FLAG_MULTILINE:
 135                 av = AT_MULTILINE.get(av, av)
 136             if flags & SRE_FLAG_LOCALE:
 137                 av = AT_LOCALE.get(av, av)
 138             elif flags & SRE_FLAG_UNICODE:
 139                 av = AT_UNICODE.get(av, av)
 140             emit(ATCODES[av])
 141         elif op is BRANCH:
 142             emit(OPCODES[op])
 143             tail = []
 144             tailappend = tail.append
 145             for av in av[1]:
 146                 skip = _len(code); emit(0)
 147                 # _compile_info(code, av, flags)
 148                 _compile(code, av, flags)
 149                 emit(OPCODES[JUMP])
 150                 tailappend(_len(code)); emit(0)
 151                 code[skip] = _len(code) - skip
 152             emit(0) # end of branch
 153             for tail in tail:
 154                 code[tail] = _len(code) - tail
 155         elif op is CATEGORY:
 156             emit(OPCODES[op])
 157             if flags & SRE_FLAG_LOCALE:
 158                 av = CH_LOCALE[av]
 159             elif flags & SRE_FLAG_UNICODE:
 160                 av = CH_UNICODE[av]
 161             emit(CHCODES[av])
 162         elif op is GROUPREF:
 163             if flags & SRE_FLAG_IGNORECASE:
 164                 emit(OPCODES[OP_IGNORE[op]])
 165             else:
 166                 emit(OPCODES[op])
 167             emit(av-1)
 168         elif op is GROUPREF_EXISTS:
 169             emit(OPCODES[op])
 170             emit(av[0]-1)
 171             skipyes = _len(code); emit(0)
 172             _compile(code, av[1], flags)
 173             if av[2]:
 174                 emit(OPCODES[JUMP])
 175                 skipno = _len(code); emit(0)
 176                 code[skipyes] = _len(code) - skipyes + 1
 177                 _compile(code, av[2], flags)
 178                 code[skipno] = _len(code) - skipno
 179             else:
 180                 code[skipyes] = _len(code) - skipyes + 1
 181         else:
 182             raise ValueError, ("unsupported operand type", op)
 183
 184 def _compile_charset(charset, flags, code, fixup=None):
 185     # compile charset subprogram
 186     emit = code.append
 187     if fixup is None:
 188         fixup = _identityfunction
 189     for op, av in _optimize_charset(charset, fixup):
 190         emit(OPCODES[op])
 191         if op is NEGATE:
 192             pass
 193         elif op is LITERAL:
 194             emit(fixup(av))
 195         elif op is RANGE:
 196             emit(fixup(av[0]))
 197             emit(fixup(av[1]))
 198         elif op is CHARSET:
 199             code.extend(av)
 200         elif op is BIGCHARSET:
 201             code.extend(av)
 202         elif op is CATEGORY:
 203             if flags & SRE_FLAG_LOCALE:
 204                 emit(CHCODES[CH_LOCALE[av]])
 205             elif flags & SRE_FLAG_UNICODE:
 206                 emit(CHCODES[CH_UNICODE[av]])
 207             else:
 208                 emit(CHCODES[av])
 209         else:
 210             raise error, "internal: unsupported set operator"
 211     emit(OPCODES[FAILURE])
 212
 213 def _optimize_charset(charset, fixup):
 214     # internal: optimize character set
 215     out = []
 216     outappend = out.append
 217     charmap = [0]*256
 218     try:
 219         for op, av in charset:
 220             if op is NEGATE:
 221                 outappend((op, av))
 222             elif op is LITERAL:
 223                 charmap[fixup(av)] = 1
 224             elif op is RANGE:
 225                 for i in range(fixup(av[0]), fixup(av[1])+1):
 226                     charmap[i] = 1
 227             elif op is CATEGORY:
 228                 # XXX: could append to charmap tail
 229                 return charset # cannot compress
 230     except IndexError:
 231         # character set contains unicode characters
 232         return _optimize_unicode(charset, fixup)
 233     # compress character map
 234     i = p = n = 0
 235     runs = []
 236     runsappend = runs.append
 237     for c in charmap:
 238         if c:
 239             if n == 0:
 240                 p = i
 241             n = n + 1
 242         elif n:
 243             runsappend((p, n))
 244             n = 0
 245         i = i + 1
 246     if n:
 247         runsappend((p, n))
 248     if len(runs) <= 2:
 249         # use literal/range
 250         for p, n in runs:
 251             if n == 1:
 252                 outappend((LITERAL, p))
 253             else:
 254                 outappend((RANGE, (p, p+n-1)))
 255         if len(out) < len(charset):
 256             return out
 257     else:
 258         # use bitmap
 259         data = _mk_bitmap(charmap)
 260         outappend((CHARSET, data))
 261         return out
 262     return charset
 263
 264 def _mk_bitmap(bits):
 265     data = []
 266     dataappend = data.append
 267     if _sre.CODESIZE == 2:
 268         start = (1, 0)
 269     else:
 270         start = (1L, 0L)
 271     m, v = start
 272     for c in bits:
 273         if c:
 274             v = v + m
 275         m = m + m
 276         if m > MAXCODE:
 277             dataappend(v)
 278             m, v = start
 279     return data
 280
 281 # To represent a big charset, first a bitmap of all characters in the
 282 # set is constructed. Then, this bitmap is sliced into chunks of 256
 283 # characters, duplicate chunks are eliminated, and each chunk is
 284 # given a number. In the compiled expression, the charset is
 285 # represented by a 16-bit word sequence, consisting of one word for
 286 # the number of different chunks, a sequence of 256 bytes (128 words)
 287 # of chunk numbers indexed by their original chunk position, and a
 288 # sequence of chunks (16 words each).
 289
 290 # Compression is normally good: in a typical charset, large ranges of
 291 # Unicode will be either completely excluded (e.g. if only cyrillic
 292 # letters are to be matched), or completely included (e.g. if large
 293 # subranges of Kanji match). These ranges will be represented by
 294 # chunks of all one-bits or all zero-bits.
 295
 296 # Matching can be also done efficiently: the more significant byte of
 297 # the Unicode character is an index into the chunk number, and the
 298 # less significant byte is a bit index in the chunk (just like the
 299 # CHARSET matching).
 300
 301 # In UCS-4 mode, the BIGCHARSET opcode still supports only subsets
 302 # of the basic multilingual plane; an efficient representation
 303 # for all of UTF-16 has not yet been developed. This means,
 304 # in particular, that negated charsets cannot be represented as
 305 # bigcharsets.
 306
 307 def _optimize_unicode(charset, fixup):
 308     try:
 309         import array
 310     except ImportError:
 311         return charset
 312     charmap = [0]*65536
 313     negate = 0
 314     try:
 315         for op, av in charset:
 316             if op is NEGATE:
 317                 negate = 1
 318             elif op is LITERAL:
 319                 charmap[fixup(av)] = 1
 320             elif op is RANGE:
 321                 for i in xrange(fixup(av[0]), fixup(av[1])+1):
 322                     charmap[i] = 1
 323             elif op is CATEGORY:
 324                 # XXX: could expand category
 325                 return charset # cannot compress
 326     except IndexError:
 327         # non-BMP characters
 328         return charset
 329     if negate:
 330         if sys.maxunicode != 65535:
 331             # XXX: negation does not work with big charsets
 332             return charset
 333         for i in xrange(65536):
 334             charmap[i] = not charmap[i]
 335     comps = {}
 336     mapping = [0]*256
 337     block = 0
 338     data = []
 339     for i in xrange(256):
 340         chunk = tuple(charmap[i*256:(i+1)*256])
 341         new = comps.setdefault(chunk, block)
 342         mapping[i] = new
 343         if new == block:
 344             block = block + 1
 345             data = data + _mk_bitmap(chunk)
 346     header = [block]
 347     if _sre.CODESIZE == 2:
 348         code = 'H'
 349     else:
 350         code = 'I'
 351     # Convert block indices to byte array of 256 bytes
 352     mapping = array.array('b', mapping).tostring()
 353     # Convert byte array to word array
 354     mapping = array.array(code, mapping)
 355     assert mapping.itemsize == _sre.CODESIZE
 356     header = header + mapping.tolist()
 357     data[0:0] = header
 358     return [(BIGCHARSET, data)]
 359
 360 def _simple(av):
 361     # check if av is a "simple" operator
 362     lo, hi = av[2].getwidth()
 363     if lo == 0 and hi == MAXREPEAT:
 364         raise error, "nothing to repeat"
 365     return lo == hi == 1 and av[2][0][0] != SUBPATTERN
 366
 367 def _compile_info(code, pattern, flags):
 368     # internal: compile an info block.  in the current version,
 369     # this contains min/max pattern width, and an optional literal
 370     # prefix or a character map
 371     lo, hi = pattern.getwidth()
 372     if lo == 0:
 373         return # not worth it
 374     # look for a literal prefix
 375     prefix = []
 376     prefixappend = prefix.append
 377     prefix_skip = 0
 378     charset = [] # not used
 379     charsetappend = charset.append
 380     if not (flags & SRE_FLAG_IGNORECASE):
 381         # look for literal prefix
 382         for op, av in pattern.data:
 383             if op is LITERAL:
 384                 if len(prefix) == prefix_skip:
 385                     prefix_skip = prefix_skip + 1
 386                 prefixappend(av)
 387             elif op is SUBPATTERN and len(av[1]) == 1:
 388                 op, av = av[1][0]
 389                 if op is LITERAL:
 390                     prefixappend(av)
 391                 else:
 392                     break
 393             else:
 394                 break
 395         # if no prefix, look for charset prefix
 396         if not prefix and pattern.data:
 397             op, av = pattern.data[0]
 398             if op is SUBPATTERN and av[1]:
 399                 op, av = av[1][0]
 400                 if op is LITERAL:
 401                     charsetappend((op, av))
 402                 elif op is BRANCH:
 403                     c = []
 404                     cappend = c.append
 405                     for p in av[1]:
 406                         if not p:
 407                             break
 408                         op, av = p[0]
 409                         if op is LITERAL:
 410                             cappend((op, av))
 411                         else:
 412                             break
 413                     else:
 414                         charset = c
 415             elif op is BRANCH:
 416                 c = []
 417                 cappend = c.append
 418                 for p in av[1]:
 419                     if not p:
 420                         break
 421                     op, av = p[0]
 422                     if op is LITERAL:
 423                         cappend((op, av))
 424                     else:
 425                         break
 426                 else:
 427                     charset = c
 428             elif op is IN:
 429                 charset = av
 430 ##     if prefix:
 431 ##         print "*** PREFIX", prefix, prefix_skip
 432 ##     if charset:
 433 ##         print "*** CHARSET", charset
 434     # add an info block
 435     emit = code.append
 436     emit(OPCODES[INFO])
 437     skip = len(code); emit(0)
 438     # literal flag
 439     mask = 0
 440     if prefix:
 441         mask = SRE_INFO_PREFIX
 442         if len(prefix) == prefix_skip == len(pattern.data):
 443             mask = mask + SRE_INFO_LITERAL
 444     elif charset:
 445         mask = mask + SRE_INFO_CHARSET
 446     emit(mask)
 447     # pattern length
 448     if lo < MAXCODE:
 449         emit(lo)
 450     else:
 451         emit(MAXCODE)
 452         prefix = prefix[:MAXCODE]
 453     if hi < MAXCODE:
 454         emit(hi)
 455     else:
 456         emit(0)
 457     # add literal prefix
 458     if prefix:
 459         emit(len(prefix)) # length
 460         emit(prefix_skip) # skip
 461         code.extend(prefix)
 462         # generate overlap table
 463         table = [-1] + ([0]*len(prefix))
 464         for i in xrange(len(prefix)):
 465             table[i+1] = table[i]+1
 466             while table[i+1] > 0 and prefix[i] != prefix[table[i+1]-1]:
 467                 table[i+1] = table[table[i+1]-1]+1
 468         code.extend(table[1:]) # don't store first entry
 469     elif charset:
 470         _compile_charset(charset, flags, code)
 471     code[skip] = len(code) - skip
 472
 473 try:
 474     unicode
 475 except NameError:
 476     STRING_TYPES = (type(""),)
 477 else:
 478     STRING_TYPES = (type(""), type(unicode("")))
 479
 480 def isstring(obj):
 481     for tp in STRING_TYPES:
 482         if isinstance(obj, tp):
 483             return 1
 484     return 0
 485
 486 def _code(p, flags):
 487
 488     flags = p.pattern.flags | flags
 489     code = []
 490
 491     # compile info block
 492     _compile_info(code, p, flags)
 493
 494     # compile the pattern
 495     _compile(code, p.data, flags)
 496
 497     code.append(OPCODES[SUCCESS])
 498
 499     return code
 500
 501 def compile(p, flags=0):
 502     # internal: convert pattern list to internal format
 503
 504     if isstring(p):
 505         pattern = p
 506         p = sre_parse.parse(p, flags)
 507     else:
 508         pattern = None
 509
 510     code = _code(p, flags)
 511
 512     # print code
 513
 514     # XXX: <fl> get rid of this limitation!
 515     if p.pattern.groups > 100:
 516         raise AssertionError(
 517             "sorry, but this version only supports 100 named groups"
 518             )
 519
 520     # map in either direction
 521     groupindex = p.pattern.groupdict
 522     indexgroup = [None] * p.pattern.groups
 523     for k, i in groupindex.items():
 524         indexgroup[i] = k
 525
 526     return _sre.compile(
 527         pattern, flags | p.pattern.flags, code,
 528         p.pattern.groups-1,
 529         groupindex, indexgroup
 530         )