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         )