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/Lib/sre_compile.py

http://unladen-swallow.googlecode.com/
Python | 530 lines | 448 code | 19 blank | 63 comment | 107 complexity | 437e9e6833641b6bc0ae4cb6bce68b14 MD5 | raw file
  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
 13import _sre, sys
 14import sre_parse
 15from sre_constants import *
 16
 17assert _sre.MAGIC == MAGIC, "SRE module mismatch"
 18
 19if _sre.CODESIZE == 2:
 20    MAXCODE = 65535
 21else:
 22    MAXCODE = 0xFFFFFFFFL
 23
 24def _identityfunction(x):
 25    return x
 26
 27def 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
 38def _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
184def _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
213def _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
264def _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
307def _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
360def _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
367def _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
473try:
474    unicode
475except NameError:
476    STRING_TYPES = (type(""),)
477else:
478    STRING_TYPES = (type(""), type(unicode("")))
479
480def isstring(obj):
481    for tp in STRING_TYPES:
482        if isinstance(obj, tp):
483            return 1
484    return 0
485
486def _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
501def 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        )