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455 lines
14 KiB
455 lines
14 KiB
# |
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# Secret Labs' Regular Expression Engine |
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# |
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# convert template to internal format |
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# |
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# Copyright (c) 1997-2001 by Secret Labs AB. All rights reserved. |
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# |
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# See the sre.py file for information on usage and redistribution. |
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# |
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"""Internal support module for sre""" |
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import _sre, sys |
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from sre_constants import * |
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assert _sre.MAGIC == MAGIC, "SRE module mismatch" |
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MAXCODE = 65535 |
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def _compile(code, pattern, flags): |
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# internal: compile a (sub)pattern |
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emit = code.append |
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for op, av in pattern: |
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if op in (LITERAL, NOT_LITERAL): |
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if flags & SRE_FLAG_IGNORECASE: |
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emit(OPCODES[OP_IGNORE[op]]) |
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emit(_sre.getlower(av, flags)) |
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else: |
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emit(OPCODES[op]) |
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emit(av) |
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elif op is IN: |
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if flags & SRE_FLAG_IGNORECASE: |
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emit(OPCODES[OP_IGNORE[op]]) |
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def fixup(literal, flags=flags): |
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return _sre.getlower(literal, flags) |
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else: |
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emit(OPCODES[op]) |
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fixup = lambda x: x |
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skip = len(code); emit(0) |
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_compile_charset(av, flags, code, fixup) |
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code[skip] = len(code) - skip |
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elif op is ANY: |
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if flags & SRE_FLAG_DOTALL: |
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emit(OPCODES[ANY_ALL]) |
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else: |
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emit(OPCODES[ANY]) |
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elif op in (REPEAT, MIN_REPEAT, MAX_REPEAT): |
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if flags & SRE_FLAG_TEMPLATE: |
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raise error, "internal: unsupported template operator" |
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emit(OPCODES[REPEAT]) |
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skip = len(code); emit(0) |
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emit(av[0]) |
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emit(av[1]) |
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_compile(code, av[2], flags) |
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emit(OPCODES[SUCCESS]) |
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code[skip] = len(code) - skip |
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elif _simple(av) and op == MAX_REPEAT: |
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emit(OPCODES[REPEAT_ONE]) |
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skip = len(code); emit(0) |
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emit(av[0]) |
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emit(av[1]) |
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_compile(code, av[2], flags) |
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emit(OPCODES[SUCCESS]) |
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code[skip] = len(code) - skip |
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else: |
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emit(OPCODES[REPEAT]) |
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skip = len(code); emit(0) |
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emit(av[0]) |
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emit(av[1]) |
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_compile(code, av[2], flags) |
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code[skip] = len(code) - skip |
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if op == MAX_REPEAT: |
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emit(OPCODES[MAX_UNTIL]) |
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else: |
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emit(OPCODES[MIN_UNTIL]) |
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elif op is SUBPATTERN: |
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if av[0]: |
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emit(OPCODES[MARK]) |
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emit((av[0]-1)*2) |
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# _compile_info(code, av[1], flags) |
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_compile(code, av[1], flags) |
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if av[0]: |
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emit(OPCODES[MARK]) |
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emit((av[0]-1)*2+1) |
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elif op in (SUCCESS, FAILURE): |
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emit(OPCODES[op]) |
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elif op in (ASSERT, ASSERT_NOT): |
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emit(OPCODES[op]) |
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skip = len(code); emit(0) |
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if av[0] >= 0: |
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emit(0) # look ahead |
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else: |
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lo, hi = av[1].getwidth() |
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if lo != hi: |
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raise error, "look-behind requires fixed-width pattern" |
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emit(lo) # look behind |
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_compile(code, av[1], flags) |
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emit(OPCODES[SUCCESS]) |
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code[skip] = len(code) - skip |
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elif op is CALL: |
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emit(OPCODES[op]) |
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skip = len(code); emit(0) |
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_compile(code, av, flags) |
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emit(OPCODES[SUCCESS]) |
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code[skip] = len(code) - skip |
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elif op is AT: |
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emit(OPCODES[op]) |
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if flags & SRE_FLAG_MULTILINE: |
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av = AT_MULTILINE.get(av, av) |
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if flags & SRE_FLAG_LOCALE: |
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av = AT_LOCALE.get(av, av) |
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elif flags & SRE_FLAG_UNICODE: |
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av = AT_UNICODE.get(av, av) |
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emit(ATCODES[av]) |
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elif op is BRANCH: |
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emit(OPCODES[op]) |
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tail = [] |
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for av in av[1]: |
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skip = len(code); emit(0) |
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# _compile_info(code, av, flags) |
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_compile(code, av, flags) |
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emit(OPCODES[JUMP]) |
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tail.append(len(code)); emit(0) |
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code[skip] = len(code) - skip |
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emit(0) # end of branch |
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for tail in tail: |
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code[tail] = len(code) - tail |
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elif op is CATEGORY: |
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emit(OPCODES[op]) |
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if flags & SRE_FLAG_LOCALE: |
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av = CH_LOCALE[av] |
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elif flags & SRE_FLAG_UNICODE: |
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av = CH_UNICODE[av] |
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emit(CHCODES[av]) |
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elif op is GROUPREF: |
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if flags & SRE_FLAG_IGNORECASE: |
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emit(OPCODES[OP_IGNORE[op]]) |
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else: |
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emit(OPCODES[op]) |
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emit(av-1) |
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else: |
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raise ValueError, ("unsupported operand type", op) |
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def _compile_charset(charset, flags, code, fixup=None): |
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# compile charset subprogram |
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emit = code.append |
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if not fixup: |
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fixup = lambda x: x |
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for op, av in _optimize_charset(charset, fixup): |
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emit(OPCODES[op]) |
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if op is NEGATE: |
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pass |
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elif op is LITERAL: |
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emit(fixup(av)) |
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elif op is RANGE: |
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emit(fixup(av[0])) |
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emit(fixup(av[1])) |
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elif op is CHARSET: |
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code.extend(av) |
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elif op is BIGCHARSET: |
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code.extend(av) |
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elif op is CATEGORY: |
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if flags & SRE_FLAG_LOCALE: |
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emit(CHCODES[CH_LOCALE[av]]) |
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elif flags & SRE_FLAG_UNICODE: |
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emit(CHCODES[CH_UNICODE[av]]) |
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else: |
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emit(CHCODES[av]) |
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else: |
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raise error, "internal: unsupported set operator" |
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emit(OPCODES[FAILURE]) |
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def _optimize_charset(charset, fixup): |
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# internal: optimize character set |
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out = [] |
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charmap = [0]*256 |
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try: |
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for op, av in charset: |
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if op is NEGATE: |
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out.append((op, av)) |
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elif op is LITERAL: |
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charmap[fixup(av)] = 1 |
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elif op is RANGE: |
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for i in range(fixup(av[0]), fixup(av[1])+1): |
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charmap[i] = 1 |
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elif op is CATEGORY: |
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# XXX: could append to charmap tail |
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return charset # cannot compress |
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except IndexError: |
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if sys.maxunicode != 65535: |
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# XXX: big charsets don't work in UCS-4 builds |
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return charset |
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# character set contains unicode characters |
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return _optimize_unicode(charset, fixup) |
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# compress character map |
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i = p = n = 0 |
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runs = [] |
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for c in charmap: |
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if c: |
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if n == 0: |
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p = i |
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n = n + 1 |
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elif n: |
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runs.append((p, n)) |
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n = 0 |
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i = i + 1 |
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if n: |
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runs.append((p, n)) |
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if len(runs) <= 2: |
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# use literal/range |
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for p, n in runs: |
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if n == 1: |
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out.append((LITERAL, p)) |
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else: |
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out.append((RANGE, (p, p+n-1))) |
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if len(out) < len(charset): |
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return out |
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else: |
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# use bitmap |
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data = _mk_bitmap(charmap) |
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out.append((CHARSET, data)) |
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return out |
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return charset |
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def _mk_bitmap(bits): |
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data = [] |
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m = 1; v = 0 |
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for c in bits: |
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if c: |
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v = v + m |
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m = m << 1 |
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if m > MAXCODE: |
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data.append(v) |
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m = 1; v = 0 |
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return data |
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# To represent a big charset, first a bitmap of all characters in the |
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# set is constructed. Then, this bitmap is sliced into chunks of 256 |
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# characters, duplicate chunks are eliminitated, and each chunk is |
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# given a number. In the compiled expression, the charset is |
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# represented by a 16-bit word sequence, consisting of one word for |
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# the number of different chunks, a sequence of 256 bytes (128 words) |
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# of chunk numbers indexed by their original chunk position, and a |
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# sequence of chunks (16 words each). |
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# Compression is normally good: in a typical charset, large ranges of |
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# Unicode will be either completely excluded (e.g. if only cyrillic |
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# letters are to be matched), or completely included (e.g. if large |
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# subranges of Kanji match). These ranges will be represented by |
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# chunks of all one-bits or all zero-bits. |
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# Matching can be also done efficiently: the more significant byte of |
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# the Unicode character is an index into the chunk number, and the |
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# less significant byte is a bit index in the chunk (just like the |
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# CHARSET matching). |
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def _optimize_unicode(charset, fixup): |
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charmap = [0]*65536 |
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negate = 0 |
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for op, av in charset: |
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if op is NEGATE: |
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negate = 1 |
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elif op is LITERAL: |
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charmap[fixup(av)] = 1 |
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elif op is RANGE: |
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for i in range(fixup(av[0]), fixup(av[1])+1): |
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charmap[i] = 1 |
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elif op is CATEGORY: |
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# XXX: could expand category |
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return charset # cannot compress |
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if negate: |
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for i in range(65536): |
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charmap[i] = not charmap[i] |
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comps = {} |
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mapping = [0]*256 |
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block = 0 |
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data = [] |
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for i in range(256): |
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chunk = tuple(charmap[i*256:(i+1)*256]) |
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new = comps.setdefault(chunk, block) |
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mapping[i] = new |
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if new == block: |
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block = block + 1 |
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data = data + _mk_bitmap(chunk) |
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header = [block] |
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assert MAXCODE == 65535 |
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for i in range(128): |
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if sys.byteorder == 'big': |
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header.append(256*mapping[2*i]+mapping[2*i+1]) |
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else: |
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header.append(mapping[2*i]+256*mapping[2*i+1]) |
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data[0:0] = header |
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return [(BIGCHARSET, data)] |
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def _simple(av): |
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# check if av is a "simple" operator |
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lo, hi = av[2].getwidth() |
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if lo == 0 and hi == MAXREPEAT: |
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raise error, "nothing to repeat" |
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return lo == hi == 1 and av[2][0][0] != SUBPATTERN |
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def _compile_info(code, pattern, flags): |
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# internal: compile an info block. in the current version, |
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# this contains min/max pattern width, and an optional literal |
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# prefix or a character map |
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lo, hi = pattern.getwidth() |
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if lo == 0: |
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return # not worth it |
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# look for a literal prefix |
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prefix = [] |
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prefix_skip = 0 |
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charset = [] # not used |
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if not (flags & SRE_FLAG_IGNORECASE): |
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# look for literal prefix |
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for op, av in pattern.data: |
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if op is LITERAL: |
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if len(prefix) == prefix_skip: |
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prefix_skip = prefix_skip + 1 |
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prefix.append(av) |
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elif op is SUBPATTERN and len(av[1]) == 1: |
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op, av = av[1][0] |
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if op is LITERAL: |
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prefix.append(av) |
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else: |
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break |
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else: |
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break |
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# if no prefix, look for charset prefix |
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if not prefix and pattern.data: |
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op, av = pattern.data[0] |
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if op is SUBPATTERN and av[1]: |
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op, av = av[1][0] |
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if op is LITERAL: |
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charset.append((op, av)) |
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elif op is BRANCH: |
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c = [] |
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for p in av[1]: |
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if not p: |
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break |
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op, av = p[0] |
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if op is LITERAL: |
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c.append((op, av)) |
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else: |
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break |
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else: |
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charset = c |
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elif op is BRANCH: |
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c = [] |
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for p in av[1]: |
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if not p: |
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break |
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op, av = p[0] |
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if op is LITERAL: |
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c.append((op, av)) |
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else: |
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break |
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else: |
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charset = c |
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elif op is IN: |
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charset = av |
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## if prefix: |
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## print "*** PREFIX", prefix, prefix_skip |
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## if charset: |
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## print "*** CHARSET", charset |
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# add an info block |
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emit = code.append |
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emit(OPCODES[INFO]) |
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skip = len(code); emit(0) |
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# literal flag |
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mask = 0 |
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if prefix: |
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mask = SRE_INFO_PREFIX |
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if len(prefix) == prefix_skip == len(pattern.data): |
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mask = mask + SRE_INFO_LITERAL |
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elif charset: |
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mask = mask + SRE_INFO_CHARSET |
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emit(mask) |
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# pattern length |
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if lo < MAXCODE: |
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emit(lo) |
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else: |
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emit(MAXCODE) |
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prefix = prefix[:MAXCODE] |
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if hi < MAXCODE: |
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emit(hi) |
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else: |
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emit(0) |
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# add literal prefix |
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if prefix: |
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emit(len(prefix)) # length |
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emit(prefix_skip) # skip |
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code.extend(prefix) |
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# generate overlap table |
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table = [-1] + ([0]*len(prefix)) |
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for i in range(len(prefix)): |
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table[i+1] = table[i]+1 |
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while table[i+1] > 0 and prefix[i] != prefix[table[i+1]-1]: |
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table[i+1] = table[table[i+1]-1]+1 |
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code.extend(table[1:]) # don't store first entry |
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elif charset: |
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_compile_charset(charset, 0, code) |
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code[skip] = len(code) - skip |
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STRING_TYPES = [type("")] |
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try: |
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STRING_TYPES.append(type(unicode(""))) |
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except NameError: |
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pass |
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def _code(p, flags): |
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flags = p.pattern.flags | flags |
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code = [] |
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# compile info block |
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_compile_info(code, p, flags) |
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# compile the pattern |
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_compile(code, p.data, flags) |
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code.append(OPCODES[SUCCESS]) |
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return code |
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def compile(p, flags=0): |
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# internal: convert pattern list to internal format |
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if type(p) in STRING_TYPES: |
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import sre_parse |
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pattern = p |
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p = sre_parse.parse(p, flags) |
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else: |
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pattern = None |
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code = _code(p, flags) |
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# print code |
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# XXX: <fl> get rid of this limitation! |
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assert p.pattern.groups <= 100,\ |
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"sorry, but this version only supports 100 named groups" |
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# map in either direction |
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groupindex = p.pattern.groupdict |
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indexgroup = [None] * p.pattern.groups |
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for k, i in groupindex.items(): |
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indexgroup[i] = k |
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return _sre.compile( |
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pattern, flags, code, |
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p.pattern.groups-1, |
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groupindex, indexgroup |
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)
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