489 lines
15 KiB
Python
489 lines
15 KiB
Python
#
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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
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import sre_parse
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from sre_constants import *
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from _sre import MAXREPEAT
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assert _sre.MAGIC == MAGIC, "SRE module mismatch"
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if _sre.CODESIZE == 2:
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MAXCODE = 65535
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else:
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MAXCODE = 0xFFFFFFFF
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def _identityfunction(x):
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return x
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_LITERAL_CODES = set([LITERAL, NOT_LITERAL])
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_REPEATING_CODES = set([REPEAT, MIN_REPEAT, MAX_REPEAT])
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_SUCCESS_CODES = set([SUCCESS, FAILURE])
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_ASSERT_CODES = set([ASSERT, ASSERT_NOT])
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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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_len = len
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LITERAL_CODES = _LITERAL_CODES
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REPEATING_CODES = _REPEATING_CODES
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SUCCESS_CODES = _SUCCESS_CODES
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ASSERT_CODES = _ASSERT_CODES
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for op, av in pattern:
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if op in LITERAL_CODES:
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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 = _identityfunction
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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 REPEATING_CODES:
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if flags & SRE_FLAG_TEMPLATE:
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raise error("internal: unsupported template operator")
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elif _simple(av) and op is not REPEAT:
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if op is MAX_REPEAT:
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emit(OPCODES[REPEAT_ONE])
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else:
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emit(OPCODES[MIN_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 is 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_CODES:
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emit(OPCODES[op])
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elif op in ASSERT_CODES:
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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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tailappend = tail.append
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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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tailappend(_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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elif op is GROUPREF_EXISTS:
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emit(OPCODES[op])
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emit(av[0]-1)
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skipyes = _len(code); emit(0)
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_compile(code, av[1], flags)
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if av[2]:
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emit(OPCODES[JUMP])
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skipno = _len(code); emit(0)
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code[skipyes] = _len(code) - skipyes + 1
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_compile(code, av[2], flags)
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code[skipno] = _len(code) - skipno
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else:
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code[skipyes] = _len(code) - skipyes + 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 fixup is None:
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fixup = _identityfunction
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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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tail = []
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charmap = bytearray(256)
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for op, av in charset:
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while True:
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try:
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if 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 NEGATE:
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out.append((op, av))
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else:
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tail.append((op, av))
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except IndexError:
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if len(charmap) == 256:
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# character set contains non-UCS1 character codes
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charmap += b'\0' * 0xff00
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continue
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# character set contains non-BMP character codes
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tail.append((op, av))
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break
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# compress character map
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runs = []
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q = 0
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while True:
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p = charmap.find(1, q)
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if p < 0:
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break
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if len(runs) >= 2:
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runs = None
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break
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q = charmap.find(0, p)
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if q < 0:
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runs.append((p, len(charmap)))
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break
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runs.append((p, q))
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if runs is not None:
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# use literal/range
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for p, q in runs:
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if q - p == 1:
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out.append((LITERAL, p))
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else:
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out.append((RANGE, (p, q - 1)))
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out += tail
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if len(out) < len(charset):
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return out
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return charset
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# use bitmap
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if len(charmap) == 256:
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data = _mk_bitmap(charmap)
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out.append((CHARSET, data))
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out += tail
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return out
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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 eliminated, 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 32-bit word sequence, consisting of one word for
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# the number of different chunks, a sequence of 256 bytes (64 words)
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# of chunk numbers indexed by their original chunk position, and a
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# sequence of 256-bit chunks (8 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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charmap = bytes(charmap) # should be hashable
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comps = {}
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mapping = bytearray(256)
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block = 0
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data = bytearray()
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for i in range(0, 65536, 256):
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chunk = charmap[i: i + 256]
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if chunk in comps:
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mapping[i // 256] = comps[chunk]
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else:
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mapping[i // 256] = comps[chunk] = block
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block += 1
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data += chunk
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data = _mk_bitmap(data)
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data[0:0] = [block] + _bytes_to_codes(mapping)
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out.append((BIGCHARSET, data))
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out += tail
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return out
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_CODEBITS = _sre.CODESIZE * 8
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_BITS_TRANS = b'0' + b'1' * 255
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def _mk_bitmap(bits, _CODEBITS=_CODEBITS, _int=int):
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s = bits.translate(_BITS_TRANS)[::-1]
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return [_int(s[i - _CODEBITS: i], 2)
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for i in range(len(s), 0, -_CODEBITS)]
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def _bytes_to_codes(b):
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# Convert block indices to word array
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import array
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a = array.array('I', b)
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assert a.itemsize == _sre.CODESIZE
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assert len(a) * a.itemsize == len(b)
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return a.tolist()
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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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return lo == hi == 1 and av[2][0][0] != SUBPATTERN
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def _generate_overlap_table(prefix):
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"""
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Generate an overlap table for the following prefix.
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An overlap table is a table of the same size as the prefix which
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informs about the potential self-overlap for each index in the prefix:
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- if overlap[i] == 0, prefix[i:] can't overlap prefix[0:...]
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- if overlap[i] == k with 0 < k <= i, prefix[i-k+1:i+1] overlaps with
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prefix[0:k]
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"""
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table = [0] * len(prefix)
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for i in range(1, len(prefix)):
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idx = table[i - 1]
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while prefix[i] != prefix[idx]:
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if idx == 0:
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table[i] = 0
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break
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idx = table[idx - 1]
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else:
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table[i] = idx + 1
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return table
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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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prefixappend = prefix.append
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prefix_skip = 0
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charset = [] # not used
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charsetappend = charset.append
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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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prefixappend(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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prefixappend(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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charsetappend((op, av))
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elif op is BRANCH:
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c = []
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cappend = c.append
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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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cappend((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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cappend = c.append
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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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cappend((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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code.extend(_generate_overlap_table(prefix))
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elif charset:
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_compile_charset(charset, flags, code)
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code[skip] = len(code) - skip
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def isstring(obj):
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return isinstance(obj, (str, bytes))
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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 isstring(p):
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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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if p.pattern.groups > 100:
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raise AssertionError(
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"sorry, but this version only supports 100 named groups"
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)
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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 | p.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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