mirror of https://github.com/python/cpython
326 lines
10 KiB
Python
326 lines
10 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) 1997-2000 by Secret Labs AB. All rights reserved.
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#
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# Portions of this engine have been developed in cooperation with
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# CNRI. Hewlett-Packard provided funding for 2.0 integration and
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# other compatibility work.
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#
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import _sre
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from sre_constants import *
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MAXCODE = 65535
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def _charset(charset, fixup=None):
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# internal: optimize character set
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if not fixup:
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fixup = lambda x: x
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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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# FIXME: could append to charmap tail
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return charset # cannot compress
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except IndexError:
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# unicode
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return charset
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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 = []
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m = 1; v = 0
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for c in charmap:
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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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out.append((CHARSET, data))
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return out
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return charset
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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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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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for op, av in _charset(av, 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 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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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[op])
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else:
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emit(OPCODES[CATEGORY])
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emit(CHCODES[CATEGORY_NOT_LINEBREAK])
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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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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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else:
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lo, hi = av[2].getwidth()
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if lo == 0:
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raise error, "nothing to repeat"
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if 0 and lo == hi == 1 and op is MAX_REPEAT:
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# FIXME: <fl> need a better way to figure out when
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# it's safe to use this one (in the parser, probably)
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emit(OPCODES[MAX_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[op])
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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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mark = MAXCODE
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if av[2][0][0] == SUBPATTERN:
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# repeated subpattern
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gid, foo = av[2][0][1]
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if gid:
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mark = (gid-1)*2
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emit(mark)
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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 op is SUBPATTERN:
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gid = av[0]
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if gid:
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emit(OPCODES[MARK])
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emit((gid-1)*2)
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_compile(code, av[1], flags)
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if gid:
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emit(OPCODES[MARK])
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emit((gid-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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emit(ATCODES[AT_MULTILINE.get(av, av)])
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else:
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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(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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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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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 in (MARK, INDEX):
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emit(OPCODES[op])
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emit(av)
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else:
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raise ValueError, ("unsupported operand type", op)
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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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charset = [] # not used
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if not (flags & SRE_FLAG_IGNORECASE):
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for op, av in pattern.data:
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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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# 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) == 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))
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if prefix:
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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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for char in charset:
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emit(OPCODES[LITERAL])
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emit(char)
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emit(OPCODES[FAILURE])
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code[skip] = len(code) - skip
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def compile(p, flags=0):
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# internal: convert pattern list to internal format
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# compile, as necessary
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if type(p) in (type(""), type(u"")):
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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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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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# FIXME: <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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