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|
#
# Secret Labs' Regular Expression Engine
#
# convert template to internal format
#
# Copyright (c) 1997-2000 by Secret Labs AB. All rights reserved.
#
# Portions of this engine have been developed in cooperation with
# CNRI. Hewlett-Packard provided funding for 2.0 integration and
# other compatibility work.
#
import _sre
from sre_constants import *
MAXCODE = 65535
def _charset(charset, fixup):
# internal: optimize character set
out = []
charmap = [0]*256
try:
for op, av in charset:
if op is NEGATE:
out.append((op, av))
elif op is LITERAL:
charmap[fixup(av)] = 1
elif op is RANGE:
for i in range(fixup(av[0]), fixup(av[1])+1):
charmap[i] = 1
elif op is CATEGORY:
# FIXME: could append to charmap tail
return charset # cannot compress
except IndexError:
# unicode
return charset
# compress character map
i = p = n = 0
runs = []
for c in charmap:
if c:
if n == 0:
p = i
n = n + 1
elif n:
runs.append((p, n))
n = 0
i = i + 1
if n:
runs.append((p, n))
if len(runs) <= 2:
# use literal/range
for p, n in runs:
if n == 1:
out.append((LITERAL, p))
else:
out.append((RANGE, (p, p+n-1)))
if len(out) < len(charset):
return out
else:
# use bitmap
data = []
m = 1; v = 0
for c in charmap:
if c:
v = v + m
m = m << 1
if m > MAXCODE:
data.append(v)
m = 1; v = 0
out.append((CHARSET, data))
return out
return charset
def _compile(code, pattern, flags):
# internal: compile a (sub)pattern
emit = code.append
for op, av in pattern:
if op in (LITERAL, NOT_LITERAL):
if flags & SRE_FLAG_IGNORECASE:
emit(OPCODES[OP_IGNORE[op]])
else:
emit(OPCODES[op])
emit(av)
elif op is IN:
if flags & SRE_FLAG_IGNORECASE:
emit(OPCODES[OP_IGNORE[op]])
def fixup(literal, flags=flags):
return _sre.getlower(literal, flags)
else:
emit(OPCODES[op])
fixup = lambda x: x
skip = len(code); emit(0)
for op, av in _charset(av, fixup):
emit(OPCODES[op])
if op is NEGATE:
pass
elif op is LITERAL:
emit(fixup(av))
elif op is RANGE:
emit(fixup(av[0]))
emit(fixup(av[1]))
elif op is CHARSET:
code.extend(av)
elif op is CATEGORY:
if flags & SRE_FLAG_LOCALE:
emit(CHCODES[CH_LOCALE[av]])
elif flags & SRE_FLAG_UNICODE:
emit(CHCODES[CH_UNICODE[av]])
else:
emit(CHCODES[av])
else:
raise error, "internal: unsupported set operator"
emit(OPCODES[FAILURE])
code[skip] = len(code) - skip
elif op is ANY:
if flags & SRE_FLAG_DOTALL:
emit(OPCODES[op])
else:
emit(OPCODES[CATEGORY])
emit(CHCODES[CATEGORY_NOT_LINEBREAK])
elif op in (REPEAT, MIN_REPEAT, MAX_REPEAT):
if flags & SRE_FLAG_TEMPLATE:
emit(OPCODES[REPEAT])
skip = len(code); emit(0)
emit(av[0])
emit(av[1])
_compile(code, av[2], flags)
emit(OPCODES[SUCCESS])
code[skip] = len(code) - skip
else:
lo, hi = av[2].getwidth()
if lo == 0:
raise error, "nothing to repeat"
if 0 and lo == hi == 1 and op is MAX_REPEAT:
# FIXME: <fl> need a better way to figure out when
# it's safe to use this one (in the parser, probably)
emit(OPCODES[MAX_REPEAT_ONE])
skip = len(code); emit(0)
emit(av[0])
emit(av[1])
_compile(code, av[2], flags)
emit(OPCODES[SUCCESS])
code[skip] = len(code) - skip
else:
emit(OPCODES[op])
skip = len(code); emit(0)
emit(av[0])
emit(av[1])
_compile(code, av[2], flags)
emit(OPCODES[SUCCESS])
code[skip] = len(code) - skip
elif op is SUBPATTERN:
group = av[0]
if group:
emit(OPCODES[MARK])
emit((group-1)*2)
_compile(code, av[1], flags)
if group:
emit(OPCODES[MARK])
emit((group-1)*2+1)
elif op in (SUCCESS, FAILURE):
emit(OPCODES[op])
elif op in (ASSERT, ASSERT_NOT):
emit(OPCODES[op])
skip = len(code); emit(0)
if av[0] >= 0:
emit(0) # look ahead
else:
lo, hi = av[1].getwidth()
if lo != hi:
raise error, "look-behind requires fixed-width pattern"
emit(lo) # look behind
_compile(code, av[1], flags)
emit(OPCODES[SUCCESS])
code[skip] = len(code) - skip
elif op is CALL:
emit(OPCODES[op])
skip = len(code); emit(0)
_compile(code, av, flags)
emit(OPCODES[SUCCESS])
code[skip] = len(code) - skip
elif op is AT:
emit(OPCODES[op])
if flags & SRE_FLAG_MULTILINE:
emit(ATCODES[AT_MULTILINE.get(av, av)])
else:
emit(ATCODES[av])
elif op is BRANCH:
emit(OPCODES[op])
tail = []
for av in av[1]:
skip = len(code); emit(0)
_compile(code, av, flags)
emit(OPCODES[JUMP])
tail.append(len(code)); emit(0)
code[skip] = len(code) - skip
emit(0) # end of branch
for tail in tail:
code[tail] = len(code) - tail
elif op is CATEGORY:
emit(OPCODES[op])
if flags & SRE_FLAG_LOCALE:
emit(CHCODES[CH_LOCALE[av]])
elif flags & SRE_FLAG_UNICODE:
emit(CHCODES[CH_UNICODE[av]])
else:
emit(CHCODES[av])
elif op is GROUP:
if flags & SRE_FLAG_IGNORECASE:
emit(OPCODES[OP_IGNORE[op]])
else:
emit(OPCODES[op])
emit(av-1)
elif op in (MARK, INDEX):
emit(OPCODES[op])
emit(av)
else:
raise ValueError, ("unsupported operand type", op)
def _compile_info(code, pattern, flags):
# internal: compile an info block. in the current version,
# this contains min/max pattern width, and an optional literal
# prefix or a character map
lo, hi = pattern.getwidth()
if lo == 0:
return # not worth it
# look for a literal prefix
prefix = []
charset = [] # not used
if not (flags & SRE_FLAG_IGNORECASE):
for op, av in pattern.data:
if op is LITERAL:
prefix.append(av)
else:
break
# add an info block
emit = code.append
emit(OPCODES[INFO])
skip = len(code); emit(0)
# literal flag
mask = 0
if prefix:
mask = SRE_INFO_PREFIX
if len(prefix) == len(pattern.data):
mask = mask + SRE_INFO_LITERAL
elif charset:
mask = mask + SRE_INFO_CHARSET
emit(mask)
# pattern length
if lo < MAXCODE:
emit(lo)
else:
emit(MAXCODE)
prefix = prefix[:MAXCODE]
if hi < MAXCODE:
emit(hi)
else:
emit(0)
# add literal prefix
if prefix:
emit(len(prefix))
if prefix:
code.extend(prefix)
# generate overlap table
table = [-1] + ([0]*len(prefix))
for i in range(len(prefix)):
table[i+1] = table[i]+1
while table[i+1] > 0 and prefix[i] != prefix[table[i+1]-1]:
table[i+1] = table[table[i+1]-1]+1
code.extend(table[1:]) # don't store first entry
elif charset:
for char in charset:
emit(OPCODES[LITERAL])
emit(char)
emit(OPCODES[FAILURE])
code[skip] = len(code) - skip
def compile(p, flags=0):
# internal: convert pattern list to internal format
# compile, as necessary
if type(p) in (type(""), type(u"")):
import sre_parse
pattern = p
p = sre_parse.parse(p, flags)
else:
pattern = None
flags = p.pattern.flags | flags
code = []
# compile info block
_compile_info(code, p, flags)
# compile the pattern
_compile(code, p.data, flags)
code.append(OPCODES[SUCCESS])
# FIXME: <fl> get rid of this limitation!
assert p.pattern.groups <= 100,\
"sorry, but this version only supports 100 named groups"
# map in either direction
groupindex = p.pattern.groupdict
indexgroup = [None] * p.pattern.groups
for k, i in groupindex.items():
indexgroup[i] = k
return _sre.compile(
pattern, flags, code,
p.pattern.groups-1,
groupindex, indexgroup
)
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