#
# Secret Labs' Regular Expression Engine
#
# convert template to internal format
#
# Copyright (c) 1997-2001 by Secret Labs AB. All rights reserved.
#
# See the sre.py file for information on usage and redistribution.
#
"""Internal support module for sre"""
import _sre, sys
import sre_parse
from sre_constants import *
assert _sre.MAGIC == MAGIC, "SRE module mismatch"
if _sre.CODESIZE == 2:
MAXCODE = 65535
else:
MAXCODE = 0xFFFFFFFF
def _identityfunction(x):
return x
_LITERAL_CODES = set([LITERAL, NOT_LITERAL])
_REPEATING_CODES = set([REPEAT, MIN_REPEAT, MAX_REPEAT])
_SUCCESS_CODES = set([SUCCESS, FAILURE])
_ASSERT_CODES = set([ASSERT, ASSERT_NOT])
def _compile(code, pattern, flags):
# internal: compile a (sub)pattern
emit = code.append
_len = len
LITERAL_CODES = _LITERAL_CODES
REPEATING_CODES = _REPEATING_CODES
SUCCESS_CODES = _SUCCESS_CODES
ASSERT_CODES = _ASSERT_CODES
for op, av in pattern:
if op in LITERAL_CODES:
if flags & SRE_FLAG_IGNORECASE:
emit(OPCODES[OP_IGNORE[op]])
emit(_sre.getlower(av, flags))
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 = _identityfunction
skip = _len(code); emit(0)
_compile_charset(av, flags, code, fixup)
code[skip] = _len(code) - skip
elif op is ANY:
if flags & SRE_FLAG_DOTALL:
emit(OPCODES[ANY_ALL])
else:
emit(OPCODES[ANY])
elif op in REPEATING_CODES:
if flags & SRE_FLAG_TEMPLATE:
raise error("internal: unsupported template operator")
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
elif _simple(av) and op is not REPEAT:
if op is MAX_REPEAT:
emit(OPCODES[REPEAT_ONE])
else:
emit(OPCODES[MIN_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[REPEAT])
skip = _len(code); emit(0)
emit(av[0])
emit(av[1])
_compile(code, av[2], flags)
code[skip] = _len(code) - skip
if op is MAX_REPEAT:
emit(OPCODES[MAX_UNTIL])
else:
emit(OPCODES[MIN_UNTIL])
elif op is SUBPATTERN:
if av[0]:
emit(OPCODES[MARK])
emit((av[0]-1)*2)
# _compile_info(code, av[1], flags)
_compile(code, av[1], flags)
if av[0]:
emit(OPCODES[MARK])
emit((av[0]-1)*2+1)
elif op in SUCCESS_CODES:
emit(OPCODES[op])
elif op in ASSERT_CODES:
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:
av = AT_MULTILINE.get(av, av)
if flags & SRE_FLAG_LOCALE:
av = AT_LOCALE.get(av, av)
elif flags & SRE_FLAG_UNICODE:
av = AT_UNICODE.get(av, av)
emit(ATCODES[av])
elif op is BRANCH:
emit(OPCODES[op])
tail = []
tailappend = tail.append
for av in av[1]:
skip = _len(code); emit(0)
# _compile_info(code, av, flags)
_compile(code, av, flags)
emit(OPCODES[JUMP])
tailappend(_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:
av = CH_LOCALE[av]
elif flags & SRE_FLAG_UNICODE:
av = CH_UNICODE[av]
emit(CHCODES[av])
elif op is GROUPREF:
if flags & SRE_FLAG_IGNORECASE:
emit(OPCODES[OP_IGNORE[op]])
else:
emit(OPCODES[op])
emit(av-1)
elif op is GROUPREF_EXISTS:
emit(OPCODES[op])
emit(av[0]-1)
skipyes = _len(code); emit(0)
_compile(code, av[1], flags)
if av[2]:
emit(OPCODES[JUMP])
skipno = _len(code); emit(0)
code[skipyes] = _len(code) - skipyes + 1
_compile(code, av[2], flags)
code[skipno] = _len(code) - skipno
else:
code[skipyes] = _len(code) - skipyes + 1
else:
raise ValueError("unsupported operand type", op)
def _compile_charset(charset, flags, code, fixup=None):
# compile charset subprogram
emit = code.append
if fixup is None:
fixup = _identityfunction
for op, av in _optimize_charset(charset, 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 BIGCHARSET:
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])
def _optimize_charset(charset, fixup):
# internal: optimize character set
out = []
outappend = out.append
charmap = [0]*256
try:
for op, av in charset:
if op is NEGATE:
outappend((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:
# XXX: could append to charmap tail
return charset # cannot compress
except IndexError:
# character set contains unicode characters
return _optimize_unicode(charset, fixup)
# compress character map
i = p = n = 0
runs = []
runsappend = runs.append
for c in charmap:
if c:
if n == 0:
p = i
n = n + 1
elif n:
runsappend((p, n))
n = 0
i = i + 1
if n:
runsappend((p, n))
if len(runs) <= 2:
# use literal/range
for p, n in runs:
if n == 1:
outappend((LITERAL, p))
else:
outappend((RANGE, (p, p+n-1)))
if len(out) < len(charset):
return out
else:
# use bitmap
data = _mk_bitmap(charmap)
outappend((CHARSET, data))
return out
return charset
def _mk_bitmap(bits):
data = []
dataappend = data.append
if _sre.CODESIZE == 2:
start = (1, 0)
else:
start = (1, 0)
m, v = start
for c in bits:
if c:
v = v + m
m = m + m
if m > MAXCODE:
dataappend(v)
m, v = start
return data
# To represent a big charset, first a bitmap of all characters in the
# set is constructed. Then, this bitmap is sliced into chunks of 256
# characters, duplicate chunks are eliminated, and each chunk is
# given a number. In the compiled expression, the charset is
# represented by a 16-bit word sequence, consisting of one word for
# the number of different chunks, a sequence of 256 bytes (128 words)
# of chunk numbers indexed by their original chunk position, and a
# sequence of chunks (16 words each).
# Compression is normally good: in a typical charset, large ranges of
# Unicode will be either completely excluded (e.g. if only cyrillic
# letters are to be matched), or completely included (e.g. if large
# subranges of Kanji match). These ranges will be represented by
# chunks of all one-bits or all zero-bits.
# Matching can be also done efficiently: the more significant byte of
# the Unicode character is an index into the chunk number, and the
# less significant byte is a bit index in the chunk (just like the
# CHARSET matching).
# In UCS-4 mode, the BIGCHARSET opcode still supports only subsets
# of the basic multilingual plane; an efficient representation
# for all of UTF-16 has not yet been developed. This means,
# in particular, that negated charsets cannot be represented as
# bigcharsets.
def _optimize_unicode(charset, fixup):
try:
import array
except ImportError:
return charset
charmap = [0]*65536
negate = 0
try:
for op, av in charset:
if op is NEGATE:
negate = 1
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:
# XXX: could expand category
return charset # cannot compress
except IndexError:
# non-BMP characters
return charset
if negate:
if sys.maxunicode != 65535:
# XXX: negation does not work with big charsets
return charset
for i in range(65536):
charmap[i] = not charmap[i]
comps = {}
mapping = [0]*256
block = 0
data = []
for i in range(256):
chunk = tuple(charmap[i*256:(i+1)*256])
new = comps.setdefault(chunk, block)
mapping[i] = new
if new == block:
block = block + 1
data = data + _mk_bitmap(chunk)
header = [block]
if _sre.CODESIZE == 2:
code = 'H'
else:
code = 'I'
# Convert block indices to byte array of 256 bytes
mapping = array.array('b', mapping).tostring()
# Convert byte array to word array
mapping = array.array(code, mapping)
assert mapping.itemsize == _sre.CODESIZE
assert len(mapping) * mapping.itemsize == 256
header = header + mapping.tolist()
data[0:0] = header
return [(BIGCHARSET, data)]
def _simple(av):
# check if av is a "simple" operator
lo, hi = av[2].getwidth()
if lo == 0 and hi == MAXREPEAT:
raise error("nothing to repeat")
return lo == hi == 1 and av[2][0][0] != SUBPATTERN
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 = []
prefixappend = prefix.append
prefix_skip = 0
charset = [] # not used
charsetappend = charset.append
if not (flags & SRE_FLAG_IGNORECASE):
# look for literal prefix
for op, av in pattern.data:
if op is LITERAL:
if len(prefix) == prefix_skip:
prefix_skip = prefix_skip + 1
prefixappend(av)
elif op is SUBPATTERN and len(av[1]) == 1:
op, av = av[1][0]
if op is LITERAL:
prefixappend(av)
else:
break
else:
break
# if no prefix, look for charset prefix
if not prefix and pattern.data:
op, av = pattern.data[0]
if op is SUBPATTERN and av[1]:
op, av = av[1][0]
if op is LITERAL:
charsetappend((op, av))
elif op is BRANCH:
c = []
cappend = c.append
for p in av[1]:
if not p:
break
op, av = p[0]
if op is LITERAL:
cappend((op, av))
else:
break
else:
charset = c
elif op is BRANCH:
c = []
cappend = c.append
for p in av[1]:
if not p:
break
op, av = p[0]
if op is LITERAL:
cappend((op, av))
else:
break
else:
charset = c
elif op is IN:
charset = av
## if prefix:
## print "*** PREFIX", prefix, prefix_skip
## if charset:
## print "*** CHARSET", charset
# 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) == prefix_skip == 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)) # length
emit(prefix_skip) # skip
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:
_compile_charset(charset, flags, code)
code[skip] = len(code) - skip
def isstring(obj):
return isinstance(obj, (str, bytes))
def _code(p, flags):
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])
return code
def compile(p, flags=0):
# internal: convert pattern list to internal format
if isstring(p):
pattern = p
p = sre_parse.parse(p, flags)
else:
pattern = None
code = _code(p, flags)
# print code
# XXX: <fl> get rid of this limitation!
if p.pattern.groups > 100:
raise AssertionError(
"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 | p.pattern.flags, code,
p.pattern.groups-1,
groupindex, indexgroup
)
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