mirror of https://github.com/python/cpython
498 lines
12 KiB
Python
498 lines
12 KiB
Python
#
|
|
# Secret Labs' Regular Expression Engine
|
|
# $Id$
|
|
#
|
|
# convert re-style regular expression to SRE template. the current
|
|
# implementation is somewhat incomplete, and not very fast. should
|
|
# definitely be rewritten before Python 1.6 goes beta.
|
|
#
|
|
# Copyright (c) 1998-2000 by Secret Labs AB. All rights reserved.
|
|
#
|
|
# This code can only be used for 1.6 alpha testing. All other use
|
|
# require explicit permission from Secret Labs AB.
|
|
#
|
|
# Portions of this engine have been developed in cooperation with
|
|
# CNRI. Hewlett-Packard provided funding for 1.6 integration and
|
|
# other compatibility work.
|
|
#
|
|
|
|
# FIXME: comments marked with the FIXME tag are open issues. all such
|
|
# issues should be closed before the final beta.
|
|
|
|
import string, sys
|
|
|
|
from sre_constants import *
|
|
|
|
SPECIAL_CHARS = ".\\[{()*+?^$|"
|
|
REPEAT_CHARS = "*+?{"
|
|
|
|
# FIXME: string in tuple tests may explode with if char is unicode :-(
|
|
DIGITS = tuple(string.digits)
|
|
|
|
OCTDIGITS = tuple("01234567")
|
|
HEXDIGITS = tuple("0123456789abcdefABCDEF")
|
|
|
|
ESCAPES = {
|
|
"\\a": (LITERAL, chr(7)),
|
|
"\\b": (LITERAL, chr(8)),
|
|
"\\f": (LITERAL, chr(12)),
|
|
"\\n": (LITERAL, chr(10)),
|
|
"\\r": (LITERAL, chr(13)),
|
|
"\\t": (LITERAL, chr(9)),
|
|
"\\v": (LITERAL, chr(11))
|
|
}
|
|
|
|
CATEGORIES = {
|
|
"\\A": (AT, AT_BEGINNING), # start of string
|
|
"\\b": (AT, AT_BOUNDARY),
|
|
"\\B": (AT, AT_NON_BOUNDARY),
|
|
"\\d": (IN, [(CATEGORY, CATEGORY_DIGIT)]),
|
|
"\\D": (IN, [(CATEGORY, CATEGORY_NOT_DIGIT)]),
|
|
"\\s": (IN, [(CATEGORY, CATEGORY_SPACE)]),
|
|
"\\S": (IN, [(CATEGORY, CATEGORY_NOT_SPACE)]),
|
|
"\\w": (IN, [(CATEGORY, CATEGORY_WORD)]),
|
|
"\\W": (IN, [(CATEGORY, CATEGORY_NOT_WORD)]),
|
|
"\\Z": (AT, AT_END), # end of string
|
|
}
|
|
|
|
class Pattern:
|
|
# FIXME: <fl> rename class, and store flags in here too!
|
|
def __init__(self):
|
|
self.flags = []
|
|
self.groups = 1
|
|
self.groupdict = {}
|
|
def getgroup(self, name=None):
|
|
gid = self.groups
|
|
self.groups = gid + 1
|
|
if name:
|
|
self.groupdict[name] = gid
|
|
return gid
|
|
def setflag(self, flag):
|
|
if flag in self.flags:
|
|
self.flags.append(flag)
|
|
|
|
class SubPattern:
|
|
# a subpattern, in intermediate form
|
|
def __init__(self, pattern, data=None):
|
|
self.pattern = pattern
|
|
if not data:
|
|
data = []
|
|
self.data = data
|
|
self.flags = []
|
|
self.width = None
|
|
def __repr__(self):
|
|
return repr(self.data)
|
|
def __len__(self):
|
|
return len(self.data)
|
|
def __delitem__(self, index):
|
|
del self.data[index]
|
|
def __getitem__(self, index):
|
|
return self.data[index]
|
|
def __setitem__(self, index, code):
|
|
self.data[index] = code
|
|
def __getslice__(self, start, stop):
|
|
return SubPattern(self.pattern, self.data[start:stop])
|
|
def insert(self, index, code):
|
|
self.data.insert(index, code)
|
|
def append(self, code):
|
|
self.data.append(code)
|
|
def getwidth(self):
|
|
# determine the width (min, max) for this subpattern
|
|
if self.width:
|
|
return self.width
|
|
lo = hi = 0L
|
|
for op, av in self.data:
|
|
if op is BRANCH:
|
|
l = sys.maxint
|
|
h = 0
|
|
for av in av[1]:
|
|
i, j = av.getwidth()
|
|
l = min(l, i)
|
|
h = min(h, j)
|
|
lo = lo + i
|
|
hi = hi + j
|
|
elif op is CALL:
|
|
i, j = av.getwidth()
|
|
lo = lo + i
|
|
hi = hi + j
|
|
elif op is SUBPATTERN:
|
|
i, j = av[1].getwidth()
|
|
lo = lo + i
|
|
hi = hi + j
|
|
elif op in (MIN_REPEAT, MAX_REPEAT):
|
|
i, j = av[2].getwidth()
|
|
lo = lo + i * av[0]
|
|
hi = hi + j * av[1]
|
|
elif op in (ANY, RANGE, IN, LITERAL, NOT_LITERAL, CATEGORY):
|
|
lo = lo + 1
|
|
hi = hi + 1
|
|
elif op == SUCCESS:
|
|
break
|
|
self.width = int(min(lo, sys.maxint)), int(min(hi, sys.maxint))
|
|
return self.width
|
|
def set(self, flag):
|
|
if not flag in self.flags:
|
|
self.flags.append(flag)
|
|
def reset(self, flag):
|
|
if flag in self.flags:
|
|
self.flags.remove(flag)
|
|
|
|
class Tokenizer:
|
|
def __init__(self, string):
|
|
self.string = list(string)
|
|
self.next = self.__next()
|
|
def __next(self):
|
|
if not self.string:
|
|
return None
|
|
char = self.string[0]
|
|
if char[0] == "\\":
|
|
try:
|
|
c = self.string[1]
|
|
except IndexError:
|
|
raise SyntaxError, "bogus escape"
|
|
char = char + c
|
|
try:
|
|
if c == "x":
|
|
# hexadecimal constant
|
|
for i in xrange(2, sys.maxint):
|
|
c = self.string[i]
|
|
if str(c) not in HEXDIGITS:
|
|
break
|
|
char = char + c
|
|
elif str(c) in DIGITS:
|
|
# decimal (or octal) number
|
|
for i in xrange(2, sys.maxint):
|
|
c = self.string[i]
|
|
# FIXME: if larger than current number of
|
|
# groups, interpret as an octal number
|
|
if str(c) not in DIGITS:
|
|
break
|
|
char = char + c
|
|
except IndexError:
|
|
pass # use what we've got this far
|
|
del self.string[0:len(char)]
|
|
return char
|
|
def match(self, char):
|
|
if char == self.next:
|
|
self.next = self.__next()
|
|
return 1
|
|
return 0
|
|
def match_set(self, set):
|
|
if self.next and self.next in set:
|
|
self.next = self.__next()
|
|
return 1
|
|
return 0
|
|
def get(self):
|
|
this = self.next
|
|
self.next = self.__next()
|
|
return this
|
|
|
|
def _fixescape(escape, character_class=0):
|
|
# convert escape to (type, value)
|
|
if character_class:
|
|
# inside a character class, we'll look in the character
|
|
# escapes dictionary first
|
|
code = ESCAPES.get(escape)
|
|
if code:
|
|
return code
|
|
code = CATEGORIES.get(escape)
|
|
else:
|
|
code = CATEGORIES.get(escape)
|
|
if code:
|
|
return code
|
|
code = ESCAPES.get(escape)
|
|
if code:
|
|
return code
|
|
if not character_class:
|
|
try:
|
|
group = int(escape[1:])
|
|
# FIXME: only valid if group <= current number of groups
|
|
return GROUP, group
|
|
except ValueError:
|
|
pass
|
|
try:
|
|
if escape[1:2] == "x":
|
|
escape = escape[2:]
|
|
return LITERAL, chr(int(escape[-2:], 16) & 0xff)
|
|
elif str(escape[1:2]) in DIGITS:
|
|
return LITERAL, chr(int(escape[1:], 8) & 0xff)
|
|
elif len(escape) == 2:
|
|
return LITERAL, escape[1]
|
|
except ValueError:
|
|
pass
|
|
raise SyntaxError, "bogus escape: %s" % repr(escape)
|
|
|
|
def _branch(subpattern, items):
|
|
|
|
# form a branch operator from a set of items (FIXME: move this
|
|
# optimization to the compiler module!)
|
|
|
|
# check if all items share a common prefix
|
|
while 1:
|
|
prefix = None
|
|
for item in items:
|
|
if not item:
|
|
break
|
|
if prefix is None:
|
|
prefix = item[0]
|
|
elif item[0] != prefix:
|
|
break
|
|
else:
|
|
# all subitems start with a common "prefix".
|
|
# move it out of the branch
|
|
for item in items:
|
|
del item[0]
|
|
subpattern.append(prefix)
|
|
continue # check next one
|
|
break
|
|
|
|
# check if the branch can be replaced by a character set
|
|
for item in items:
|
|
if len(item) != 1 or item[0][0] != LITERAL:
|
|
break
|
|
else:
|
|
# we can store this as a character set instead of a
|
|
# branch (FIXME: use a range if possible)
|
|
set = []
|
|
for item in items:
|
|
set.append(item[0])
|
|
subpattern.append((IN, set))
|
|
return
|
|
|
|
subpattern.append((BRANCH, (None, items)))
|
|
|
|
def _parse(source, pattern, flags=()):
|
|
|
|
# parse regular expression pattern into an operator list.
|
|
|
|
subpattern = SubPattern(pattern)
|
|
|
|
this = None
|
|
|
|
while 1:
|
|
|
|
if str(source.next) in ("|", ")"):
|
|
break # end of subpattern
|
|
this = source.get()
|
|
if this is None:
|
|
break # end of pattern
|
|
|
|
if this and this[0] not in SPECIAL_CHARS:
|
|
subpattern.append((LITERAL, this))
|
|
|
|
elif this == "[":
|
|
# character set
|
|
set = []
|
|
## if source.match(":"):
|
|
## pass # handle character classes
|
|
if source.match("^"):
|
|
set.append((NEGATE, None))
|
|
# check remaining characters
|
|
start = set[:]
|
|
while 1:
|
|
this = source.get()
|
|
if this == "]" and set != start:
|
|
break
|
|
elif this and this[0] == "\\":
|
|
code1 = _fixescape(this, 1)
|
|
elif this:
|
|
code1 = LITERAL, this
|
|
else:
|
|
raise SyntaxError, "unexpected end of regular expression"
|
|
if source.match("-"):
|
|
# potential range
|
|
this = source.get()
|
|
if this == "]":
|
|
set.append(code1)
|
|
set.append((LITERAL, "-"))
|
|
break
|
|
else:
|
|
if this[0] == "\\":
|
|
code2 = _fixescape(this, 1)
|
|
else:
|
|
code2 = LITERAL, this
|
|
if code1[0] != LITERAL or code2[0] != LITERAL:
|
|
raise SyntaxError, "illegal range"
|
|
if len(code1[1]) != 1 or len(code2[1]) != 1:
|
|
raise SyntaxError, "illegal range"
|
|
set.append((RANGE, (code1[1], code2[1])))
|
|
else:
|
|
if code1[0] is IN:
|
|
code1 = code1[1][0]
|
|
set.append(code1)
|
|
|
|
# FIXME: <fl> move set optimization to support function
|
|
if len(set)==1 and set[0][0] is LITERAL:
|
|
subpattern.append(set[0]) # optimization
|
|
elif len(set)==2 and set[0][0] is NEGATE and set[1][0] is LITERAL:
|
|
subpattern.append((NOT_LITERAL, set[1][1])) # optimization
|
|
else:
|
|
# FIXME: <fl> add charmap optimization
|
|
subpattern.append((IN, set))
|
|
|
|
elif this and this[0] in REPEAT_CHARS:
|
|
# repeat previous item
|
|
if this == "?":
|
|
min, max = 0, 1
|
|
elif this == "*":
|
|
min, max = 0, sys.maxint
|
|
elif this == "+":
|
|
min, max = 1, sys.maxint
|
|
elif this == "{":
|
|
min, max = 0, sys.maxint
|
|
lo = hi = ""
|
|
while str(source.next) in DIGITS:
|
|
lo = lo + source.get()
|
|
if source.match(","):
|
|
while str(source.next) in DIGITS:
|
|
hi = hi + source.get()
|
|
else:
|
|
hi = lo
|
|
if not source.match("}"):
|
|
raise SyntaxError, "bogus range"
|
|
if lo:
|
|
min = int(lo)
|
|
if hi:
|
|
max = int(hi)
|
|
# FIXME: <fl> check that hi >= lo!
|
|
else:
|
|
raise SyntaxError, "not supported"
|
|
# figure out which item to repeat
|
|
# FIXME: should back up to the right mark, right?
|
|
if subpattern:
|
|
index = len(subpattern)-1
|
|
while subpattern[index][0] is MARK:
|
|
index = index - 1
|
|
item = subpattern[index:index+1]
|
|
else:
|
|
raise SyntaxError, "nothing to repeat"
|
|
if source.match("?"):
|
|
subpattern[index] = (MIN_REPEAT, (min, max, item))
|
|
else:
|
|
subpattern[index] = (MAX_REPEAT, (min, max, item))
|
|
elif this == ".":
|
|
subpattern.append((ANY, None))
|
|
elif this == "(":
|
|
group = 1
|
|
name = None
|
|
if source.match("?"):
|
|
group = 0
|
|
# options
|
|
if source.match("P"):
|
|
# named group: skip forward to end of name
|
|
if source.match("<"):
|
|
name = ""
|
|
while 1:
|
|
char = source.get()
|
|
if char is None or char == ">":
|
|
break
|
|
name = name + char
|
|
group = 1
|
|
elif source.match(":"):
|
|
# non-capturing group
|
|
group = 2
|
|
elif source.match_set("iI"):
|
|
pattern.setflag("i")
|
|
elif source.match_set("lL"):
|
|
pattern.setflag("l")
|
|
elif source.match_set("mM"):
|
|
pattern.setflag("m")
|
|
elif source.match_set("sS"):
|
|
pattern.setflag("s")
|
|
elif source.match_set("xX"):
|
|
pattern.setflag("x")
|
|
if group:
|
|
# parse group contents
|
|
b = []
|
|
if group == 2:
|
|
# anonymous group
|
|
group = None
|
|
else:
|
|
group = pattern.getgroup(name)
|
|
if group:
|
|
subpattern.append((MARK, (group-1)*2))
|
|
while 1:
|
|
p = _parse(source, pattern, flags)
|
|
if source.match(")"):
|
|
if b:
|
|
b.append(p)
|
|
_branch(subpattern, b)
|
|
else:
|
|
subpattern.append((SUBPATTERN, (group, p)))
|
|
break
|
|
elif source.match("|"):
|
|
b.append(p)
|
|
else:
|
|
raise SyntaxError, "group not properly closed"
|
|
if group:
|
|
subpattern.append((MARK, (group-1)*2+1))
|
|
else:
|
|
# FIXME: should this really be a while loop?
|
|
while 1:
|
|
char = source.get()
|
|
if char is None or char == ")":
|
|
break
|
|
|
|
elif this == "^":
|
|
subpattern.append((AT, AT_BEGINNING))
|
|
|
|
elif this == "$":
|
|
subpattern.append((AT, AT_END))
|
|
|
|
elif this and this[0] == "\\":
|
|
code =_fixescape(this)
|
|
subpattern.append(code)
|
|
|
|
else:
|
|
raise SyntaxError, "parser error"
|
|
|
|
return subpattern
|
|
|
|
def parse(source, flags=()):
|
|
s = Tokenizer(source)
|
|
g = Pattern()
|
|
b = []
|
|
while 1:
|
|
p = _parse(s, g, flags)
|
|
tail = s.get()
|
|
if tail == "|":
|
|
b.append(p)
|
|
elif tail == ")":
|
|
raise SyntaxError, "unbalanced parenthesis"
|
|
elif tail is None:
|
|
if b:
|
|
b.append(p)
|
|
p = SubPattern(g)
|
|
_branch(p, b)
|
|
break
|
|
else:
|
|
raise SyntaxError, "bogus characters at end of regular expression"
|
|
return p
|
|
|
|
if __name__ == "__main__":
|
|
from pprint import pprint
|
|
from testpatterns import PATTERNS
|
|
a = b = c = 0
|
|
for pattern, flags in PATTERNS:
|
|
if flags:
|
|
continue
|
|
print "-"*68
|
|
try:
|
|
p = parse(pattern)
|
|
print repr(pattern), "->"
|
|
pprint(p.data)
|
|
import sre_compile
|
|
try:
|
|
code = sre_compile.compile(p)
|
|
c = c + 1
|
|
except:
|
|
pass
|
|
a = a + 1
|
|
except SyntaxError, v:
|
|
print "**", repr(pattern), v
|
|
b = b + 1
|
|
print "-"*68
|
|
print a, "of", b, "patterns successfully parsed"
|
|
print c, "of", b, "patterns successfully compiled"
|
|
|