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bpo-30340: Enhanced regular expressions optimization. (#1542) 

This increased the performance of matching some patterns up to 25 times.
This commit is contained in:
Serhiy Storchaka 2017-05-14 08:32:33 +03:00 committed by GitHub
parent cbddf58c79
commit 821a9d146b
4 changed files with 95 additions and 54 deletions
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15
Lib/sre_compile.py
View File

@ -20,6 +20,7 @@ _LITERAL_CODES = {LITERAL, NOT_LITERAL}
_REPEATING_CODES = {REPEAT, MIN_REPEAT, MAX_REPEAT}
_SUCCESS_CODES = {SUCCESS, FAILURE}
_ASSERT_CODES = {ASSERT, ASSERT_NOT}
_UNIT_CODES = _LITERAL_CODES | {ANY, IN}
# Sets of lowercase characters which have the same uppercase.
_equivalences = (
@ -125,7 +126,7 @@ def _compile(code, pattern, flags):
elif op in REPEATING_CODES:
if flags & SRE_FLAG_TEMPLATE:
raise error("internal: unsupported template operator %r" % (op,))
elif _simple(av) and op is not REPEAT:
if _simple(av[2]):
if op is MAX_REPEAT:
emit(REPEAT_ONE)
else:
@ -404,10 +405,14 @@ def _bytes_to_codes(b):
assert len(a) * a.itemsize == len(b)
return a.tolist()
def _simple(av):
# check if av is a "simple" operator
lo, hi = av[2].getwidth()
return lo == hi == 1 and av[2][0][0] != SUBPATTERN
def _simple(p):
# check if this subpattern is a "simple" operator
if len(p) != 1:
return False
op, av = p[0]
if op is SUBPATTERN:
return av[0] is None and _simple(av[-1])
return op in _UNIT_CODES
def _generate_overlap_table(prefix):
"""

105
Lib/sre_parse.py
View File

@ -114,6 +114,7 @@ class SubPattern:
data = []
self.data = data
self.width = None
def dump(self, level=0):
nl = True
seqtypes = (tuple, list)
@ -404,6 +405,15 @@ def _escape(source, escape, state):
pass
raise source.error("bad escape %s" % escape, len(escape))
def _uniq(items):
if len(set(items)) == len(items):
return items
newitems = []
for item in items:
if item not in newitems:
newitems.append(item)
return newitems
def _parse_sub(source, state, verbose, nested=True):
# parse an alternation: a|b|c
@ -420,7 +430,6 @@ def _parse_sub(source, state, verbose, nested=True):
return items[0]
subpattern = SubPattern(state)
subpatternappend = subpattern.append
# check if all items share a common prefix
while True:
@ -437,35 +446,31 @@ def _parse_sub(source, state, verbose, nested=True):
# move it out of the branch
for item in items:
del item[0]
subpatternappend(prefix)
subpattern.append(prefix)
continue # check next one
break
# check if the branch can be replaced by a character set
set = []
for item in items:
if len(item) != 1 or item[0][0] is not LITERAL:
if len(item) != 1:
break
op, av = item[0]
if op is LITERAL:
set.append((op, av))
elif op is IN and av[0][0] is not NEGATE:
set.extend(av)
else:
break
else:
# we can store this as a character set instead of a
# branch (the compiler may optimize this even more)
subpatternappend((IN, [item[0] for item in items]))
subpattern.append((IN, _uniq(set)))
return subpattern
subpattern.append((BRANCH, (None, items)))
return subpattern
def _parse_sub_cond(source, state, condgroup, verbose):
item_yes = _parse(source, state, verbose)
if source.match("|"):
item_no = _parse(source, state, verbose)
if source.next == "|":
raise source.error("conditional backref with more than two branches")
else:
item_no = None
subpattern = SubPattern(state)
subpattern.append((GROUPREF_EXISTS, (condgroup, item_yes, item_no)))
return subpattern
def _parse(source, state, verbose, first=False):
# parse a simple pattern
subpattern = SubPattern(state)
@ -511,16 +516,14 @@ def _parse(source, state, verbose, first=False):
setappend = set.append
## if sourcematch(":"):
## pass # handle character classes
if sourcematch("^"):
setappend((NEGATE, None))
negate = sourcematch("^")
# check remaining characters
start = set[:]
while True:
this = sourceget()
if this is None:
raise source.error("unterminated character set",
source.tell() - here)
if this == "]" and set != start:
if this == "]" and set:
break
elif this[0] == "\\":
code1 = _class_escape(source, this)
@ -556,13 +559,19 @@ def _parse(source, state, verbose, first=False):
code1 = code1[1][0]
setappend(code1)
set = _uniq(set)
# XXX: <fl> should move set optimization to compiler!
if _len(set)==1 and set[0][0] is LITERAL:
subpatternappend(set[0]) # optimization
elif _len(set)==2 and set[0][0] is NEGATE and set[1][0] is LITERAL:
subpatternappend((NOT_LITERAL, set[1][1])) # optimization
if _len(set) == 1 and set[0][0] is LITERAL:
# optimization
if negate:
subpatternappend((NOT_LITERAL, set[0][1]))
else:
subpatternappend(set[0])
else:
# XXX: <fl> should add charmap optimization here
if negate:
set.insert(0, (NEGATE, None))
# charmap optimization can't be added here because
# global flags still are not known
subpatternappend((IN, set))
elif this in REPEAT_CHARS:
@ -579,6 +588,7 @@ def _parse(source, state, verbose, first=False):
if source.next == "}":
subpatternappend((LITERAL, _ord(this)))
continue
min, max = 0, MAXREPEAT
lo = hi = ""
while source.next in DIGITS:
@ -592,6 +602,7 @@ def _parse(source, state, verbose, first=False):
subpatternappend((LITERAL, _ord(this)))
source.seek(here)
continue
if lo:
min = int(lo)
if min >= MAXREPEAT:
@ -610,12 +621,16 @@ def _parse(source, state, verbose, first=False):
item = subpattern[-1:]
else:
item = None
if not item or (_len(item) == 1 and item[0][0] is AT):
if not item or item[0][0] is AT:
raise source.error("nothing to repeat",
source.tell() - here + len(this))
if item[0][0] in _REPEATCODES:
raise source.error("multiple repeat",
source.tell() - here + len(this))
if item[0][0] is SUBPATTERN:
group, add_flags, del_flags, p = item[0][1]
if group is None and not add_flags and not del_flags:
item = p
if sourcematch("?"):
subpattern[-1] = (MIN_REPEAT, (min, max, item))
else:
@ -628,7 +643,6 @@ def _parse(source, state, verbose, first=False):
start = source.tell() - 1
group = True
name = None
condgroup = None
add_flags = 0
del_flags = 0
if sourcematch("?"):
@ -660,6 +674,7 @@ def _parse(source, state, verbose, first=False):
state.checklookbehindgroup(gid, source)
subpatternappend((GROUPREF, gid))
continue
else:
char = sourceget()
if char is None:
@ -678,6 +693,7 @@ def _parse(source, state, verbose, first=False):
if sourceget() == ")":
break
continue
elif char in "=!<":
# lookahead assertions
dir = 1
@ -704,10 +720,10 @@ def _parse(source, state, verbose, first=False):
else:
subpatternappend((ASSERT_NOT, (dir, p)))
continue
elif char == "(":
# conditional backreference group
condname = source.getuntil(")")
group = None
if condname.isidentifier():
condgroup = state.groupdict.get(condname)
if condgroup is None:
@ -728,6 +744,19 @@ def _parse(source, state, verbose, first=False):
msg = "invalid group reference %d" % condgroup
raise source.error(msg, len(condname) + 1)
state.checklookbehindgroup(condgroup, source)
item_yes = _parse(source, state, verbose)
if source.match("|"):
item_no = _parse(source, state, verbose)
if source.next == "|":
raise source.error("conditional backref with more than two branches")
else:
item_no = None
if not source.match(")"):
raise source.error("missing ), unterminated subpattern",
source.tell() - start)
subpatternappend((GROUPREF_EXISTS, (condgroup, item_yes, item_no)))
continue
elif char in FLAGS or char == "-":
# flags
flags = _parse_flags(source, state, char)
@ -744,6 +773,7 @@ def _parse(source, state, verbose, first=False):
if (state.flags & SRE_FLAG_VERBOSE) and not verbose:
raise Verbose
continue
add_flags, del_flags = flags
group = None
else:
@ -756,12 +786,9 @@ def _parse(source, state, verbose, first=False):
group = state.opengroup(name)
except error as err:
raise source.error(err.msg, len(name) + 1) from None
if condgroup:
p = _parse_sub_cond(source, state, condgroup, verbose)
else:
sub_verbose = ((verbose or (add_flags & SRE_FLAG_VERBOSE)) and
not (del_flags & SRE_FLAG_VERBOSE))
p = _parse_sub(source, state, sub_verbose)
sub_verbose = ((verbose or (add_flags & SRE_FLAG_VERBOSE)) and
not (del_flags & SRE_FLAG_VERBOSE))
p = _parse_sub(source, state, sub_verbose)
if not source.match(")"):
raise source.error("missing ), unterminated subpattern",
source.tell() - start)
@ -773,11 +800,19 @@ def _parse(source, state, verbose, first=False):
subpatternappend((AT, AT_BEGINNING))
elif this == "$":
subpattern.append((AT, AT_END))
subpatternappend((AT, AT_END))
else:
raise AssertionError("unsupported special character %r" % (char,))
# unpack non-capturing groups
for i in range(len(subpattern))[::-1]:
op, av = subpattern[i]
if op is SUBPATTERN:
group, add_flags, del_flags, p = av
if group is None and not add_flags and not del_flags:
subpattern[i: i+1] = p
return subpattern
def _parse_flags(source, state, char):

26
Lib/test/test_re.py
View File

@ -1695,20 +1695,18 @@ class ReTests(unittest.TestCase):
dump = '''\
SUBPATTERN 1 0 0
LITERAL 46
SUBPATTERN None 0 0
BRANCH
IN
LITERAL 99
LITERAL 104
OR
LITERAL 112
LITERAL 121
SUBPATTERN None 0 0
GROUPREF_EXISTS 1
AT AT_END
ELSE
LITERAL 58
LITERAL 32
BRANCH
IN
LITERAL 99
LITERAL 104
OR
LITERAL 112
LITERAL 121
GROUPREF_EXISTS 1
AT AT_END
ELSE
LITERAL 58
LITERAL 32
'''
self.assertEqual(out.getvalue(), dump)
# Debug output is output again even a second time (bypassing

3
Misc/NEWS
View File

@ -326,6 +326,9 @@ Library
- bpo-30048: Fixed ``Task.cancel()`` can be ignored when the task is
running coroutine and the coroutine returned without any more ``await``.
- bpo-30340: Enhanced regular expressions optimization. This increased
the performance of matching some patterns up to 25 times.
- bpo-30298: Weaken the condition of deprecation warnings for inline modifiers.
Now allowed several subsequential inline modifiers at the start of the
pattern (e.g. ``'(?i)(?s)...'``). In verbose mode whitespaces and comments