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

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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
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@ -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):
"""