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When computing minimum length, don't scan subsequent branches if any branch in 

a group has zero minimum length.
This commit is contained in:
Philip.Hazel 2019-09-07 15:16:10 +00:00
parent 7bbdc58513
commit 27d40c8ad8
2 changed files with 8 additions and 2 deletions
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4
ChangeLog
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@ -139,6 +139,10 @@ case after a bumpalong and (b) when one case has been found, it searches only
up to that position for an earlier occurrence of the other case. This fix up to that position for an earlier occurrence of the other case. This fix
applies to both interpretive pcre2_match() and to pcre2_dfa_match(). applies to both interpretive pcre2_match() and to pcre2_dfa_match().
30. While scanning to find the minimum length of a group, if any branch has
minimum length zero, there is no need to scan any subsequent branches (a small
compile-time performance improvement).
Version 10.33 16-April-2019 Version 10.33 16-April-2019
--------------------------- ---------------------------

6
src/pcre2_study.c
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@ -223,7 +223,9 @@ for (;;)
/* Reached end of a branch; if it's a ket it is the end of a nested /* Reached end of a branch; if it's a ket it is the end of a nested
call. If it's ALT it is an alternation in a nested call. If it is END it's call. If it's ALT it is an alternation in a nested call. If it is END it's
the end of the outer call. All can be handled by the same code. */ the end of the outer call. All can be handled by the same code. If the
length of any branch is zero, there is no need to scan any subsequent
branches. */
case OP_ALT: case OP_ALT:
case OP_KET: case OP_KET:
@ -233,7 +235,7 @@ for (;;)
case OP_END: case OP_END:
if (length < 0 || (!had_recurse && branchlength < length)) if (length < 0 || (!had_recurse && branchlength < length))
length = branchlength; length = branchlength;
if (op != OP_ALT) return length; if (op != OP_ALT || length == 0) return length;
nextbranch = cc + GET(cc, 1); nextbranch = cc + GET(cc, 1);
cc += 1 + LINK_SIZE; cc += 1 + LINK_SIZE;
branchlength = 0; branchlength = 0;