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Improve minimum length finder in the presence of back references when there are

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multiple groups with the same number.
This commit is contained in:
ph10 2019-06-16 15:37:45 +00:00
parent 8dd228d5ba
commit 770fd48acd
3 changed files with 15 additions and 11 deletions
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8
ChangeLog
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@ -31,11 +31,17 @@ minimum is potentially useful.
9. Some changes to the way the minimum subject length is handled:
* When PCRE2_NO_START_OPTIMIZE is set, no minimum length is computed;
pcre2test no longer shows a value (of zero).
pcre2test omits this item instead of showing a value of zero.
* When no minimum length is set by the normal scan, but a first and/or last
code unit is recorded, set the minimum to 1 or 2 as appropriate.
* When a pattern contains multiple groups with the same number, a back
reference cannot know which one to scan for a minimum length. This used to
cause the minimum length finder to give up with no result. Now it treats
such references as not adding to the minimum length (which it should have
done all along).
10. A (*MARK) value inside a successful condition was not being returned by the
interpretive matcher (it was returned by JIT). This bug has been mended.

12
src/pcre2_study.c
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@ -92,7 +92,6 @@ Returns: the minimum length
-1 \C in UTF-8 mode
or (*ACCEPT)
or pattern too complicated
or back reference to duplicate name/number
-2 internal error (missing capturing bracket)
-3 internal error (opcode not listed)
*/
@ -135,7 +134,7 @@ for (;;)
int d, min, recno;
PCRE2_UCHAR *cs, *ce;
PCRE2_UCHAR op = *cc;
if (branchlength >= UINT16_MAX) return UINT16_MAX;
switch (op)
@ -452,12 +451,12 @@ for (;;)
that case we must set the minimum length to zero. */
/* Duplicate named pattern back reference. We cannot reliably find a length
for this if duplicate numbers are present in the pattern. */
for this if duplicate numbers are present in the pattern, so we set the
length to zero here also. */
case OP_DNREF:
case OP_DNREFI:
if (dupcapused) return -1;
if ((re->overall_options & PCRE2_MATCH_UNSET_BACKREF) == 0)
if (!dupcapused && (re->overall_options & PCRE2_MATCH_UNSET_BACKREF) == 0)
{
int count = GET2(cc, 1+IMM2_SIZE);
PCRE2_UCHAR *slot =
@ -524,14 +523,13 @@ for (;;)
case OP_REF:
case OP_REFI:
if (dupcapused) return -1;
recno = GET2(cc, 1);
if (recno <= backref_cache[0] && backref_cache[recno] >= 0)
d = backref_cache[recno];
else
{
int i;
if ((re->overall_options & PCRE2_MATCH_UNSET_BACKREF) == 0)
if (!dupcapused && (re->overall_options & PCRE2_MATCH_UNSET_BACKREF) == 0)
{
ce = cs = (PCRE2_UCHAR *)PRIV(find_bracket)(startcode, utf, recno);
if (cs == NULL) return -2;

6
testdata/testoutput2 vendored
View File

@ -14607,7 +14607,7 @@ Subject length lower bound = 65535
Capture group count = 1
Max back reference = 1
Starting code units: a b
Subject length lower bound = 0
Subject length lower bound = 1
/(?|(aaa)|(b))(?1)/I
Capture group count = 1
@ -14625,7 +14625,7 @@ Max back reference = 1
Named capture groups:
a 1
Starting code units: a b
Subject length lower bound = 0
Subject length lower bound = 1
/(?|(?'a'aaa)|(?'a'b))(?'a'cccc)\k'a'/I,dupnames
Capture group count = 2
@ -14636,7 +14636,7 @@ Named capture groups:
Options: dupnames
Starting code units: a b
Last code unit = 'c'
Subject length lower bound = 1
Subject length lower bound = 5
/ab{3cd/
ab{3cd