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Postings from July 2000
Mike Guy followed up on Per Lindquist's bug report with:
:Here's a cut down version of your test case which shows the effect:
:
: use re 'debug';
: $_ = "P FIRST = 0\nP " . join(" = 0\nP ", 1..5) . " = 0\nP LAST = 0\n";
: /(.*)LAST(.*=).*/;
[...]
:Back to the bug: the debug output shows that in perl5.005_03, the
:RE engine is indeed behaving as described above. But the output
:under perl5.6.0 shows that instead of the quadratic rummage over
:'P FIRST = 0', it's doing a cubic search.
This is caused by the change commented out below. I'll try to see if
I can determine when that change helps, and if there is some way to
distinguish the cases.
It would help if I could determine which patch applied the change, and
see the comments that accompanied it: if anyone knows of a way to
discover this I would love to know of it. Barrie Slaymaker's excellent
source browser was great while it lasted (or perhaps it just moved
without me being aware of it - Barrie?), and I don't know of a useful
replacement.
Hugo
---
WARNING: not a proposed patch, just an indication of the problem area.
--- regexec.c.old Fri Jul 14 03:19:57 2000
+++ regexec.c Fri Jul 14 03:20:40 2000
@@ -1398,7 +1398,7 @@
dontbother = minlen - 1;
end = HOPc(strend, -dontbother) - 1;
/* for multiline we only have to try after newlines */
- if (prog->check_substr) {
+/* if (prog->check_substr) {
if (s == startpos)
goto after_try;
while (1) {
@@ -1416,7 +1416,7 @@
s++;
}
} else {
- if (s > startpos)
+*/ if (s > startpos)
s--;
while (s < end) {
if (*s++ == '\n') { /* don't need PL_utf8skip here */
@@ -1425,8 +1425,8 @@
}
}
}
- }
- goto phooey;
+/* }
+*/ goto phooey;
} else if (prog->reganch & ROPT_ANCH_GPOS) {
if (regtry(prog, PL_reg_ganch))
goto got_it;
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