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Commit8505ebf

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Fix regexp_matches() handling of zero-length matches.
We'd find the same match twice if it was of zero length and not immediatelyadjacent to the previous match. replace_text_regexp() got similar casesright, so adjust this search logic to match that. Note that even thoughthe regexp_split_to_xxx() functions share this code, they did not displayequivalent misbehavior, because the second match would be considereddegenerate and ignored.Jeevan Chalke, with some cosmetic changes by me.
1 parente73357c commit8505ebf

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4 files changed

+75
-8
lines changed

4 files changed

+75
-8
lines changed

‎src/backend/utils/adt/regexp.c‎

Lines changed: 6 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -957,14 +957,13 @@ setup_regexp_matches(text *orig_str, text *pattern, text *flags,
957957
break;
958958

959959
/*
960-
* Advance search position. Normally we startjust after the end of
961-
* the previous match, butalways advance at least one character (the
962-
*special case can occur if the pattern matches zero characters just
963-
*after the prior match or at the end of the string).
960+
* Advance search position. Normally we startthe next search at the
961+
*end ofthe previous match; butif the match was of zero length, we
962+
*have to advance by one character, or we'd just find the same match
963+
*again.
964964
*/
965-
if (start_search<pmatch[0].rm_eo)
966-
start_search=pmatch[0].rm_eo;
967-
else
965+
start_search=prev_match_end;
966+
if (pmatch[0].rm_so==pmatch[0].rm_eo)
968967
start_search++;
969968
if (start_search>wide_len)
970969
break;

‎src/backend/utils/adt/varlena.c‎

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2961,7 +2961,10 @@ replace_text_regexp(text *src_text, void *regexp,
29612961
break;
29622962

29632963
/*
2964-
* Search from next character when the matching text is zero width.
2964+
* Advance search position. Normally we start the next search at the
2965+
* end of the previous match; but if the match was of zero length, we
2966+
* have to advance by one character, or we'd just find the same match
2967+
* again.
29652968
*/
29662969
search_start=data_pos;
29672970
if (pmatch[0].rm_so==pmatch[0].rm_eo)

‎src/test/regress/expected/strings.out‎

Lines changed: 58 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -440,6 +440,64 @@ SELECT regexp_matches('foobarbequebaz', $re$barbeque$re$);
440440
{barbeque}
441441
(1 row)
442442

443+
-- start/end-of-line matches are of zero length
444+
SELECT regexp_matches('foo' || chr(10) || 'bar' || chr(10) || 'bequq' || chr(10) || 'baz', '^', 'mg');
445+
regexp_matches
446+
----------------
447+
{""}
448+
{""}
449+
{""}
450+
{""}
451+
(4 rows)
452+
453+
SELECT regexp_matches('foo' || chr(10) || 'bar' || chr(10) || 'bequq' || chr(10) || 'baz', '$', 'mg');
454+
regexp_matches
455+
----------------
456+
{""}
457+
{""}
458+
{""}
459+
{""}
460+
(4 rows)
461+
462+
SELECT regexp_matches('1' || chr(10) || '2' || chr(10) || '3' || chr(10) || '4' || chr(10), '^.?', 'mg');
463+
regexp_matches
464+
----------------
465+
{1}
466+
{2}
467+
{3}
468+
{4}
469+
{""}
470+
(5 rows)
471+
472+
SELECT regexp_matches(chr(10) || '1' || chr(10) || '2' || chr(10) || '3' || chr(10) || '4' || chr(10), '.?$', 'mg');
473+
regexp_matches
474+
----------------
475+
{""}
476+
{1}
477+
{""}
478+
{2}
479+
{""}
480+
{3}
481+
{""}
482+
{4}
483+
{""}
484+
{""}
485+
(10 rows)
486+
487+
SELECT regexp_matches(chr(10) || '1' || chr(10) || '2' || chr(10) || '3' || chr(10) || '4', '.?$', 'mg');
488+
regexp_matches
489+
----------------
490+
{""}
491+
{1}
492+
{""}
493+
{2}
494+
{""}
495+
{3}
496+
{""}
497+
{4}
498+
{""}
499+
(9 rows)
500+
443501
-- give me errors
444502
SELECT regexp_matches('foobarbequebaz', $re$(bar)(beque)$re$, 'gz');
445503
ERROR: invalid regexp option: "z"

‎src/test/regress/sql/strings.sql‎

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -158,6 +158,13 @@ SELECT regexp_matches('foobarbequebaz', $re$(bar)(.+)?(beque)$re$);
158158
-- no capture groups
159159
SELECT regexp_matches('foobarbequebaz', $re$barbeque$re$);
160160

161+
-- start/end-of-line matches are of zero length
162+
SELECT regexp_matches('foo'|| chr(10)||'bar'|| chr(10)||'bequq'|| chr(10)||'baz','^','mg');
163+
SELECT regexp_matches('foo'|| chr(10)||'bar'|| chr(10)||'bequq'|| chr(10)||'baz','$','mg');
164+
SELECT regexp_matches('1'|| chr(10)||'2'|| chr(10)||'3'|| chr(10)||'4'|| chr(10),'^.?','mg');
165+
SELECT regexp_matches(chr(10)||'1'|| chr(10)||'2'|| chr(10)||'3'|| chr(10)||'4'|| chr(10),'.?$','mg');
166+
SELECT regexp_matches(chr(10)||'1'|| chr(10)||'2'|| chr(10)||'3'|| chr(10)||'4','.?$','mg');
167+
161168
-- give me errors
162169
SELECT regexp_matches('foobarbequebaz', $re$(bar)(beque)$re$,'gz');
163170
SELECT regexp_matches('foobarbequebaz', $re$(barbeque$re$);

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