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Fix regexp_matches() handling of zero-length matches.

2013年7月31日 15:31:22 +0000 (11:31 -0400)

We'd find the same match twice if it was of zero length and not immediately
adjacent to the previous match. replace_text_regexp() got similar cases
right, so adjust this search logic to match that. Note that even though
the regexp_split_to_xxx() functions share this code, they did not display
equivalent misbehavior, because the second match would be considered
degenerate and ignored.

Jeevan Chalke, with some cosmetic changes by me.

src/backend/utils/adt/regexp.c patch | blob | blame | history

src/backend/utils/adt/varlena.c patch | blob | blame | history

src/test/regress/expected/strings.out patch | blob | blame | history

src/test/regress/sql/strings.sql patch | blob | blame | history

diff --git a/src/backend/utils/adt/regexp.c b/src/backend/utils/adt/regexp.c

index 6a89fabf4bf25f71587b485c7bec1bb1a7f8285b..ee37dfe991a7a3c3895ffa3d5fa8afd19de0a7e3 100644 (file)

--- a/src/backend/utils/adt/regexp.c

+++ b/src/backend/utils/adt/regexp.c

@@ -957,14 +957,13 @@ setup_regexp_matches(text *orig_str, text *pattern, text *flags,

break;

- * Advance search position. Normally we start just after the end of

- * the previous match, but always advance at least one character (the

- * special case can occur if the pattern matches zero characters just

- * after the prior match or at the end of the string).

+ * Advance search position. Normally we start the next search at the

+ * end of the previous match; but if the match was of zero length, we

+ * have to advance by one character, or we'd just find the same match

+ * again.

- if (start_search < pmatch[0].rm_eo)

- start_search = pmatch[0].rm_eo;

- else

+ start_search = prev_match_end;

+ if (pmatch[0].rm_so == pmatch[0].rm_eo)

start_search++;

if (start_search > wide_len)

break;

diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c

index 4aa344896f9f704b8a1681a8978c0218ee49b510..5e2c2ddc532c604a05f365f0cf6761033a35be76 100644 (file)

--- a/src/backend/utils/adt/varlena.c

+++ b/src/backend/utils/adt/varlena.c

@@ -3083,7 +3083,10 @@ replace_text_regexp(text *src_text, void *regexp,

break;

- * Search from next character when the matching text is zero width.

+ * Advance search position. Normally we start the next search at the

+ * end of the previous match; but if the match was of zero length, we

+ * have to advance by one character, or we'd just find the same match

+ * again.

search_start = data_pos;

if (pmatch[0].rm_so == pmatch[0].rm_eo)

diff --git a/src/test/regress/expected/strings.out b/src/test/regress/expected/strings.out

index 281c69528aa986a57642b65fb7244de688cf50e1..19708c32fdd30b9566050b55ef82843b72989923 100644 (file)

--- a/src/test/regress/expected/strings.out

+++ b/src/test/regress/expected/strings.out

@@ -440,6 +440,64 @@ SELECT regexp_matches('foobarbequebaz', $re$barbeque$re$);

{barbeque}

(1 row)

+-- start/end-of-line matches are of zero length

+SELECT regexp_matches('foo' || chr(10) || 'bar' || chr(10) || 'bequq' || chr(10) || 'baz', '^', 'mg');

+ regexp_matches

+----------------

+ {""}

+(4 rows)

+SELECT regexp_matches('foo' || chr(10) || 'bar' || chr(10) || 'bequq' || chr(10) || 'baz', '$', 'mg');

+ regexp_matches

+----------------

+ {""}

+(4 rows)

+SELECT regexp_matches('1' || chr(10) || '2' || chr(10) || '3' || chr(10) || '4' || chr(10), '^.?', 'mg');

+ regexp_matches

+----------------

+ {1}

+ {2}

+ {3}

+ {4}

+ {""}

+(5 rows)

+SELECT regexp_matches(chr(10) || '1' || chr(10) || '2' || chr(10) || '3' || chr(10) || '4' || chr(10), '.?$', 'mg');

+ regexp_matches

+----------------

+ {""}

+ {1}

+ {""}

+ {2}

+ {""}

+ {3}

+ {""}

+ {4}

+ {""}

+(10 rows)

+SELECT regexp_matches(chr(10) || '1' || chr(10) || '2' || chr(10) || '3' || chr(10) || '4', '.?$', 'mg');

+ regexp_matches

+----------------

+ {""}

+ {1}

+ {""}

+ {2}

+ {""}

+ {3}

+ {""}

+ {4}

+ {""}

+(9 rows)

-- give me errors

SELECT regexp_matches('foobarbequebaz', $re$(bar)(beque)$re,ドル 'gz');

ERROR: invalid regexp option: "z"

diff --git a/src/test/regress/sql/strings.sql b/src/test/regress/sql/strings.sql

index e7841aa20d77e315b7bdf056d7da4a8d46578fcb..f9cfaeb44ac2f55d8f5c859a0951aaba9e1dd381 100644 (file)

--- a/src/test/regress/sql/strings.sql

+++ b/src/test/regress/sql/strings.sql

@@ -158,6 +158,13 @@ SELECT regexp_matches('foobarbequebaz', $re$(bar)(.+)?(beque)$re$);

-- no capture groups

SELECT regexp_matches('foobarbequebaz', $re$barbeque$re$);

+-- start/end-of-line matches are of zero length

+SELECT regexp_matches('foo' || chr(10) || 'bar' || chr(10) || 'bequq' || chr(10) || 'baz', '^', 'mg');

+SELECT regexp_matches('foo' || chr(10) || 'bar' || chr(10) || 'bequq' || chr(10) || 'baz', '$', 'mg');

+SELECT regexp_matches('1' || chr(10) || '2' || chr(10) || '3' || chr(10) || '4' || chr(10), '^.?', 'mg');

+SELECT regexp_matches(chr(10) || '1' || chr(10) || '2' || chr(10) || '3' || chr(10) || '4' || chr(10), '.?$', 'mg');

+SELECT regexp_matches(chr(10) || '1' || chr(10) || '2' || chr(10) || '3' || chr(10) || '4', '.?$', 'mg');

-- give me errors

SELECT regexp_matches('foobarbequebaz', $re$(bar)(beque)$re,ドル 'gz');

SELECT regexp_matches('foobarbequebaz', $re$(barbeque$re$);

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