diff options
Diffstat (limited to 'doc/src/sgml/func.sgml')
| -rw-r--r-- | doc/src/sgml/func.sgml | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 2946122350..4d482ec91f 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -4477,13 +4477,27 @@ SELECT foo FROM regexp_split_to_table('the quick brown fox', E'\\s*') AS foo; where no substring matching <replaceable>re</> begins (AREs only) </entry> </row> + + <row> + <entry> <literal>(?<=</><replaceable>re</><literal>)</> </entry> + <entry> <firstterm>positive lookbehind</> matches at any point + where a substring matching <replaceable>re</> ends + (AREs only) </entry> + </row> + + <row> + <entry> <literal>(?<!</><replaceable>re</><literal>)</> </entry> + <entry> <firstterm>negative lookbehind</> matches at any point + where no substring matching <replaceable>re</> ends + (AREs only) </entry> + </row> </tbody> </tgroup> </table> <para> - Lookahead constraints cannot contain <firstterm>back references</> - (see <xref linkend="posix-escape-sequences">), + Lookahead and lookbehind constraints cannot contain <firstterm>back + references</> (see <xref linkend="posix-escape-sequences">), and all parentheses within them are considered non-capturing. </para> </sect3> @@ -5355,7 +5369,7 @@ SELECT regexp_matches('abc01234xyz', '(?:(.*?)(\d+)(.*)){1,1}'); the lack of special treatment for a trailing newline, the addition of complemented bracket expressions to the things affected by newline-sensitive matching, - the restrictions on parentheses and back references in lookahead + the restrictions on parentheses and back references in lookahead/lookbehind constraints, and the longest/shortest-match (rather than first-match) matching semantics. </para> |