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Code review for regexp_matches/regexp_split patch. Refactor to avoid assuming
that cached compiled patterns will still be there when the function is next called. Clean up looping logic, thereby fixing bug identified by Pavel Stehule. Share setup code between the two functions, add some comments, and avoid risky mixing of int and size_t variables. Clean up the documentation a tad, and accept all the flag characters mentioned in table 9-19 rather than just a subset.
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‎doc/src/sgml/func.sgml

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<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.383 2007/07/18 03:12:42 momjian Exp $ -->
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<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.384 2007/08/11 03:56:24 tgl Exp $ -->
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<chapter id="functions">
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<title>Functions and Operators</title>
@@ -1499,7 +1499,7 @@
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<entry><literal><function>regexp_matches</function>(<parameter>string</parameter> <type>text</type>, <parameter>pattern</parameter> <type>text</type> [, <parameter>flags</parameter> <type>text</type>])</literal></entry>
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<entry><type>setof text[]</type></entry>
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<entry>
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Return all capture groups resulting from matching POSIX regular
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Return all captured substrings resulting from matching a POSIX regular
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expression against the <parameter>string</parameter>. See
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<xref linkend="functions-posix-regexp"> for more information.
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</entry>
@@ -1511,7 +1511,7 @@
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<entry><literal><function>regexp_replace</function>(<parameter>string</parameter> <type>text</type>, <parameter>pattern</parameter> <type>text</type>, <parameter>replacement</parameter> <type>text</type> [, <parameter>flags</parameter> <type>text</type>])</literal></entry>
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<entry><type>text</type></entry>
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<entry>
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Replace substring matching POSIX regular expression. See
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Replace substring(s) matching a POSIX regular expression. See
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<xref linkend="functions-posix-regexp"> for more information.
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</entry>
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<entry><literal>regexp_replace('Thomas', '.[mN]a.', 'M')</literal></entry>
@@ -1522,7 +1522,7 @@
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<entry><literal><function>regexp_split_to_array</function>(<parameter>string</parameter> <type>text</type>, <parameter>pattern</parameter> <type>text</type> [, <parameter>flags</parameter> <type>text</type> ])</literal></entry>
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<entry><type>text[]</type></entry>
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<entry>
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Split <parameter>string</parameter> using POSIX regular expression as
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Split <parameter>string</parameter> using a POSIX regular expression as
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the delimiter. See <xref linkend="functions-posix-regexp"> for more
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information.
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</entry>
@@ -1534,7 +1534,7 @@
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<entry><literal><function>regexp_split_to_table</function>(<parameter>string</parameter> <type>text</type>, <parameter>pattern</parameter> <type>text</type> [, <parameter>flags</parameter> <type>text</type>])</literal></entry>
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<entry><type>setof text</type></entry>
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<entry>
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Split <parameter>string</parameter> using POSIX regular expression as
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Split <parameter>string</parameter> using a POSIX regular expression as
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the delimiter. See <xref linkend="functions-posix-regexp"> for more
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information.
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</entry>
@@ -2856,11 +2856,9 @@ cast(-44 as bit(12)) <lineannotation>111111010100</lineannotation>
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<acronym>SQL</acronym> <function>LIKE</function> operator, the
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more recent <function>SIMILAR TO</function> operator (added in
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SQL:1999), and <acronym>POSIX</acronym>-style regular
2859-
expressions.
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Additionally, a pattern matching function,
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<function>substring</function>, is available, using either
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<function>SIMILAR TO</function>-style or POSIX-style regular
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expressions.
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expressions. Aside from the basic <quote>does this string match
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this pattern?</> operators, functions are available to extract
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or replace matching substrings and to split a string at the matches.
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</para>
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<tip>
@@ -3186,15 +3184,20 @@ substring('foobar' from '#"o_b#"%' for '#') <lineannotation>NULL</lineannotat
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end of the string.
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</para>
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<para>
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Some examples:
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<para>
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Some examples:
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<programlisting>
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'abc' ~ 'abc' <lineannotation>true</lineannotation>
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'abc' ~ '^a' <lineannotation>true</lineannotation>
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'abc' ~ '(b|d)' <lineannotation>true</lineannotation>
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'abc' ~ '^(b|c)' <lineannotation>false</lineannotation>
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</programlisting>
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</para>
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</para>
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<para>
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The <acronym>POSIX</acronym> pattern language is described in much
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greater detail below.
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</para>
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<para>
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The <function>substring</> function with two parameters,
@@ -3246,9 +3249,7 @@ substring('foobar' from 'o(.)b') <lineannotation>o</lineannotation>
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function's behavior. Flag <literal>i</> specifies case-insensitive
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matching, while flag <literal>g</> specifies replacement of each matching
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substring rather than only the first one. Other supported flags are
3249-
<literal>m</>, <literal>n</>, <literal>p</>, <literal>w</> and
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<literal>x</>, whose meanings correspond to those shown in
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<xref linkend="posix-embedded-options-table">.
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described in <xref linkend="posix-embedded-options-table">.
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</para>
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<para>
@@ -3264,23 +3265,25 @@ regexp_replace('foobarbaz', 'b(..)', E'X\\1Y', 'g')
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</para>
32653266

32663267
<para>
3267-
The <function>regexp_matches</> function returns all of the capture
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groups resulting from matching a POSIX regular expression pattern.
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The <function>regexp_matches</> function returns all of the captured
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substrings resulting from matching a POSIX regular expression pattern.
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It has the syntax
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<function>regexp_matches</function>(<replaceable>string</>, <replaceable>pattern</>
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<optional>, <replaceable>flags</> </optional>).
3272-
If there is no match to the <replaceable>pattern</>, the function returns no rows.
3273-
If there is a match, the function returns the contents of all of the capture groups
3274-
in a text array, or if there were no capture groups in the pattern, it returns the
3275-
contents of the entire match as a single-element text array.
3273+
If there is no match to the <replaceable>pattern</>, the function returns
3274+
no rows. If there is a match, the function returns a text array whose
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<replaceable>n</>'th element is the substring matching the
3276+
<replaceable>n</>'th parenthesized subexpression of the pattern
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(not counting <quote>non-capturing</> parentheses; see below for
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details). If the pattern does not contain any parenthesized
3279+
subexpressions, then the result is a single-element text array containing
3280+
the substring matching the whole pattern.
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The <replaceable>flags</> parameter is an optional text
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string containing zero or more single-letter flags that change the
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function's behavior. Flag <literal>i</> specifies case-insensitive
3279-
matching, while flag <literal>g</> causes the return of each matching
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substring rather than only the first one. Other supported
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flags are <literal>m</>, <literal>n</>, <literal>p</>, <literal>w</> and
3282-
<literal>x</>, whose meanings are described in
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<xref linkend="posix-embedded-options-table">.
3283+
function's behavior. Flag <literal>g</> causes the function to find
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each match in the string, not only the first one, and return a row for
3285+
each such match. Other supported
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flags are described in <xref linkend="posix-embedded-options-table">.
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</para>
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<para>
@@ -3319,16 +3322,14 @@ SELECT regexp_matches('foobarbequebaz', 'barbeque');
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returns the text from the end of the last match to the end of the string.
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The <replaceable>flags</> parameter is an optional text string containing
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zero or more single-letter flags that change the function's behavior.
3322-
<function>regexp_split_to_table</function> supports the flags <literal>i</>,
3323-
<literal>m</>, <literal>n</>, <literal>p</>, <literal>w</> and
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<literal>x</>, whose meanings are described in
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<function>regexp_split_to_table</function> supports the flags described in
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<xref linkend="posix-embedded-options-table">.
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</para>
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<para>
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The <function>regexp_split_to_array</> function behaves the same as
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<function>regexp_split_to_table</>, except that <function>regexp_split_to_array</>
3331-
returns its results as a <type>text[]</>. It has the syntax
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returns its result as an array of <type>text</>. It has the syntax
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<function>regexp_split_to_array</function>(<replaceable>string</>, <replaceable>pattern</>
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<optional>, <replaceable>flags</> </optional>).
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The parameters are the same as for <function>regexp_split_to_table</>.

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