sigmasternchen/php-doc-en
1
0
Fork 0
mirror of https://github.com/sigmasternchen/php-doc-en synced 2025-03-16 00:48:54 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

added pcre \g description (patch from Peter O'Callaghan)

Browse source 
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@299124 c90b9560-bf6c-de11-be94-00142212c4b1
This commit is contained in:
Peter Cowburn 2010-05-07 20:28:05 +00:00
parent 5106f79967
commit 1ad390c81a
1 changed files with 26 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

31
reference/pcre/pattern.syntax.xml
View file

@ -1282,7 +1282,8 @@
As of PHP 4.3.3, it is possible to name a subpattern using the syntax
<literal>(?P&lt;name&gt;pattern)</literal>. This subpattern will then
be indexed in the matches array by its normal numeric position and
also by name.
also by name. PHP 5.2.2 introduced two alternative syntaxes
<literal>(?&lt;name&gt;pattern)</literal> and <literal>(?'name'pattern)</literal>.
</para>
</section>
@ -1537,12 +1538,32 @@
reference. This can be done using alternation, as in the
example above, or by a quantifier with a minimum of zero.
</para>
<para>
As of PHP 5.2.2, the <literal>\g</literal> escape sequence can be
used for absolute and relative referencing of subpatterns.
This escape sequence must be followed by an unsigned number or a negative
number, optionally enclosed in braces. The sequences <literal>\1</literal>,
<literal>\g1</literal> and <literal>\g{1}</literal> are synonymous
with one another. The use of this pattern with an unsigned number can
help remove the ambiguity inherent when using digits following a
backslash. The sequence helps to distinguish back references from octal
characters and also makes it easier to have a back reference followed
by a literal number, e.g. <literal>\g{2}1</literal>.
</para>
<para>
The use of the <literal>\g</literal> sequence with a negative number
signifies a relative reference. For example, <literal>(foo)(bar)\g{-1}</literal>
would match the sequence "foobarbar" and <literal>(foo)(bar)\g{-2}</literal>
matches "foobarfoo". This can be useful in long patterns as an alternative
to keeping track of the number of subpatterns in order to reference
a specific previous subpattern.
</para>
<para>
Back references to the named subpatterns can be achieved by
<literal>(?P=name)</literal> or, since PHP 5.2.4, also by
<literal>\k&lt;name&gt;</literal>, <literal>\k'name'</literal>,
<literal>\k{name}</literal> or <literal>\g{name}</literal>.
<literal>(?P=name)</literal> or, since PHP 5.2.2, also by
<literal>\k&lt;name&gt;</literal> or <literal>\k'name'</literal>.
Additionally PHP 5.2.4 added support for <literal>\k{name}</literal>
and <literal>\g{name}</literal>.
</para>
</section>