filter.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->

<refentry xml:id="ds-map.filter" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>Ds\Map::filter</refname>
  <refpurpose>
    Creates a new map using a <type>callable</type> to determine which pairs to include
  </refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <modifier>public</modifier> <type>Ds\Map</type><methodname>Ds\Map::filter</methodname>
   <methodparam choice="opt"><type>callable</type><parameter>callback</parameter></methodparam>
  </methodsynopsis>
  <para>
    Creates a new map using a <type>callable</type> to determine which pairs to include.
  </para>

 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term><parameter>callback</parameter></term>
    <listitem>
        <para>
            <methodsynopsis xmlns="http://docbook.org/ns/docbook">
                <type>bool</type>
                <methodname><replaceable>callback</replaceable></methodname>
                <methodparam><type>mixed</type><parameter>key</parameter></methodparam>
                <methodparam><type>mixed</type><parameter>value</parameter></methodparam>
            </methodsynopsis>
        </para>
        <para>
            Optional <type>callable</type> which returns &true; if the pair should be included, &false; otherwise.
        </para>
        <para>
            If a callback is not provided, only values which are &true;
            (see <link linkend="language.types.boolean.casting">converting to boolean</link>)
            will be included.
        </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
    A new map containing all the pairs for which
    either the <parameter>callback</parameter> returned &true;, or all values that
    convert to &true; if a <parameter>callback</parameter> was not provided.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <example>
   <title><function>Ds\Map::filter</function> example using callback function</title>
   <programlisting role="php">
<![CDATA[
<?php
$map = new \Ds\Map(["a", "b", "c", "d", "e"]);

var_dump($map->filter(function($key, $value) {
    return $key % 2 == 0;
}));
?>
]]>
   </programlisting>
   &example.outputs.similar;
   <screen>
<![CDATA[
object(Ds\Map)#3 (3) {
  [0]=>
  object(Ds\Pair)#2 (2) {
    ["key"]=>
    int(0)
    ["value"]=>
    string(1) "a"
  }
  [1]=>
  object(Ds\Pair)#4 (2) {
    ["key"]=>
    int(2)
    ["value"]=>
    string(1) "c"
  }
  [2]=>
  object(Ds\Pair)#5 (2) {
    ["key"]=>
    int(4)
    ["value"]=>
    string(1) "e"
  }
}
]]>
   </screen>
  </example>
  <example>
   <title><function>Ds\Map::filter</function> example without a callback function</title>
   <programlisting role="php">
<![CDATA[
<?php
$map = new \Ds\Map(["a" => 0, "b" => 1, "c" => true, "d" => false]);

var_dump($map->filter());
?>
]]>
   </programlisting>
   &example.outputs.similar;
   <screen>
<![CDATA[
object(Ds\Map)#2 (3) {
  [0]=>
  int(1)
  [1]=>
  string(1) "a"
  [2]=>
  bool(true)
}
]]>
   </screen>
  </example>
 </refsect1>


</refentry>

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