intersect.xml

<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="ds-map.intersect" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>Ds\Map::intersect</refname>
  <refpurpose>Creates a new map by intersecting keys with another map</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <modifier>public</modifier> <type>Ds\Map</type><methodname>Ds\Map::intersect</methodname>
   <methodparam><type>Ds\Map</type><parameter>map</parameter></methodparam>
  </methodsynopsis>
  <para>
    Creates a new map containing the pairs of the current instance whose keys
    are also present in the given <parameter>map</parameter>.

    In other words, returns a copy of the current instance with all keys removed that
    are not also in the other <parameter>map</parameter>.
  </para>
  <para>
    <code>A ∩ B = {x : x ∈ A ∧ x ∈ B}</code>
  </para>

  <note>
    <para>
        Values from the current instance will be kept.
    </para>
  </note>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term><parameter>map</parameter></term>
    <listitem>
     <para>
        The other map, containing the keys to intersect with.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
    <para>
    The key intersection of the current instance and another <parameter>map</parameter>.
    </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><link xlink:href="https://en.wikipedia.org/wiki/Intersection_(set_theory)">Intersection</link> on Wikipedia</member>
   </simplelist>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <example>
   <title><function>Ds\Map::intersect</function> example</title>
   <programlisting role="php">
<![CDATA[
<?php
$a = new \Ds\Map(["a" => 1, "b" => 2, "c" => 3]);
$b = new \Ds\Map(["b" => 4, "c" => 5, "d" => 6]);

var_dump($a->intersect($b));
?>
]]>
   </programlisting>
   &example.outputs.similar;
   <screen>
<![CDATA[
object(Ds\Map)#3 (2) {
  [0]=>
  object(Ds\Pair)#4 (2) {
    ["key"]=>
    string(1) "b"
    ["value"]=>
    int(2)
  }
  [1]=>
  object(Ds\Pair)#5 (2) {
    ["key"]=>
    string(1) "c"
    ["value"]=>
    int(3)
  }
}
]]>
   </screen>
  </example>
 </refsect1>


</refentry>

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