mirror of
https://github.com/sigmasternchen/php-doc-en
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22a082800b
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@344343 c90b9560-bf6c-de11-be94-00142212c4b1
129 lines
2.8 KiB
XML
129 lines
2.8 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<refentry xml:id="pht-queue.front" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<refnamediv>
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<refname>pht\Queue::front</refname>
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<refpurpose>Returns the first value from a queue</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<modifier>public</modifier> <type>mixed</type><methodname>pht\Queue::front</methodname>
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<void />
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</methodsynopsis>
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<para>
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This method will remove a value from the front of the queue (in constant
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time). Attempting to return the front value from an empty queue will result
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in an <classname>Error</classname> exception.
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</para>
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<caution>
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<para>
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Due to the fact that all values in a <classname>pht\Queue</classname> are
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serialised, extracting a value from the queue will require it to be
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deserialised. This can incur a noticeable performance hit if the inspection
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of the queue's front value is performed within a loop.
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</para>
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</caution>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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&no.function.parameters;
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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The value on the front of the queue.
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</para>
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<para>
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<example>
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<title>Retrieving the front value of a queue</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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use pht\Queue;
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$queue = new Queue();
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$queue->push(1);
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var_dump($queue->front());
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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int(1)
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]]>
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</screen>
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</example>
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</para>
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<para>
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<example>
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<title>Retrieving the front value in a loop (bad example - don't do this)</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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use pht\Queue;
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$queue = new Queue();
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$queue->push(array_fill(0, 2000, 0));
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for ($i = 0; $i < count($queue->front()); ++$i); // quadratic runtime
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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<example>
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<title>Retrieving the front value in a loop (good example)</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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use pht\Queue;
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$queue = new Queue();
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$queue->push(array_fill(0, 2000, 0));
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$front = $queue->front(); // create a separate variable
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for ($i = 0; $i < count($front); ++$i); // linear runtime
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]]>
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</programlisting>
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</example>
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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