mirror of
https://github.com/sigmasternchen/php-doc-en
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845661fc07
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@339744 c90b9560-bf6c-de11-be94-00142212c4b1
141 lines
4.2 KiB
XML
141 lines
4.2 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<phpdoc:classref xml:id="class.ds-deque" xmlns:phpdoc="http://php.net/ns/phpdoc" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xi="http://www.w3.org/2001/XInclude">
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<title>Deque</title>
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<titleabbrev></titleabbrev>
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<partintro>
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<!-- {{{ Ds\Deque intro -->
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<section xml:id="ds-deque.intro">
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&reftitle.intro;
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<para>
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A Deque (pronounced “deck”) is a sequence of values
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in a contiguous buffer that grows and shrinks automatically.
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The name is a common abbreviation of “double-ended queue” and is used
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internally by <classname>Ds\Queue</classname>.
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</para>
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<para>
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Two pointers are used to keep track of a head and a tail. The pointers can
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“wrap around” the end of the buffer, which avoids the need to move other
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values around to make room. This makes shift and unshift very fast —
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something a <classname>Ds\Vector</classname> can’t compete with.
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</para>
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<para>
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Accessing a value by index requires a translation between the index and its
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corresponding position in the buffer: <code>((head + position) % capacity)</code>.
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</para>
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</section>
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<!-- }}} -->
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<section xml:id="ds-deque.strengths">
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<title xmlns="http://docbook.org/ns/docbook">Strengths</title>
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<para>
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<simplelist>
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<member>Supports array syntax (square brackets).</member>
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<member>Uses less overall memory than an &array; for the same number of values.</member>
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<member>Automatically frees allocated memory when its size drops low enough.</member>
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<member>
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<function>get</function>,
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<function>set</function>,
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<function>push</function>,
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<function>pop</function>,
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<function>shift</function>, and
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<function>unshift</function> are all O(1).
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</member>
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</simplelist>
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</para>
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</section>
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<section xml:id="ds-deque.weaknesses">
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<title xmlns="http://docbook.org/ns/docbook">Weaknesses</title>
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<para>
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<simplelist>
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<member>Capacity must be a power of 2.</member>
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<member>
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<function>insert</function> and
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<function>remove</function> are O(n).
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</member>
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</simplelist>
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</para>
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</section>
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<section xml:id="ds-deque.synopsis">
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&reftitle.classsynopsis;
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<!-- {{{ Synopsis -->
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<classsynopsis>
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<ooclass><classname>Ds\Deque</classname></ooclass>
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<!-- {{{ Class synopsis -->
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<classsynopsisinfo>
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<ooclass>
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<classname>Ds\Deque</classname>
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</ooclass>
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<oointerface>
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<interfacename>Ds\Sequence</interfacename>
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</oointerface>
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</classsynopsisinfo>
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<!-- }}} -->
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<classsynopsisinfo role="comment">Constants</classsynopsisinfo>
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<fieldsynopsis>
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<modifier>const</modifier>
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<type>int</type>
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<varname linkend="ds-deque.constants.min-capacity">Ds\Deque::MIN_CAPACITY</varname>
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<initializer>8</initializer>
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</fieldsynopsis>
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<classsynopsisinfo role="comment">&Methods;</classsynopsisinfo>
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<xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('class.ds-deque')/db:refentry/db:refsect1[@role='description']/descendant::db:methodsynopsis[not(@role='procedural')])" />
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</classsynopsis>
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<!-- }}} -->
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</section>
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<!-- {{{ Ds\Deque constants -->
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<section xml:id="ds-deque.constants">
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&reftitle.constants;
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<variablelist>
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<varlistentry xml:id="ds-deque.constants.min-capacity">
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<term><constant>Ds\Deque::MIN_CAPACITY</constant></term>
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<listitem>
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<para></para>
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</listitem>
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</varlistentry>
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</variablelist>
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</section>
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<!-- }}} -->
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</partintro>
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&reference.ds.ds.entities.deque;
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</phpdoc:classref>
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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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