boost-react-native-bundle

<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Compressed_Pair</title> <link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="compressed_pair.html" title="Compressed_Pair"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td> <td align="center"><a href="../../../../index.html">Home</a></td> <td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"></div> <div class="article"> <div class="titlepage"> <div> <div><h2 class="title"> <a name="compressed_pair"></a>Compressed_Pair</h2></div> <div><div class="authorgroup"> <div class="author"><h3 class="author"> <span class="firstname">Steve</span> <span class="surname">Cleary</span> </h3></div> <div class="author"><h3 class="author"> <span class="firstname">Beman</span> <span class="surname">Dawes</span> </h3></div> <div class="author"><h3 class="author"> <span class="firstname">Howard</span> <span class="surname">Hinnant</span> </h3></div> <div class="author"><h3 class="author"> <span class="firstname">John</span> <span class="surname">Maddock</span> </h3></div> </div></div> <div><p class="copyright">Copyright © 2000 Steve Cleary, Beman Dawes, Howard Hinnant & John Maddock</p></div> <div><div class="legalnotice"> <a name="compressed_pair.legal"></a><p> Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) </p> </div></div> </div> <hr> </div> <div class="toc"> <p><b>Table of Contents</b></p> <dl class="toc"> <dt><span class="section"><a href="compressed_pair.html#compressed_pair.overview">Overview</a></span></dt> <dt><span class="section"><a href="compressed_pair.html#compressed_pair.synopsis">Synopsis</a></span></dt> <dt><span class="section"><a href="compressed_pair.html#compressed_pair.acknowledgments">Acknowledgments</a></span></dt> </dl> </div> <div class="section"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="compressed_pair.overview"></a><a class="link" href="compressed_pair.html#compressed_pair.overview" title="Overview">Overview</a> </h2></div></div></div> <p> All of the contents of <code class="computeroutput"><span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">compressed_pair</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> are defined inside <code class="computeroutput"><span class="keyword">namespace</span> <span class="identifier">boost</span></code>. </p> <p> The class <code class="computeroutput"><span class="identifier">compressed_pair</span></code> is very similar to <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></code>, but if either of the template arguments are empty classes, then the <span class="emphasis"><em>empty base-class optimisation</em></span> is applied to compress the size of the pair. </p> </div> <div class="section"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="compressed_pair.synopsis"></a><a class="link" href="compressed_pair.html#compressed_pair.synopsis" title="Synopsis">Synopsis</a> </h2></div></div></div> <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T2</span><span class="special">></span> <span class="keyword">class</span> <span class="identifier">compressed_pair</span> <span class="special">{</span> <span class="keyword">public</span><span class="special">:</span> <span class="keyword">typedef</span> <span class="identifier">T1</span> <span class="identifier">first_type</span><span class="special">;</span> <span class="keyword">typedef</span> <span class="identifier">T2</span> <span class="identifier">second_type</span><span class="special">;</span> <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">call_traits</span><span class="special"><</span><span class="identifier">first_type</span><span class="special">>::</span><span class="identifier">param_type</span> <span class="identifier">first_param_type</span><span class="special">;</span> <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">call_traits</span><span class="special"><</span><span class="identifier">second_type</span><span class="special">>::</span><span class="identifier">param_type</span> <span class="identifier">second_param_type</span><span class="special">;</span> <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">call_traits</span><span class="special"><</span><span class="identifier">first_type</span><span class="special">>::</span><span class="identifier">reference</span> <span class="identifier">first_reference</span><span class="special">;</span> <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">call_traits</span><span class="special"><</span><span class="identifier">second_type</span><span class="special">>::</span><span class="identifier">reference</span> <span class="identifier">second_reference</span><span class="special">;</span> <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">call_traits</span><span class="special"><</span><span class="identifier">first_type</span><span class="special">>::</span><span class="identifier">const_reference</span> <span class="identifier">first_const_reference</span><span class="special">;</span> <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">call_traits</span><span class="special"><</span><span class="identifier">second_type</span><span class="special">>::</span><span class="identifier">const_reference</span> <span class="identifier">second_const_reference</span><span class="special">;</span> <span class="identifier">compressed_pair</span><span class="special">()</span> <span class="special">:</span> <span class="identifier">base</span><span class="special">()</span> <span class="special">{}</span> <span class="identifier">compressed_pair</span><span class="special">(</span><span class="identifier">first_param_type</span> <span class="identifier">x</span><span class="special">,</span> <span class="identifier">second_param_type</span> <span class="identifier">y</span><span class="special">);</span> <span class="keyword">explicit</span> <span class="identifier">compressed_pair</span><span class="special">(</span><span class="identifier">first_param_type</span> <span class="identifier">x</span><span class="special">);</span> <span class="keyword">explicit</span> <span class="identifier">compressed_pair</span><span class="special">(</span><span class="identifier">second_param_type</span> <span class="identifier">y</span><span class="special">);</span> <span class="identifier">compressed_pair</span><span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span><span class="keyword">const</span> <span class="identifier">compressed_pair</span><span class="special">&);</span> <span class="identifier">first_reference</span> <span class="identifier">first</span><span class="special">();</span> <span class="identifier">first_const_reference</span> <span class="identifier">first</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> <span class="identifier">second_reference</span> <span class="identifier">second</span><span class="special">();</span> <span class="identifier">second_const_reference</span> <span class="identifier">second</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">compressed_pair</span><span class="special">&</span> <span class="identifier">y</span><span class="special">);</span> <span class="special">};</span> </pre> <p> The two members of the pair can be accessed using the member functions <code class="computeroutput"><span class="identifier">first</span><span class="special">()</span></code> and <code class="computeroutput"><span class="identifier">second</span><span class="special">()</span></code>. Note that not all member functions can be instantiated for all template parameter types. In particular <code class="computeroutput"><span class="identifier">compressed_pair</span></code> can be instantiated for reference and array types, however in these cases the range of constructors that can be used are limited. If types <code class="computeroutput"><span class="identifier">T1</span></code> and <code class="computeroutput"><span class="identifier">T2</span></code> are the same type, then there is only one version of the single-argument constructor, and this constructor initialises both values in the pair to the passed value. </p> <p> Note that if either member is a POD type, then that member is not zero-initialized by the <code class="computeroutput"><span class="identifier">compressed_pair</span></code> default constructor: it's up to you to supply an initial value for these types if you want them to have a default value. </p> <p> Note that <code class="computeroutput"><span class="identifier">compressed_pair</span></code> can not be instantiated if either of the template arguments is a union type, unless there is compiler support for <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_union</span></code>, or if <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_union</span></code> is specialised for the union type. </p> <p> Finally, a word of caution for Visual C++ 6 users: if either argument is an empty type, then assigning to that member will produce memory corruption, unless the empty type has a "do nothing" assignment operator defined. This is due to a bug in the way VC6 generates implicit assignment operators. </p> </div> <div class="section"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="compressed_pair.acknowledgments"></a><a class="link" href="compressed_pair.html#compressed_pair.acknowledgments" title="Acknowledgments">Acknowledgments</a> </h2></div></div></div> <p> Based on contributions by Steve Cleary, Beman Dawes, Howard Hinnant and John Maddock. </p> <p> Maintained by <a href="mailto:john%40johnmaddock.co.uk" target="_top">John Maddock</a>. </p> </div> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"><p><small>Last revised: October 30, 2014 at 10:17:14 GMT</small></p></td> <td align="right"><div class="copyright-footer"></div></td> </tr></table> <hr> <div class="spirit-nav"></div> </body> </html>