boost-react-native-bundle

<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Function operator,</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="../../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../../proto/reference.html#header.boost.proto.transform.env_hpp" title="Header <boost/proto/transform/env.hpp>"> <link rel="prev" href="env_var_idp207017488.html" title="Function env_var"> <link rel="next" href="_env_var.html" title="Struct template _env_var"> </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"> <a accesskey="p" href="env_var_idp207017488.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../proto/reference.html#header.boost.proto.transform.env_hpp"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="_env_var.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="refentry"> <a name="boost.proto.operator,_idp207031008"></a><div class="titlepage"></div> <div class="refnamediv"> <h2>Function operator,</h2> boost::proto::operator, — For composing a larger transform environment from two smaller ones. </div> <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis">// In header: <<a class="link" href="../../proto/reference.html#header.boost.proto.transform.env_hpp" title="Header <boost/proto/transform/env.hpp>">boost/proto/transform/env.hpp</a>> template<typename Env, typename Key, typename Value> <a class="link" href="env.html" title="Struct template env">proto::env</a><Key, Value, <code>UNCVREF</code>(typename <a class="link" href="result_of/as_env.html" title="Struct template as_env">proto::result_of::as_env</a><Env &>::type)> operator,(Env & other, <a class="link" href="env.html" title="Struct template env">proto::env</a><Key, Value> const & head); template<typename Env, typename Key, typename Value> <a class="link" href="env.html" title="Struct template env">proto::env</a><Key, Value, <code>UNCVREF</code>(typename <a class="link" href="result_of/as_env.html" title="Struct template as_env">proto::result_of::as_env</a><Env const &>::type)> operator,(Env const & other, <a class="link" href="env.html" title="Struct template env">proto::env</a><Key, Value> const & head);</pre></div> <div class="refsect1"> <a name="idp389017184"></a><h2>Description</h2> The effect of this function is to take two transform environments and compose them into a larger environment that contains the key/values pairs of the two. The first argument is allowed to not be a transform environment, in which case it is turned into one with the <code class="computeroutput"><a class="link" href="as_env_idp206990048.html" title="Function as_env">proto::as_env()</a></code> function before composition with the second argument. The second argument is required to be a transform environment with exactly one key/value pair. Example: Given user-defined keys <code class="computeroutput">key0</code> and <code class="computeroutput">key1</code> of types <code class="computeroutput">key0_type</code> and <code class="computeroutput">key1_type</code>, the following code demonstrates how the chained use of <code class="computeroutput">operator,</code> can build a composite transform environment containing a number of key/value pairs: <pre class="programlisting"><code class="computeroutput"><a class="link" href="env.html" title="Struct template env">proto::env</a></code>< key1_type , int , <code class="computeroutput"><a class="link" href="env.html" title="Struct template env">proto::env</a></code>< key0_type , char const (&)[6] , <code class="computeroutput"><a class="link" href="env.html" title="Struct template env">proto::env</a></code><<code class="computeroutput"><a class="link" href="data_type.html" title="Struct data_type">proto::data_type</a></code>, int> > > myenv = (<code class="computeroutput"><a class="link" href="data.html" title="Global data">proto::data</a></code> = 1, key0 = "hello", key1 = 42); // NOTE: operator, here --^ and here --^ // Check the results: assert(1 == myenv[proto::data]); assert(0 == std::strcmp(myenv[key0], "hello")); assert(42 == myenv[key1]);</pre> Note: In the return type and the "Returns" clause, <code class="computeroutput"><code>UNCVREF</code>(X)</code> is the type <code class="computeroutput">X</code> stripped of top-level reference and cv-qualifiers. Note: In the "Returns" clause, <code class="computeroutput"><code>cv</code></code> is replaced with <code class="computeroutput">const</code> for the second overload, and nothing for the first. See also: <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="computeroutput"><a class="link" href="env.html#idp206859168-bb">proto::env::operator[]</a></code></li></ul></div> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody><tr> <td>Returns:</td> <td><code class="computeroutput"><a class="link" href="env.html" title="Struct template env">proto::env</a><Key, Value, <code>UNCVREF</code>(typename <a class="link" href="result_of/as_env.html" title="Struct template as_env">proto::result_of::as_env</a><Env <code>cv</code> &>::type)>(head[Key()], <a class="link" href="as_env_idp206990048.html" title="Function as_env">proto::as_env</a>(other))</code></td> </tr></tbody> </table></div> </div> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler 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>) </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="env_var_idp207017488.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../proto/reference.html#header.boost.proto.transform.env_hpp"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="_env_var.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>