66d54af3
 Hu Chunming
提交_GLIBCXX_USE_CX...
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<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Boost Function Object Adapter Library</title>
</head>
<body>
<h1>Identity</h1>
<p>The header <a href="../../boost/functional/identity.hpp">
<boost/functional/identity.hpp></a> provides the function object
<code>boost::identity</code> whose <code>operator()</code> returns its
argument. It is an implementation of C++20's <code>std::identity</code>
that supports C++03 and above.</p>
<h2>Example</h2>
<p>It is commonly used as the default projection in constrained algorithms.</p>
<pre>
<code>template<class Range, class Projection = boost::identity>
void print(Range&& range, Projection projection = {});</code>
</pre>
<h2>Reference</h2>
<pre>
<code>namespace boost {
struct identity {
using is_transparent = <em>unspecified</em>;
template<class T>
T&& operator()(T&& value) const noexcept;
};
} // boost</code>
</pre>
<h3>Operators</h3>
<dl>
<dt><code>template<class T>
T&& operator()(T&& value) const noexcept;</code></dt>
<dd>Returns <code>std::forward<T>(value)</code></dd>
</dl>
<hr>
<p>Copyright 2021 Glen Joseph Fernandes.</p>
<p>Distributed under the
<a href="http://www.boost.org/LICENSE_1_0.txt">Boost Software License,
Version 1.0</a>.</p>
</body>
</html>
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