367 lines
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HTML
367 lines
17 KiB
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<title>basic_streambuf</title>
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<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
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<link rel="home" href="../../index.html" title="Asio">
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
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<table cellpadding="2" width="100%"><tr><td valign="top"><img alt="asio C++ library" width="250" height="60" src="../../asio.png"></td></tr></table>
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<hr>
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<div class="spirit-nav">
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<a accesskey="p" href="basic_stream_socket__rebind_executor/other.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="basic_streambuf/basic_streambuf.html"><img src="../../next.png" alt="Next"></a>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="asio.reference.basic_streambuf"></a><a class="link" href="basic_streambuf.html" title="basic_streambuf">basic_streambuf</a>
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</h3></div></div></div>
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<p>
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<a class="indexterm" name="asio.indexterm.basic_streambuf"></a>
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</p>
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<p>
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Automatically resizable buffer class based on std::streambuf.
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</p>
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<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span>
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<span class="keyword">typename</span> <span class="identifier">Allocator</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator</span><span class="special"><</span><span class="keyword">char</span><span class="special">>></span>
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<span class="keyword">class</span> <span class="identifier">basic_streambuf</span> <span class="special">:</span>
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<span class="identifier">noncopyable</span>
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</pre>
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<h5>
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<a name="asio.reference.basic_streambuf.h0"></a>
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<span><a name="asio.reference.basic_streambuf.types"></a></span><a class="link" href="basic_streambuf.html#asio.reference.basic_streambuf.types">Types</a>
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</h5>
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<div class="informaltable"><table class="table">
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<colgroup>
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<col>
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<col>
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</colgroup>
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<thead><tr>
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<th>
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<p>
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Name
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</th>
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<th>
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<p>
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Description
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</p>
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</th>
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</tr></thead>
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<tbody>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/const_buffers_type.html" title="basic_streambuf::const_buffers_type"><span class="bold"><strong>const_buffers_type</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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The type used to represent the input sequence as a list of buffers.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/mutable_buffers_type.html" title="basic_streambuf::mutable_buffers_type"><span class="bold"><strong>mutable_buffers_type</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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The type used to represent the output sequence as a list of buffers.
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</p>
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</td>
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</tr>
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</tbody>
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</table></div>
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<h5>
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<a name="asio.reference.basic_streambuf.h1"></a>
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<span><a name="asio.reference.basic_streambuf.member_functions"></a></span><a class="link" href="basic_streambuf.html#asio.reference.basic_streambuf.member_functions">Member
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Functions</a>
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</h5>
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<div class="informaltable"><table class="table">
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<colgroup>
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<col>
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<col>
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</colgroup>
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<thead><tr>
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<th>
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<p>
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Name
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</p>
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</th>
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<th>
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<p>
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Description
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</p>
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</th>
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</tr></thead>
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<tbody>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/basic_streambuf.html" title="basic_streambuf::basic_streambuf"><span class="bold"><strong>basic_streambuf</strong></span></a> <span class="silver">[constructor]</span>
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</p>
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</td>
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<td>
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<p>
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Construct a basic_streambuf object.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/capacity.html" title="basic_streambuf::capacity"><span class="bold"><strong>capacity</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Get the current capacity of the basic_streambuf.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/commit.html" title="basic_streambuf::commit"><span class="bold"><strong>commit</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Move characters from the output sequence to the input sequence.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/consume.html" title="basic_streambuf::consume"><span class="bold"><strong>consume</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Remove characters from the input sequence.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/data.html" title="basic_streambuf::data"><span class="bold"><strong>data</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Get a list of buffers that represents the input sequence.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/max_size.html" title="basic_streambuf::max_size"><span class="bold"><strong>max_size</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Get the maximum size of the basic_streambuf.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/prepare.html" title="basic_streambuf::prepare"><span class="bold"><strong>prepare</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Get a list of buffers that represents the output sequence, with
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the given size.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/size.html" title="basic_streambuf::size"><span class="bold"><strong>size</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Get the size of the input sequence.
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</p>
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</td>
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</tr>
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</tbody>
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</table></div>
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<h5>
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<a name="asio.reference.basic_streambuf.h2"></a>
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<span><a name="asio.reference.basic_streambuf.protected_member_functions"></a></span><a class="link" href="basic_streambuf.html#asio.reference.basic_streambuf.protected_member_functions">Protected
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Member Functions</a>
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</h5>
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<div class="informaltable"><table class="table">
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<colgroup>
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<col>
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<col>
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</colgroup>
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<thead><tr>
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<th>
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<p>
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Name
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</p>
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</th>
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<th>
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<p>
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Description
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</p>
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</th>
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</tr></thead>
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<tbody>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/overflow.html" title="basic_streambuf::overflow"><span class="bold"><strong>overflow</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Override std::streambuf behaviour.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/reserve.html" title="basic_streambuf::reserve"><span class="bold"><strong>reserve</strong></span></a>
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</p>
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</td>
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<td>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_streambuf/underflow.html" title="basic_streambuf::underflow"><span class="bold"><strong>underflow</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Override std::streambuf behaviour.
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</p>
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</td>
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</tr>
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</tbody>
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</table></div>
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<p>
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The <code class="computeroutput"><span class="identifier">basic_streambuf</span></code> class
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is derived from <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">streambuf</span></code> to associate the streambuf's
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input and output sequences with one or more character arrays. These character
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arrays are internal to the <code class="computeroutput"><span class="identifier">basic_streambuf</span></code>
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object, but direct access to the array elements is provided to permit them
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to be used efficiently with I/O operations. Characters written to the output
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sequence of a <code class="computeroutput"><span class="identifier">basic_streambuf</span></code>
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object are appended to the input sequence of the same object.
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</p>
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<p>
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The <code class="computeroutput"><span class="identifier">basic_streambuf</span></code> class's
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public interface is intended to permit the following implementation strategies:
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</p>
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<div class="itemizedlist"><ul class="itemizedlist" type="disc">
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<li class="listitem">
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A single contiguous character array, which is reallocated as necessary
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to accommodate changes in the size of the character sequence. This is
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the implementation approach currently used in Asio.
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</li>
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<li class="listitem">
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A sequence of one or more character arrays, where each array is of the
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same size. Additional character array objects are appended to the sequence
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to accommodate changes in the size of the character sequence.
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</li>
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<li class="listitem">
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A sequence of one or more character arrays of varying sizes. Additional
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character array objects are appended to the sequence to accommodate changes
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in the size of the character sequence.
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</li>
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</ul></div>
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<p>
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The constructor for <a class="link" href="basic_streambuf.html" title="basic_streambuf"><code class="computeroutput"><span class="identifier">basic_streambuf</span></code></a> accepts a <code class="computeroutput"><span class="identifier">size_t</span></code> argument specifying the maximum
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of the sum of the sizes of the input sequence and output sequence. During
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the lifetime of the <code class="computeroutput"><span class="identifier">basic_streambuf</span></code>
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object, the following invariant holds:
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</p>
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<pre class="programlisting"><span class="identifier">size</span><span class="special">()</span> <span class="special"><=</span> <span class="identifier">max_size</span><span class="special">()</span>
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</pre>
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<p>
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Any member function that would, if successful, cause the invariant to be
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violated shall throw an exception of class <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">length_error</span></code>.
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</p>
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<p>
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The constructor for <code class="computeroutput"><span class="identifier">basic_streambuf</span></code>
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takes an Allocator argument. A copy of this argument is used for any memory
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allocation performed, by the constructor and by all member functions, during
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the lifetime of each <code class="computeroutput"><span class="identifier">basic_streambuf</span></code>
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object.
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</p>
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<h5>
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<a name="asio.reference.basic_streambuf.h3"></a>
|
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<span><a name="asio.reference.basic_streambuf.examples"></a></span><a class="link" href="basic_streambuf.html#asio.reference.basic_streambuf.examples">Examples</a>
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</h5>
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<p>
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Writing directly from an streambuf to a socket:
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</p>
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<pre class="programlisting"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">streambuf</span> <span class="identifier">b</span><span class="special">;</span>
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<span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span> <span class="identifier">os</span><span class="special">(&</span><span class="identifier">b</span><span class="special">);</span>
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<span class="identifier">os</span> <span class="special"><<</span> <span class="string">"Hello, World!\n"</span><span class="special">;</span>
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<span class="comment">// try sending some data in input sequence</span>
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<span class="identifier">size_t</span> <span class="identifier">n</span> <span class="special">=</span> <span class="identifier">sock</span><span class="special">.</span><span class="identifier">send</span><span class="special">(</span><span class="identifier">b</span><span class="special">.</span><span class="identifier">data</span><span class="special">());</span>
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<span class="identifier">b</span><span class="special">.</span><span class="identifier">consume</span><span class="special">(</span><span class="identifier">n</span><span class="special">);</span> <span class="comment">// sent data is removed from input sequence</span>
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</pre>
|
||
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<p>
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Reading from a socket directly into a streambuf:
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</p>
|
||
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<pre class="programlisting"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">streambuf</span> <span class="identifier">b</span><span class="special">;</span>
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<span class="comment">// reserve 512 bytes in output sequence</span>
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||
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<span class="identifier">asio</span><span class="special">::</span><span class="identifier">streambuf</span><span class="special">::</span><span class="identifier">mutable_buffers_type</span> <span class="identifier">bufs</span> <span class="special">=</span> <span class="identifier">b</span><span class="special">.</span><span class="identifier">prepare</span><span class="special">(</span><span class="number">512</span><span class="special">);</span>
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||
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<span class="identifier">size_t</span> <span class="identifier">n</span> <span class="special">=</span> <span class="identifier">sock</span><span class="special">.</span><span class="identifier">receive</span><span class="special">(</span><span class="identifier">bufs</span><span class="special">);</span>
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||
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||
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<span class="comment">// received data is "committed" from output sequence to input sequence</span>
|
||
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|
<span class="identifier">b</span><span class="special">.</span><span class="identifier">commit</span><span class="special">(</span><span class="identifier">n</span><span class="special">);</span>
|
||
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||
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<span class="identifier">std</span><span class="special">::</span><span class="identifier">istream</span> <span class="identifier">is</span><span class="special">(&</span><span class="identifier">b</span><span class="special">);</span>
|
||
|
|
<span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">s</span><span class="special">;</span>
|
||
|
|
<span class="identifier">is</span> <span class="special">>></span> <span class="identifier">s</span><span class="special">;</span>
|
||
|
|
</pre>
|
||
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<h5>
|
||
|
|
<a name="asio.reference.basic_streambuf.h4"></a>
|
||
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|
<span><a name="asio.reference.basic_streambuf.requirements"></a></span><a class="link" href="basic_streambuf.html#asio.reference.basic_streambuf.requirements">Requirements</a>
|
||
|
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</h5>
|
||
|
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<p>
|
||
|
|
<span class="emphasis"><em>Header: </em></span><code class="literal">asio/basic_streambuf.hpp</code>
|
||
|
|
</p>
|
||
|
|
<p>
|
||
|
|
<span class="emphasis"><em>Convenience header: </em></span><code class="literal">asio.hpp</code>
|
||
|
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</p>
|
||
|
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</div>
|
||
|
|
<div class="copyright-footer">Copyright © 2003-2023 Christopher M. Kohlhoff<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>)
|
||
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</p>
|
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||
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