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  26 <div class="titlepage"><div><div><h5 class="title">
  27 <a name="beast.ref.boost__beast__http__async_read.overload1"></a><a class="link" href="overload1.html" title="http::async_read (1 of 2 overloads)">http::async_read
  28         (1 of 2 overloads)</a>
  29 </h5></div></div></div>
  30 <p>
  31           Read a complete message asynchronously from a stream using a parser.
  32         </p>
  33 <h6>
  34 <a name="beast.ref.boost__beast__http__async_read.overload1.h0"></a>
  35           <span class="phrase"><a name="beast.ref.boost__beast__http__async_read.overload1.synopsis"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__http__async_read.overload1.synopsis">Synopsis</a>
  36         </h6>
  37 <p>
  38           Defined in header <code class="literal">&lt;<a href="../../../../../../../boost/beast/http/read.hpp" target="_top">boost/beast/http/read.hpp</a>&gt;</code>
  39         </p>
  40 <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
  41     <span class="keyword">class</span> <a href="../../../../../../../doc/html/boost_asio/reference/AsyncReadStream.html" target="_top"><span class="emphasis"><em>AsyncReadStream</em></span></a><span class="special">,</span>
  42     <span class="keyword">class</span> <a class="link" href="../../concepts/DynamicBuffer.html" title="DynamicBuffer"><span class="emphasis"><em>DynamicBuffer</em></span></a><span class="special">,</span>
  43     <span class="keyword">bool</span> <span class="identifier">isRequest</span><span class="special">,</span>
  44     <span class="keyword">class</span> <a href="../../../../../../../doc/html/boost_asio/reference/ReadHandler.html" target="_top"><span class="emphasis"><em>ReadHandler</em></span></a> <span class="special">=</span> <span class="identifier">net</span><span class="special">::</span><span class="identifier">default_completion_token_t</span><span class="special">&lt;</span>            <span class="identifier">executor_type</span><span class="special">&lt;</span><span class="identifier">AsyncReadStream</span><span class="special">&gt;&gt;&gt;</span>
  45 <a href="../../../../../../../doc/html/boost_asio/reference/asynchronous_operations.html#boost_asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type" target="_top"><span class="emphasis"><em>DEDUCED</em></span></a>
  46 <span class="identifier">async_read</span><span class="special">(</span>
  47     <span class="identifier">AsyncReadStream</span><span class="special">&amp;</span> <span class="identifier">stream</span><span class="special">,</span>
  48     <span class="identifier">DynamicBuffer</span><span class="special">&amp;</span> <span class="identifier">buffer</span><span class="special">,</span>
  49     <span class="identifier">basic_parser</span><span class="special">&lt;</span> <span class="identifier">isRequest</span> <span class="special">&gt;&amp;</span> <span class="identifier">parser</span><span class="special">,</span>
  50     <span class="identifier">ReadHandler</span><span class="special">&amp;&amp;</span> <span class="identifier">handler</span> <span class="special">=</span> <span class="identifier">net</span><span class="special">::</span><span class="identifier">default_completion_token_t</span><span class="special">&lt;</span> <span class="identifier">executor_type</span><span class="special">&lt;</span> <span class="identifier">AsyncReadStream</span> <span class="special">&gt;&gt;{});</span>
  51 </pre>
  52 <h6>
  53 <a name="beast.ref.boost__beast__http__async_read.overload1.h1"></a>
  54           <span class="phrase"><a name="beast.ref.boost__beast__http__async_read.overload1.description"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__http__async_read.overload1.description">Description</a>
  55         </h6>
  56 <p>
  57           This function is used to asynchronously read a complete message from a
  58           stream into an instance of <a class="link" href="../boost__beast__http__basic_parser.html" title="http::basic_parser"><code class="computeroutput"><span class="identifier">http</span><span class="special">::</span><span class="identifier">basic_parser</span></code></a>. The function call
  59           always returns immediately. The asynchronous operation will continue until
  60           one of the following conditions is true:
  61         </p>
  62 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  63 <li class="listitem">
  64               <a class="link" href="../boost__beast__http__basic_parser/is_done.html" title="http::basic_parser::is_done"><code class="computeroutput"><span class="identifier">http</span><span class="special">::</span><span class="identifier">basic_parser</span><span class="special">::</span><span class="identifier">is_done</span></code></a> returns <code class="computeroutput"><span class="keyword">true</span></code>
  65             </li>
  66 <li class="listitem">
  67               An error occurs.
  68             </li>
  69 </ul></div>
  70 <p>
  71           This operation is implemented in terms of zero or more calls to the next
  72           layer's <code class="computeroutput"><span class="identifier">async_read_some</span></code>
  73           function, and is known as a <span class="emphasis"><em>composed operation</em></span>. The
  74           program must ensure that the stream performs no other reads until this
  75           operation completes. The implementation may read additional bytes from
  76           the stream that lie past the end of the message being read. These additional
  77           bytes are stored in the dynamic buffer, which must be preserved for subsequent
  78           reads. If the end of file error is received while reading from the stream,
  79           then the error returned from this function will be:
  80         </p>
  81 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  82 <li class="listitem">
  83               <a class="link" href="../boost__beast__http__error.html" title="http::error"><code class="computeroutput"><span class="identifier">http</span><span class="special">::</span><span class="identifier">end_of_stream</span></code></a>
  84               if no bytes were parsed, or
  85             </li>
  86 <li class="listitem">
  87               <a class="link" href="../boost__beast__http__error.html" title="http::error"><code class="computeroutput"><span class="identifier">http</span><span class="special">::</span><span class="identifier">partial_message</span></code></a>
  88               if any bytes were parsed but the message was incomplete, otherwise:
  89             </li>
  90 <li class="listitem">
  91               A successful result. The next attempt to read will return <a class="link" href="../boost__beast__http__error.html" title="http::error"><code class="computeroutput"><span class="identifier">http</span><span class="special">::</span><span class="identifier">end_of_stream</span></code></a>
  92             </li>
  93 </ul></div>
  94 <h6>
  95 <a name="beast.ref.boost__beast__http__async_read.overload1.h2"></a>
  96           <span class="phrase"><a name="beast.ref.boost__beast__http__async_read.overload1.parameters"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__http__async_read.overload1.parameters">Parameters</a>
  97         </h6>
  98 <div class="informaltable"><table class="table">
  99 <colgroup>
 100 <col>
 101 <col>
 102 </colgroup>
 103 <thead><tr>
 104 <th>
 105                   <p>
 106                     Name
 107                   </p>
 108                 </th>
 109 <th>
 110                   <p>
 111                     Description
 112                   </p>
 113                 </th>
 114 </tr></thead>
 115 <tbody>
 116 <tr>
 117 <td>
 118                   <p>
 119                     <code class="computeroutput"><span class="identifier">stream</span></code>
 120                   </p>
 121                 </td>
 122 <td>
 123                   <p>
 124                     The stream from which the data is to be read. The type must meet
 125                     the <span class="emphasis"><em>AsyncReadStream</em></span> requirements.
 126                   </p>
 127                 </td>
 128 </tr>
 129 <tr>
 130 <td>
 131                   <p>
 132                     <code class="computeroutput"><span class="identifier">buffer</span></code>
 133                   </p>
 134                 </td>
 135 <td>
 136                   <p>
 137                     Storage for additional bytes read by the implementation from
 138                     the stream. This is both an input and an output parameter; on
 139                     entry, the parser will be presented with any remaining data in
 140                     the dynamic buffer's readable bytes sequence first. The type
 141                     must meet the <span class="emphasis"><em>DynamicBuffer</em></span> requirements.
 142                     The object must remain valid at least until the handler is called;
 143                     ownership is not transferred.
 144                   </p>
 145                 </td>
 146 </tr>
 147 <tr>
 148 <td>
 149                   <p>
 150                     <code class="computeroutput"><span class="identifier">parser</span></code>
 151                   </p>
 152                 </td>
 153 <td>
 154                   <p>
 155                     The parser to use. The object must remain valid at least until
 156                     the handler is called; ownership is not transferred.
 157                   </p>
 158                 </td>
 159 </tr>
 160 <tr>
 161 <td>
 162                   <p>
 163                     <code class="computeroutput"><span class="identifier">handler</span></code>
 164                   </p>
 165                 </td>
 166 <td>
 167                   <p>
 168                     The completion handler to invoke when the operation completes.
 169                     The implementation takes ownership of the handler by performing
 170                     a decay-copy. The equivalent function signature of the handler
 171                     must be:
 172                   </p>
 173 <pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span class="special">(</span>
 174     <span class="identifier">error_code</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">error</span><span class="special">,</span>        <span class="comment">// result of operation</span>
 175     <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_transferred</span>   <span class="comment">// the total number of bytes transferred from the stream</span>
 176 <span class="special">);</span>
 177 </pre>
 178                   <p>
 179                     Regardless of whether the asynchronous operation completes immediately
 180                     or not, the handler will not be invoked from within this function.
 181                     Invocation of the handler will be performed in a manner equivalent
 182                     to using <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">post</span></code>.
 183                   </p>
 184                 </td>
 185 </tr>
 186 </tbody>
 187 </table></div>
 188 <h6>
 189 <a name="beast.ref.boost__beast__http__async_read.overload1.h3"></a>
 190           <span class="phrase"><a name="beast.ref.boost__beast__http__async_read.overload1.remarks"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__http__async_read.overload1.remarks">Remarks</a>
 191         </h6>
 192 <p>
 193           The completion handler will receive as a parameter the total number of
 194           bytes transferred from the stream. This may be zero for the case where
 195           there is sufficient pre-existing message data in the dynamic buffer. The
 196           implementation will call <a class="link" href="../boost__beast__http__basic_parser/eager.html" title="http::basic_parser::eager"><code class="computeroutput"><span class="identifier">http</span><span class="special">::</span><span class="identifier">basic_parser</span><span class="special">::</span><span class="identifier">eager</span></code></a> with the value <code class="computeroutput"><span class="keyword">true</span></code> on the parser passed in.
 197         </p>
 198 <p>
 199           Convenience header <code class="literal">&lt;<a href="../../../../../../../boost/beast/http.hpp" target="_top">boost/beast/http.hpp</a>&gt;</code>
 200         </p>
 201 </div>
 202 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 203 <td align="left"></td>
 204 <td align="right"><div class="copyright-footer">Copyright &#169; 2016-2019 Vinnie
 205       Falco<p>
 206         Distributed under the Boost Software License, Version 1.0. (See accompanying
 207         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>)
 208       </p>
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