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  26 <div class="titlepage"><div><div><h4 class="title">
  27 <a name="boost_asio.reference.read_until.overload8"></a><a class="link" href="overload8.html" title="read_until (8 of 8 overloads)">read_until
  28         (8 of 8 overloads)</a>
  29 </h4></div></div></div>
  30 <p>
  31           Read data into a streambuf until a function object indicates a match.
  32         </p>
  33 <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
  34     <span class="keyword">typename</span> <a class="link" href="../SyncReadStream.html" title="Buffer-oriented synchronous read stream requirements">SyncReadStream</a><span class="special">,</span>
  35     <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">,</span>
  36     <span class="keyword">typename</span> <span class="identifier">MatchCondition</span><span class="special">&gt;</span>
  37 <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">read_until</span><span class="special">(</span>
  38     <span class="identifier">SyncReadStream</span> <span class="special">&amp;</span> <span class="identifier">s</span><span class="special">,</span>
  39     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">basic_streambuf</span><span class="special">&lt;</span> <span class="identifier">Allocator</span> <span class="special">&gt;</span> <span class="special">&amp;</span> <span class="identifier">b</span><span class="special">,</span>
  40     <span class="identifier">MatchCondition</span> <span class="identifier">match_condition</span><span class="special">,</span>
  41     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&amp;</span> <span class="identifier">ec</span><span class="special">,</span>
  42     <span class="keyword">typename</span> <span class="identifier">enable_if</span><span class="special">&lt;</span> <span class="identifier">is_match_condition</span><span class="special">&lt;</span> <span class="identifier">MatchCondition</span> <span class="special">&gt;::</span><span class="identifier">value</span> <span class="special">&gt;::</span><span class="identifier">type</span> <span class="special">*</span>  <span class="special">=</span> <span class="number">0</span><span class="special">);</span>
  43 </pre>
  44 <p>
  45           This function is used to read data into the specified streambuf until a
  46           user-defined match condition function object, when applied to the data
  47           contained in the streambuf, indicates a successful match. The call will
  48           block until one of the following conditions is true:
  49         </p>
  50 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  51 <li class="listitem">
  52               The match condition function object returns a std::pair where the second
  53               element evaluates to true.
  54             </li>
  55 <li class="listitem">
  56               An error occurred.
  57             </li>
  58 </ul></div>
  59 <p>
  60           This operation is implemented in terms of zero or more calls to the stream's
  61           read_some function. If the match condition function object already indicates
  62           a match, the function returns immediately.
  63         </p>
  64 <h6>
  65 <a name="boost_asio.reference.read_until.overload8.h0"></a>
  66           <span class="phrase"><a name="boost_asio.reference.read_until.overload8.parameters"></a></span><a class="link" href="overload8.html#boost_asio.reference.read_until.overload8.parameters">Parameters</a>
  67         </h6>
  68 <div class="variablelist">
  69 <p class="title"><b></b></p>
  70 <dl class="variablelist">
  71 <dt><span class="term">s</span></dt>
  72 <dd><p>
  73                 The stream from which the data is to be read. The type must support
  74                 the SyncReadStream concept.
  75               </p></dd>
  76 <dt><span class="term">b</span></dt>
  77 <dd><p>
  78                 A streambuf object into which the data will be read.
  79               </p></dd>
  80 <dt><span class="term">match_condition</span></dt>
  81 <dd>
  82 <p>
  83                 The function object to be called to determine whether a match exists.
  84                 The signature of the function object must be:
  85 </p>
  86 <pre class="programlisting"><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">&gt;</span> <span class="identifier">match_condition</span><span class="special">(</span><span class="identifier">iterator</span> <span class="identifier">begin</span><span class="special">,</span> <span class="identifier">iterator</span> <span class="identifier">end</span><span class="special">);</span>
  87 </pre>
  88 <p>
  89                 where <code class="computeroutput"><span class="identifier">iterator</span></code> represents
  90                 the type:
  91 </p>
  92 <pre class="programlisting"><span class="identifier">buffers_iterator</span><span class="special">&lt;</span><span class="identifier">basic_streambuf</span><span class="special">&lt;</span><span class="identifier">Allocator</span><span class="special">&gt;::</span><span class="identifier">const_buffers_type</span><span class="special">&gt;</span>
  93 </pre>
  94 <p>
  95                 The iterator parameters <code class="computeroutput"><span class="identifier">begin</span></code>
  96                 and <code class="computeroutput"><span class="identifier">end</span></code> define the
  97                 range of bytes to be scanned to determine whether there is a match.
  98                 The <code class="computeroutput"><span class="identifier">first</span></code> member
  99                 of the return value is an iterator marking one-past-the-end of the
 100                 bytes that have been consumed by the match function. This iterator
 101                 is used to calculate the <code class="computeroutput"><span class="identifier">begin</span></code>
 102                 parameter for any subsequent invocation of the match condition. The
 103                 <code class="computeroutput"><span class="identifier">second</span></code> member of
 104                 the return value is true if a match has been found, false otherwise.
 105               </p>
 106 </dd>
 107 <dt><span class="term">ec</span></dt>
 108 <dd><p>
 109                 Set to indicate what error occurred, if any.
 110               </p></dd>
 111 </dl>
 112 </div>
 113 <h6>
 114 <a name="boost_asio.reference.read_until.overload8.h1"></a>
 115           <span class="phrase"><a name="boost_asio.reference.read_until.overload8.return_value"></a></span><a class="link" href="overload8.html#boost_asio.reference.read_until.overload8.return_value">Return
 116           Value</a>
 117         </h6>
 118 <p>
 119           The number of bytes in the streambuf's get area that have been fully consumed
 120           by the match function. Returns 0 if an error occurred.
 121         </p>
 122 <h6>
 123 <a name="boost_asio.reference.read_until.overload8.h2"></a>
 124           <span class="phrase"><a name="boost_asio.reference.read_until.overload8.remarks"></a></span><a class="link" href="overload8.html#boost_asio.reference.read_until.overload8.remarks">Remarks</a>
 125         </h6>
 126 <p>
 127           After a successful read_until operation, the streambuf may contain additional
 128           data beyond that which matched the function object. An application will
 129           typically leave that data in the streambuf for a subsequent
 130         </p>
 131 <p>
 132           The default implementation of the <code class="computeroutput"><span class="identifier">is_match_condition</span></code>
 133           type trait evaluates to true for function pointers and function objects
 134           with a <code class="computeroutput"><span class="identifier">result_type</span></code> typedef.
 135           It must be specialised for other user-defined function objects.
 136         </p>
 137 </div>
 138 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 139 <td align="left"></td>
 140 <td align="right"><div class="copyright-footer">Copyright &#169; 2003-2014 Christopher M. Kohlhoff<p>
 141         Distributed under the Boost Software License, Version 1.0. (See accompanying
 142         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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