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<title>read_until (8 of 8 overloads)</title>
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<div class="section" title="read_until (8 of 8 overloads)">
<div class="titlepage"><div><div><h4 class="title">
<a name="boost_asio.reference.read_until.overload8"></a><a class="link" href="overload8.html" title="read_until (8 of 8 overloads)"> read_until
(8 of 8 overloads)</a>
</h4></div></div></div>
<p>
Read data into a streambuf until a function object indicates a match.
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span>
<span class="keyword">typename</span> <a class="link" href="../SyncReadStream.html" title="Buffer-oriented synchronous read stream requirements">SyncReadStream</a><span class="special">,</span>
<span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">,</span>
<span class="keyword">typename</span> <span class="identifier">MatchCondition</span><span class="special">></span>
<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>
<span class="identifier">SyncReadStream</span> <span class="special">&</span> <span class="identifier">s</span><span class="special">,</span>
<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"><</span> <span class="identifier">Allocator</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">b</span><span class="special">,</span>
<span class="identifier">MatchCondition</span> <span class="identifier">match_condition</span><span class="special">,</span>
<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">&</span> <span class="identifier">ec</span><span class="special">,</span>
<span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">enable_if</span><span class="special"><</span> <span class="identifier">is_match_condition</span><span class="special"><</span> <span class="identifier">MatchCondition</span> <span class="special">></span> <span class="special">>::</span><span class="identifier">type</span> <span class="special">*</span> <span class="special">=</span> <span class="number">0</span><span class="special">);</span>
</pre>
<p>
This function is used to read data into the specified streambuf until a
user-defined match condition function object, when applied to the data
contained in the streambuf, indicates a successful match. The call will
block until one of the following conditions is true:
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
The match condition function object returns a std::pair where the second
element evaluates to true.
</li>
<li class="listitem">
An error occurred.
</li>
</ul></div>
<p>
This operation is implemented in terms of zero or more calls to the stream's
read_some function. If the match condition function object already indicates
a match, the function returns immediately.
</p>
<a name="boost_asio.reference.read_until.overload8.parameters"></a><h6>
<a name="id1075853"></a>
<a class="link" href="overload8.html#boost_asio.reference.read_until.overload8.parameters">Parameters</a>
</h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term">s</span></dt>
<dd><p>
The stream from which the data is to be read. The type must support
the SyncReadStream concept.
</p></dd>
<dt><span class="term">b</span></dt>
<dd><p>
A streambuf object into which the data will be read.
</p></dd>
<dt><span class="term">match_condition</span></dt>
<dd>
<p>
The function object to be called to determine whether a match exists.
The signature of the function object must be:
</p>
<pre class="programlisting"><span class="identifier">pair</span><span class="special"><</span><span class="identifier">iterator</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">></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>
</pre>
<p>
where <code class="computeroutput"><span class="identifier">iterator</span></code> represents
the type:
</p>
<pre class="programlisting"><span class="identifier">buffers_iterator</span><span class="special"><</span><span class="identifier">basic_streambuf</span><span class="special"><</span><span class="identifier">Allocator</span><span class="special">>::</span><span class="identifier">const_buffers_type</span><span class="special">></span>
</pre>
<p>
The iterator parameters <code class="computeroutput"><span class="identifier">begin</span></code>
and <code class="computeroutput"><span class="identifier">end</span></code> define the
range of bytes to be scanned to determine whether there is a match.
The <code class="computeroutput"><span class="identifier">first</span></code> member of
the return value is an iterator marking one-past-the-end of the bytes
that have been consumed by the match function. This iterator is used
to calculate the <code class="computeroutput"><span class="identifier">begin</span></code>
parameter for any subsequent invocation of the match condition. The
<code class="computeroutput"><span class="identifier">second</span></code> member of the
return value is true if a match has been found, false otherwise.
</p>
</dd>
<dt><span class="term">ec</span></dt>
<dd><p>
Set to indicate what error occurred, if any.
</p></dd>
</dl>
</div>
<a name="boost_asio.reference.read_until.overload8.return_value"></a><h6>
<a name="id1076127"></a>
<a class="link" href="overload8.html#boost_asio.reference.read_until.overload8.return_value">Return
Value</a>
</h6>
<p>
The number of bytes in the streambuf's get area that have been fully consumed
by the match function. Returns 0 if an error occurred.
</p>
<a name="boost_asio.reference.read_until.overload8.remarks"></a><h6>
<a name="id1076155"></a>
<a class="link" href="overload8.html#boost_asio.reference.read_until.overload8.remarks">Remarks</a>
</h6>
<p>
After a successful read_until operation, the streambuf may contain additional
data beyond that which matched the function object. An application will
typically leave that data in the streambuf for a subsequent
</p>
<p>
The default implementation of the <code class="computeroutput"><span class="identifier">is_match_condition</span></code>
type trait evaluates to true for function pointers and function objects
with a <code class="computeroutput"><span class="identifier">result_type</span></code> typedef.
It must be specialised for other user-defined function objects.
</p>
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<td align="right"><div class="copyright-footer">Copyright © 2003 - 2010 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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