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<title>read_until (24 of 24 overloads)</title>
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<div class="titlepage"><div><div><h4 class="title">
<a name="boost_asio.reference.read_until.overload24"></a><a class="link" href="overload24.html" title="read_until (24 of 24 overloads)">read_until
(24 of 24 overloads)</a>
</h4></div></div></div>
<p>
Read data into a dynamic buffer sequence until a function object indicates
a match.
</p>
<pre class="programlisting">template&lt;
typename <a class="link" href="../SyncReadStream.html" title="Buffer-oriented synchronous read stream requirements">SyncReadStream</a>,
typename <a class="link" href="../DynamicBuffer_v2.html" title="Dynamic buffer requirements (version 2)">DynamicBuffer_v2</a>,
typename MatchCondition&gt;
std::size_t read_until(
SyncReadStream &amp; s,
DynamicBuffer_v2 buffers,
MatchCondition match_condition,
boost::system::error_code &amp; ec,
typename constraint&lt; is_match_condition&lt; MatchCondition &gt;::value &gt;::type = 0,
typename constraint&lt; is_dynamic_buffer_v2&lt; DynamicBuffer_v2 &gt;::value &gt;::type = 0);
</pre>
<p>
This function is used to read data into the specified dynamic buffer sequence
until a user-defined match condition function object, when applied to the
data contained in the dynamic buffer sequence, indicates a successful match.
The call will block until one of the following conditions is true:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-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>
<h6>
<a name="boost_asio.reference.read_until.overload24.h0"></a>
<span class="phrase"><a name="boost_asio.reference.read_until.overload24.parameters"></a></span><a class="link" href="overload24.html#boost_asio.reference.read_until.overload24.parameters">Parameters</a>
</h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<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">buffers</span></dt>
<dd><p>
A dynamic buffer sequence 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">pair&lt;iterator, bool&gt; match_condition(iterator begin, iterator end);
</pre>
<p>
where <code class="computeroutput">iterator</code> represents the type:
</p>
<pre class="programlisting">buffers_iterator&lt;DynamicBuffer_v2::const_buffers_type&gt;
</pre>
<p>
The iterator parameters <code class="computeroutput">begin</code> and <code class="computeroutput">end</code> define
the range of bytes to be scanned to determine whether there is a
match. The <code class="computeroutput">first</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">begin</code>
parameter for any subsequent invocation of the match condition. The
<code class="computeroutput">second</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>
<h6>
<a name="boost_asio.reference.read_until.overload24.h1"></a>
<span class="phrase"><a name="boost_asio.reference.read_until.overload24.return_value"></a></span><a class="link" href="overload24.html#boost_asio.reference.read_until.overload24.return_value">Return
Value</a>
</h6>
<p>
The number of bytes in the dynamic buffer sequence's get area that have
been fully consumed by the match function. Returns 0 if an error occurred.
</p>
<h6>
<a name="boost_asio.reference.read_until.overload24.h2"></a>
<span class="phrase"><a name="boost_asio.reference.read_until.overload24.remarks"></a></span><a class="link" href="overload24.html#boost_asio.reference.read_until.overload24.remarks">Remarks</a>
</h6>
<p>
After a successful read_until operation, the dynamic buffer sequence may
contain additional data beyond that which matched the function object.
An application will typically leave that data in the dynamic buffer sequence
for a subsequent read_until operation to examine.
</p>
<p>
The default implementation of the <code class="computeroutput">is_match_condition</code> type
trait evaluates to true for function pointers and function objects with
a <code class="computeroutput">result_type</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 © 2003-2021 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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