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| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="boost_asio.reference.read_until.overload7"></a><a class="link" href="overload7.html" title="read_until (7 of 8 overloads)">read_until |
| (7 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="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.overload7.parameters"></a><h6> |
| <a name="id1300108"></a> |
| <a class="link" href="overload7.html#boost_asio.reference.read_until.overload7.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> |
| </dl> |
| </div> |
| <a name="boost_asio.reference.read_until.overload7.return_value"></a><h6> |
| <a name="id1300371"></a> |
| <a class="link" href="overload7.html#boost_asio.reference.read_until.overload7.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. |
| </p> |
| <a name="boost_asio.reference.read_until.overload7.exceptions"></a><h6> |
| <a name="id1300400"></a> |
| <a class="link" href="overload7.html#boost_asio.reference.read_until.overload7.exceptions">Exceptions</a> |
| </h6> |
| <div class="variablelist"> |
| <p class="title"><b></b></p> |
| <dl> |
| <dt><span class="term">boost::system::system_error</span></dt> |
| <dd><p> |
| Thrown on failure. |
| </p></dd> |
| </dl> |
| </div> |
| <a name="boost_asio.reference.read_until.overload7.remarks"></a><h6> |
| <a name="id1300442"></a> |
| <a class="link" href="overload7.html#boost_asio.reference.read_until.overload7.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> |
| <a name="boost_asio.reference.read_until.overload7.examples"></a><h6> |
| <a name="id1300499"></a> |
| <a class="link" href="overload7.html#boost_asio.reference.read_until.overload7.examples">Examples</a> |
| </h6> |
| <p> |
| To read data into a streambuf until whitespace is encountered: |
| </p> |
| <pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffers_iterator</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">streambuf</span><span class="special">::</span><span class="identifier">const_buffers_type</span><span class="special">></span> <span class="identifier">iterator</span><span class="special">;</span> |
| |
| <span class="identifier">std</span><span class="special">::</span><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_whitespace</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> |
| <span class="special">{</span> |
| <span class="identifier">iterator</span> <span class="identifier">i</span> <span class="special">=</span> <span class="identifier">begin</span><span class="special">;</span> |
| <span class="keyword">while</span> <span class="special">(</span><span class="identifier">i</span> <span class="special">!=</span> <span class="identifier">end</span><span class="special">)</span> |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">isspace</span><span class="special">(*</span><span class="identifier">i</span><span class="special">++))</span> |
| <span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span class="special">,</span> <span class="keyword">true</span><span class="special">);</span> |
| <span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span class="special">,</span> <span class="keyword">false</span><span class="special">);</span> |
| <span class="special">}</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">streambuf</span> <span class="identifier">b</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">read_until</span><span class="special">(</span><span class="identifier">s</span><span class="special">,</span> <span class="identifier">b</span><span class="special">,</span> <span class="identifier">match_whitespace</span><span class="special">);</span> |
| </pre> |
| <p> |
| To read data into a streambuf until a matching character is found: |
| </p> |
| <pre class="programlisting"><span class="keyword">class</span> <span class="identifier">match_char</span> |
| <span class="special">{</span> |
| <span class="keyword">public</span><span class="special">:</span> |
| <span class="keyword">explicit</span> <span class="identifier">match_char</span><span class="special">(</span><span class="keyword">char</span> <span class="identifier">c</span><span class="special">)</span> <span class="special">:</span> <span class="identifier">c_</span><span class="special">(</span><span class="identifier">c</span><span class="special">)</span> <span class="special">{}</span> |
| |
| <span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">></span> |
| <span class="identifier">std</span><span class="special">::</span><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="keyword">operator</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> <span class="keyword">const</span> |
| <span class="special">{</span> |
| <span class="identifier">Iterator</span> <span class="identifier">i</span> <span class="special">=</span> <span class="identifier">begin</span><span class="special">;</span> |
| <span class="keyword">while</span> <span class="special">(</span><span class="identifier">i</span> <span class="special">!=</span> <span class="identifier">end</span><span class="special">)</span> |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">c_</span> <span class="special">==</span> <span class="special">*</span><span class="identifier">i</span><span class="special">++)</span> |
| <span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span class="special">,</span> <span class="keyword">true</span><span class="special">);</span> |
| <span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span class="special">,</span> <span class="keyword">false</span><span class="special">);</span> |
| <span class="special">}</span> |
| |
| <span class="keyword">private</span><span class="special">:</span> |
| <span class="keyword">char</span> <span class="identifier">c_</span><span class="special">;</span> |
| <span class="special">};</span> |
| |
| <span class="keyword">namespace</span> <span class="identifier">asio</span> <span class="special">{</span> |
| <span class="keyword">template</span> <span class="special"><></span> <span class="keyword">struct</span> <span class="identifier">is_match_condition</span><span class="special"><</span><span class="identifier">match_char</span><span class="special">></span> |
| <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">true_type</span> <span class="special">{};</span> |
| <span class="special">}</span> <span class="comment">// namespace asio |
| </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">streambuf</span> <span class="identifier">b</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">read_until</span><span class="special">(</span><span class="identifier">s</span><span class="special">,</span> <span class="identifier">b</span><span class="special">,</span> <span class="identifier">match_char</span><span class="special">(</span><span class="char">'a'</span><span class="special">));</span> |
| </pre> |
| </div> |
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| <td align="left"></td> |
| <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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