<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>read_until (5 of 8 overloads)</title> <link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.2"> <link rel="home" href="../../../boost_asio.html" title="Boost.Asio"> <link rel="up" href="../read_until.html" title="read_until"> <link rel="prev" href="overload4.html" title="read_until (4 of 8 overloads)"> <link rel="next" href="overload6.html" title="read_until (6 of 8 overloads)"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td> <td align="center"><a href="../../../../../index.html">Home</a></td> <td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="overload4.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../read_until.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="overload6.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="section"> <div class="titlepage"><div><div><h4 class="title"> <a name="boost_asio.reference.read_until.overload5"></a><a class="link" href="overload5.html" title="read_until (5 of 8 overloads)"> read_until (5 of 8 overloads)</a> </h4></div></div></div> <p> Read data into a streambuf until some part of the data it contains matches a regular expression. </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="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="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">regex</span> <span class="special">&</span> <span class="identifier">expr</span><span class="special">);</span> </pre> <p> This function is used to read data into the specified streambuf until the streambuf's get area contains some data that matches a regular expression. The call will block until one of the following conditions is true: </p> <div class="itemizedlist"><ul class="itemizedlist" type="disc"> <li class="listitem"> A substring of the streambuf's get area matches the regular expression. </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 streambuf's get area already contains data that matches the regular expression, the function returns immediately. </p> <a name="boost_asio.reference.read_until.overload5.parameters"></a><h6> <a name="id1298917"></a> <a class="link" href="overload5.html#boost_asio.reference.read_until.overload5.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">expr</span></dt> <dd><p> The regular expression. </p></dd> </dl> </div> <a name="boost_asio.reference.read_until.overload5.return_value"></a><h6> <a name="id1298989"></a> <a class="link" href="overload5.html#boost_asio.reference.read_until.overload5.return_value">Return Value</a> </h6> <p> The number of bytes in the streambuf's get area up to and including the substring that matches the regular expression. </p> <a name="boost_asio.reference.read_until.overload5.exceptions"></a><h6> <a name="id1299017"></a> <a class="link" href="overload5.html#boost_asio.reference.read_until.overload5.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.overload5.remarks"></a><h6> <a name="id1299057"></a> <a class="link" href="overload5.html#boost_asio.reference.read_until.overload5.remarks">Remarks</a> </h6> <p> After a successful read_until operation, the streambuf may contain additional data beyond that which matched the regular expression. An application will typically leave that data in the streambuf for a subsequent read_until operation to examine. </p> <a name="boost_asio.reference.read_until.overload5.example"></a><h6> <a name="id1299088"></a> <a class="link" href="overload5.html#boost_asio.reference.read_until.overload5.example">Example</a> </h6> <p> To read data into a streambuf until a CR-LF sequence is encountered: </p> <pre class="programlisting"><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">boost</span><span class="special">::</span><span class="identifier">regex</span><span class="special">(</span><span class="string">"\r\n"</span><span class="special">));</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">istream</span> <span class="identifier">is</span><span class="special">(&</span><span class="identifier">b</span><span class="special">);</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">line</span><span class="special">;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">getline</span><span class="special">(</span><span class="identifier">is</span><span class="special">,</span> <span class="identifier">line</span><span class="special">);</span> </pre> <p> After the <code class="computeroutput"><span class="identifier">read_until</span></code> operation completes successfully, the buffer <code class="computeroutput"><span class="identifier">b</span></code> contains the data which matched the regular expression: </p> <pre class="programlisting"><span class="special">{</span> <span class="char">'a'</span><span class="special">,</span> <span class="char">'b'</span><span class="special">,</span> <span class="special">...,</span> <span class="char">'c'</span><span class="special">,</span> <span class="char">'\r'</span><span class="special">,</span> <span class="char">'\n'</span><span class="special">,</span> <span class="char">'d'</span><span class="special">,</span> <span class="char">'e'</span><span class="special">,</span> <span class="special">...</span> <span class="special">}</span> </pre> <p> The call to <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">getline</span></code> then extracts the data up to and including the match, so that the string <code class="computeroutput"><span class="identifier">line</span></code> contains: </p> <pre class="programlisting"><span class="special">{</span> <span class="char">'a'</span><span class="special">,</span> <span class="char">'b'</span><span class="special">,</span> <span class="special">...,</span> <span class="char">'c'</span><span class="special">,</span> <span class="char">'\r'</span><span class="special">,</span> <span class="char">'\n'</span> <span class="special">}</span> </pre> <p> The remaining data is left in the buffer <code class="computeroutput"><span class="identifier">b</span></code> as follows: </p> <pre class="programlisting"><span class="special">{</span> <span class="char">'d'</span><span class="special">,</span> <span class="char">'e'</span><span class="special">,</span> <span class="special">...</span> <span class="special">}</span> </pre> <p> This data may be the start of a new line, to be extracted by a subsequent <code class="computeroutput"><span class="identifier">read_until</span></code> operation. </p> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <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>) </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="overload4.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../read_until.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="overload6.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>