1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Incremental Read ��</title> 5<link rel="stylesheet" href="../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../index.html" title="Chapter 1. Boost.Beast"> 8<link rel="up" href="../parser_stream_operations.html" title="Parser Stream Operations"> 9<link rel="prev" href="../parser_stream_operations.html" title="Parser Stream Operations"> 10<link rel="next" href="../buffer_oriented_serializing.html" title="Buffer-Oriented Serializing"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="../parser_stream_operations.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../parser_stream_operations.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../buffer_oriented_serializing.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="beast.using_http.parser_stream_operations.incremental_read"></a><a class="link" href="incremental_read.html" title="Incremental Read ��">Incremental 28 Read ��</a> 29</h4></div></div></div> 30<p> 31 This function uses <a class="link" href="../../ref/boost__beast__http__buffer_body.html" title="http::buffer_body"><code class="computeroutput"><span class="identifier">buffer_body</span></code></a> and parser stream 32 operations to read a message body progressively using a small, fixed-size 33 buffer: 34 </p> 35<pre class="programlisting"><span class="comment">/* This function reads a message using a fixed size buffer to hold 36 portions of the body, and prints the body contents to a `std::ostream`. 37*/</span> 38<span class="keyword">template</span><span class="special"><</span> 39 <span class="keyword">bool</span> <span class="identifier">isRequest</span><span class="special">,</span> 40 <span class="keyword">class</span> <span class="identifier">SyncReadStream</span><span class="special">,</span> 41 <span class="keyword">class</span> <span class="identifier">DynamicBuffer</span><span class="special">></span> 42<span class="keyword">void</span> 43<span class="identifier">read_and_print_body</span><span class="special">(</span> 44 <span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span><span class="special">&</span> <span class="identifier">os</span><span class="special">,</span> 45 <span class="identifier">SyncReadStream</span><span class="special">&</span> <span class="identifier">stream</span><span class="special">,</span> 46 <span class="identifier">DynamicBuffer</span><span class="special">&</span> <span class="identifier">buffer</span><span class="special">,</span> 47 <span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">ec</span><span class="special">)</span> 48<span class="special">{</span> 49 <span class="identifier">parser</span><span class="special"><</span><span class="identifier">isRequest</span><span class="special">,</span> <span class="identifier">buffer_body</span><span class="special">></span> <span class="identifier">p</span><span class="special">;</span> 50 <span class="identifier">read_header</span><span class="special">(</span><span class="identifier">stream</span><span class="special">,</span> <span class="identifier">buffer</span><span class="special">,</span> <span class="identifier">p</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span> 51 <span class="keyword">if</span><span class="special">(</span><span class="identifier">ec</span><span class="special">)</span> 52 <span class="keyword">return</span><span class="special">;</span> 53 <span class="keyword">while</span><span class="special">(!</span> <span class="identifier">p</span><span class="special">.</span><span class="identifier">is_done</span><span class="special">())</span> 54 <span class="special">{</span> 55 <span class="keyword">char</span> <span class="identifier">buf</span><span class="special">[</span><span class="number">512</span><span class="special">];</span> 56 <span class="identifier">p</span><span class="special">.</span><span class="identifier">get</span><span class="special">().</span><span class="identifier">body</span><span class="special">().</span><span class="identifier">data</span> <span class="special">=</span> <span class="identifier">buf</span><span class="special">;</span> 57 <span class="identifier">p</span><span class="special">.</span><span class="identifier">get</span><span class="special">().</span><span class="identifier">body</span><span class="special">().</span><span class="identifier">size</span> <span class="special">=</span> <span class="keyword">sizeof</span><span class="special">(</span><span class="identifier">buf</span><span class="special">);</span> 58 <span class="identifier">read</span><span class="special">(</span><span class="identifier">stream</span><span class="special">,</span> <span class="identifier">buffer</span><span class="special">,</span> <span class="identifier">p</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span> 59 <span class="keyword">if</span><span class="special">(</span><span class="identifier">ec</span> <span class="special">==</span> <span class="identifier">error</span><span class="special">::</span><span class="identifier">need_buffer</span><span class="special">)</span> 60 <span class="identifier">ec</span> <span class="special">=</span> <span class="special">{};</span> 61 <span class="keyword">if</span><span class="special">(</span><span class="identifier">ec</span><span class="special">)</span> 62 <span class="keyword">return</span><span class="special">;</span> 63 <span class="identifier">os</span><span class="special">.</span><span class="identifier">write</span><span class="special">(</span><span class="identifier">buf</span><span class="special">,</span> <span class="keyword">sizeof</span><span class="special">(</span><span class="identifier">buf</span><span class="special">)</span> <span class="special">-</span> <span class="identifier">p</span><span class="special">.</span><span class="identifier">get</span><span class="special">().</span><span class="identifier">body</span><span class="special">().</span><span class="identifier">size</span><span class="special">);</span> 64 <span class="special">}</span> 65<span class="special">}</span> 66</pre> 67</div> 68<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 69<td align="left"></td> 70<td align="right"><div class="copyright-footer">Copyright © 2016-2019 Vinnie 71 Falco<p> 72 Distributed under the Boost Software License, Version 1.0. (See accompanying 73 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>) 74 </p> 75</div></td> 76</tr></table> 77<hr> 78<div class="spirit-nav"> 79<a accesskey="p" href="../parser_stream_operations.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../parser_stream_operations.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../buffer_oriented_serializing.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 80</div> 81</body> 82</html> 83
