1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>http::read_header (1 of 2 overloads)</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="../boost__beast__http__read_header.html" title="http::read_header"> 9<link rel="prev" href="../boost__beast__http__read_header.html" title="http::read_header"> 10<link rel="next" href="overload2.html" title="http::read_header (2 of 2 overloads)"> 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="../boost__beast__http__read_header.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost__beast__http__read_header.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="overload2.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h5 class="title"> 27<a name="beast.ref.boost__beast__http__read_header.overload1"></a><a class="link" href="overload1.html" title="http::read_header (1 of 2 overloads)">http::read_header 28 (1 of 2 overloads)</a> 29</h5></div></div></div> 30<p> 31 Read a complete message header from a stream using a parser. 32 </p> 33<h6> 34<a name="beast.ref.boost__beast__http__read_header.overload1.h0"></a> 35 <span class="phrase"><a name="beast.ref.boost__beast__http__read_header.overload1.synopsis"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__http__read_header.overload1.synopsis">Synopsis</a> 36 </h6> 37<p> 38 Defined in header <code class="literal"><<a href="../../../../../../../boost/beast/http/read.hpp" target="_top">boost/beast/http/read.hpp</a>></code> 39 </p> 40<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> 41 <span class="keyword">class</span> <a href="../../../../../../../doc/html/boost_asio/reference/SyncReadStream.html" target="_top"><span class="emphasis"><em>SyncReadStream</em></span></a><span class="special">,</span> 42 <span class="keyword">class</span> <a class="link" href="../../concepts/DynamicBuffer.html" title="DynamicBuffer"><span class="emphasis"><em>DynamicBuffer</em></span></a><span class="special">,</span> 43 <span class="keyword">bool</span> <span class="identifier">isRequest</span><span class="special">></span> 44<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> 45<span class="identifier">read_header</span><span class="special">(</span> 46 <span class="identifier">SyncReadStream</span><span class="special">&</span> <span class="identifier">stream</span><span class="special">,</span> 47 <span class="identifier">DynamicBuffer</span><span class="special">&</span> <span class="identifier">buffer</span><span class="special">,</span> 48 <span class="identifier">basic_parser</span><span class="special"><</span> <span class="identifier">isRequest</span> <span class="special">>&</span> <span class="identifier">parser</span><span class="special">);</span> 49</pre> 50<h6> 51<a name="beast.ref.boost__beast__http__read_header.overload1.h1"></a> 52 <span class="phrase"><a name="beast.ref.boost__beast__http__read_header.overload1.description"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__http__read_header.overload1.description">Description</a> 53 </h6> 54<p> 55 This function is used to read a complete message header from a stream into 56 an instance of <a class="link" href="../boost__beast__http__basic_parser.html" title="http::basic_parser"><code class="computeroutput"><span class="identifier">basic_parser</span></code></a>. The call will block 57 until one of the following conditions is true: 58 </p> 59<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 60<li class="listitem"> 61 <a class="link" href="../boost__beast__http__basic_parser/is_header_done.html" title="http::basic_parser::is_header_done"><code class="computeroutput"><span class="identifier">basic_parser</span><span class="special">::</span><span class="identifier">is_header_done</span></code></a> returns <code class="computeroutput"><span class="keyword">true</span></code> 62 </li> 63<li class="listitem"> 64 An error occurs. 65 </li> 66</ul></div> 67<p> 68 This operation is implemented in terms of one or more calls to the stream's 69 <code class="computeroutput"><span class="identifier">read_some</span></code> function. The 70 implementation may read additional bytes from the stream that lie past 71 the end of the message being read. These additional bytes are stored in 72 the dynamic buffer, which must be preserved for subsequent reads. If the 73 end of file error is received while reading from the stream, then the error 74 returned from this function will be: 75 </p> 76<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 77<li class="listitem"> 78 <a class="link" href="../boost__beast__http__error.html" title="http::error"><code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">end_of_stream</span></code></a> 79 if no bytes were parsed, or 80 </li> 81<li class="listitem"> 82 <a class="link" href="../boost__beast__http__error.html" title="http::error"><code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">partial_message</span></code></a> 83 if any bytes were parsed but the message was incomplete, otherwise: 84 </li> 85<li class="listitem"> 86 A successful result. The next attempt to read will return <a class="link" href="../boost__beast__http__error.html" title="http::error"><code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">end_of_stream</span></code></a> 87 </li> 88</ul></div> 89<h6> 90<a name="beast.ref.boost__beast__http__read_header.overload1.h2"></a> 91 <span class="phrase"><a name="beast.ref.boost__beast__http__read_header.overload1.parameters"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__http__read_header.overload1.parameters">Parameters</a> 92 </h6> 93<div class="informaltable"><table class="table"> 94<colgroup> 95<col> 96<col> 97</colgroup> 98<thead><tr> 99<th> 100 <p> 101 Name 102 </p> 103 </th> 104<th> 105 <p> 106 Description 107 </p> 108 </th> 109</tr></thead> 110<tbody> 111<tr> 112<td> 113 <p> 114 <code class="computeroutput"><span class="identifier">stream</span></code> 115 </p> 116 </td> 117<td> 118 <p> 119 The stream from which the data is to be read. The type must meet 120 the <span class="emphasis"><em>SyncReadStream</em></span> requirements. 121 </p> 122 </td> 123</tr> 124<tr> 125<td> 126 <p> 127 <code class="computeroutput"><span class="identifier">buffer</span></code> 128 </p> 129 </td> 130<td> 131 <p> 132 Storage for additional bytes read by the implementation from 133 the stream. This is both an input and an output parameter; on 134 entry, the parser will be presented with any remaining data in 135 the dynamic buffer's readable bytes sequence first. The type 136 must meet the <span class="emphasis"><em>DynamicBuffer</em></span> requirements. 137 </p> 138 </td> 139</tr> 140<tr> 141<td> 142 <p> 143 <code class="computeroutput"><span class="identifier">parser</span></code> 144 </p> 145 </td> 146<td> 147 <p> 148 The parser to use. 149 </p> 150 </td> 151</tr> 152</tbody> 153</table></div> 154<h6> 155<a name="beast.ref.boost__beast__http__read_header.overload1.h3"></a> 156 <span class="phrase"><a name="beast.ref.boost__beast__http__read_header.overload1.return_value"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__http__read_header.overload1.return_value">Return 157 Value</a> 158 </h6> 159<p> 160 The number of bytes transferred from the stream. 161 </p> 162<h6> 163<a name="beast.ref.boost__beast__http__read_header.overload1.h4"></a> 164 <span class="phrase"><a name="beast.ref.boost__beast__http__read_header.overload1.exceptions"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__http__read_header.overload1.exceptions">Exceptions</a> 165 </h6> 166<div class="informaltable"><table class="table"> 167<colgroup> 168<col> 169<col> 170</colgroup> 171<thead><tr> 172<th> 173 <p> 174 Type 175 </p> 176 </th> 177<th> 178 <p> 179 Thrown On 180 </p> 181 </th> 182</tr></thead> 183<tbody><tr> 184<td> 185 <p> 186 <code class="computeroutput"><span class="identifier">system_error</span></code> 187 </p> 188 </td> 189<td> 190 <p> 191 Thrown on failure. 192 </p> 193 </td> 194</tr></tbody> 195</table></div> 196<h6> 197<a name="beast.ref.boost__beast__http__read_header.overload1.h5"></a> 198 <span class="phrase"><a name="beast.ref.boost__beast__http__read_header.overload1.remarks"></a></span><a class="link" href="overload1.html#beast.ref.boost__beast__http__read_header.overload1.remarks">Remarks</a> 199 </h6> 200<p> 201 The function returns the total number of bytes transferred from the stream. 202 This may be zero for the case where there is sufficient pre-existing message 203 data in the dynamic buffer. The implementation will call <a class="link" href="../boost__beast__http__basic_parser/eager/overload1.html" title="http::basic_parser::eager (1 of 2 overloads)"><code class="computeroutput"><span class="identifier">basic_parser</span><span class="special">::</span><span class="identifier">eager</span></code></a> with the value <code class="computeroutput"><span class="keyword">false</span></code> on the parser passed in. 204 </p> 205</div> 206<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 207<td align="left"></td> 208<td align="right"><div class="copyright-footer">Copyright © 2016-2019 Vinnie 209 Falco<p> 210 Distributed under the Boost Software License, Version 1.0. (See accompanying 211 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>) 212 </p> 213</div></td> 214</tr></table> 215<hr> 216<div class="spirit-nav"> 217<a accesskey="p" href="../boost__beast__http__read_header.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost__beast__http__read_header.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="overload2.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 218</div> 219</body> 220</html> 221
