1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>DynamicBuffer</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="../concepts.html" title="Concepts"> 9<link rel="prev" href="BufferSequence.html" title="BufferSequence"> 10<link rel="next" href="Fields.html" title="Fields"> 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="BufferSequence.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../concepts.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="Fields.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h3 class="title"> 27<a name="beast.concepts.DynamicBuffer"></a><a class="link" href="DynamicBuffer.html" title="DynamicBuffer">DynamicBuffer</a> 28</h3></div></div></div> 29<p> 30 A dynamic buffer encapsulates memory storage that may be automatically resized 31 as required, where the memory is divided into an input sequence followed 32 by an output sequence. These memory regions are internal to the dynamic buffer, 33 but direct access to the elements is provided to permit them to be efficiently 34 used with I/O operations, such as the send or receive operations of a socket. 35 Data written to the output sequence of a dynamic buffer object is appended 36 to the input sequence of the same object. 37 </p> 38<p> 39 The interface to this concept is intended to permit the following implementation 40 strategies: 41 </p> 42<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 43<li class="listitem"> 44 A single contiguous octet array, which is reallocated as necessary to 45 accommodate changes in the size of the octet sequence. This is the implementation 46 approach currently offered by <a class="link" href="../ref/boost__beast__flat_buffer.html" title="flat_buffer"><code class="computeroutput"><span class="identifier">flat_buffer</span></code></a>. 47 </li> 48<li class="listitem"> 49 A sequence of one or more octet arrays, where each array is of the same 50 size. Additional octet array objects are appended to the sequence to 51 accommodate changes in the size of the octet sequence. 52 </li> 53<li class="listitem"> 54 A sequence of one or more octet arrays of varying sizes. Additional octet 55 array objects are appended to the sequence to accommodate changes in 56 the size of the character sequence. This is the implementation approach 57 currently offered by <a class="link" href="../ref/boost__beast__multi_buffer.html" title="multi_buffer"><code class="computeroutput"><span class="identifier">multi_buffer</span></code></a>. 58 </li> 59</ul></div> 60<h5> 61<a name="beast.concepts.DynamicBuffer.h0"></a> 62 <span class="phrase"><a name="beast.concepts.DynamicBuffer.associated_with"></a></span><a class="link" href="DynamicBuffer.html#beast.concepts.DynamicBuffer.associated_with">Associated 63 With</a> 64 </h5> 65<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 66<li class="listitem"> 67 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">is_dynamic_buffer</span></code> 68 </li> 69<li class="listitem"> 70 <a href="../../../../../../doc/html/boost_asio/reference/ConstBufferSequence.html" target="_top"><span class="emphasis"><em>ConstBufferSequence</em></span></a> 71 </li> 72<li class="listitem"> 73 <a href="../../../../../../doc/html/boost_asio/reference/MutableBufferSequence.html" target="_top"><span class="emphasis"><em>MutableBufferSequence</em></span></a> 74 </li> 75</ul></div> 76<h5> 77<a name="beast.concepts.DynamicBuffer.h1"></a> 78 <span class="phrase"><a name="beast.concepts.DynamicBuffer.requirements"></a></span><a class="link" href="DynamicBuffer.html#beast.concepts.DynamicBuffer.requirements">Requirements</a> 79 </h5> 80<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 81<li class="listitem"> 82 <code class="computeroutput"><span class="identifier">D</span></code> denotes a dynamic buffer 83 class. 84 </li> 85<li class="listitem"> 86 <code class="computeroutput"><span class="identifier">a</span></code> denotes a value of 87 type <code class="computeroutput"><span class="identifier">D</span></code>. 88 </li> 89<li class="listitem"> 90 <code class="computeroutput"><span class="identifier">c</span></code> denotes a (possibly 91 const) value of type <code class="computeroutput"><span class="identifier">D</span></code>. 92 </li> 93<li class="listitem"> 94 <code class="computeroutput"><span class="identifier">n</span></code> denotes a value of 95 type <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span></code>. 96 </li> 97<li class="listitem"> 98 <code class="computeroutput"><span class="identifier">T</span></code> denotes a type meeting 99 the requirements for <a href="../../../../../../doc/html/boost_asio/reference/ConstBufferSequence.html" target="_top"><span class="emphasis"><em>ConstBufferSequence</em></span></a>. 100 </li> 101<li class="listitem"> 102 <code class="computeroutput"><span class="identifier">U</span></code> denotes a type meeting 103 the requirements for <a href="../../../../../../doc/html/boost_asio/reference/MutableBufferSequence.html" target="_top"><span class="emphasis"><em>MutableBufferSequence</em></span></a>. 104 </li> 105</ul></div> 106<div class="table"> 107<a name="beast.concepts.DynamicBuffer.valid_expressions"></a><p class="title"><b>Table 1.40. Valid expressions</b></p> 108<div class="table-contents"><table class="table" summary="Valid expressions"> 109<colgroup> 110<col> 111<col> 112<col> 113</colgroup> 114<thead><tr> 115<th> 116 <p> 117 Expression 118 </p> 119 </th> 120<th> 121 <p> 122 Type 123 </p> 124 </th> 125<th> 126 <p> 127 Semantics, Pre/Post-conditions 128 </p> 129 </th> 130</tr></thead> 131<tbody> 132<tr> 133<td> 134 <p> 135 <code class="computeroutput"><span class="identifier">D</span><span class="special">::</span><span class="identifier">const_buffers_type</span></code> 136 </p> 137 </td> 138<td> 139 <p> 140 <code class="computeroutput"><span class="identifier">T</span></code> 141 </p> 142 </td> 143<td> 144 <p> 145 This type represents the memory associated with the input sequence. 146 </p> 147 </td> 148</tr> 149<tr> 150<td> 151 <p> 152 <code class="computeroutput"><span class="identifier">D</span><span class="special">::</span><span class="identifier">mutable_buffers_type</span></code> 153 </p> 154 </td> 155<td> 156 <p> 157 <code class="computeroutput"><span class="identifier">U</span></code> 158 </p> 159 </td> 160<td> 161 <p> 162 This type represents the memory associated with the output sequence. 163 </p> 164 </td> 165</tr> 166<tr> 167<td> 168 <p> 169 <code class="computeroutput"><span class="identifier">c</span><span class="special">.</span><span class="identifier">size</span><span class="special">()</span></code> 170 </p> 171 </td> 172<td> 173 <p> 174 <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span></code> 175 </p> 176 </td> 177<td> 178 <p> 179 Returns the size, in bytes, of the input sequence. 180 </p> 181 </td> 182</tr> 183<tr> 184<td> 185 <p> 186 <code class="computeroutput"><span class="identifier">c</span><span class="special">.</span><span class="identifier">max_size</span><span class="special">()</span></code> 187 </p> 188 </td> 189<td> 190 <p> 191 <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span></code> 192 </p> 193 </td> 194<td> 195 <p> 196 Returns the permitted maximum of the sum of the sizes of the input 197 sequence and output sequence. 198 </p> 199 </td> 200</tr> 201<tr> 202<td> 203 <p> 204 <code class="computeroutput"><span class="identifier">c</span><span class="special">.</span><span class="identifier">capacity</span><span class="special">()</span></code> 205 </p> 206 </td> 207<td> 208 <p> 209 <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span></code> 210 </p> 211 </td> 212<td> 213 <p> 214 Returns the maximum sum of the sizes of the input sequence and 215 output sequence that the dynamic buffer can hold without requiring 216 reallocation. 217 </p> 218 </td> 219</tr> 220<tr> 221<td> 222 <p> 223 <code class="computeroutput"><span class="identifier">c</span><span class="special">.</span><span class="identifier">data</span><span class="special">()</span></code> 224 </p> 225 </td> 226<td> 227 <p> 228 <code class="computeroutput"><span class="identifier">D</span><span class="special">::</span><span class="identifier">const_buffers_type</span></code> 229 </p> 230 </td> 231<td> 232 <p> 233 Returns a constant buffer sequence u that represents the memory 234 associated with the input sequence, and where <code class="computeroutput"><span class="identifier">buffer_size</span><span class="special">(</span><span class="identifier">u</span><span class="special">)</span> <span class="special">==</span> <span class="identifier">size</span><span class="special">()</span></code>. 235 </p> 236 </td> 237</tr> 238<tr> 239<td> 240 <p> 241 <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">prepare</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span></code> 242 </p> 243 </td> 244<td> 245 <p> 246 <code class="computeroutput"><span class="identifier">D</span><span class="special">::</span><span class="identifier">mutable_buffers_type</span></code> 247 </p> 248 </td> 249<td> 250 <p> 251 Returns a mutable buffer sequence u representing the output sequence, 252 and where <code class="computeroutput"><span class="identifier">buffer_size</span><span class="special">(</span><span class="identifier">u</span><span class="special">)</span> <span class="special">==</span> <span class="identifier">n</span></code>. The dynamic buffer reallocates 253 memory as required. All constant or mutable buffer sequences previously 254 obtained using <code class="computeroutput"><span class="identifier">data</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">prepare</span><span class="special">()</span></code> are invalidated. 255 </p> 256 <p> 257 Throws: <code class="computeroutput"><span class="identifier">length_error</span></code> 258 if <code class="computeroutput"><span class="identifier">size</span><span class="special">()</span> 259 <span class="special">+</span> <span class="identifier">n</span></code> 260 exceeds <code class="computeroutput"><span class="identifier">max_size</span><span class="special">()</span></code>. 261 </p> 262 </td> 263</tr> 264<tr> 265<td> 266 <p> 267 <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">commit</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span></code> 268 </p> 269 </td> 270<td> 271 </td> 272<td> 273 <p> 274 Appends <code class="computeroutput"><span class="identifier">n</span></code> bytes 275 from the start of the output sequence to the end of the input sequence. 276 The remainder of the output sequence is discarded. If <code class="computeroutput"><span class="identifier">n</span></code> is greater than the size of 277 the output sequence, the entire output sequence is appended to 278 the input sequence. All constant or mutable buffer sequences previously 279 obtained using <code class="computeroutput"><span class="identifier">data</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">prepare</span><span class="special">()</span></code> are invalidated. 280 </p> 281 </td> 282</tr> 283<tr> 284<td> 285 <p> 286 <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">consume</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span></code> 287 </p> 288 </td> 289<td> 290 </td> 291<td> 292 <p> 293 Removes <code class="computeroutput"><span class="identifier">n</span></code> bytes 294 from beginning of the input sequence. If <code class="computeroutput"><span class="identifier">n</span></code> 295 is greater than the size of the input sequence, the entire input 296 sequence is removed. All constant or mutable buffer sequences previously 297 obtained using <code class="computeroutput"><span class="identifier">data</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">prepare</span><span class="special">()</span></code> are invalidated. 298 </p> 299 </td> 300</tr> 301</tbody> 302</table></div> 303</div> 304<br class="table-break"><h5> 305<a name="beast.concepts.DynamicBuffer.h2"></a> 306 <span class="phrase"><a name="beast.concepts.DynamicBuffer.models"></a></span><a class="link" href="DynamicBuffer.html#beast.concepts.DynamicBuffer.models">Models</a> 307 </h5> 308<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 309<li class="listitem"> 310 <a class="link" href="../ref/boost__beast__basic_flat_buffer.html" title="basic_flat_buffer"><code class="computeroutput"><span class="identifier">basic_flat_buffer</span></code></a> 311 </li> 312<li class="listitem"> 313 <a class="link" href="../ref/boost__beast__basic_multi_buffer.html" title="basic_multi_buffer"><code class="computeroutput"><span class="identifier">basic_multi_buffer</span></code></a> 314 </li> 315<li class="listitem"> 316 <a class="link" href="../ref/boost__beast__flat_buffer.html" title="flat_buffer"><code class="computeroutput"><span class="identifier">flat_buffer</span></code></a> 317 </li> 318<li class="listitem"> 319 <a class="link" href="../ref/boost__beast__flat_static_buffer.html" title="flat_static_buffer"><code class="computeroutput"><span class="identifier">flat_static_buffer</span></code></a> 320 </li> 321<li class="listitem"> 322 <a class="link" href="../ref/boost__beast__flat_static_buffer_base.html" title="flat_static_buffer_base"><code class="computeroutput"><span class="identifier">flat_static_buffer_base</span></code></a> 323 </li> 324<li class="listitem"> 325 <a class="link" href="../ref/boost__beast__static_buffer.html" title="static_buffer"><code class="computeroutput"><span class="identifier">static_buffer</span></code></a> 326 </li> 327<li class="listitem"> 328 <a class="link" href="../ref/boost__beast__static_buffer_base.html" title="static_buffer_base"><code class="computeroutput"><span class="identifier">static_buffer_base</span></code></a> 329 </li> 330<li class="listitem"> 331 <a class="link" href="../ref/boost__beast__multi_buffer.html" title="multi_buffer"><code class="computeroutput"><span class="identifier">multi_buffer</span></code></a> 332 </li> 333</ul></div> 334</div> 335<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 336<td align="left"></td> 337<td align="right"><div class="copyright-footer">Copyright © 2016-2019 Vinnie 338 Falco<p> 339 Distributed under the Boost Software License, Version 1.0. (See accompanying 340 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>) 341 </p> 342</div></td> 343</tr></table> 344<hr> 345<div class="spirit-nav"> 346<a accesskey="p" href="BufferSequence.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../concepts.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="Fields.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 347</div> 348</body> 349</html> 350
