1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Associative Sequence</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. Fusion 2.2"> 8<link rel="up" href="../concepts.html" title="Concepts"> 9<link rel="prev" href="random_access_sequence.html" title="Random Access Sequence"> 10<link rel="next" href="unbounded_sequence.html" title="Unbounded Sequence"> 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="random_access_sequence.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="unbounded_sequence.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="fusion.sequence.concepts.associative_sequence"></a><a class="link" href="associative_sequence.html" title="Associative Sequence">Associative 28 Sequence</a> 29</h4></div></div></div> 30<h6> 31<a name="fusion.sequence.concepts.associative_sequence.h0"></a> 32 <span class="phrase"><a name="fusion.sequence.concepts.associative_sequence.description"></a></span><a class="link" href="associative_sequence.html#fusion.sequence.concepts.associative_sequence.description">Description</a> 33 </h6> 34<p> 35 An Associative Sequence allows efficient retrieval of elements based on 36 keys. Like associative sequences in <a href="http://www.boost.org/libs/mpl" target="_top">MPL</a>, 37 and unlike associative containers in <a href="http://en.wikipedia.org/wiki/Standard_Template_Library" target="_top">STL</a>, 38 Fusion associative sequences have no implied ordering relation. Instead, 39 type identity is used to impose an equivalence relation on keys. Keys are 40 not checked for uniqueness. 41 </p> 42<div class="variablelist"> 43<p class="title"><b>Notation</b></p> 44<dl class="variablelist"> 45<dt><span class="term"><code class="computeroutput"><span class="identifier">s</span></code></span></dt> 46<dd><p> 47 An Associative Sequence 48 </p></dd> 49<dt><span class="term"><code class="computeroutput"><span class="identifier">S</span></code></span></dt> 50<dd><p> 51 An Associative Sequence type 52 </p></dd> 53<dt><span class="term"><code class="computeroutput"><span class="identifier">K</span></code></span></dt> 54<dd><p> 55 An arbitrary <span class="emphasis"><em>key</em></span> type 56 </p></dd> 57<dt><span class="term"><code class="computeroutput"><span class="identifier">o</span></code></span></dt> 58<dd><p> 59 An arbitrary object 60 </p></dd> 61<dt><span class="term"><code class="computeroutput"><span class="identifier">e</span></code></span></dt> 62<dd><p> 63 A Sequence element 64 </p></dd> 65</dl> 66</div> 67<h6> 68<a name="fusion.sequence.concepts.associative_sequence.h1"></a> 69 <span class="phrase"><a name="fusion.sequence.concepts.associative_sequence.valid_expressions"></a></span><a class="link" href="associative_sequence.html#fusion.sequence.concepts.associative_sequence.valid_expressions">Valid 70 Expressions</a> 71 </h6> 72<p> 73 For any Associative Sequence the following expressions must be valid: 74 </p> 75<div class="informaltable"><table class="table"> 76<colgroup> 77<col> 78<col> 79<col> 80<col> 81</colgroup> 82<thead><tr> 83<th> 84 <p> 85 Expression 86 </p> 87 </th> 88<th> 89 <p> 90 Return type 91 </p> 92 </th> 93<th> 94 <p> 95 Type Requirements 96 </p> 97 </th> 98<th> 99 <p> 100 Runtime Complexity 101 </p> 102 </th> 103</tr></thead> 104<tbody> 105<tr> 106<td> 107 <p> 108 <code class="computeroutput"><a class="link" href="../intrinsic/functions/has_key.html" title="has_key"><code class="computeroutput"><span class="identifier">has_key</span></code></a><span class="special"><</span><span class="identifier">K</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span></code> 109 </p> 110 </td> 111<td> 112 <p> 113 <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL 114 Boolean Constant</a>. Convertible to bool. 115 </p> 116 </td> 117<td> 118 </td> 119<td> 120 <p> 121 Constant 122 </p> 123 </td> 124</tr> 125<tr> 126<td> 127 <p> 128 <code class="computeroutput"><a class="link" href="../intrinsic/functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">K</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span></code> 129 </p> 130 </td> 131<td> 132 <p> 133 Any type 134 </p> 135 </td> 136<td> 137 </td> 138<td> 139 <p> 140 Constant 141 </p> 142 </td> 143</tr> 144<tr> 145<td> 146 <p> 147 <code class="computeroutput"><a class="link" href="../intrinsic/functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">K</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span> 148 <span class="special">=</span> <span class="identifier">o</span></code> 149 </p> 150 </td> 151<td> 152 <p> 153 Any type 154 </p> 155 </td> 156<td> 157 <p> 158 <code class="computeroutput"><span class="identifier">s</span></code> is mutable 159 and <code class="computeroutput"><span class="identifier">e</span> <span class="special">=</span> 160 <span class="identifier">o</span></code>, where <code class="computeroutput"><span class="identifier">e</span></code> is the first element in the 161 sequence, is a valid expression. 162 </p> 163 </td> 164<td> 165 <p> 166 Constant 167 </p> 168 </td> 169</tr> 170</tbody> 171</table></div> 172<h6> 173<a name="fusion.sequence.concepts.associative_sequence.h2"></a> 174 <span class="phrase"><a name="fusion.sequence.concepts.associative_sequence.result_type_expressions"></a></span><a class="link" href="associative_sequence.html#fusion.sequence.concepts.associative_sequence.result_type_expressions">Result 175 Type Expressions</a> 176 </h6> 177<div class="informaltable"><table class="table"> 178<colgroup> 179<col> 180<col> 181</colgroup> 182<thead><tr> 183<th> 184 <p> 185 Expression 186 </p> 187 </th> 188<th> 189 <p> 190 Compile Time Complexity 191 </p> 192 </th> 193</tr></thead> 194<tbody> 195<tr> 196<td> 197 <p> 198 <code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/has_key.html" title="has_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">has_key</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> 199 <span class="identifier">K</span><span class="special">>::</span><span class="identifier">type</span></code> 200 </p> 201 </td> 202<td> 203 <p> 204 Amortized constant time 205 </p> 206 </td> 207</tr> 208<tr> 209<td> 210 <p> 211 <code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> 212 <span class="identifier">K</span><span class="special">>::</span><span class="identifier">type</span></code> 213 </p> 214 </td> 215<td> 216 <p> 217 Amortized constant time 218 </p> 219 </td> 220</tr> 221<tr> 222<td> 223 <p> 224 <code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/value_at_key.html" title="value_at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_at_key</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> <span class="identifier">K</span><span class="special">>::</span><span class="identifier">type</span></code> 225 </p> 226 </td> 227<td> 228 <p> 229 Amortized constant time 230 </p> 231 </td> 232</tr> 233</tbody> 234</table></div> 235<div class="note"><table border="0" summary="Note"> 236<tr> 237<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../../doc/src/images/note.png"></td> 238<th align="left">Note</th> 239</tr> 240<tr><td align="left" valign="top"><p> 241 <code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> <span class="identifier">K</span><span class="special">></span></code> 242 returns the actual type returned by <code class="computeroutput"><a class="link" href="../intrinsic/functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">K</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span></code>. 243 In most cases, this is a reference. Hence, there is no way to know the 244 exact element type using <code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> <span class="identifier">K</span><span class="special">></span></code>.The 245 element at <code class="computeroutput"><span class="identifier">K</span></code> may actually 246 be a reference to begin with. For this purpose, you can use <code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/value_at_key.html" title="value_at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_at_key</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> <span class="identifier">K</span><span class="special">></span></code>. 247 </p></td></tr> 248</table></div> 249<h6> 250<a name="fusion.sequence.concepts.associative_sequence.h3"></a> 251 <span class="phrase"><a name="fusion.sequence.concepts.associative_sequence.expression_semantics"></a></span><a class="link" href="associative_sequence.html#fusion.sequence.concepts.associative_sequence.expression_semantics">Expression 252 Semantics</a> 253 </h6> 254<div class="informaltable"><table class="table"> 255<colgroup> 256<col> 257<col> 258</colgroup> 259<thead><tr> 260<th> 261 <p> 262 Expression 263 </p> 264 </th> 265<th> 266 <p> 267 Semantics 268 </p> 269 </th> 270</tr></thead> 271<tbody> 272<tr> 273<td> 274 <p> 275 <code class="computeroutput"><a class="link" href="../intrinsic/functions/has_key.html" title="has_key"><code class="computeroutput"><span class="identifier">has_key</span></code></a><span class="special"><</span><span class="identifier">K</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span></code> 276 </p> 277 </td> 278<td> 279 <p> 280 A boolean Integral Constant <code class="computeroutput"><span class="identifier">c</span></code> 281 such that <code class="computeroutput"><span class="identifier">c</span><span class="special">::</span><span class="identifier">value</span> <span class="special">==</span> 282 <span class="keyword">true</span></code> if and only if there 283 is one or more elements with the key <code class="computeroutput"><span class="identifier">k</span></code> 284 in <code class="computeroutput"><span class="identifier">s</span></code>; see <a class="link" href="../intrinsic/functions/has_key.html" title="has_key"><code class="computeroutput"><span class="identifier">has_key</span></code></a>. 285 </p> 286 </td> 287</tr> 288<tr> 289<td> 290 <p> 291 <code class="computeroutput"><a class="link" href="../intrinsic/functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">K</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span></code> 292 </p> 293 </td> 294<td> 295 <p> 296 The element associated with the key <code class="computeroutput"><span class="identifier">K</span></code> 297 in the sequence <code class="computeroutput"><span class="identifier">s</span></code>; 298 see <a class="link" href="../intrinsic/functions/at.html" title="at"><code class="computeroutput"><span class="identifier">at</span></code></a>. 299 </p> 300 </td> 301</tr> 302</tbody> 303</table></div> 304<h6> 305<a name="fusion.sequence.concepts.associative_sequence.h4"></a> 306 <span class="phrase"><a name="fusion.sequence.concepts.associative_sequence.models"></a></span><a class="link" href="associative_sequence.html#fusion.sequence.concepts.associative_sequence.models">Models</a> 307 </h6> 308<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 309<li class="listitem"> 310 <a class="link" href="../../container/set.html" title="set"><code class="computeroutput"><span class="identifier">set</span></code></a> 311 </li> 312<li class="listitem"> 313 <a class="link" href="../../container/map.html" title="map"><code class="computeroutput"><span class="identifier">map</span></code></a> 314 </li> 315<li class="listitem"> 316 <a class="link" href="../../view/filter_view.html" title="filter_view"><code class="computeroutput"><span class="identifier">filter_view</span></code></a> 317 (where adapted sequence is an <a class="link" href="associative_sequence.html" title="Associative Sequence">Associative 318 Sequence</a> and a <a class="link" href="forward_sequence.html" title="Forward Sequence">Forward 319 Sequence</a>) 320 </li> 321<li class="listitem"> 322 <a class="link" href="../../view/iterator_range.html" title="iterator_range"><code class="computeroutput"><span class="identifier">iterator_range</span></code></a> 323 (where adapted iterators are <a class="link" href="../../iterator/concepts/associative_iterator.html" title="Associative Iterator">Associative 324 Iterator</a>s) 325 </li> 326<li class="listitem"> 327 <a class="link" href="../../view/joint_view.html" title="joint_view"><code class="computeroutput"><span class="identifier">joint_view</span></code></a> 328 (where adapted sequences are <a class="link" href="associative_sequence.html" title="Associative Sequence">Associative 329 Sequence</a>s and <a class="link" href="forward_sequence.html" title="Forward Sequence">Forward 330 Sequence</a>s) 331 </li> 332<li class="listitem"> 333 <a class="link" href="../../view/reverse_view.html" title="reverse_view"><code class="computeroutput"><span class="identifier">reverse_view</span></code></a> 334 (where adapted sequence is an <a class="link" href="associative_sequence.html" title="Associative Sequence">Associative 335 Sequence</a> and a <a class="link" href="bidirectional_sequence.html" title="Bidirectional Sequence">Bidirectional 336 Sequence</a>) 337 </li> 338</ul></div> 339</div> 340<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 341<td align="left"></td> 342<td align="right"><div class="copyright-footer">Copyright © 2001-2006, 2011, 2012 Joel de Guzman, 343 Dan Marsden, Tobias Schwinger<p> 344 Distributed under the Boost Software License, Version 1.0. (See accompanying 345 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>) 346 </p> 347</div></td> 348</tr></table> 349<hr> 350<div class="spirit-nav"> 351<a accesskey="p" href="random_access_sequence.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="unbounded_sequence.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 352</div> 353</body> 354</html> 355
