1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Addability, Subtractability and Aggregate on Overlap</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.Icl"> 8<link rel="up" href="../concepts.html" title="Concepts"> 9<link rel="prev" href="sets_and_maps.html" title="Sets and Maps"> 10<link rel="next" href="map_traits.html" title="Map Traits"> 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="../../../../../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="sets_and_maps.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="map_traits.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="boost_icl.concepts.aggrovering"></a><a class="link" href="aggrovering.html" title="Addability, Subtractability and Aggregate on Overlap">Addability, Subtractability 28 and Aggregate on Overlap</a> 29</h3></div></div></div> 30<p> 31 While <span class="emphasis"><em><span class="bold"><strong>addition</strong></span></em></span> and 32 <span class="emphasis"><em><span class="bold"><strong>subtraction</strong></span></em></span> on <code class="computeroutput"><span class="identifier">Sets</span></code> are implemented as <span class="emphasis"><em><span class="bold"><strong>set union</strong></span></em></span> and <span class="emphasis"><em><span class="bold"><strong>set 33 difference</strong></span></em></span>, for <code class="computeroutput"><span class="identifier">Maps</span></code> 34 we want to implement <span class="emphasis"><em><span class="bold"><strong>aggregation</strong></span></em></span> 35 on the associated values for the case of collision (of key elements) or overlap 36 (of key intervals), which has been refered to as <span class="emphasis"><em><span class="bold"><strong>aggregate 37 on overlap</strong></span></em></span> above. This kind of <code class="computeroutput"><span class="identifier">Addability</span></code> 38 and <code class="computeroutput"><span class="identifier">Subtractability</span></code> allows 39 to compute a lot of useful aggregation results on an <code class="computeroutput"><a class="link" href="../../boost/icl/interval_map.html" title="Class template interval_map">interval_map's</a></code> 40 associated values, just by adding and subtracting value pairs. Various examples 41 of <span class="emphasis"><em><span class="bold"><strong>aggregate on overlap</strong></span></em></span> 42 are given in <a class="link" href="../examples.html" title="Examples">section examples</a>. 43 In addition, this concept of <code class="computeroutput"><span class="identifier">Addability</span></code> 44 and <code class="computeroutput"><span class="identifier">Subtractability</span></code> contains 45 the classical <code class="computeroutput"><span class="identifier">Insertability</span></code> 46 and <code class="computeroutput"><span class="identifier">Erasability</span></code> of key value 47 pairs as a special case so it provides a broader new semantics without loss 48 of the <span class="emphasis"><em>classical</em></span> one. 49 </p> 50<p> 51 Aggregation is implemented for functions <code class="computeroutput"><span class="identifier">add</span></code> 52 and <code class="computeroutput"><span class="identifier">subtract</span></code> by propagating 53 a <code class="computeroutput"><span class="identifier">Combiner</span></code> functor to combine 54 associated values of type <code class="computeroutput"><span class="identifier">CodomainT</span></code>. 55 The standard <code class="computeroutput"><span class="identifier">Combiner</span></code> is 56 set as default template parameter <code class="computeroutput"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span><span class="special">></span><span class="keyword">class</span> <span class="identifier">Combine</span> <span class="special">=</span> <span class="identifier">inplace_plus</span></code>, which is again generically 57 implemented by <code class="computeroutput"><span class="keyword">operator</span> <span class="special">+=</span></code> 58 for all Addable types. 59 </p> 60<p> 61 For <code class="computeroutput"><span class="identifier">Combine</span></code> functors, the 62 Icl provides an <code class="computeroutput"><a class="link" href="../../boost/icl/inverse.html" title="Struct template inverse">inverse</a></code> 63 functor. 64 </p> 65<div class="informaltable"><table class="table"> 66<colgroup> 67<col> 68<col> 69</colgroup> 70<thead><tr> 71<th> 72 <p> 73 <code class="computeroutput"><span class="identifier">Combine</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 74 </p> 75 </th> 76<th> 77 <p> 78 <code class="computeroutput"><span class="identifier">inverse</span><span class="special"><</span><span class="identifier">Combine</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> 79 <span class="special">>::</span><span class="identifier">type</span></code> 80 </p> 81 </th> 82</tr></thead> 83<tbody> 84<tr> 85<td> 86 <p> 87 <code class="computeroutput"><a class="link" href="../../boost/icl/inplace_plus.html" title="Struct template inplace_plus">inplace_plus</a></code><code class="computeroutput"><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 88 </p> 89 </td> 90<td> 91 <p> 92 <code class="computeroutput"><a class="link" href="../../boost/icl/inplace_minus.html" title="Struct template inplace_minus">inplace_minus</a></code><code class="computeroutput"><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 93 </p> 94 </td> 95</tr> 96<tr> 97<td> 98 <p> 99 <code class="computeroutput"><a class="link" href="../../boost/icl/inplace_et.html" title="Struct template inplace_et">inplace_et</a></code><code class="computeroutput"><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 100 </p> 101 </td> 102<td> 103 <p> 104 <code class="computeroutput"><a class="link" href="../../boost/icl/inplace_caret.html" title="Struct template inplace_caret">inplace_caret</a></code><code class="computeroutput"><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 105 </p> 106 </td> 107</tr> 108<tr> 109<td> 110 <p> 111 <code class="computeroutput"><a class="link" href="../../boost/icl/inplace_star.html" title="Struct template inplace_star">inplace_star</a></code><code class="computeroutput"><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 112 </p> 113 </td> 114<td> 115 <p> 116 <code class="computeroutput"><a class="link" href="../../boost/icl/inplace_slash.html" title="Struct template inplace_slash">inplace_slash</a></code><code class="computeroutput"><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 117 </p> 118 </td> 119</tr> 120<tr> 121<td> 122 <p> 123 <code class="computeroutput"><a class="link" href="../../boost/icl/inplace_max.html" title="Struct template inplace_max">inplace_max</a></code><code class="computeroutput"><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 124 </p> 125 </td> 126<td> 127 <p> 128 <code class="computeroutput"><a class="link" href="../../boost/icl/inplace_min.html" title="Struct template inplace_min">inplace_min</a></code><code class="computeroutput"><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 129 </p> 130 </td> 131</tr> 132<tr> 133<td> 134 <p> 135 <code class="computeroutput"><a class="link" href="../../boost/icl/inplace_identity.html" title="Struct template inplace_identity">inplace_identity</a></code><code class="computeroutput"><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 136 </p> 137 </td> 138<td> 139 <p> 140 <code class="computeroutput"><a class="link" href="../../boost/icl/inplace_erasure.html" title="Struct template inplace_erasure">inplace_erasure</a></code><code class="computeroutput"><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 141 </p> 142 </td> 143</tr> 144<tr> 145<td> 146 <p> 147 <code class="computeroutput"><span class="identifier">Functor</span></code> 148 </p> 149 </td> 150<td> 151 <p> 152 <code class="computeroutput"><a class="link" href="../../boost/icl/inplace_erasure.html" title="Struct template inplace_erasure">inplace_erasure</a></code><code class="computeroutput"><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> 153 </p> 154 </td> 155</tr> 156</tbody> 157</table></div> 158<p> 159 The meta function <code class="computeroutput"><a class="link" href="../../boost/icl/inverse.html" title="Struct template inverse">inverse</a></code> 160 is mutually implemented for all but the default functor <code class="computeroutput"><span class="identifier">Functor</span></code> 161 such that e.g. <code class="computeroutput"><span class="identifier">inverse</span><span class="special"><</span><span class="identifier">inplace_minus</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="special">>::</span><span class="identifier">type</span></code> 162 yields <code class="computeroutput"><span class="identifier">inplace_plus</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code>. 163 Not in every case, e.g. <code class="computeroutput"><span class="identifier">max</span><span class="special">/</span><span class="identifier">min</span></code>, does 164 the <code class="computeroutput"><a class="link" href="../../boost/icl/inverse.html" title="Struct template inverse">inverse</a></code> functor invert 165 the effect of it's antetype. But for the default it does: 166 </p> 167<div class="informaltable"><table class="table"> 168<colgroup> 169<col> 170<col> 171<col> 172</colgroup> 173<thead><tr> 174<th> 175 </th> 176<th> 177 <p> 178 <code class="computeroutput"><span class="identifier">_add</span><span class="special"><</span><span class="identifier">Combine</span><span class="special"><</span><span class="identifier">CodomainT</span><span class="special">></span> 179 <span class="special">>((</span><span class="identifier">k</span><span class="special">,</span><span class="identifier">x</span><span class="special">))</span></code> 180 </p> 181 </th> 182<th> 183 <p> 184 <code class="computeroutput"><span class="identifier">_subtract</span><span class="special"><</span><span class="identifier">inverse</span><span class="special"><</span><span class="identifier">Combine</span><span class="special"><</span><span class="identifier">CodomainT</span><span class="special">></span> 185 <span class="special">>::</span><span class="identifier">type</span><span class="special">>((</span><span class="identifier">k</span><span class="special">,</span><span class="identifier">x</span><span class="special">))</span></code> 186 </p> 187 </th> 188</tr></thead> 189<tbody> 190<tr> 191<td> 192 <p> 193 Instance 194 </p> 195 </td> 196<td> 197 <p> 198 <code class="computeroutput"><span class="identifier">_add</span><span class="special"><</span><span class="identifier">inplace_plus</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> 199 <span class="special">>((</span><span class="identifier">k</span><span class="special">,</span><span class="identifier">x</span><span class="special">))</span></code> 200 </p> 201 </td> 202<td> 203 <p> 204 <code class="computeroutput"><span class="identifier">_subtract</span><span class="special"><</span><span class="identifier">inplace_minus</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> 205 <span class="special">>((</span><span class="identifier">k</span><span class="special">,</span><span class="identifier">x</span><span class="special">))</span></code> 206 </p> 207 </td> 208</tr> 209<tr> 210<td> 211 <p> 212 Inversion 213 </p> 214 </td> 215<td> 216 <p> 217 adds <code class="computeroutput"><span class="identifier">x</span></code> on overlap. 218 This inverts a preceding <code class="computeroutput"><span class="identifier">subtract</span></code> 219 of <code class="computeroutput"><span class="identifier">x</span></code> on <code class="computeroutput"><span class="identifier">k</span></code> 220 </p> 221 </td> 222<td> 223 <p> 224 subtracts <code class="computeroutput"><span class="identifier">x</span></code> on 225 overlap. This inverts a preceding <code class="computeroutput"><span class="identifier">add</span></code> 226 of <code class="computeroutput"><span class="identifier">x</span></code> on <code class="computeroutput"><span class="identifier">k</span></code> 227 </p> 228 </td> 229</tr> 230</tbody> 231</table></div> 232<p> 233 As already mentioned aggregating <code class="computeroutput"><span class="identifier">Addability</span></code> 234 and <code class="computeroutput"><span class="identifier">Subtractability</span></code> on <code class="computeroutput"><span class="identifier">Maps</span></code> contains the <span class="emphasis"><em>classical</em></span> 235 <code class="computeroutput"><span class="identifier">Insertability</span></code> and <code class="computeroutput"><span class="identifier">Erasability</span></code> of key value pairs as a special 236 case: 237 </p> 238<div class="informaltable"><table class="table"> 239<colgroup> 240<col> 241<col> 242</colgroup> 243<thead><tr> 244<th> 245 <p> 246 aggregating function 247 </p> 248 </th> 249<th> 250 <p> 251 equivalent <span class="emphasis"><em>classical</em></span> function 252 </p> 253 </th> 254</tr></thead> 255<tbody> 256<tr> 257<td> 258 <p> 259 <code class="computeroutput"><span class="identifier">_add</span><span class="special"><</span><span class="identifier">inplace_identity</span><span class="special"><</span><span class="identifier">CodomainT</span><span class="special">></span> 260 <span class="special">>(</span><span class="keyword">const</span> 261 <span class="identifier">value_type</span><span class="special">&)</span></code> 262 </p> 263 </td> 264<td> 265 <p> 266 <code class="computeroutput"><span class="identifier">insert</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">value_type</span><span class="special">&)</span></code> 267 </p> 268 </td> 269</tr> 270<tr> 271<td> 272 <p> 273 <code class="computeroutput"><span class="identifier">_subtract</span><span class="special"><</span><span class="identifier">inplace_erasure</span><span class="special"><</span><span class="identifier">CodomainT</span><span class="special">></span> 274 <span class="special">>(</span><span class="keyword">const</span> 275 <span class="identifier">value_type</span><span class="special">&)</span></code> 276 </p> 277 </td> 278<td> 279 <p> 280 <code class="computeroutput"><span class="identifier">erase</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">value_type</span><span class="special">&)</span></code> 281 </p> 282 </td> 283</tr> 284</tbody> 285</table></div> 286<p> 287 The aggregating member function templates <code class="computeroutput"><span class="identifier">_add</span></code> 288 and <code class="computeroutput"><span class="identifier">_subtract</span></code> are not in 289 the public interface of <code class="computeroutput"><a class="link" href="../../boost/icl/interval_base_map.html" title="Class template interval_base_map">interval_maps</a></code>, 290 because the <code class="computeroutput"><span class="identifier">Combine</span></code> functor 291 is intended to be an invariant of <code class="computeroutput"><a class="link" href="../../boost/icl/interval_base_map.html" title="Class template interval_base_map">interval_map's</a></code> 292 template instance to avoid, that clients spoil the aggregation by accidentally 293 calling varying aggregation functors. But you could instantiate an <code class="computeroutput"><a class="link" href="../../boost/icl/interval_map.html" title="Class template interval_map">interval_map</a></code> to have <code class="computeroutput"><span class="identifier">insert</span><span class="special">/</span><span class="identifier">erase</span></code> semantics this way: 294</p> 295<pre class="programlisting"><span class="identifier">interval_map</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">int</span><span class="special">,</span><span class="identifier">partial_absorber</span><span class="special">,</span> 296 <span class="identifier">std</span><span class="special">::</span><span class="identifier">less</span><span class="special">,</span> 297 <span class="identifier">inplace_identity</span> <span class="comment">//Combine parameter specified</span> 298 <span class="special">></span> <span class="identifier">m</span><span class="special">;</span> 299<span class="identifier">interval</span><span class="special"><</span><span class="keyword">int</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">itv</span> <span class="special">=</span> <span class="identifier">interval</span><span class="special"><</span><span class="keyword">int</span><span class="special">>::</span><span class="identifier">rightopen</span><span class="special">(</span><span class="number">2</span><span class="special">,</span><span class="number">7</span><span class="special">);</span> 300<span class="identifier">m</span><span class="special">.</span><span class="identifier">add</span><span class="special">(</span><span class="identifier">make_pair</span><span class="special">(</span><span class="identifier">itv</span><span class="special">,</span><span class="number">42</span><span class="special">));</span> <span class="comment">//same as insert</span> 301<span class="identifier">m</span><span class="special">.</span><span class="identifier">subtract</span><span class="special">(</span><span class="identifier">make_pair</span><span class="special">(</span><span class="identifier">itv</span><span class="special">,</span><span class="number">42</span><span class="special">));</span> <span class="comment">//same as erase </span> 302</pre> 303<p> 304 </p> 305<p> 306 This is, of course, only a clarifying example. Member functions <code class="computeroutput"><span class="identifier">insert</span></code> and <code class="computeroutput"><span class="identifier">erase</span></code> 307 are available in <code class="computeroutput"><a class="link" href="../../boost/icl/interval_base_map.html" title="Class template interval_base_map">interval_map's</a></code> 308 interface so they can be called directly. 309 </p> 310</div> 311<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 312<td align="left"></td> 313<td align="right"><div class="copyright-footer">Copyright © 2007-2010 Joachim 314 Faulhaber<br>Copyright © 1999-2006 Cortex Software 315 GmbH<p> 316 Distributed under the Boost Software License, Version 1.0. (See accompanying 317 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>) 318 </p> 319</div></td> 320</tr></table> 321<hr> 322<div class="spirit-nav"> 323<a accesskey="p" href="sets_and_maps.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="map_traits.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 324</div> 325</body> 326</html> 327
