1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Projects</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="../index.html" title="Chapter 1. Boost.Icl"> 9<link rel="prev" href="examples/custom_interval.html" title="Custom interval"> 10<link rel="next" href="concepts.html" title="Concepts"> 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="examples/custom_interval.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.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="concepts.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h2 class="title" style="clear: both"> 27<a name="boost_icl.projects"></a><a class="link" href="projects.html" title="Projects">Projects</a> 28</h2></div></div></div> 29<div class="toc"><dl class="toc"><dt><span class="section"><a href="projects.html#boost_icl.projects.large_bitset">Large Bitset</a></span></dt></dl></div> 30<p> 31 <span class="emphasis"><em><span class="bold"><strong>Projects</strong></span></em></span> are examples 32 on the usage of interval containers that go beyond small toy snippets of code. 33 The code presented here addresses more serious applications that approach the 34 quality of real world programming. At the same time it aims to guide the reader 35 more deeply into various aspects of the library. In order not to overburden 36 the reader with implementation details, the code in <span class="emphasis"><em><span class="bold"><strong>projects</strong></span></em></span> 37 tries to be <span class="emphasis"><em><span class="bold"><strong>minimal</strong></span></em></span>. 38 It has a focus on the main aspects of the projects and is not intended to be 39 complete and mature like the library code itself. Cause it's minimal, project 40 code lives in <code class="computeroutput"><span class="keyword">namespace</span> <span class="identifier">mini</span></code>. 41 </p> 42<div class="section"> 43<div class="titlepage"><div><div><h3 class="title"> 44<a name="boost_icl.projects.large_bitset"></a><a class="link" href="projects.html#boost_icl.projects.large_bitset" title="Large Bitset">Large Bitset</a> 45</h3></div></div></div> 46<div class="toc"><dl class="toc"> 47<dt><span class="section"><a href="projects.html#boost_icl.projects.large_bitset.using_large_bitset">Using 48 large_bitset</a></span></dt> 49<dt><span class="section"><a href="projects.html#boost_icl.projects.large_bitset.the_interval_bitmap">The 50 interval_bitmap</a></span></dt> 51<dt><span class="section"><a href="projects.html#boost_icl.projects.large_bitset.a_class_implementation_for_the_bitset_type">A 52 class implementation for the bitset type</a></span></dt> 53<dt><span class="section"><a href="projects.html#boost_icl.projects.large_bitset.implementation_of_a_large_bitset">Implementation 54 of a large bitset</a></span></dt> 55</dl></div> 56<p> 57 Bitsets are just sets. Sets of unsigned integrals, to be more precise. The 58 prefix <span class="emphasis"><em><span class="bold"><strong>bit</strong></span></em></span> usually 59 only indicates, that the representation of those sets is organized in a compressed 60 form that exploits the fact, that we can switch on an off single bits in 61 machine words. Bitsets are therefore known to be very small and thus efficient. 62 The efficiency of bitsets is usually coupled to the precondition that the 63 range of values of elements is relatively small, like [0..32) or [0..64), 64 values that can be typically represented in single or a small number of machine 65 words. If we wanted to represent a set containing two values {1, 1000000}, 66 we would be much better off using other sets like e.g. an <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">set</span></code>. 67 </p> 68<p> 69 Bitsets compress well, if elements spread over narrow ranges only. Interval 70 sets compress well, if many elements are clustered over intervals. They can 71 span large sets very efficiently then. In project <span class="emphasis"><em><span class="bold"><strong>Large 72 Bitset</strong></span></em></span> we want to <span class="emphasis"><em><span class="bold"><strong>combine 73 the bit compression and the interval compression</strong></span></em></span> to 74 achieve a set implementation, that is capable of spanning large chunks of 75 contiguous elements using intervals and also to represent more narrow <span class="emphasis"><em>nests</em></span> 76 of varying bit sequences using bitset compression. As we will see, this can 77 be achieved using only a small amount of code because most of the properties 78 we need are provided by an <code class="computeroutput"><a class="link" href="../boost/icl/interval_map.html" title="Class template interval_map">interval_map</a></code> 79 of <code class="computeroutput"><span class="identifier">bitsets</span></code>: 80 </p> 81<p> 82</p> 83<pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">interval_map</span><span class="special"><</span><span class="identifier">IntegralT</span><span class="special">,</span> <span class="identifier">SomeBitSet</span><span class="special"><</span><span class="identifier">N</span><span class="special">>,</span> <span class="identifier">partial_absorber</span><span class="special">,</span> 84 <span class="identifier">std</span><span class="special">::</span><span class="identifier">less</span><span class="special">,</span> <span class="identifier">inplace_bit_add</span><span class="special">,</span> <span class="identifier">inplace_bit_and</span><span class="special">></span> <span class="identifier">IntervalBitmap</span><span class="special">;</span> 85</pre> 86<p> 87 </p> 88<p> 89 Such an <code class="computeroutput"><span class="identifier">IntervalBitmap</span></code> represents 90 <code class="computeroutput"><span class="identifier">k</span><span class="special">*</span><span class="identifier">N</span></code> bits for every segment. 91</p> 92<pre class="programlisting"><span class="special">[</span><span class="identifier">a</span><span class="special">,</span> <span class="identifier">a</span><span class="special">+</span><span class="identifier">k</span><span class="special">)-></span><span class="char">'1111....1111'</span> <span class="comment">// N bits associated: Represents a total of k*N bits. </span> 93</pre> 94<p> 95 </p> 96<p> 97 For the interval <code class="computeroutput"><span class="special">[</span><span class="identifier">a</span><span class="special">,</span> <span class="identifier">a</span><span class="special">+</span><span class="identifier">k</span><span class="special">)</span></code> above 98 all bits are set. But we can also have individual <span class="emphasis"><em>nests</em></span> 99 or <span class="emphasis"><em>clusters</em></span> of bitsequences. 100 </p> 101<p> 102</p> 103<pre class="programlisting"><span class="special">[</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">b</span><span class="special">+</span><span class="number">1</span><span class="special">)-></span><span class="char">'01001011...1'</span> 104<span class="special">[</span><span class="identifier">b</span><span class="special">+</span><span class="number">1</span><span class="special">,</span><span class="identifier">b</span><span class="special">+</span><span class="number">2</span><span class="special">)-></span><span class="char">'11010001...0'</span> 105<span class="special">.</span> <span class="special">.</span> <span class="special">.</span> 106</pre> 107<p> 108 </p> 109<p> 110 and we can span intervals of equal bit sequences that represent periodic 111 patterns. 112 </p> 113<p> 114</p> 115<pre class="programlisting"><span class="special">[</span><span class="identifier">c</span><span class="special">,</span><span class="identifier">d</span><span class="special">)-></span><span class="char">'010101....01'</span> <span class="comment">// Every second bit is set in range [c,d)</span> 116<span class="special">[</span><span class="identifier">d</span><span class="special">,</span><span class="identifier">e</span><span class="special">)-></span><span class="char">'001100..0011'</span> <span class="comment">// Every two bits alterate in range [d,e)</span> 117<span class="special">[</span><span class="identifier">e</span><span class="special">,</span><span class="identifier">f</span><span class="special">)-></span><span class="char">'bit-sequence'</span> <span class="comment">// 'bit-sequence' reoccurs every N bits in range [e,f)</span> 118</pre> 119<p> 120 </p> 121<p> 122 An <code class="computeroutput"><span class="identifier">IntervalBitmap</span></code> can represent 123 <code class="computeroutput"><span class="identifier">N</span><span class="special">*(</span><span class="number">2</span><span class="special">^</span><span class="identifier">M</span><span class="special">)</span></code> elements, if <code class="computeroutput"><span class="identifier">M</span></code> 124 is the number of bits of the integral type <code class="computeroutput"><span class="identifier">IntegralT</span></code>. 125 Unlike bitsets, that usually represent <span class="emphasis"><em><span class="bold"><strong>unsigned</strong></span></em></span> 126 integral numbers, large_bitset may range over negative numbers as well. There 127 are fields where such large bitsets implementations are needed. E.g. for 128 the compact representation of large file allocation tables. What remains 129 to be done for project <span class="bold"><strong>Large Bitset</strong></span> is to 130 code a wrapper <code class="computeroutput"><span class="keyword">class</span> <span class="identifier">large_bitset</span></code> 131 around <code class="computeroutput"><span class="identifier">IntervalBitmap</span></code> so 132 that <code class="computeroutput"><span class="identifier">large_bitset</span></code> looks and 133 feels like a usual set class. 134 </p> 135<div class="section"> 136<div class="titlepage"><div><div><h4 class="title"> 137<a name="boost_icl.projects.large_bitset.using_large_bitset"></a><a class="link" href="projects.html#boost_icl.projects.large_bitset.using_large_bitset" title="Using large_bitset">Using 138 large_bitset</a> 139</h4></div></div></div> 140<p> 141 To quicken your appetite for a look at the implementation here are a few 142 use cases first. Within the examples that follow, we will use <code class="computeroutput"><span class="identifier">nat</span></code><code class="literal"><span class="emphasis"><em>k</em></span></code> 143 for unsigned integrals and <code class="computeroutput"><span class="identifier">bits</span></code><code class="literal"><span class="emphasis"><em>k</em></span></code> 144 for bitsets containing <code class="literal"><span class="emphasis"><em>k</em></span></code> bits. 145 </p> 146<p> 147 Let's start large. In the first example . . . 148 </p> 149<p> 150</p> 151<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">test_large</span><span class="special">()</span> 152<span class="special">{</span> 153 <span class="keyword">const</span> <span class="identifier">nat64</span> <span class="identifier">much</span> <span class="special">=</span> <span class="number">0</span><span class="identifier">xffffffffffffffffull</span><span class="special">;</span> 154 <span class="identifier">large_bitset</span><span class="special"><></span> <span class="identifier">venti</span><span class="special">;</span> <span class="comment">// ... the largest, I can think of ;)</span> 155 <span class="identifier">venti</span> <span class="special">+=</span> <span class="identifier">discrete_interval</span><span class="special"><</span><span class="identifier">nat64</span><span class="special">>(</span><span class="number">0</span><span class="special">,</span> <span class="identifier">much</span><span class="special">);</span> 156 157 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"----- Test function test_large() -----------------------------------------------\n"</span><span class="special">;</span> 158 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"We have just turned on the awesome amount of 18,446,744,073,709,551,616 bits ;-)\n"</span><span class="special">;</span> 159 <span class="identifier">venti</span><span class="special">.</span><span class="identifier">show_segments</span><span class="special">();</span> 160</pre> 161<p> 162 </p> 163<p> 164 . . . we are testing the limits. First we set all bits and then we switch 165 off the very last bit. 166 </p> 167<p> 168</p> 169<pre class="programlisting"> <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"---- Let's swich off the very last bit -----------------------------------------\n"</span><span class="special">;</span> 170 <span class="identifier">venti</span> <span class="special">-=</span> <span class="identifier">much</span><span class="special">;</span> 171 <span class="identifier">venti</span><span class="special">.</span><span class="identifier">show_segments</span><span class="special">();</span> 172 173 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"---- Venti is plenty ... let's do something small: A tall ----------------------\n\n"</span><span class="special">;</span> 174<span class="special">}</span> 175</pre> 176<p> 177 </p> 178<p> 179 Program output (<span class="emphasis"><em>a little beautified</em></span>): 180</p> 181<pre class="programlisting"><span class="special">-----</span> <span class="identifier">Test</span> <span class="identifier">function</span> <span class="identifier">test_large</span><span class="special">()</span> <span class="special">-----------------------------------------------</span> 182<span class="identifier">We</span> <span class="identifier">have</span> <span class="identifier">just</span> <span class="identifier">turned</span> <span class="identifier">on</span> <span class="identifier">the</span> <span class="identifier">awesome</span> <span class="identifier">amount</span> <span class="identifier">of</span> <span class="number">18</span><span class="special">,</span><span class="number">446</span><span class="special">,</span><span class="number">744</span><span class="special">,</span><span class="number">073</span><span class="special">,</span><span class="number">709</span><span class="special">,</span><span class="number">551</span><span class="special">,</span><span class="number">616</span> <span class="identifier">bits</span> <span class="special">;-)</span> 183<span class="special">[</span> <span class="number">0</span><span class="special">,</span> <span class="number">288230376151711744</span><span class="special">)</span> <span class="special">-></span> <span class="number">1111111111111111111111111111111111111111111111111111111111111111</span> 184<span class="special">----</span> <span class="identifier">Let</span><span class="char">'s swich off the very last bit ----------------------------------------- 185[ 0, 288230376151711743) -> 1111111111111111111111111111111111111111111111111111111111111111 186[288230376151711743, 288230376151711744) -> 1111111111111111111111111111111111111111111111111111111111111110 187---- Venti is plenty ... let'</span><span class="identifier">s</span> <span class="keyword">do</span> <span class="identifier">something</span> <span class="identifier">small</span><span class="special">:</span> <span class="identifier">A</span> <span class="identifier">tall</span> <span class="special">----------------------</span> 188</pre> 189<p> 190 </p> 191<p> 192 More readable is a smaller version of <code class="computeroutput"><span class="identifier">large_bitset</span></code>. 193 In function <code class="computeroutput"><span class="identifier">test_small</span><span class="special">()</span></code> we apply a few more operations . . . 194 </p> 195<p> 196</p> 197<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">test_small</span><span class="special">()</span> 198<span class="special">{</span> 199 <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">nat32</span><span class="special">,</span> <span class="identifier">bits8</span><span class="special">></span> <span class="identifier">tall</span><span class="special">;</span> <span class="comment">// small is tall ...</span> 200 <span class="comment">// ... because even this 'small' large_bitset </span> 201 <span class="comment">// can represent up to 2^32 == 4,294,967,296 bits.</span> 202 203 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"----- Test function test_small() -----------\n"</span><span class="special">;</span> 204 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"-- Switch on all bits in range [0,64] ------\n"</span><span class="special">;</span> 205 <span class="identifier">tall</span> <span class="special">+=</span> <span class="identifier">discrete_interval</span><span class="special"><</span><span class="identifier">nat</span><span class="special">>(</span><span class="number">0</span><span class="special">,</span> <span class="number">64</span><span class="special">);</span> 206 <span class="identifier">tall</span><span class="special">.</span><span class="identifier">show_segments</span><span class="special">();</span> 207 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"--------------------------------------------\n"</span><span class="special">;</span> 208 209 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"-- Turn off bits: 25,27,28 -----------------\n"</span><span class="special">;</span> 210 211 <span class="special">(((</span><span class="identifier">tall</span> <span class="special">-=</span> <span class="number">25</span><span class="special">)</span> <span class="special">-=</span> <span class="number">27</span><span class="special">)</span> <span class="special">-=</span> <span class="number">28</span><span class="special">)</span> <span class="special">;</span> 212 <span class="identifier">tall</span><span class="special">.</span><span class="identifier">show_segments</span><span class="special">();</span> 213 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"--------------------------------------------\n"</span><span class="special">;</span> 214 215 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"-- Flip bits in range [24,30) --------------\n"</span><span class="special">;</span> 216 <span class="identifier">tall</span> <span class="special">^=</span> <span class="identifier">discrete_interval</span><span class="special"><</span><span class="identifier">nat</span><span class="special">>::</span><span class="identifier">right_open</span><span class="special">(</span><span class="number">24</span><span class="special">,</span><span class="number">30</span><span class="special">);</span> 217 <span class="identifier">tall</span><span class="special">.</span><span class="identifier">show_segments</span><span class="special">();</span> 218 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"--------------------------------------------\n"</span><span class="special">;</span> 219 220 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"-- Remove the first 10 bits ----------------\n"</span><span class="special">;</span> 221 <span class="identifier">tall</span> <span class="special">-=</span> <span class="identifier">discrete_interval</span><span class="special"><</span><span class="identifier">nat</span><span class="special">>::</span><span class="identifier">right_open</span><span class="special">(</span><span class="number">0</span><span class="special">,</span><span class="number">10</span><span class="special">);</span> 222 <span class="identifier">tall</span><span class="special">.</span><span class="identifier">show_segments</span><span class="special">();</span> 223 224 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"-- Remove even bits in range [0,72) --------\n"</span><span class="special">;</span> 225 <span class="keyword">int</span> <span class="identifier">bit</span><span class="special">;</span> 226 <span class="keyword">for</span><span class="special">(</span><span class="identifier">bit</span><span class="special">=</span><span class="number">0</span><span class="special">;</span> <span class="identifier">bit</span><span class="special"><</span><span class="number">72</span><span class="special">;</span> <span class="identifier">bit</span><span class="special">++)</span> <span class="keyword">if</span><span class="special">(!(</span><span class="identifier">bit</span><span class="special">%</span><span class="number">2</span><span class="special">))</span> <span class="identifier">tall</span> <span class="special">-=</span> <span class="identifier">bit</span><span class="special">;</span> 227 <span class="identifier">tall</span><span class="special">.</span><span class="identifier">show_segments</span><span class="special">();</span> 228 229 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"-- Set odd bits in range [0,72) --------\n"</span><span class="special">;</span> 230 <span class="keyword">for</span><span class="special">(</span><span class="identifier">bit</span><span class="special">=</span><span class="number">0</span><span class="special">;</span> <span class="identifier">bit</span><span class="special"><</span><span class="number">72</span><span class="special">;</span> <span class="identifier">bit</span><span class="special">++)</span> <span class="keyword">if</span><span class="special">(</span><span class="identifier">bit</span><span class="special">%</span><span class="number">2</span><span class="special">)</span> <span class="identifier">tall</span> <span class="special">+=</span> <span class="identifier">bit</span><span class="special">;</span> 231 <span class="identifier">tall</span><span class="special">.</span><span class="identifier">show_segments</span><span class="special">();</span> 232 233 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"--------------------------------------------\n\n"</span><span class="special">;</span> 234 235<span class="special">}</span> 236</pre> 237<p> 238 </p> 239<p> 240 . . . producing this output: 241</p> 242<pre class="programlisting"><span class="special">-----</span> <span class="identifier">Test</span> <span class="identifier">function</span> <span class="identifier">test_small</span><span class="special">()</span> <span class="special">-----------</span> 243<span class="special">--</span> <span class="identifier">Switch</span> <span class="identifier">on</span> <span class="identifier">all</span> <span class="identifier">bits</span> <span class="identifier">in</span> <span class="identifier">range</span> <span class="special">[</span><span class="number">0</span><span class="special">,</span><span class="number">64</span><span class="special">]</span> <span class="special">------</span> 244<span class="special">[</span><span class="number">0</span><span class="special">,</span><span class="number">8</span><span class="special">)-></span><span class="number">11111111</span> 245<span class="special">[</span><span class="number">8</span><span class="special">,</span><span class="number">9</span><span class="special">)-></span><span class="number">10000000</span> 246<span class="special">--------------------------------------------</span> 247<span class="special">--</span> <span class="identifier">Turn</span> <span class="identifier">off</span> <span class="identifier">bits</span><span class="special">:</span> <span class="number">25</span><span class="special">,</span><span class="number">27</span><span class="special">,</span><span class="number">28</span> <span class="special">-----------------</span> 248<span class="special">[</span><span class="number">0</span><span class="special">,</span><span class="number">3</span><span class="special">)-></span><span class="number">11111111</span> 249<span class="special">[</span><span class="number">3</span><span class="special">,</span><span class="number">4</span><span class="special">)-></span><span class="number">10100111</span> 250<span class="special">[</span><span class="number">4</span><span class="special">,</span><span class="number">8</span><span class="special">)-></span><span class="number">11111111</span> 251<span class="special">[</span><span class="number">8</span><span class="special">,</span><span class="number">9</span><span class="special">)-></span><span class="number">10000000</span> 252<span class="special">--------------------------------------------</span> 253<span class="special">--</span> <span class="identifier">Flip</span> <span class="identifier">bits</span> <span class="identifier">in</span> <span class="identifier">range</span> <span class="special">[</span><span class="number">24</span><span class="special">,</span><span class="number">30</span><span class="special">)</span> <span class="special">--------------</span> 254<span class="special">[</span><span class="number">0</span><span class="special">,</span><span class="number">3</span><span class="special">)-></span><span class="number">11111111</span> 255<span class="special">[</span><span class="number">3</span><span class="special">,</span><span class="number">4</span><span class="special">)-></span><span class="number">01011011</span> 256<span class="special">[</span><span class="number">4</span><span class="special">,</span><span class="number">8</span><span class="special">)-></span><span class="number">11111111</span> 257<span class="special">[</span><span class="number">8</span><span class="special">,</span><span class="number">9</span><span class="special">)-></span><span class="number">10000000</span> 258<span class="special">--------------------------------------------</span> 259<span class="special">--</span> <span class="identifier">Remove</span> <span class="identifier">the</span> <span class="identifier">first</span> <span class="number">10</span> <span class="identifier">bits</span> <span class="special">----------------</span> 260<span class="special">[</span><span class="number">1</span><span class="special">,</span><span class="number">2</span><span class="special">)-></span><span class="number">00111111</span> 261<span class="special">[</span><span class="number">2</span><span class="special">,</span><span class="number">3</span><span class="special">)-></span><span class="number">11111111</span> 262<span class="special">[</span><span class="number">3</span><span class="special">,</span><span class="number">4</span><span class="special">)-></span><span class="number">01011011</span> 263<span class="special">[</span><span class="number">4</span><span class="special">,</span><span class="number">8</span><span class="special">)-></span><span class="number">11111111</span> 264<span class="special">[</span><span class="number">8</span><span class="special">,</span><span class="number">9</span><span class="special">)-></span><span class="number">10000000</span> 265<span class="special">--</span> <span class="identifier">Remove</span> <span class="identifier">even</span> <span class="identifier">bits</span> <span class="identifier">in</span> <span class="identifier">range</span> <span class="special">[</span><span class="number">0</span><span class="special">,</span><span class="number">72</span><span class="special">)</span> <span class="special">--------</span> 266<span class="special">[</span><span class="number">1</span><span class="special">,</span><span class="number">2</span><span class="special">)-></span><span class="number">00010101</span> 267<span class="special">[</span><span class="number">2</span><span class="special">,</span><span class="number">3</span><span class="special">)-></span><span class="number">01010101</span> 268<span class="special">[</span><span class="number">3</span><span class="special">,</span><span class="number">4</span><span class="special">)-></span><span class="number">01010001</span> 269<span class="special">[</span><span class="number">4</span><span class="special">,</span><span class="number">8</span><span class="special">)-></span><span class="number">01010101</span> 270<span class="special">--</span> <span class="identifier">Set</span> <span class="identifier">odd</span> <span class="identifier">bits</span> <span class="identifier">in</span> <span class="identifier">range</span> <span class="special">[</span><span class="number">0</span><span class="special">,</span><span class="number">72</span><span class="special">)</span> <span class="special">--------</span> 271<span class="special">[</span><span class="number">0</span><span class="special">,</span><span class="number">9</span><span class="special">)-></span><span class="number">01010101</span> 272<span class="special">--------------------------------------------</span> 273</pre> 274<p> 275 </p> 276<p> 277 Finally, we present a little <span class="emphasis"><em>picturesque</em></span> example, 278 that demonstrates that <code class="computeroutput"><span class="identifier">large_bitset</span></code> 279 can also serve as a self compressing bitmap, that we can 'paint' with. 280 </p> 281<p> 282</p> 283<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">test_picturesque</span><span class="special">()</span> 284<span class="special">{</span> 285 <span class="keyword">typedef</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">nat</span><span class="special">,</span> <span class="identifier">bits8</span><span class="special">></span> <span class="identifier">Bit8Set</span><span class="special">;</span> 286 287 <span class="identifier">Bit8Set</span> <span class="identifier">square</span><span class="special">,</span> <span class="identifier">stare</span><span class="special">;</span> 288 <span class="identifier">square</span> <span class="special">+=</span> <span class="identifier">discrete_interval</span><span class="special"><</span><span class="identifier">nat</span><span class="special">>(</span><span class="number">0</span><span class="special">,</span><span class="number">8</span><span class="special">);</span> 289 <span class="keyword">for</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span><span class="special">=</span><span class="number">1</span><span class="special">;</span> <span class="identifier">i</span><span class="special"><</span><span class="number">5</span><span class="special">;</span> <span class="identifier">i</span><span class="special">++)</span> 290 <span class="special">{</span> 291 <span class="identifier">square</span> <span class="special">+=</span> <span class="number">8</span><span class="special">*</span><span class="identifier">i</span><span class="special">;</span> 292 <span class="identifier">square</span> <span class="special">+=</span> <span class="number">8</span><span class="special">*</span><span class="identifier">i</span><span class="special">+</span><span class="number">7</span><span class="special">;</span> 293 <span class="special">}</span> 294 295 <span class="identifier">square</span> <span class="special">+=</span> <span class="identifier">discrete_interval</span><span class="special"><</span><span class="identifier">nat</span><span class="special">>(</span><span class="number">41</span><span class="special">,</span><span class="number">47</span><span class="special">);</span> 296 297 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"----- Test function test_picturesque() -----\n"</span><span class="special">;</span> 298 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"-------- empty face: "</span> 299 <span class="special"><<</span> <span class="identifier">square</span><span class="special">.</span><span class="identifier">interval_count</span><span class="special">()</span> <span class="special"><<</span> <span class="string">" intervals -----\n"</span><span class="special">;</span> 300 <span class="identifier">square</span><span class="special">.</span><span class="identifier">show_matrix</span><span class="special">(</span><span class="string">" *"</span><span class="special">);</span> 301 302 <span class="identifier">stare</span> <span class="special">+=</span> <span class="number">18</span><span class="special">;</span> <span class="identifier">stare</span> <span class="special">+=</span> <span class="number">21</span><span class="special">;</span> 303 <span class="identifier">stare</span> <span class="special">+=</span> <span class="identifier">discrete_interval</span><span class="special"><</span><span class="identifier">nat</span><span class="special">>(</span><span class="number">34</span><span class="special">,</span><span class="number">38</span><span class="special">);</span> 304 305 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"-------- compressed smile: "</span> 306 <span class="special"><<</span> <span class="identifier">stare</span><span class="special">.</span><span class="identifier">interval_count</span><span class="special">()</span> <span class="special"><<</span> <span class="string">" intervals -----\n"</span><span class="special">;</span> 307 <span class="identifier">stare</span><span class="special">.</span><span class="identifier">show_matrix</span><span class="special">(</span><span class="string">" *"</span><span class="special">);</span> 308 309 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"-------- staring bitset: "</span> 310 <span class="special"><<</span> <span class="special">(</span><span class="identifier">square</span> <span class="special">+</span> <span class="identifier">stare</span><span class="special">).</span><span class="identifier">interval_count</span><span class="special">()</span> <span class="special"><<</span> <span class="string">" intervals -----\n"</span><span class="special">;</span> 311 <span class="special">(</span><span class="identifier">square</span> <span class="special">+</span> <span class="identifier">stare</span><span class="special">).</span><span class="identifier">show_matrix</span><span class="special">(</span><span class="string">" *"</span><span class="special">);</span> 312 313 <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"--------------------------------------------\n"</span><span class="special">;</span> 314<span class="special">}</span> 315</pre> 316<p> 317 </p> 318<p> 319 Note that we have two <code class="computeroutput"><span class="identifier">large_bitsets</span></code> 320 for the <span class="emphasis"><em>outline</em></span> and the <span class="emphasis"><em>interior</em></span>. 321 Both parts are compressed but we can compose both by <code class="computeroutput"><span class="keyword">operator</span> 322 <span class="special">+</span></code>, because the right <span class="emphasis"><em>positions</em></span> 323 are provided. This is the program output: 324 </p> 325<p> 326</p> 327<pre class="programlisting"><span class="special">-----</span> <span class="identifier">Test</span> <span class="identifier">function</span> <span class="identifier">test_picturesque</span><span class="special">()</span> <span class="special">-----</span> 328<span class="special">--------</span> <span class="identifier">empty</span> <span class="identifier">face</span><span class="special">:</span> <span class="number">3</span> <span class="identifier">intervals</span> <span class="special">-----</span> 329<span class="special">********</span> 330<span class="special">*</span> <span class="special">*</span> 331<span class="special">*</span> <span class="special">*</span> 332<span class="special">*</span> <span class="special">*</span> 333<span class="special">*</span> <span class="special">*</span> 334 <span class="special">******</span> 335<span class="special">--------</span> <span class="identifier">compressed</span> <span class="identifier">smile</span><span class="special">:</span> <span class="number">2</span> <span class="identifier">intervals</span> <span class="special">-----</span> 336 <span class="special">*</span> <span class="special">*</span> 337 <span class="special">****</span> 338<span class="special">--------</span> <span class="identifier">staring</span> <span class="identifier">bitset</span><span class="special">:</span> <span class="number">6</span> <span class="identifier">intervals</span> <span class="special">-----</span> 339<span class="special">********</span> 340<span class="special">*</span> <span class="special">*</span> 341<span class="special">*</span> <span class="special">*</span> <span class="special">*</span> <span class="special">*</span> 342<span class="special">*</span> <span class="special">*</span> 343<span class="special">*</span> <span class="special">****</span> <span class="special">*</span> 344 <span class="special">******</span> 345<span class="special">--------------------------------------------</span> 346</pre> 347<p> 348 </p> 349<p> 350 So, may be you are curious how this class template is coded on top of 351 <code class="computeroutput"><a class="link" href="../boost/icl/interval_map.html" title="Class template interval_map">interval_map</a></code> using 352 only about 250 lines of code. This is shown in the sections that follow. 353 </p> 354</div> 355<div class="section"> 356<div class="titlepage"><div><div><h4 class="title"> 357<a name="boost_icl.projects.large_bitset.the_interval_bitmap"></a><a class="link" href="projects.html#boost_icl.projects.large_bitset.the_interval_bitmap" title="The interval_bitmap">The 358 interval_bitmap</a> 359</h4></div></div></div> 360<p> 361 To begin, let's look at the basic data type again, that will be providing 362 the major functionality: 363 </p> 364<p> 365</p> 366<pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">interval_map</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span> <span class="identifier">BitSetT</span><span class="special">,</span> <span class="identifier">partial_absorber</span><span class="special">,</span> 367 <span class="identifier">std</span><span class="special">::</span><span class="identifier">less</span><span class="special">,</span> <span class="identifier">inplace_bit_add</span><span class="special">,</span> <span class="identifier">inplace_bit_and</span><span class="special">></span> <span class="identifier">IntervalBitmap</span><span class="special">;</span> 368</pre> 369<p> 370 </p> 371<p> 372 <code class="computeroutput"><span class="identifier">DomainT</span></code> is supposed to 373 be an integral type, the bitset type <code class="computeroutput"><span class="identifier">BitSetT</span></code> 374 will be a wrapper class around an unsigned integral type. <code class="computeroutput"><span class="identifier">BitSetT</span></code> has to implement bitwise operators 375 that will be called by the functors <code class="computeroutput"><span class="identifier">inplace_bit_add</span><span class="special"><</span><span class="identifier">BitSetT</span><span class="special">></span></code> and <code class="computeroutput"><span class="identifier">inplace_bit_and</span><span class="special"><</span><span class="identifier">BitSetT</span><span class="special">></span></code>. The type trait of interval_map is 376 <code class="computeroutput"><span class="identifier">partial_absorber</span></code>, which 377 means that it is <span class="emphasis"><em>partial</em></span> and that empty <code class="computeroutput"><span class="identifier">BitSetTs</span></code> are not stored in the map. This 378 is desired and keeps the <code class="computeroutput"><span class="identifier">interval_map</span></code> 379 minimal, storing only bitsets, that contain at least one bit switched on. 380 Functor template <code class="computeroutput"><span class="identifier">inplace_bit_add</span></code> 381 for parameter <code class="computeroutput"><span class="identifier">Combine</span></code> indicates 382 that we do not expect <code class="computeroutput"><span class="keyword">operator</span> <span class="special">+=</span></code> as addition but the bitwise operator 383 <code class="computeroutput"><span class="special">|=</span></code>. For template parameter 384 <code class="computeroutput"><span class="identifier">Section</span></code> which is instaniated 385 by <code class="computeroutput"><span class="identifier">inplace_bit_and</span></code> we expect 386 the bitwise <code class="computeroutput"><span class="special">&=</span></code> operator. 387 </p> 388</div> 389<div class="section"> 390<div class="titlepage"><div><div><h4 class="title"> 391<a name="boost_icl.projects.large_bitset.a_class_implementation_for_the_bitset_type"></a><a class="link" href="projects.html#boost_icl.projects.large_bitset.a_class_implementation_for_the_bitset_type" title="A class implementation for the bitset type">A 392 class implementation for the bitset type</a> 393</h4></div></div></div> 394<p> 395 The code of the project is enclosed in a <code class="computeroutput"><span class="keyword">namespace</span> 396 <span class="identifier">mini</span></code>. The name indicates, that 397 the implementation is a <span class="emphasis"><em>minimal</em></span> example implementation. 398 The name of the bitset class will be <code class="computeroutput"><span class="identifier">bits</span></code> 399 or <code class="computeroutput"><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span></code> if qualified. 400 </p> 401<p> 402 To be used as a codomain parameter of class template <code class="computeroutput"><a class="link" href="../boost/icl/interval_map.html" title="Class template interval_map">interval_map</a></code>, 403 <code class="computeroutput"><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span></code> has to implement all the functions 404 that are required for a codomain_type in general, which are the default 405 constructor <code class="computeroutput"><span class="identifier">bits</span><span class="special">()</span></code> 406 and an equality <code class="computeroutput"><span class="keyword">operator</span><span class="special">==</span></code>. 407 Moreover <code class="computeroutput"><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span></code> has to implement operators required 408 by the instantiations for parameter <code class="computeroutput"><span class="identifier">Combine</span></code> 409 and <code class="computeroutput"><span class="identifier">Section</span></code> which are 410 <code class="computeroutput"><span class="identifier">inplace_bit_add</span></code> and <code class="computeroutput"><span class="identifier">inplace_bit_and</span></code>. From functors <code class="computeroutput"><span class="identifier">inplace_bit_add</span></code> and <code class="computeroutput"><span class="identifier">inplace_bit_and</span></code> 411 there are inverse functors <code class="computeroutput"><span class="identifier">inplace_bit_subtract</span></code> 412 and <code class="computeroutput"><span class="identifier">inplace_bit_xor</span></code>. Those 413 functors use operators <code class="computeroutput"><span class="special">|=</span> <span class="special">&=</span> <span class="special">^=</span></code> 414 and <code class="computeroutput"><span class="special">~</span></code>. Finally if we want 415 to apply lexicographical and subset comparison on large_bitset, we also 416 need an <code class="computeroutput"><span class="keyword">operator</span> <span class="special"><</span></code>. 417 All the operators that we need can be implemented for <code class="computeroutput"><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span></code> 418 on a few lines: 419 </p> 420<p> 421</p> 422<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">NaturalT</span><span class="special">></span> <span class="keyword">class</span> <span class="identifier">bits</span> 423<span class="special">{</span> 424<span class="keyword">public</span><span class="special">:</span> 425 <span class="keyword">typedef</span> <span class="identifier">NaturalT</span> <span class="identifier">word_type</span><span class="special">;</span> 426 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keyword">int</span> <span class="identifier">digits</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special"><</span><span class="identifier">NaturalT</span><span class="special">>::</span><span class="identifier">digits</span><span class="special">;</span> 427 <span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">word_type</span> <span class="identifier">w1</span> <span class="special">=</span> <span class="keyword">static_cast</span><span class="special"><</span><span class="identifier">NaturalT</span><span class="special">>(</span><span class="number">1</span><span class="special">)</span> <span class="special">;</span> 428 429 <span class="identifier">bits</span><span class="special">():</span><span class="identifier">_bits</span><span class="special">(){}</span> 430 <span class="keyword">explicit</span> <span class="identifier">bits</span><span class="special">(</span><span class="identifier">word_type</span> <span class="identifier">value</span><span class="special">):</span><span class="identifier">_bits</span><span class="special">(</span><span class="identifier">value</span><span class="special">){}</span> 431 432 <span class="identifier">word_type</span> <span class="identifier">word</span><span class="special">()</span><span class="keyword">const</span><span class="special">{</span> <span class="keyword">return</span> <span class="identifier">_bits</span><span class="special">;</span> <span class="special">}</span> 433 <span class="identifier">bits</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">|=</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">bits</span><span class="special">&</span> <span class="identifier">value</span><span class="special">){</span><span class="identifier">_bits</span> <span class="special">|=</span> <span class="identifier">value</span><span class="special">.</span><span class="identifier">_bits</span><span class="special">;</span> <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;}</span> 434 <span class="identifier">bits</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">&=</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">bits</span><span class="special">&</span> <span class="identifier">value</span><span class="special">){</span><span class="identifier">_bits</span> <span class="special">&=</span> <span class="identifier">value</span><span class="special">.</span><span class="identifier">_bits</span><span class="special">;</span> <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;}</span> 435 <span class="identifier">bits</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">^=</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">bits</span><span class="special">&</span> <span class="identifier">value</span><span class="special">){</span><span class="identifier">_bits</span> <span class="special">^=</span> <span class="identifier">value</span><span class="special">.</span><span class="identifier">_bits</span><span class="special">;</span> <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;}</span> 436 <span class="identifier">bits</span> <span class="keyword">operator</span> <span class="special">~</span> <span class="special">()</span><span class="keyword">const</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">bits</span><span class="special">(~</span><span class="identifier">_bits</span><span class="special">);</span> <span class="special">}</span> 437 <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special"><</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">bits</span><span class="special">&</span> <span class="identifier">value</span><span class="special">)</span><span class="keyword">const</span><span class="special">{</span><span class="keyword">return</span> <span class="identifier">_bits</span> <span class="special"><</span> <span class="identifier">value</span><span class="special">.</span><span class="identifier">_bits</span><span class="special">;}</span> 438 <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special">==</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">bits</span><span class="special">&</span> <span class="identifier">value</span><span class="special">)</span><span class="keyword">const</span><span class="special">{</span><span class="keyword">return</span> <span class="identifier">_bits</span> <span class="special">==</span> <span class="identifier">value</span><span class="special">.</span><span class="identifier">_bits</span><span class="special">;}</span> 439 440 <span class="keyword">bool</span> <span class="identifier">contains</span><span class="special">(</span><span class="identifier">word_type</span> <span class="identifier">element</span><span class="special">)</span><span class="keyword">const</span><span class="special">{</span> <span class="keyword">return</span> <span class="special">((</span><span class="identifier">w1</span> <span class="special"><<</span> <span class="identifier">element</span><span class="special">)</span> <span class="special">&</span> <span class="identifier">_bits</span><span class="special">)</span> <span class="special">!=</span> <span class="number">0</span><span class="special">;</span> <span class="special">}</span> 441 <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">as_string</span><span class="special">(</span><span class="keyword">const</span> <span class="keyword">char</span> <span class="identifier">off_on</span><span class="special">[</span><span class="number">2</span><span class="special">]</span> <span class="special">=</span> <span class="string">" 1"</span><span class="special">)</span><span class="keyword">const</span><span class="special">;</span> 442 443<span class="keyword">private</span><span class="special">:</span> 444 <span class="identifier">word_type</span> <span class="identifier">_bits</span><span class="special">;</span> 445<span class="special">};</span> 446</pre> 447<p> 448 </p> 449<p> 450 Finally there is one important piece of meta information, we have to provide: 451 <code class="computeroutput"><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span></code> has to be recognized as a <code class="computeroutput"><span class="identifier">Set</span></code> by the icl code. Otherwise we can 452 not exploit the fact that a map of sets is model of <code class="computeroutput"><span class="identifier">Set</span></code> 453 and the resulting large_bitset would not behave like a set. So we have 454 to say that <code class="computeroutput"><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span></code> shall be sets: 455 </p> 456<p> 457</p> 458<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">icl</span> 459<span class="special">{</span> 460 <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">NaturalT</span><span class="special">></span> 461 <span class="keyword">struct</span> <span class="identifier">is_set</span><span class="special"><</span><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span><span class="special"><</span><span class="identifier">NaturalT</span><span class="special">></span> <span class="special">></span> 462 <span class="special">{</span> 463 <span class="keyword">typedef</span> <span class="identifier">is_set</span><span class="special"><</span><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span><span class="special"><</span><span class="identifier">NaturalT</span><span class="special">></span> <span class="special">></span> <span class="identifier">type</span><span class="special">;</span> 464 <span class="identifier">BOOST_STATIC_CONSTANT</span><span class="special">(</span><span class="keyword">bool</span><span class="special">,</span> <span class="identifier">value</span> <span class="special">=</span> <span class="keyword">true</span><span class="special">);</span> 465 <span class="special">};</span> 466 467 <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">NaturalT</span><span class="special">></span> 468 <span class="keyword">struct</span> <span class="identifier">has_set_semantics</span><span class="special"><</span><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span><span class="special"><</span><span class="identifier">NaturalT</span><span class="special">></span> <span class="special">></span> 469 <span class="special">{</span> 470 <span class="keyword">typedef</span> <span class="identifier">has_set_semantics</span><span class="special"><</span><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span><span class="special"><</span><span class="identifier">NaturalT</span><span class="special">></span> <span class="special">></span> <span class="identifier">type</span><span class="special">;</span> 471 <span class="identifier">BOOST_STATIC_CONSTANT</span><span class="special">(</span><span class="keyword">bool</span><span class="special">,</span> <span class="identifier">value</span> <span class="special">=</span> <span class="keyword">true</span><span class="special">);</span> 472 <span class="special">};</span> 473<span class="special">}}</span> 474</pre> 475<p> 476 </p> 477<p> 478 This is done by adding a partial template specialization to the type trait 479 template <code class="computeroutput"><span class="identifier">icl</span><span class="special">::</span><span class="identifier">is_set</span></code>. For the extension of this type 480 trait template and the result values of inclusion_compare we need these 481 <code class="computeroutput"><span class="preprocessor">#includes</span></code> for the implementation 482 of <code class="computeroutput"><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span></code>: 483 </p> 484<p> 485</p> 486<pre class="programlisting"> <span class="comment">// These includes are needed ...</span> 487<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">string</span><span class="special">></span> <span class="comment">// for conversion to output and to</span> 488<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">icl</span><span class="special">/</span><span class="identifier">type_traits</span><span class="special">/</span><span class="identifier">has_set_semantics</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">>//</span><span class="identifier">declare</span> <span class="identifier">that</span> <span class="identifier">bits</span> <span class="identifier">has</span> <span class="identifier">the</span> 489 <span class="comment">// behavior of a set.</span> 490</pre> 491<p> 492 </p> 493</div> 494<div class="section"> 495<div class="titlepage"><div><div><h4 class="title"> 496<a name="boost_icl.projects.large_bitset.implementation_of_a_large_bitset"></a><a class="link" href="projects.html#boost_icl.projects.large_bitset.implementation_of_a_large_bitset" title="Implementation of a large bitset">Implementation 497 of a large bitset</a> 498</h4></div></div></div> 499<div class="toc"><dl class="toc"> 500<dt><span class="section"><a href="projects.html#boost_icl.projects.large_bitset.implementation_of_a_large_bitset.large_bitset__public_interface">large_bitset: 501 Public interface</a></span></dt> 502<dt><span class="section"><a href="projects.html#boost_icl.projects.large_bitset.implementation_of_a_large_bitset.large_bitset__private_implementation">large_bitset: 503 Private implementation</a></span></dt> 504</dl></div> 505<p> 506 Having finished our <code class="computeroutput"><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span></code> 507 implementation, we can start to code the wrapper class that hides the efficient 508 interval map of mini::bits and exposes a simple and convenient set behavior 509 to the world of users. 510 </p> 511<p> 512 Let's start with the required <code class="computeroutput"><span class="preprocessor">#include</span></code>s 513 this time: 514 </p> 515<p> 516</p> 517<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> <span class="comment">// to organize output</span> 518<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">limits</span><span class="special">></span> <span class="comment">// limits and associated constants</span> 519<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">operators</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> <span class="comment">// to define operators with minimal effort</span> 520<span class="preprocessor">#include</span> <span class="string">"meta_log.hpp"</span> <span class="comment">// a meta logarithm</span> 521<span class="preprocessor">#include</span> <span class="string">"bits.hpp"</span> <span class="comment">// a minimal bitset implementation</span> 522<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">icl</span><span class="special">/</span><span class="identifier">interval_map</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> <span class="comment">// base of large bitsets</span> 523 524<span class="keyword">namespace</span> <span class="identifier">mini</span> <span class="comment">// minimal implementations for example projects</span> 525<span class="special">{</span> 526</pre> 527<p> 528 </p> 529<p> 530 Besides <code class="computeroutput"><span class="identifier">boost</span><span class="special">/</span><span class="identifier">icl</span><span class="special">/</span><span class="identifier">interval_map</span><span class="special">.</span><span class="identifier">hpp</span></code> and <code class="computeroutput"><span class="identifier">bits</span><span class="special">.</span><span class="identifier">hpp</span></code> 531 the most important include here is <code class="computeroutput"><span class="identifier">boost</span><span class="special">/</span><span class="identifier">operators</span><span class="special">.</span><span class="identifier">hpp</span></code>. 532 We use this library in order to further minimize the code and to provide 533 pretty extensive operator functionality using very little code. 534 </p> 535<p> 536 For a short and concise naming of the most important unsigned integer types 537 and the corresponding <code class="computeroutput"><span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits</span></code> 538 we define this: 539 </p> 540<p> 541</p> 542<pre class="programlisting"><span class="keyword">typedef</span> <span class="keyword">unsigned</span> <span class="keyword">char</span> <span class="identifier">nat8</span><span class="special">;</span> <span class="comment">// nati i: number bits</span> 543<span class="keyword">typedef</span> <span class="keyword">unsigned</span> <span class="keyword">short</span> <span class="identifier">nat16</span><span class="special">;</span> 544<span class="keyword">typedef</span> <span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="identifier">nat32</span><span class="special">;</span> 545<span class="keyword">typedef</span> <span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">nat64</span><span class="special">;</span> 546<span class="keyword">typedef</span> <span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="identifier">nat</span><span class="special">;</span> 547 548<span class="keyword">typedef</span> <span class="identifier">bits</span><span class="special"><</span><span class="identifier">nat8</span><span class="special">></span> <span class="identifier">bits8</span><span class="special">;</span> 549<span class="keyword">typedef</span> <span class="identifier">bits</span><span class="special"><</span><span class="identifier">nat16</span><span class="special">></span> <span class="identifier">bits16</span><span class="special">;</span> 550<span class="keyword">typedef</span> <span class="identifier">bits</span><span class="special"><</span><span class="identifier">nat32</span><span class="special">></span> <span class="identifier">bits32</span><span class="special">;</span> 551<span class="keyword">typedef</span> <span class="identifier">bits</span><span class="special"><</span><span class="identifier">nat64</span><span class="special">></span> <span class="identifier">bits64</span><span class="special">;</span> 552</pre> 553<p> 554 </p> 555<div class="section"> 556<div class="titlepage"><div><div><h5 class="title"> 557<a name="boost_icl.projects.large_bitset.implementation_of_a_large_bitset.large_bitset__public_interface"></a><a class="link" href="projects.html#boost_icl.projects.large_bitset.implementation_of_a_large_bitset.large_bitset__public_interface" title="large_bitset: Public interface">large_bitset: 558 Public interface</a> 559</h5></div></div></div> 560<p> 561 And now let's code <code class="computeroutput"><span class="identifier">large_bitset</span></code>. 562 </p> 563<p> 564</p> 565<pre class="programlisting"><span class="keyword">template</span> 566<span class="special"><</span> 567 <span class="keyword">typename</span> <span class="identifier">DomainT</span> <span class="special">=</span> <span class="identifier">nat64</span><span class="special">,</span> 568 <span class="keyword">typename</span> <span class="identifier">BitSetT</span> <span class="special">=</span> <span class="identifier">bits64</span><span class="special">,</span> 569 <span class="identifier">ICL_COMPARE</span> <span class="identifier">Compare</span> <span class="special">=</span> <span class="identifier">ICL_COMPARE_INSTANCE</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">less</span><span class="special">,</span> <span class="identifier">DomainT</span><span class="special">),</span> 570 <span class="identifier">ICL_INTERVAL</span><span class="special">(</span><span class="identifier">ICL_COMPARE</span><span class="special">)</span> <span class="identifier">Interval</span> <span class="special">=</span> <span class="identifier">ICL_INTERVAL_INSTANCE</span><span class="special">(</span><span class="identifier">ICL_INTERVAL_DEFAULT</span><span class="special">,</span> <span class="identifier">DomainT</span><span class="special">,</span> <span class="identifier">Compare</span><span class="special">),</span> 571 <span class="identifier">ICL_ALLOC</span> <span class="identifier">Alloc</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator</span> 572<span class="special">></span> 573<span class="keyword">class</span> <span class="identifier">large_bitset</span> 574 <span class="special">:</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">equality_comparable</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">></span> 575 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">less_than_comparable</span><span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">></span> 576 577 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">addable</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">></span> 578 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">orable</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">></span> 579 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">subtractable</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">></span> 580 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">andable</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">></span> 581 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">xorable</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">></span> 582 583 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">addable2</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">>,</span> <span class="identifier">DomainT</span> 584 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">orable2</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">>,</span> <span class="identifier">DomainT</span> 585 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">subtractable2</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">>,</span> <span class="identifier">DomainT</span> 586 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">andable2</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">>,</span> <span class="identifier">DomainT</span> 587 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">xorable2</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">>,</span> <span class="identifier">DomainT</span> 588 589 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">addable2</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">>,</span> <span class="identifier">ICL_INTERVAL_TYPE</span><span class="special">(</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">)</span> 590 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">orable2</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">>,</span> <span class="identifier">ICL_INTERVAL_TYPE</span><span class="special">(</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">)</span> 591 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">subtractable2</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">>,</span> <span class="identifier">ICL_INTERVAL_TYPE</span><span class="special">(</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">)</span> 592 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">andable2</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">>,</span> <span class="identifier">ICL_INTERVAL_TYPE</span><span class="special">(</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">)</span> 593 <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">xorable2</span> <span class="special"><</span> <span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">BitSetT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">,</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">Alloc</span><span class="special">>,</span> <span class="identifier">ICL_INTERVAL_TYPE</span><span class="special">(</span><span class="identifier">Interval</span><span class="special">,</span><span class="identifier">DomainT</span><span class="special">,</span><span class="identifier">Compare</span><span class="special">)</span> 594 <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="special">></span> 595 <span class="comment">//^ & - | + ^ & - | + ^ & - | + < == </span> 596 <span class="comment">//segment element container</span> 597</pre> 598<p> 599 </p> 600<p> 601 The first template parameter <code class="computeroutput"><span class="identifier">DomainT</span></code> 602 will be instantiated with an integral type that defines the kind of numbers 603 that can be elements of the set. Since we want to go for a large set 604 we use <code class="computeroutput"><span class="identifier">nat64</span></code> as default 605 which is a 64 bit unsigned integer ranging from <code class="computeroutput"><span class="number">0</span></code> 606 to <code class="computeroutput"><span class="number">2</span><span class="special">^</span><span class="number">64</span><span class="special">-</span><span class="number">1</span></code>. 607 As bitset parameter we also choose a 64-bit default. Parameters <code class="computeroutput"><span class="identifier">Combine</span></code> and <code class="computeroutput"><span class="identifier">Interval</span></code> 608 are necessary to be passed to dependent type expressions. An allocator 609 can be chosen, if desired. 610 </p> 611<p> 612 The nested list of private inheritance contains groups of template instantiations 613 from <a href="http://www.boost.org/doc/libs/1_39_0/libs/utility/operators.htm" target="_top">Boost.Operator</a>, 614 that provides derivable operators from more fundamental once. Implementing 615 the fundamental operators, we get the derivable ones <span class="emphasis"><em>for free</em></span>. 616 Below is a short overview of what we get using Boost.Operator, where 617 <a class="link" href="interface/function_synopsis.html#interval_set_types"><span class="bold"><strong>S</strong></span></a> 618 stands for <code class="computeroutput"><span class="identifier">large_bitset</span></code>, 619 <a class="link" href="interface/function_synopsis.html#interval_type"><span class="bold"><strong>i</strong></span></a> 620 for it's <code class="computeroutput"><span class="identifier">interval_type</span></code> 621 and <a class="link" href="interface/function_synopsis.html#element_type"><span class="bold"><strong>e</strong></span></a> 622 for it's <code class="computeroutput"><span class="identifier">domain_type</span></code> 623 or <code class="computeroutput"><span class="identifier">element_type</span></code>. 624 </p> 625<div class="informaltable"><table class="table"> 626<colgroup> 627<col> 628<col> 629<col> 630</colgroup> 631<thead><tr> 632<th> 633 <p> 634 Group 635 </p> 636 </th> 637<th> 638 <p> 639 fundamental 640 </p> 641 </th> 642<th> 643 <p> 644 derivable 645 </p> 646 </th> 647</tr></thead> 648<tbody> 649<tr> 650<td> 651 <p> 652 Equality, ordering 653 </p> 654 </td> 655<td> 656 <p> 657 <code class="computeroutput"><span class="special">==</span></code> 658 </p> 659 </td> 660<td> 661 <p> 662 <code class="computeroutput"><span class="special">!=</span></code> 663 </p> 664 </td> 665</tr> 666<tr> 667<td> 668 </td> 669<td> 670 <p> 671 <code class="computeroutput"><span class="special"><</span></code> 672 </p> 673 </td> 674<td> 675 <p> 676 <code class="computeroutput"><span class="special">></span> <span class="special"><=</span> 677 <span class="special">>=</span></code> 678 </p> 679 </td> 680</tr> 681<tr> 682<td> 683 <p> 684 Set operators (<a class="link" href="interface/function_synopsis.html#interval_set_types"><span class="bold"><strong>S</strong></span></a> x <a class="link" href="interface/function_synopsis.html#interval_set_types"><span class="bold"><strong>S</strong></span></a>) 685 </p> 686 </td> 687<td> 688 <p> 689 <code class="computeroutput"><span class="special">+=</span> <span class="special">|=</span> 690 <span class="special">-=</span> <span class="special">&=</span> 691 <span class="special">^=</span></code> 692 </p> 693 </td> 694<td> 695 <p> 696 <code class="computeroutput"><span class="special">+</span> <span class="special">|</span> 697 <span class="special">-</span> <span class="special">&</span> 698 <span class="special">^</span></code> 699 </p> 700 </td> 701</tr> 702<tr> 703<td> 704 <p> 705 Set operators (<a class="link" href="interface/function_synopsis.html#interval_set_types"><span class="bold"><strong>S</strong></span></a> x <a class="link" href="interface/function_synopsis.html#element_type"><span class="bold"><strong>e</strong></span></a>) 706 </p> 707 </td> 708<td> 709 <p> 710 <code class="computeroutput"><span class="special">+=</span> <span class="special">|=</span> 711 <span class="special">-=</span> <span class="special">&=</span> 712 <span class="special">^=</span></code> 713 </p> 714 </td> 715<td> 716 <p> 717 <code class="computeroutput"><span class="special">+</span> <span class="special">|</span> 718 <span class="special">-</span> <span class="special">&</span> 719 <span class="special">^</span></code> 720 </p> 721 </td> 722</tr> 723<tr> 724<td> 725 <p> 726 Set operators (<a class="link" href="interface/function_synopsis.html#interval_set_types"><span class="bold"><strong>S</strong></span></a> x <a class="link" href="interface/function_synopsis.html#interval_type"><span class="bold"><strong>i</strong></span></a>) 727 </p> 728 </td> 729<td> 730 <p> 731 <code class="computeroutput"><span class="special">+=</span> <span class="special">|=</span> 732 <span class="special">-=</span> <span class="special">&=</span> 733 <span class="special">^=</span></code> 734 </p> 735 </td> 736<td> 737 <p> 738 <code class="computeroutput"><span class="special">+</span> <span class="special">|</span> 739 <span class="special">-</span> <span class="special">&</span> 740 <span class="special">^</span></code> 741 </p> 742 </td> 743</tr> 744</tbody> 745</table></div> 746<p> 747 There is a number of associated types 748 </p> 749<p> 750</p> 751<pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">icl</span><span class="special">::</span><span class="identifier">interval_map</span> 752 <span class="special"><</span><span class="identifier">DomainT</span><span class="special">,</span> <span class="identifier">BitSetT</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">icl</span><span class="special">::</span><span class="identifier">partial_absorber</span><span class="special">,</span> 753 <span class="identifier">std</span><span class="special">::</span><span class="identifier">less</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">icl</span><span class="special">::</span><span class="identifier">inplace_bit_add</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">icl</span><span class="special">::</span><span class="identifier">inplace_bit_and</span><span class="special">></span> <span class="identifier">interval_bitmap_type</span><span class="special">;</span> 754 755<span class="keyword">typedef</span> <span class="identifier">DomainT</span> <span class="identifier">domain_type</span><span class="special">;</span> 756<span class="keyword">typedef</span> <span class="identifier">DomainT</span> <span class="identifier">element_type</span><span class="special">;</span> 757<span class="keyword">typedef</span> <span class="identifier">BitSetT</span> <span class="identifier">bitset_type</span><span class="special">;</span> 758<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">BitSetT</span><span class="special">::</span><span class="identifier">word_type</span> <span class="identifier">word_type</span><span class="special">;</span> 759<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">interval_bitmap_type</span><span class="special">::</span><span class="identifier">interval_type</span> <span class="identifier">interval_type</span><span class="special">;</span> 760<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">interval_bitmap_type</span><span class="special">::</span><span class="identifier">value_type</span> <span class="identifier">value_type</span><span class="special">;</span> 761</pre> 762<p> 763 </p> 764<p> 765 most importantly the implementing <code class="computeroutput"><span class="identifier">interval_bitmap_type</span></code> 766 that is used for the implementing container. 767 </p> 768<p> 769</p> 770<pre class="programlisting"><span class="keyword">private</span><span class="special">:</span> 771 <span class="identifier">interval_bitmap_type</span> <span class="identifier">_map</span><span class="special">;</span> 772</pre> 773<p> 774 </p> 775<p> 776 In order to use <a href="http://www.boost.org/doc/libs/1_39_0/libs/utility/operators.htm" target="_top">Boost.Operator</a> 777 we have to implement the fundamental operators as class members. This 778 can be done quite schematically. 779 </p> 780<p> 781</p> 782<pre class="programlisting"><span class="keyword">public</span><span class="special">:</span> 783 <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special">==(</span><span class="keyword">const</span> <span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span><span class="keyword">const</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">_map</span> <span class="special">==</span> <span class="identifier">rhs</span><span class="special">.</span><span class="identifier">_map</span><span class="special">;</span> <span class="special">}</span> 784 <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special"><</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span><span class="keyword">const</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">_map</span> <span class="special"><</span> <span class="identifier">rhs</span><span class="special">.</span><span class="identifier">_map</span><span class="special">;</span> <span class="special">}</span> 785 786 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">+=(</span><span class="keyword">const</span> <span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">{</span><span class="identifier">_map</span> <span class="special">+=</span> <span class="identifier">rhs</span><span class="special">.</span><span class="identifier">_map</span><span class="special">;</span> <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;}</span> 787 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">|=(</span><span class="keyword">const</span> <span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">{</span><span class="identifier">_map</span> <span class="special">|=</span> <span class="identifier">rhs</span><span class="special">.</span><span class="identifier">_map</span><span class="special">;</span> <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;}</span> 788 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">-=(</span><span class="keyword">const</span> <span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">{</span><span class="identifier">_map</span> <span class="special">-=</span> <span class="identifier">rhs</span><span class="special">.</span><span class="identifier">_map</span><span class="special">;</span> <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;}</span> 789 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">&=(</span><span class="keyword">const</span> <span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">{</span><span class="identifier">_map</span> <span class="special">&=</span> <span class="identifier">rhs</span><span class="special">.</span><span class="identifier">_map</span><span class="special">;</span> <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;}</span> 790 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">^=(</span><span class="keyword">const</span> <span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">{</span><span class="identifier">_map</span> <span class="special">^=</span> <span class="identifier">rhs</span><span class="special">.</span><span class="identifier">_map</span><span class="special">;</span> <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;}</span> 791 792 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">+=(</span><span class="keyword">const</span> <span class="identifier">element_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">{</span><span class="keyword">return</span> <span class="identifier">add</span><span class="special">(</span><span class="identifier">interval_type</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">));</span> <span class="special">}</span> 793 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">|=(</span><span class="keyword">const</span> <span class="identifier">element_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">{</span><span class="keyword">return</span> <span class="identifier">add</span><span class="special">(</span><span class="identifier">interval_type</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">));</span> <span class="special">}</span> 794 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">-=(</span><span class="keyword">const</span> <span class="identifier">element_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">{</span><span class="keyword">return</span> <span class="identifier">subtract</span><span class="special">(</span><span class="identifier">interval_type</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">));</span> <span class="special">}</span> 795 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">&=(</span><span class="keyword">const</span> <span class="identifier">element_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">{</span><span class="keyword">return</span> <span class="identifier">intersect</span><span class="special">(</span><span class="identifier">interval_type</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">));}</span> 796 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">^=(</span><span class="keyword">const</span> <span class="identifier">element_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">{</span><span class="keyword">return</span> <span class="identifier">flip</span><span class="special">(</span><span class="identifier">interval_type</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">));</span> <span class="special">}</span> 797 798 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">+=(</span><span class="keyword">const</span> <span class="identifier">interval_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">add</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">);</span> <span class="special">}</span> 799 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">|=(</span><span class="keyword">const</span> <span class="identifier">interval_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">add</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">);</span> <span class="special">}</span> 800 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">-=(</span><span class="keyword">const</span> <span class="identifier">interval_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">subtract</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">);</span> <span class="special">}</span> 801 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">&=(</span><span class="keyword">const</span> <span class="identifier">interval_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">intersect</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">);}</span> 802 <span class="identifier">large_bitset</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">^=(</span><span class="keyword">const</span> <span class="identifier">interval_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">flip</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">);</span> <span class="special">}</span> 803</pre> 804<p> 805 </p> 806<p> 807 As we can see, the seven most important operators that work on the class 808 type <code class="computeroutput"><span class="identifier">large_bitset</span></code> can 809 be directly implemented by propagating the operation to the implementing 810 <code class="computeroutput"><span class="identifier">_map</span></code> of type <code class="computeroutput"><span class="identifier">interval_bitmap_type</span></code>. For the operators 811 that work on segment and element types, we use member functions <code class="computeroutput"><span class="identifier">add</span></code>, <code class="computeroutput"><span class="identifier">subtract</span></code>, 812 <code class="computeroutput"><span class="identifier">intersect</span></code> and <code class="computeroutput"><span class="identifier">flip</span></code>. As we will see only a small amount 813 of adaper code is needed to couple those functions with the functionality 814 of the implementing container. 815 </p> 816<p> 817 Member functions <code class="computeroutput"><span class="identifier">add</span></code>, 818 <code class="computeroutput"><span class="identifier">subtract</span></code>, <code class="computeroutput"><span class="identifier">intersect</span></code> and <code class="computeroutput"><span class="identifier">flip</span></code>, 819 that allow to combine <span class="emphasis"><em><span class="bold"><strong>intervals</strong></span></em></span> 820 to <code class="computeroutput"><span class="identifier">large_bitsets</span></code> can 821 be uniformly implemented using a private function <code class="computeroutput"><span class="identifier">segment_apply</span></code> 822 that applies <span class="emphasis"><em>addition</em></span>, <span class="emphasis"><em>subtraction</em></span>, 823 <span class="emphasis"><em>intersection</em></span> or <span class="emphasis"><em>symmetric difference</em></span>, 824 after having translated the interval's borders into the right bitset 825 positions. 826 </p> 827<p> 828</p> 829<pre class="programlisting"><span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">add</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">interval_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">segment_apply</span><span class="special">(&</span><span class="identifier">large_bitset</span><span class="special">::</span><span class="identifier">add_</span><span class="special">,</span> <span class="identifier">rhs</span><span class="special">);}</span> 830<span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">subtract</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">interval_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">segment_apply</span><span class="special">(&</span><span class="identifier">large_bitset</span><span class="special">::</span><span class="identifier">subtract_</span><span class="special">,</span> <span class="identifier">rhs</span><span class="special">);}</span> 831<span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">intersect</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">interval_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">segment_apply</span><span class="special">(&</span><span class="identifier">large_bitset</span><span class="special">::</span><span class="identifier">intersect_</span><span class="special">,</span><span class="identifier">rhs</span><span class="special">);}</span> 832<span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">flip</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">interval_type</span><span class="special">&</span> <span class="identifier">rhs</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">segment_apply</span><span class="special">(&</span><span class="identifier">large_bitset</span><span class="special">::</span><span class="identifier">flip_</span><span class="special">,</span> <span class="identifier">rhs</span><span class="special">);}</span> 833</pre> 834<p> 835 </p> 836<p> 837 In the sample programs, that we will present to demonstrate the capabilities 838 of <code class="computeroutput"><span class="identifier">large_bitset</span></code> we will 839 need a few additional functions specifically output functions in two 840 different flavors. 841 </p> 842<p> 843</p> 844<pre class="programlisting"><span class="identifier">size_t</span> <span class="identifier">interval_count</span><span class="special">()</span><span class="keyword">const</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">icl</span><span class="special">::</span><span class="identifier">interval_count</span><span class="special">(</span><span class="identifier">_map</span><span class="special">);</span> <span class="special">}</span> 845 846<span class="keyword">void</span> <span class="identifier">show_segments</span><span class="special">()</span><span class="keyword">const</span> 847<span class="special">{</span> 848 <span class="keyword">for</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">interval_bitmap_type</span><span class="special">::</span><span class="identifier">const_iterator</span> <span class="identifier">it_</span> <span class="special">=</span> <span class="identifier">_map</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> 849 <span class="identifier">it_</span> <span class="special">!=</span> <span class="identifier">_map</span><span class="special">.</span><span class="identifier">end</span><span class="special">();</span> <span class="special">++</span><span class="identifier">it_</span><span class="special">)</span> 850 <span class="special">{</span> 851 <span class="identifier">interval_type</span> <span class="identifier">itv</span> <span class="special">=</span> <span class="identifier">it_</span><span class="special">-></span><span class="identifier">first</span><span class="special">;</span> 852 <span class="identifier">bitset_type</span> <span class="identifier">bits</span> <span class="special">=</span> <span class="identifier">it_</span><span class="special">-></span><span class="identifier">second</span><span class="special">;</span> 853 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">itv</span> <span class="special"><<</span> <span class="string">"->"</span> <span class="special"><<</span> <span class="identifier">bits</span><span class="special">.</span><span class="identifier">as_string</span><span class="special">(</span><span class="string">"01"</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> 854 <span class="special">}</span> 855<span class="special">}</span> 856 857<span class="keyword">void</span> <span class="identifier">show_matrix</span><span class="special">(</span><span class="keyword">const</span> <span class="keyword">char</span> <span class="identifier">off_on</span><span class="special">[</span><span class="number">2</span><span class="special">]</span> <span class="special">=</span> <span class="string">" 1"</span><span class="special">)</span><span class="keyword">const</span> 858<span class="special">{</span> 859 <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">;</span> 860 <span class="keyword">typename</span> <span class="identifier">interval_bitmap_type</span><span class="special">::</span><span class="identifier">const_iterator</span> <span class="identifier">iter</span> <span class="special">=</span> <span class="identifier">_map</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> 861 <span class="keyword">while</span><span class="special">(</span><span class="identifier">iter</span> <span class="special">!=</span> <span class="identifier">_map</span><span class="special">.</span><span class="identifier">end</span><span class="special">())</span> 862 <span class="special">{</span> 863 <span class="identifier">element_type</span> <span class="identifier">fst</span> <span class="special">=</span> <span class="identifier">icl</span><span class="special">::</span><span class="identifier">first</span><span class="special">(</span><span class="identifier">iter</span><span class="special">-></span><span class="identifier">first</span><span class="special">),</span> <span class="identifier">lst</span> <span class="special">=</span> <span class="identifier">icl</span><span class="special">::</span><span class="identifier">last</span><span class="special">(</span><span class="identifier">iter</span><span class="special">-></span><span class="identifier">first</span><span class="special">);</span> 864 <span class="keyword">for</span><span class="special">(</span><span class="identifier">element_type</span> <span class="identifier">chunk</span> <span class="special">=</span> <span class="identifier">fst</span><span class="special">;</span> <span class="identifier">chunk</span> <span class="special"><=</span> <span class="identifier">lst</span><span class="special">;</span> <span class="identifier">chunk</span><span class="special">++)</span> 865 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">iter</span><span class="special">-></span><span class="identifier">second</span><span class="special">.</span><span class="identifier">as_string</span><span class="special">(</span><span class="identifier">off_on</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> 866 <span class="special">++</span><span class="identifier">iter</span><span class="special">;</span> 867 <span class="special">}</span> 868<span class="special">}</span> 869</pre> 870<p> 871 </p> 872<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 873<li class="listitem"> 874 The first one, <code class="computeroutput"><span class="identifier">show_segments</span><span class="special">()</span></code> shows the container content as 875 it is implemented, in the compressed form. 876 </li> 877<li class="listitem"> 878 The second function <code class="computeroutput"><span class="identifier">show_matrix</span></code> 879 shows the complete matrix of bits that is represented by the container. 880 </li> 881</ul></div> 882</div> 883<div class="section"> 884<div class="titlepage"><div><div><h5 class="title"> 885<a name="boost_icl.projects.large_bitset.implementation_of_a_large_bitset.large_bitset__private_implementation"></a><a class="link" href="projects.html#boost_icl.projects.large_bitset.implementation_of_a_large_bitset.large_bitset__private_implementation" title="large_bitset: Private implementation">large_bitset: 886 Private implementation</a> 887</h5></div></div></div> 888<p> 889 In order to implement operations like the addition of an element say 890 <code class="computeroutput"><span class="number">42</span></code> to the large bitset, we 891 need to translate the <span class="emphasis"><em>value</em></span> to the <span class="emphasis"><em>position</em></span> 892 of the associated <span class="bold"><strong>bit</strong></span> representing 893 <code class="computeroutput"><span class="number">42</span></code> in the interval container 894 of bitsets. As an example, suppose we use a 895</p> 896<pre class="programlisting"><span class="identifier">large_bitset</span><span class="special"><</span><span class="identifier">nat</span><span class="special">,</span> <span class="identifier">mini</span><span class="special">::</span><span class="identifier">bits8</span><span class="special">></span> <span class="identifier">lbs</span><span class="special">;</span> 897</pre> 898<p> 899 that carries small bitsets of 8 bits only. The first four interval of 900 <code class="computeroutput"><span class="identifier">lbs</span></code> are assumed to be 901 associated with some bitsets. Now we want to add the interval <code class="computeroutput"><span class="special">[</span><span class="identifier">a</span><span class="special">,</span><span class="identifier">b</span><span class="special">]==[</span><span class="number">5</span><span class="special">,</span><span class="number">27</span><span class="special">]</span></code>. This 902 will result in the following situation: 903</p> 904<pre class="programlisting"> <span class="special">[</span><span class="number">0</span><span class="special">,</span><span class="number">1</span><span class="special">)-></span> <span class="special">[</span><span class="number">1</span><span class="special">,</span><span class="number">2</span><span class="special">)-></span> <span class="special">[</span><span class="number">2</span><span class="special">,</span><span class="number">3</span><span class="special">)-></span> <span class="special">[</span><span class="number">3</span><span class="special">,</span><span class="number">4</span><span class="special">)-></span> 905 <span class="special">[</span><span class="number">00101100</span><span class="special">][</span><span class="number">11001011</span><span class="special">][</span><span class="number">11101001</span><span class="special">][</span><span class="number">11100000</span><span class="special">]</span> 906<span class="special">+</span> <span class="special">[</span><span class="number">111</span> <span class="number">11111111</span> <span class="number">11111111</span> <span class="number">1111</span><span class="special">]</span> <span class="special">[</span><span class="number">5</span><span class="special">,</span><span class="number">27</span><span class="special">]</span> <span class="identifier">as</span> <span class="identifier">bitset</span> 907 <span class="identifier">a</span> <span class="identifier">b</span> 908 909<span class="special">=></span> <span class="special">[</span><span class="number">0</span><span class="special">,</span><span class="number">1</span><span class="special">)-></span> <span class="special">[</span><span class="number">1</span><span class="special">,</span><span class="number">3</span><span class="special">)-></span> <span class="special">[</span><span class="number">3</span><span class="special">,</span><span class="number">4</span><span class="special">)-></span> 910 <span class="special">[</span><span class="number">00101111</span><span class="special">][</span><span class="number">11111111</span><span class="special">][</span><span class="number">11110000</span><span class="special">]</span> 911</pre> 912<p> 913 So we have to convert values 5 and 27 into a part that points to the 914 interval and a part that refers to the position within the interval, 915 which is done by a <span class="emphasis"><em>division</em></span> and a <span class="emphasis"><em>modulo</em></span> 916 computation. (In order to have a consistent representation of the bitsequences 917 across the containers, within this project, bitsets are denoted with 918 the <span class="emphasis"><em><span class="bold"><strong>least significant bit on the left!</strong></span></em></span>) 919 </p> 920<p> 921</p> 922<pre class="programlisting"><span class="identifier">A</span> <span class="special">=</span> <span class="identifier">a</span><span class="special">/</span><span class="number">8</span> <span class="special">=</span> <span class="number">5</span><span class="special">/</span><span class="number">8</span> <span class="special">=</span> <span class="number">0</span> <span class="comment">// refers to interval </span> 923<span class="identifier">B</span> <span class="special">=</span> <span class="identifier">b</span><span class="special">/</span><span class="number">8</span> <span class="special">=</span> <span class="number">27</span><span class="special">/</span><span class="number">8</span> <span class="special">=</span> <span class="number">3</span> 924<span class="identifier">R</span> <span class="special">=</span> <span class="identifier">a</span><span class="special">%</span><span class="number">8</span> <span class="special">=</span> <span class="number">5</span><span class="special">%</span><span class="number">8</span> <span class="special">=</span> <span class="number">5</span> <span class="comment">// refers to the position in the associated bitset.</span> 925<span class="identifier">S</span> <span class="special">=</span> <span class="identifier">b</span><span class="special">%</span><span class="number">8</span> <span class="special">=</span> <span class="number">27</span><span class="special">%</span><span class="number">8</span> <span class="special">=</span> <span class="number">3</span> 926</pre> 927<p> 928 </p> 929<p> 930 All <span class="emphasis"><em>division</em></span> and <span class="emphasis"><em>modulo operations</em></span> 931 needed here are always done using a divisor <code class="computeroutput"><span class="identifier">d</span></code> 932 that is a power of <code class="computeroutput"><span class="number">2</span></code>: <code class="computeroutput"><span class="identifier">d</span> <span class="special">=</span> <span class="number">2</span><span class="special">^</span><span class="identifier">x</span></code>. 933 Therefore division and modulo can be expressed by bitset operations. 934 The constants needed for those bitset computations are defined here: 935 </p> 936<p> 937</p> 938<pre class="programlisting"><span class="keyword">private</span><span class="special">:</span> <span class="comment">// Example value</span> 939 <span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">word_type</span> <span class="comment">// 8-bit case </span> 940 <span class="identifier">digits</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span> <span class="comment">// --------------------------------------------------------------</span> 941 <span class="special"><</span><span class="identifier">word_type</span><span class="special">>::</span><span class="identifier">digits</span> <span class="special">,</span> <span class="comment">// 8 Size of the associated bitsets </span> 942 <span class="identifier">divisor</span> <span class="special">=</span> <span class="identifier">digits</span> <span class="special">,</span> <span class="comment">// 8 Divisor to find intervals for values</span> 943 <span class="identifier">last</span> <span class="special">=</span> <span class="identifier">digits</span><span class="special">-</span><span class="number">1</span> <span class="special">,</span> <span class="comment">// 7 Last bit (0 based)</span> 944 <span class="identifier">shift</span> <span class="special">=</span> <span class="identifier">log2_</span><span class="special"><</span><span class="identifier">divisor</span><span class="special">>::</span><span class="identifier">value</span> <span class="special">,</span> <span class="comment">// 3 To express the division as bit shift</span> 945 <span class="identifier">w1</span> <span class="special">=</span> <span class="keyword">static_cast</span><span class="special"><</span><span class="identifier">word_type</span><span class="special">>(</span><span class="number">1</span><span class="special">)</span> <span class="special">,</span> <span class="comment">// Helps to avoid static_casts for long long</span> 946 <span class="identifier">mask</span> <span class="special">=</span> <span class="identifier">divisor</span> <span class="special">-</span> <span class="identifier">w1</span> <span class="special">,</span> <span class="comment">// 7=11100000 Helps to express the modulo operation as bit_and</span> 947 <span class="identifier">all</span> <span class="special">=</span> <span class="special">~</span><span class="keyword">static_cast</span><span class="special"><</span><span class="identifier">word_type</span><span class="special">>(</span><span class="number">0</span><span class="special">),</span> <span class="comment">// 255=11111111 Helps to express a complete associated bitset</span> 948 <span class="identifier">top</span> <span class="special">=</span> <span class="identifier">w1</span> <span class="special"><<</span> <span class="special">(</span><span class="identifier">digits</span><span class="special">-</span><span class="identifier">w1</span><span class="special">)</span> <span class="special">;</span> <span class="comment">// 128=00000001 Value of the most significant bit of associated bitsets</span> 949 <span class="comment">// !> Note: Most signigicant bit on the right.</span> 950</pre> 951<p> 952 </p> 953<p> 954 Looking at the example again, we can see that we have to identify the 955 positions of the beginning and ending of the interval [5,27] that is 956 to insert, and then <span class="emphasis"><em><span class="bold"><strong>subdivide</strong></span></em></span> 957 that range of bitsets into three partitions. 958 </p> 959<div class="orderedlist"><ol class="orderedlist" type="1"> 960<li class="listitem"> 961 The bitset where the interval starts. 962 </li> 963<li class="listitem"> 964 the bitset where the interval ends 965 </li> 966<li class="listitem"> 967 The bitsets that are completely overlapped by the interval 968 </li> 969</ol></div> 970<p> 971</p> 972<pre class="programlisting"><span class="identifier">combine</span> <span class="identifier">interval</span> <span class="special">[</span><span class="number">5</span><span class="special">,</span><span class="number">27</span><span class="special">]</span> <span class="identifier">to</span> <span class="identifier">large_bitset</span> <span class="identifier">lbs</span> <span class="identifier">w</span><span class="special">.</span><span class="identifier">r</span><span class="special">.</span><span class="identifier">t</span><span class="special">.</span> <span class="identifier">some</span> <span class="identifier">operation</span> <span class="identifier">o</span> 973 974 <span class="special">[</span><span class="number">0</span><span class="special">,</span><span class="number">1</span><span class="special">)-></span> <span class="special">[</span><span class="number">1</span><span class="special">,</span><span class="number">2</span><span class="special">)-></span> <span class="special">[</span><span class="number">2</span><span class="special">,</span><span class="number">3</span><span class="special">)-></span> <span class="special">[</span><span class="number">3</span><span class="special">,</span><span class="number">4</span><span class="special">)-></span> 975 <span class="special">[</span><span class="number">00101100</span><span class="special">][</span><span class="number">11001011</span><span class="special">][</span><span class="number">11101001</span><span class="special">][</span><span class="number">11100000</span><span class="special">]</span> 976<span class="identifier">o</span> <span class="special">[</span><span class="number">111</span> <span class="number">11111111</span> <span class="number">11111111</span> <span class="number">1111</span><span class="special">]</span> 977 <span class="identifier">a</span> <span class="identifier">b</span> 978<span class="identifier">subdivide</span><span class="special">:</span> 979 <span class="special">[</span><span class="identifier">first</span><span class="special">!</span> <span class="special">][</span><span class="identifier">mid_1</span><span class="special">]</span> <span class="special">.</span> <span class="special">.</span> <span class="special">.[</span><span class="identifier">mid_n</span><span class="special">][</span> <span class="special">!</span><span class="identifier">last</span><span class="special">]</span> 980 <span class="special">[</span><span class="number">00000111</span><span class="special">][</span><span class="number">1.</span><span class="special">..</span><span class="number">1</span><span class="special">]</span> <span class="special">.</span> <span class="special">.</span> <span class="special">.[</span><span class="number">1.</span><span class="special">..</span><span class="number">1</span><span class="special">][</span><span class="number">11110000</span><span class="special">]</span> 981</pre> 982<p> 983 </p> 984<p> 985 After subdividing, we perform the operation <code class="computeroutput"><span class="identifier">o</span></code> 986 as follows: 987 </p> 988<div class="orderedlist"><ol class="orderedlist" type="1"> 989<li class="listitem"> 990 For the first bitset: Set all bits from ther starting bit (<code class="computeroutput"><span class="special">!</span></code>) to the end of the bitset to <code class="computeroutput"><span class="number">1</span></code>. All other bits are <code class="computeroutput"><span class="number">0</span></code>. Then perform operation <code class="computeroutput"><span class="identifier">o</span></code>: <code class="computeroutput"><span class="identifier">_map</span> 991 <span class="identifier">o</span><span class="special">=</span> 992 <span class="special">([</span><span class="number">0</span><span class="special">,</span><span class="number">1</span><span class="special">)-></span><span class="number">00000111</span><span class="special">)</span></code> 993 </li> 994<li class="listitem"> 995 For the last bitset: Set all bits from the beginning of the bitset 996 to the ending bit (<code class="computeroutput"><span class="special">!</span></code>) 997 to <code class="computeroutput"><span class="number">1</span></code>. All other bits 998 are <code class="computeroutput"><span class="number">0</span></code>. Then perform operation 999 <code class="computeroutput"><span class="identifier">o</span></code>: <code class="computeroutput"><span class="identifier">_map</span> <span class="identifier">o</span><span class="special">=</span> <span class="special">([</span><span class="number">3</span><span class="special">,</span><span class="number">4</span><span class="special">)-></span><span class="number">11110000</span><span class="special">)</span></code> 1000 </li> 1001<li class="listitem"> 1002 For the range of bitsets in between the staring and ending one, perform 1003 operation <code class="computeroutput"><span class="identifier">o</span></code>: <code class="computeroutput"><span class="identifier">_map</span> <span class="identifier">o</span><span class="special">=</span> <span class="special">([</span><span class="number">1</span><span class="special">,</span><span class="number">3</span><span class="special">)-></span><span class="number">11111111</span><span class="special">)</span></code> 1004 </li> 1005</ol></div> 1006<p> 1007 The algorithm, that has been outlined and illustrated by the example, 1008 is implemented by the private member function <code class="computeroutput"><span class="identifier">segment_apply</span></code>. 1009 To make the combiner operation a variable in this algorithm, we use a 1010 <span class="emphasis"><em>pointer to member function type</em></span> 1011 </p> 1012<p> 1013</p> 1014<pre class="programlisting"><span class="keyword">typedef</span> <span class="keyword">void</span> <span class="special">(</span><span class="identifier">large_bitset</span><span class="special">::*</span><span class="identifier">segment_combiner</span><span class="special">)(</span><span class="identifier">element_type</span><span class="special">,</span> <span class="identifier">element_type</span><span class="special">,</span> <span class="identifier">bitset_type</span><span class="special">);</span> 1015</pre> 1016<p> 1017 </p> 1018<p> 1019 as first function argument. We will pass member functions <code class="computeroutput"><span class="identifier">combine_</span></code> here, 1020</p> 1021<pre class="programlisting"><span class="identifier">combine_</span><span class="special">(</span><span class="identifier">first_of_interval</span><span class="special">,</span> <span class="identifier">end_of_interval</span><span class="special">,</span> <span class="identifier">some_bitset</span><span class="special">);</span> 1022</pre> 1023<p> 1024 that take the beginning and ending of an interval and a bitset and combine 1025 them to the implementing <code class="computeroutput"><span class="identifier">interval_bitmap_type</span> 1026 <span class="identifier">_map</span></code>. Here are these functions: 1027 </p> 1028<p> 1029</p> 1030<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">add_</span><span class="special">(</span><span class="identifier">DomainT</span> <span class="identifier">lo</span><span class="special">,</span> <span class="identifier">DomainT</span> <span class="identifier">up</span><span class="special">,</span> <span class="identifier">BitSetT</span> <span class="identifier">bits</span><span class="special">){</span><span class="identifier">_map</span> <span class="special">+=</span> <span class="identifier">value_type</span><span class="special">(</span><span class="identifier">interval_type</span><span class="special">::</span><span class="identifier">right_open</span><span class="special">(</span><span class="identifier">lo</span><span class="special">,</span><span class="identifier">up</span><span class="special">),</span> <span class="identifier">bits</span><span class="special">);}</span> 1031<span class="keyword">void</span> <span class="identifier">subtract_</span><span class="special">(</span><span class="identifier">DomainT</span> <span class="identifier">lo</span><span class="special">,</span> <span class="identifier">DomainT</span> <span class="identifier">up</span><span class="special">,</span> <span class="identifier">BitSetT</span> <span class="identifier">bits</span><span class="special">){</span><span class="identifier">_map</span> <span class="special">-=</span> <span class="identifier">value_type</span><span class="special">(</span><span class="identifier">interval_type</span><span class="special">::</span><span class="identifier">right_open</span><span class="special">(</span><span class="identifier">lo</span><span class="special">,</span><span class="identifier">up</span><span class="special">),</span> <span class="identifier">bits</span><span class="special">);}</span> 1032<span class="keyword">void</span> <span class="identifier">intersect_</span><span class="special">(</span><span class="identifier">DomainT</span> <span class="identifier">lo</span><span class="special">,</span> <span class="identifier">DomainT</span> <span class="identifier">up</span><span class="special">,</span> <span class="identifier">BitSetT</span> <span class="identifier">bits</span><span class="special">){</span><span class="identifier">_map</span> <span class="special">&=</span> <span class="identifier">value_type</span><span class="special">(</span><span class="identifier">interval_type</span><span class="special">::</span><span class="identifier">right_open</span><span class="special">(</span><span class="identifier">lo</span><span class="special">,</span><span class="identifier">up</span><span class="special">),</span> <span class="identifier">bits</span><span class="special">);}</span> 1033<span class="keyword">void</span> <span class="identifier">flip_</span><span class="special">(</span><span class="identifier">DomainT</span> <span class="identifier">lo</span><span class="special">,</span> <span class="identifier">DomainT</span> <span class="identifier">up</span><span class="special">,</span> <span class="identifier">BitSetT</span> <span class="identifier">bits</span><span class="special">){</span><span class="identifier">_map</span> <span class="special">^=</span> <span class="identifier">value_type</span><span class="special">(</span><span class="identifier">interval_type</span><span class="special">::</span><span class="identifier">right_open</span><span class="special">(</span><span class="identifier">lo</span><span class="special">,</span><span class="identifier">up</span><span class="special">),</span> <span class="identifier">bits</span><span class="special">);}</span> 1034</pre> 1035<p> 1036 </p> 1037<p> 1038 Finally we can code function <code class="computeroutput"><span class="identifier">segment_apply</span></code>, 1039 that does the partitioning and subsequent combining: 1040 </p> 1041<p> 1042</p> 1043<pre class="programlisting"><span class="identifier">large_bitset</span><span class="special">&</span> <span class="identifier">segment_apply</span><span class="special">(</span><span class="identifier">segment_combiner</span> <span class="identifier">combine</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">interval_type</span><span class="special">&</span> <span class="identifier">operand</span><span class="special">)</span> 1044<span class="special">{</span> 1045 <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">;</span> 1046 <span class="keyword">if</span><span class="special">(</span><span class="identifier">icl</span><span class="special">::</span><span class="identifier">is_empty</span><span class="special">(</span><span class="identifier">operand</span><span class="special">))</span> 1047 <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span> 1048 <span class="comment">// same as</span> 1049 <span class="identifier">element_type</span> <span class="identifier">base</span> <span class="special">=</span> <span class="identifier">icl</span><span class="special">::</span><span class="identifier">first</span><span class="special">(</span><span class="identifier">operand</span><span class="special">)</span> <span class="special">>></span> <span class="identifier">shift</span><span class="special">,</span> <span class="comment">// icl::first(operand) / divisor</span> 1050 <span class="identifier">ceil</span> <span class="special">=</span> <span class="identifier">icl</span><span class="special">::</span><span class="identifier">last</span> <span class="special">(</span><span class="identifier">operand</span><span class="special">)</span> <span class="special">>></span> <span class="identifier">shift</span><span class="special">;</span> <span class="comment">// icl::last (operand) / divisor</span> 1051 <span class="identifier">word_type</span> <span class="identifier">base_rest</span> <span class="special">=</span> <span class="identifier">icl</span><span class="special">::</span><span class="identifier">first</span><span class="special">(</span><span class="identifier">operand</span><span class="special">)</span> <span class="special">&</span> <span class="identifier">mask</span> <span class="special">,</span> <span class="comment">// icl::first(operand) % divisor</span> 1052 <span class="identifier">ceil_rest</span> <span class="special">=</span> <span class="identifier">icl</span><span class="special">::</span><span class="identifier">last</span> <span class="special">(</span><span class="identifier">operand</span><span class="special">)</span> <span class="special">&</span> <span class="identifier">mask</span> <span class="special">;</span> <span class="comment">// icl::last (operand) % divisor </span> 1053 1054 <span class="keyword">if</span><span class="special">(</span><span class="identifier">base</span> <span class="special">==</span> <span class="identifier">ceil</span><span class="special">)</span> <span class="comment">// [first, last] are within one bitset (chunk)</span> 1055 <span class="special">(</span><span class="keyword">this</span><span class="special">->*</span><span class="identifier">combine</span><span class="special">)(</span><span class="identifier">base</span><span class="special">,</span> <span class="identifier">base</span><span class="special">+</span><span class="number">1</span><span class="special">,</span> <span class="identifier">bitset_type</span><span class="special">(</span> <span class="identifier">to_upper_from</span><span class="special">(</span><span class="identifier">base_rest</span><span class="special">)</span> 1056 <span class="special">&</span> <span class="identifier">from_lower_to</span><span class="special">(</span><span class="identifier">ceil_rest</span><span class="special">)));</span> 1057 <span class="keyword">else</span> <span class="comment">// [first, last] spread over more than one bitset (chunk)</span> 1058 <span class="special">{</span> 1059 <span class="identifier">element_type</span> <span class="identifier">mid_low</span> <span class="special">=</span> <span class="identifier">base_rest</span> <span class="special">==</span> <span class="number">0</span> <span class="special">?</span> <span class="identifier">base</span> <span class="special">:</span> <span class="identifier">base</span><span class="special">+</span><span class="number">1</span><span class="special">,</span> <span class="comment">// first element of mid part </span> 1060 <span class="identifier">mid_up</span> <span class="special">=</span> <span class="identifier">ceil_rest</span> <span class="special">==</span> <span class="identifier">all</span> <span class="special">?</span> <span class="identifier">ceil</span><span class="special">+</span><span class="number">1</span> <span class="special">:</span> <span class="identifier">ceil</span> <span class="special">;</span> <span class="comment">// last element of mid part</span> 1061 1062 <span class="keyword">if</span><span class="special">(</span><span class="identifier">base_rest</span> <span class="special">></span> <span class="number">0</span><span class="special">)</span> <span class="comment">// Bitset of base interval has to be filled from base_rest to last</span> 1063 <span class="special">(</span><span class="keyword">this</span><span class="special">->*</span><span class="identifier">combine</span><span class="special">)(</span><span class="identifier">base</span><span class="special">,</span> <span class="identifier">base</span><span class="special">+</span><span class="number">1</span><span class="special">,</span> <span class="identifier">bitset_type</span><span class="special">(</span><span class="identifier">to_upper_from</span><span class="special">(</span><span class="identifier">base_rest</span><span class="special">)));</span> 1064 <span class="keyword">if</span><span class="special">(</span><span class="identifier">ceil_rest</span> <span class="special"><</span> <span class="identifier">all</span><span class="special">)</span> <span class="comment">// Bitset of ceil interval has to be filled from first to ceil_rest</span> 1065 <span class="special">(</span><span class="keyword">this</span><span class="special">->*</span><span class="identifier">combine</span><span class="special">)(</span><span class="identifier">ceil</span><span class="special">,</span> <span class="identifier">ceil</span><span class="special">+</span><span class="number">1</span><span class="special">,</span> <span class="identifier">bitset_type</span><span class="special">(</span><span class="identifier">from_lower_to</span><span class="special">(</span><span class="identifier">ceil_rest</span><span class="special">)));</span> 1066 <span class="keyword">if</span><span class="special">(</span><span class="identifier">mid_low</span> <span class="special"><</span> <span class="identifier">mid_up</span><span class="special">)</span> <span class="comment">// For the middle part all bits have to set.</span> 1067 <span class="special">(</span><span class="keyword">this</span><span class="special">->*</span><span class="identifier">combine</span><span class="special">)(</span><span class="identifier">mid_low</span><span class="special">,</span> <span class="identifier">mid_up</span><span class="special">,</span> <span class="identifier">bitset_type</span><span class="special">(</span><span class="identifier">all</span><span class="special">));</span> 1068 <span class="special">}</span> 1069 <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span> 1070<span class="special">}</span> 1071</pre> 1072<p> 1073 </p> 1074<p> 1075 The functions that help filling bitsets to and from a given bit are implemented 1076 here: 1077 </p> 1078<p> 1079</p> 1080<pre class="programlisting"><span class="keyword">static</span> <span class="identifier">word_type</span> <span class="identifier">from_lower_to</span><span class="special">(</span><span class="identifier">word_type</span> <span class="identifier">bit</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">bit</span><span class="special">==</span><span class="identifier">last</span> <span class="special">?</span> <span class="identifier">all</span> <span class="special">:</span> <span class="special">(</span><span class="identifier">w1</span><span class="special"><<(</span><span class="identifier">bit</span><span class="special">+</span><span class="identifier">w1</span><span class="special">))-</span><span class="identifier">w1</span><span class="special">;}</span> 1081<span class="keyword">static</span> <span class="identifier">word_type</span> <span class="identifier">to_upper_from</span><span class="special">(</span><span class="identifier">word_type</span> <span class="identifier">bit</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">bit</span><span class="special">==</span><span class="identifier">last</span> <span class="special">?</span> <span class="identifier">top</span> <span class="special">:</span> <span class="special">~((</span><span class="identifier">w1</span><span class="special"><<</span><span class="identifier">bit</span><span class="special">)-</span><span class="identifier">w1</span><span class="special">);</span> <span class="special">}</span> 1082</pre> 1083<p> 1084 </p> 1085<p> 1086 This completes the implementation of class template <code class="computeroutput"><span class="identifier">large_bitset</span></code>. 1087 Using only a small amount of mostly schematic code, we have been able 1088 to provide a pretty powerful, self compressing and generally usable set 1089 type for all integral domain types. 1090 </p> 1091</div> 1092</div> 1093</div> 1094</div> 1095<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 1096<td align="left"></td> 1097<td align="right"><div class="copyright-footer">Copyright © 2007-2010 Joachim 1098 Faulhaber<br>Copyright © 1999-2006 Cortex Software 1099 GmbH<p> 1100 Distributed under the Boost Software License, Version 1.0. (See accompanying 1101 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>) 1102 </p> 1103</div></td> 1104</tr></table> 1105<hr> 1106<div class="spirit-nav"> 1107<a accesskey="p" href="examples/custom_interval.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.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="concepts.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 1108</div> 1109</body> 1110</html> 1111
