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<section id='main' class="content mod">
<h1 class='fqn'><span class='in-band'>Crate <a class='mod' href=''>bit_vec</a></span><span class='out-of-band'><span id='render-detail'>
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</span><a id='src-0' class='srclink' href='../src/bit_vec/lib.rs.html#31-2088' title='goto source code'>[src]</a></span></h1>
<div class='docblock'><p>Collections implemented with bit vectors.</p>
<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
<p>This is a simple example of the <a href="http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes">Sieve of Eratosthenes</a>
which calculates prime numbers up to a given limit.</p>
<pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>bit_vec</span>::<span class='ident'>BitVec</span>;
<span class='kw'>let</span> <span class='ident'>max_prime</span> <span class='op'>=</span> <span class='number'>10000</span>;
<span class='comment'>// Store the primes as a BitVec</span>
<span class='kw'>let</span> <span class='ident'>primes</span> <span class='op'>=</span> {
<span class='comment'>// Assume all numbers are prime to begin, and then we</span>
<span class='comment'>// cross off non-primes progressively</span>
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>bv</span> <span class='op'>=</span> <span class='ident'>BitVec</span>::<span class='ident'>from_elem</span>(<span class='ident'>max_prime</span>, <span class='boolval'>true</span>);
<span class='comment'>// Neither 0 nor 1 are prime</span>
<span class='ident'>bv</span>.<span class='ident'>set</span>(<span class='number'>0</span>, <span class='boolval'>false</span>);
<span class='ident'>bv</span>.<span class='ident'>set</span>(<span class='number'>1</span>, <span class='boolval'>false</span>);
<span class='kw'>for</span> <span class='ident'>i</span> <span class='kw'>in</span> <span class='number'>2</span>.. <span class='number'>1</span> <span class='op'>+</span> (<span class='ident'>max_prime</span> <span class='kw'>as</span> <span class='ident'>f64</span>).<span class='ident'>sqrt</span>() <span class='kw'>as</span> <span class='ident'>usize</span> {
<span class='comment'>// if i is a prime</span>
<span class='kw'>if</span> <span class='ident'>bv</span>[<span class='ident'>i</span>] {
<span class='comment'>// Mark all multiples of i as non-prime (any multiples below i * i</span>
<span class='comment'>// will have been marked as non-prime previously)</span>
<span class='kw'>for</span> <span class='ident'>j</span> <span class='kw'>in</span> <span class='ident'>i</span>.. {
<span class='kw'>if</span> <span class='ident'>i</span> <span class='op'>*</span> <span class='ident'>j</span> <span class='op'>>=</span> <span class='ident'>max_prime</span> {
<span class='kw'>break</span>;
}
<span class='ident'>bv</span>.<span class='ident'>set</span>(<span class='ident'>i</span> <span class='op'>*</span> <span class='ident'>j</span>, <span class='boolval'>false</span>)
}
}
}
<span class='ident'>bv</span>
};
<span class='comment'>// Simple primality tests below our max bound</span>
<span class='kw'>let</span> <span class='ident'>print_primes</span> <span class='op'>=</span> <span class='number'>20</span>;
<span class='macro'>print</span><span class='macro'>!</span>(<span class='string'>"The primes below {} are: "</span>, <span class='ident'>print_primes</span>);
<span class='kw'>for</span> <span class='ident'>x</span> <span class='kw'>in</span> <span class='number'>0</span>..<span class='ident'>print_primes</span> {
<span class='kw'>if</span> <span class='ident'>primes</span>.<span class='ident'>get</span>(<span class='ident'>x</span>).<span class='ident'>unwrap_or</span>(<span class='boolval'>false</span>) {
<span class='macro'>print</span><span class='macro'>!</span>(<span class='string'>"{} "</span>, <span class='ident'>x</span>);
}
}
<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>""</span>);
<span class='kw'>let</span> <span class='ident'>num_primes</span> <span class='op'>=</span> <span class='ident'>primes</span>.<span class='ident'>iter</span>().<span class='ident'>filter</span>(<span class='op'>|</span><span class='ident'>x</span><span class='op'>|</span> <span class='op'>*</span><span class='ident'>x</span>).<span class='ident'>count</span>();
<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>"There are {} primes below {}"</span>, <span class='ident'>num_primes</span>, <span class='ident'>max_prime</span>);
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>num_primes</span>, <span class='number'>1_229</span>);</pre>
</div><h2 id='structs' class='section-header'><a href="#structs">Structs</a></h2>
<table>
<tr class=' module-item'>
<td><a class='struct' href='struct.BitVec.html'
title='bit_vec::BitVec'>BitVec</a></td>
<td class='docblock short'>
<p>The bitvector type.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='struct' href='struct.Blocks.html'
title='bit_vec::Blocks'>Blocks</a></td>
<td class='docblock short'>
<p>An iterator over the blocks of a <code>BitVec</code>.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='struct' href='struct.IntoIter.html'
title='bit_vec::IntoIter'>IntoIter</a></td>
<td class='docblock short'>
</td>
</tr>
<tr class=' module-item'>
<td><a class='struct' href='struct.Iter.html'
title='bit_vec::Iter'>Iter</a></td>
<td class='docblock short'>
<p>An iterator for <code>BitVec</code>.</p>
</td>
</tr></table><h2 id='traits' class='section-header'><a href="#traits">Traits</a></h2>
<table>
<tr class=' module-item'>
<td><a class='trait' href='trait.BitBlock.html'
title='bit_vec::BitBlock'>BitBlock</a></td>
<td class='docblock short'>
<p>Abstracts over a pile of bits (basically unsigned primitives)</p>
</td>
</tr></table></section>
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