2001-12-07 13:19:38 +00:00
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
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<title>Compile-Time Extrema Templates</title>
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<body bgcolor="white" text="black" link="blue" alink="red" vlink="purple">
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2004-10-05 15:45:52 +00:00
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<h1><img src="../../../boost.png" alt="boost.png (6897 bytes)"
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2001-12-07 13:19:38 +00:00
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align="middle" width="277" height="86">Compile-Time Extrema
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Templates</h1>
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<p>The class templates in <cite><a
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href="../../../boost/integer/static_min_max.hpp"><boost/integer/static_min_max.hpp></a></cite>
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provide a compile-time evaluation of the minimum or maximum of
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two integers. These facilities are useful for generic programming problems.</p>
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<h2><a name="contents">Contents</a></h2>
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<ul>
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<li><a href="#contents">Contents</a></li>
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<li><a href="#synopsis">Synopsis</a></li>
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<li><a href="#usage">Usage</a></li>
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<li><a href="#example">Example</a></li>
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<li><a href="#demo">Demonstration Program</a></li>
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<li><a href="#rationale">Rationale</a></li>
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<li><a href="#credits">Credits</a></li>
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</ul>
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<h2><a name="synopsis">Synopsis</a></h2>
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<blockquote><pre>
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namespace boost
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{
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template < long Value1, long Value2 >
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struct static_signed_min;
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template < long Value1, long Value2 >
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struct static_signed_max;
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template < unsigned long Value1, unsigned long Value2 >
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struct static_unsigned_min;
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template < unsigned long Value1, unsigned long Value2 >
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struct static_unsigned_max;
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}
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</pre></blockquote>
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<h2><a name="usage">Usage</a></h2>
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<p>The four class templates provide the combinations for finding the
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minimum or maximum of two signed or <code>unsigned</code>
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(<code>long</code>) parameters, <var>Value1</var> and <var>Value2</var>,
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at compile-time. Each template has a single static data member,
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<code>value</code>, which is set to the respective minimum or maximum
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of the template's parameters.</p>
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<h2><a name="example">Example</a></h2>
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<blockquote><pre>
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#include <boost/integer/static_min_max.hpp>
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template < unsigned long AddendSize1, unsigned long AddendSize2 >
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class adder
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{
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public:
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static unsigned long const addend1_size = AddendSize1;
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static unsigned long const addend2_size = AddendSize2;
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static unsigned long const sum_size = boost::static_unsigned_max<AddendSize1, AddendSize2>::value + 1;
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typedef int addend1_type[ addend1_size ];
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typedef int addend2_type[ addend2_size ];
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typedef int sum_type[ sum_size ];
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void operator ()( addend1_type const &a1, addend2_type const &a2, sum_type &s ) const;
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};
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//...
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int main()
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{
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int const a1[] = { 0, 4, 3 }; // 340
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int const a2[] = { 9, 8 }; // 89
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int s[ 4 ];
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adder<3,2> obj;
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obj( a1, a2, s ); // 's' should be 429 or { 9, 2, 4, 0 }
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//...
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}
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</pre></blockquote>
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<h2><a name="demo">Demonstration Program</a></h2>
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<p>The program <a
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href="../test/static_min_max_test.cpp">static_min_max_test.cpp</a> is a
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simplistic demonstration of various comparisons using the compile-time
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extrema class templates.</p>
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<h2><a name="rationale">Rationale</a></h2>
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<p>Sometimes the minimum or maximum of several values needs to be found
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for later compile-time processing, <i>e.g.</i> for a bound for another
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class template.</p>
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<h2><a name="credits">Credits</a></h2>
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<p>The author of the Boost compile-time extrema class templates is <a
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2002-07-27 20:08:51 +00:00
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href="../../../people/daryle_walker.html">Daryle Walker</a>.</p>
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2001-12-07 13:19:38 +00:00
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<hr>
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<p>Revised October 12, 2001</p>
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<p>© Copyright Daryle Walker 2001. Permission to copy, use,
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modify, sell and distribute this document is granted provided this
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copyright notice appears in all copies. This document is provided
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"as is" without express or implied warranty, and with no claim
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as to its suitability for any purpose.</p>
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</body>
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</html>
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