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52 lines
1.6 KiB
52 lines
1.6 KiB
// (C) Copyright 2007-2009 Andrew Sutton |
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// |
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// Use, modification and distribution are subject to the |
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// Boost Software License, Version 1.0 (See accompanying file |
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// LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt) |
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#ifndef BOOST_GRAPH_NUMERIC_VALUES_HPP |
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#define BOOST_GRAPH_NUMERIC_VALUES_HPP |
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#include <limits> |
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namespace boost |
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{ |
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#define BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(type) \ |
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template <> struct numeric_values<type> { \ |
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typedef type value_type; \ |
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static type zero() { return 0.0; } \ |
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static type infinity() { return std::numeric_limits<type>::infinity(); } \ |
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}; |
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/** |
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* This generic type reports various numeric values for some type. In the |
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* general case, numeric values simply treat their maximum value as infinity |
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* and the default-constructed value as 0. |
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* |
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* Specializations of this template can redefine the notions of zero and |
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* infinity for various types. For example, the class is specialized for |
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* floating point types to use the built in notion of infinity. |
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*/ |
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template <typename T> |
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struct numeric_values |
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{ |
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typedef T value_type; |
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static T zero() |
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{ return T(); } |
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static T infinity() |
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{ return (std::numeric_limits<T>::max)(); } |
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}; |
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// Specializations for floating point types refer to 0.0 and their infinity |
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// value defined by numeric_limits. |
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BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(float) |
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BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(double) |
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BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(long double) |
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#undef BOOST_GRAPH_SPECIALIZE_NUMERIC_VALUE |
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} |
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#endif
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