53 lines
1.6 KiB
C++
53 lines
1.6 KiB
C++
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// (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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