Chris@16: // (C) Copyright 2007-2009 Andrew Sutton
Chris@16: //
Chris@16: // Use, modification and distribution are subject to the
Chris@16: // Boost Software License, Version 1.0 (See accompanying file
Chris@16: // LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_GRAPH_NUMERIC_VALUES_HPP
Chris@16: #define BOOST_GRAPH_NUMERIC_VALUES_HPP
Chris@16: 
Chris@16: #include <limits>
Chris@16: 
Chris@16: namespace boost
Chris@16: {
Chris@16: 
Chris@16: #define BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(type) \
Chris@16:     template <> struct numeric_values<type> { \
Chris@16:         typedef type value_type; \
Chris@16:         static type zero() { return 0.0; } \
Chris@16:         static type infinity() { return std::numeric_limits<type>::infinity(); } \
Chris@16:     };
Chris@16: 
Chris@16:     /**
Chris@16:      * This generic type reports various numeric values for some type. In the
Chris@16:      * general case, numeric values simply treat their maximum value as infinity
Chris@16:      * and the default-constructed value as 0.
Chris@16:      *
Chris@16:      * Specializations of this template can redefine the notions of zero and
Chris@16:      * infinity for various types. For example, the class is specialized for
Chris@16:      * floating point types to use the built in notion of infinity.
Chris@16:      */
Chris@16:     template <typename T>
Chris@16:     struct numeric_values
Chris@16:     {
Chris@16:         typedef T value_type;
Chris@16: 
Chris@16:         static T zero()
Chris@16:         { return T(); }
Chris@16: 
Chris@16:         static T infinity()
Chris@16:         { return (std::numeric_limits<T>::max)(); }
Chris@16:     };
Chris@16: 
Chris@16:     // Specializations for floating point types refer to 0.0 and their infinity
Chris@16:     // value defined by numeric_limits.
Chris@16:     BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(float)
Chris@16:     BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(double)
Chris@16:     BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(long double)
Chris@16: 
Chris@16: #undef BOOST_GRAPH_SPECIALIZE_NUMERIC_VALUE
Chris@16: }
Chris@16: 
Chris@16: #endif