/Src/Dependencies/Boost/boost/graph/numeric_values.hpp

 1// (C) Copyright 2007-2009 Andrew Sutton
 2//
 3// Use, modification and distribution are subject to the
 4// Boost Software License, Version 1.0 (See accompanying file
 5// LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
 6
 7#ifndef BOOST_GRAPH_NUMERIC_VALUES_HPP
 8#define BOOST_GRAPH_NUMERIC_VALUES_HPP
 9
10#include <limits>
11
12namespace boost
13{
14
15#define BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(type) \
16    template <> struct numeric_values<type> { \
17        typedef type value_type; \
18        static type zero() { return 0.0; } \
19        static type infinity() { return std::numeric_limits<type>::infinity(); } \
20    };
21
22    /**
23     * This generic type reports various numeric values for some type. In the
24     * general case, numeric values simply treat their maximum value as infinity
25     * and the default-constructed value as 0.
26     *
27     * Specializations of this template can redefine the notions of zero and
28     * infinity for various types. For example, the class is specialized for
29     * floating point types to use the built in notion of infinity.
30     */
31    template <typename T>
32    struct numeric_values
33    {
34        typedef T value_type;
35
36        static T zero()
37        { return T(); }
38
39        static T infinity()
40        { return (std::numeric_limits<T>::max)(); }
41    };
42
43    // Specializations for floating point types refer to 0.0 and their infinity
44    // value defined by numeric_limits.
45    BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(float)
46    BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(double)
47    BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(long double)
48
49#undef BOOST_GRAPH_SPECIALIZE_NUMERIC_VALUE
50}
51
52#endif