ceph/src/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
  12 namespace boost
  13 {
  14
  15 #define BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(type)          \
  16     template <> struct numeric_values< type >               \
  17     {                                                       \
  18         typedef type value_type;                            \
  19         static type zero() { return 0.0; }                  \
  20         static type infinity()                              \
  21         {                                                   \
  22             return std::numeric_limits< type >::infinity(); \
  23         }                                                   \
  24     };
  25
  26 /**
  27  * This generic type reports various numeric values for some type. In the
  28  * general case, numeric values simply treat their maximum value as infinity
  29  * and the default-constructed value as 0.
  30  *
  31  * Specializations of this template can redefine the notions of zero and
  32  * infinity for various types. For example, the class is specialized for
  33  * floating point types to use the built in notion of infinity.
  34  */
  35 template < typename T > struct numeric_values
  36 {
  37     typedef T value_type;
  38
  39     static T zero() { return T(); }
  40
  41     static T infinity() { return (std::numeric_limits< T >::max)(); }
  42 };
  43
  44 // Specializations for floating point types refer to 0.0 and their infinity
  45 // value defined by numeric_limits.
  46 BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(float)
  47 BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(double)
  48 BOOST_GRAPH_SPECIALIZE_NUMERIC_FLOAT(long double)
  49
  50 #undef BOOST_GRAPH_SPECIALIZE_NUMERIC_VALUE
  51 }
  52
  53 #endif