ceph/src/boost/boost/icl/type_traits/unit_element.hpp

   1 /*-----------------------------------------------------------------------------+
   2 Copyright (c) 2008-2010: Joachim Faulhaber
   3 +------------------------------------------------------------------------------+
   4    Distributed under the Boost Software License, Version 1.0.
   5       (See accompanying file LICENCE.txt or copy at
   6            http://www.boost.org/LICENSE_1_0.txt)
   7 +-----------------------------------------------------------------------------*/
   8 #ifndef BOOST_ICL_TYPE_TRAITS_UNIT_ELEMENT_HPP_JOFA_080912
   9 #define BOOST_ICL_TYPE_TRAITS_UNIT_ELEMENT_HPP_JOFA_080912
  10
  11 #include <string>
  12 #include <boost/icl/type_traits/identity_element.hpp>
  13 #include <boost/icl/type_traits/succ_pred.hpp>
  14
  15 namespace boost{ namespace icl
  16 {
  17     template <class Type> struct unit_element{ static Type value(); };
  18
  19     template<> inline bool   unit_element<bool>::value()   { return true;}
  20     template<> inline float  unit_element<float>::value()  { return 1.0; }
  21     template<> inline double unit_element<double>::value() { return 1.0; }
  22     template<> inline long double unit_element<long double>::value()
  23                                                            { return 1.0; }
  24
  25     // Smallest 'visible' string that is greater than the empty string.
  26     template <>
  27     inline std::string unit_element<std::string>::value()
  28     { return std::string(" "); }
  29
  30     template <class Type>
  31     inline Type unit_element<Type>::value()
  32     { return icl::succ(identity_element<Type>::value()); }
  33
  34 }} // namespace boost icl
  35
  36 #endif
  37
  38