include/cppcoro/sequence_traits.hpp

0001 ///////////////////////////////////////////////////////////////////////////////
0002 // Copyright (c) Lewis Baker
0003 // Licenced under MIT license. See LICENSE.txt for details.
0004 ///////////////////////////////////////////////////////////////////////////////
0005 #ifndef CPPCORO_SEQUENCE_TRAITS_HPP_INCLUDED
0006 #define CPPCORO_SEQUENCE_TRAITS_HPP_INCLUDED
0007
0008 #include <type_traits>
0009
0010 namespace cppcoro
0011 {
0012     template<typename SEQUENCE>
0013     struct sequence_traits
0014     {
0015         using value_type = SEQUENCE;
0016         using difference_type = std::make_signed_t<SEQUENCE>;
0017         using size_type = std::make_unsigned_t<SEQUENCE>;
0018
0019         static constexpr value_type initial_sequence = static_cast<value_type>(-1);
0020
0021         static constexpr difference_type difference(value_type a, value_type b)
0022         {
0023             return static_cast<difference_type>(a - b);
0024         }
0025
0026         static constexpr bool precedes(value_type a, value_type b)
0027         {
0028             return difference(a, b) < 0;
0029         }
0030     };
0031 }
0032
0033 #endif