daw_json_exec_modes.h

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// Copyright (c) Darrell Wright
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Official repository: https://github.com/beached/daw_json_link
//
 
#pragma once
 
#include "daw/json/daw_json_switches.h"
#include "daw/json/impl/version.h"
 
#include <daw/daw_cpp_feature_check.h>
#include <daw/daw_is_constant_evaluated.h>
 
#include <string_view>
#include <type_traits>
 
namespace daw::json {
  inline namespace DAW_JSON_VER {
    struct default_exec_tag {
      static constexpr std::string_view name = "default_mode";
    };
    struct constexpr_exec_tag : default_exec_tag {
      static constexpr std::string_view name = "constexpr";
    };
    struct runtime_exec_tag : constexpr_exec_tag {
      static constexpr std::string_view name = "runtime";
    };
#if defined( DAW_ALLOW_SSE42 )
    struct sse42_exec_tag : runtime_exec_tag {
      static constexpr std::string_view name = "sse4.2";
    };
    using simd_exec_tag = sse42_exec_tag;
#else
    struct simd_exec_tag : runtime_exec_tag {
      static constexpr std::string_view name = "simd";
    };
#endif
 
    namespace json_details {
      template<typename ExecTag>
      DAW_ATTRIB_INLINE constexpr bool use_constexpr_exec_mode( ) {
#if defined( DAW_HAS_IF_CONSTEVAL )
        if consteval {
          return true;
        } else {
          return false;
        }
#elif defined( DAW_HAS_IS_CONSTANT_EVALUATED )
        return DAW_IS_CONSTANT_EVALUATED( );
#else
        // Cannot detect constant evaluation, only leave the constexpr code
        // paths when the runtime or simd exec mode was asked for
        return not std::is_base_of_v<runtime_exec_tag, ExecTag>;
#endif
      }
 
      template<typename ExecTag>
      DAW_ATTRIB_INLINE constexpr bool use_simd_exec_mode( ) {
#if defined( DAW_HAS_IF_CONSTEVAL ) or defined( DAW_HAS_IS_CONSTANT_EVALUATED )
        return true;
#else
        return std::is_base_of_v<simd_exec_tag, ExecTag>;
#endif
      }
    } // namespace json_details
  } // namespace DAW_JSON_VER
} // namespace daw::json