daw_nullable_value.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/impl/version.h"
 
#include "daw/json/concepts/daw_nullable_value_fwd.h"
 
#include <daw/daw_cpp_feature_check.h>
#include <daw/daw_enable_requires.h>
 
#include <memory>
#include <optional>
#include <type_traits>
 
#if defined( __cpp_aggregate_paren_init )
#if __cpp_aggregate_paren_init >= 201902L
#define DAW_HAS_AGG_PAREN_INIT
#endif
#endif
 
namespace daw::json {
  inline namespace DAW_JSON_VER {
    namespace concepts {
      template<typename T>
      struct nullable_value_traits<std::optional<T>> {
        using value_type = T;
        using nullable_type = std::optional<T>;
        static constexpr bool is_nullable = true;
 
        static constexpr value_type const &read( nullable_type const &val ) {
          assert( has_value( val ) );
          return *val;
        }
 
        DAW_JSON_CPP23_STATIC_CALL_OP constexpr nullable_type
        operator( )( construct_nullable_with_value_t, nullable_type const &opt )
          DAW_JSON_CPP23_STATIC_CALL_OP_CONST
          noexcept( std::is_nothrow_copy_constructible_v<nullable_type> ) {
          return opt;
        }
 
        DAW_JSON_CPP23_STATIC_CALL_OP constexpr nullable_type
        operator( )( construct_nullable_with_value_t,
                     nullable_type &&opt ) DAW_JSON_CPP23_STATIC_CALL_OP_CONST
          noexcept( std::is_nothrow_move_constructible_v<nullable_type> ) {
          return opt;
        }
 
        template<typename... Args DAW_ENABLEIF(
          nullable_impl::is_nullable_value_type_constructible_v<value_type,
                                                                Args...> )>
        DAW_REQUIRES( nullable_impl::is_nullable_value_type_constructible_v<
                      value_type, Args...> )
        DAW_JSON_CPP23_STATIC_CALL_OP constexpr nullable_type
        operator( )( construct_nullable_with_value_t,
                     Args &&...args ) DAW_JSON_CPP23_STATIC_CALL_OP_CONST
          noexcept( std::is_nothrow_constructible_v<value_type, Args...> ) {
#if not defined( DAW_HAS_AGG_PAREN_INIT )
          if constexpr( std::is_aggregate_v<value_type> and
                        nullable_impl::is_list_constructible_v<value_type,
                                                               Args...> ) {
            return std::optional<value_type>(
              value_type{ DAW_FWD( args )... } );
          } else {
#endif
            return std::optional<value_type>( std::in_place,
                                              DAW_FWD( args )... );
#if not defined( DAW_HAS_AGG_PAREN_INIT )
          }
#endif
        }
 
        constexpr nullable_type DAW_JSON_CPP23_STATIC_CALL_OP
        operator( )( construct_nullable_with_empty_t )
          DAW_JSON_CPP23_STATIC_CALL_OP_CONST noexcept {
          return nullable_type( );
        }
 
        static constexpr bool has_value( nullable_type const &val ) {
          return val.has_value( );
        }
      };
 
      template<typename T>
      struct nullable_value_traits<std::unique_ptr<T>> {
        using value_type = T;
        using nullable_type = std::unique_ptr<T>;
        static constexpr bool is_nullable = true;
 
        static constexpr value_type const &read( nullable_type const &val ) {
          assert( has_value( val ) );
          return *val;
        }
 
        DAW_JSON_CPP23_STATIC_CALL_OP constexpr nullable_type
        operator( )( construct_nullable_with_value_t,
                     nullable_type &&opt ) DAW_JSON_CPP23_STATIC_CALL_OP_CONST
          noexcept( std::is_nothrow_move_constructible_v<nullable_type> ) {
          return opt;
        }
 
        template<typename... Args DAW_ENABLEIF(
          nullable_impl::is_nullable_value_type_constructible_v<value_type,
                                                                Args...> )>
        DAW_REQUIRES( nullable_impl::is_nullable_value_type_constructible_v<
                      value_type, Args...> )
        DAW_JSON_CPP23_STATIC_CALL_OP constexpr nullable_type
        operator( )( construct_nullable_with_value_t,
                     Args &&...args ) DAW_JSON_CPP23_STATIC_CALL_OP_CONST
          noexcept( std::is_nothrow_constructible_v<value_type, Args...> ) {
#if not defined( DAW_HAS_AGG_PAREN_INIT )
          if constexpr( std::is_aggregate_v<value_type> and
                        nullable_impl::is_list_constructible_v<value_type,
                                                               Args...> ) {
            return std::make_unique<value_type>(
              value_type{ DAW_FWD( args )... } );
          } else {
#endif
            return std::make_unique<value_type>( DAW_FWD( args )... );
#if not defined( DAW_HAS_AGG_PAREN_INIT )
          }
#endif
        }
 
        constexpr nullable_type DAW_JSON_CPP23_STATIC_CALL_OP operator( )(
          construct_nullable_with_pointer_t,
          value_type *ptr ) DAW_JSON_CPP23_STATIC_CALL_OP_CONST noexcept {
          return nullable_type( ptr );
        }
 
        constexpr nullable_type DAW_JSON_CPP23_STATIC_CALL_OP
        operator( )( construct_nullable_with_empty_t )
          DAW_JSON_CPP23_STATIC_CALL_OP_CONST noexcept {
          return nullable_type( );
        }
 
        static constexpr bool has_value( nullable_type const &val ) {
          return static_cast<bool>( val );
        }
      };
 
      template<typename T>
      struct nullable_value_traits<std::shared_ptr<T>> {
        using value_type = T;
        using nullable_type = std::shared_ptr<T>;
        static constexpr bool is_nullable = true;
 
        static constexpr value_type const &read( nullable_type const &val ) {
          assert( has_value( val ) );
          return *val;
        }
 
        DAW_JSON_CPP23_STATIC_CALL_OP constexpr nullable_type
        operator( )( construct_nullable_with_value_t, nullable_type const &opt )
          DAW_JSON_CPP23_STATIC_CALL_OP_CONST
          noexcept( std::is_nothrow_copy_constructible_v<nullable_type> ) {
          return opt;
        }
 
        DAW_JSON_CPP23_STATIC_CALL_OP constexpr nullable_type
        operator( )( construct_nullable_with_value_t,
                     nullable_type &&opt ) DAW_JSON_CPP23_STATIC_CALL_OP_CONST
          noexcept( std::is_nothrow_move_constructible_v<nullable_type> ) {
          return opt;
        }
 
        template<typename... Args DAW_ENABLEIF(
          nullable_impl::is_nullable_value_type_constructible_v<value_type,
                                                                Args...> )>
        DAW_REQUIRES( nullable_impl::is_nullable_value_type_constructible_v<
                      value_type, Args...> )
        DAW_JSON_CPP23_STATIC_CALL_OP constexpr nullable_type
        operator( )( construct_nullable_with_value_t,
                     Args &&...args ) DAW_JSON_CPP23_STATIC_CALL_OP_CONST
          noexcept( std::is_nothrow_constructible_v<value_type, Args...> ) {
#if not defined( DAW_HAS_AGG_PAREN_INIT )
          if constexpr( std::is_aggregate_v<value_type> and
                        nullable_impl::is_list_constructible_v<value_type,
                                                               Args...> ) {
            return std::make_shared<value_type>(
              value_type{ DAW_FWD( args )... } );
          } else {
#endif
            return std::make_shared<value_type>( DAW_FWD( args )... );
#if not defined( DAW_HAS_AGG_PAREN_INIT )
          }
#endif
        }
 
        constexpr nullable_type DAW_JSON_CPP23_STATIC_CALL_OP operator( )(
          construct_nullable_with_pointer_t,
          value_type *ptr ) DAW_JSON_CPP23_STATIC_CALL_OP_CONST noexcept {
          return nullable_type( ptr );
        }
 
        constexpr nullable_type DAW_JSON_CPP23_STATIC_CALL_OP
        operator( )( construct_nullable_with_empty_t )
          DAW_JSON_CPP23_STATIC_CALL_OP_CONST noexcept {
          return nullable_type( );
        }
 
        static constexpr bool has_value( nullable_type const &val ) {
          return static_cast<bool>( val );
        }
      };
 
      template<typename T>
      struct nullable_value_traits<T *> {
        using value_type = T;
        using nullable_type = T *;
        static constexpr bool is_nullable = true;
 
        static constexpr value_type const &read( nullable_type const &val ) {
          assert( has_value( val ) );
          return *val;
        }
 
        DAW_JSON_CPP23_STATIC_CALL_OP constexpr nullable_type operator( )(
          construct_nullable_with_value_t,
          nullable_type ptr ) DAW_JSON_CPP23_STATIC_CALL_OP_CONST noexcept {
          return ptr;
        }
 
        template<typename... Args DAW_ENABLEIF(
          nullable_impl::is_nullable_value_type_constructible_v<value_type,
                                                                Args...> )>
        DAW_REQUIRES( nullable_impl::is_nullable_value_type_constructible_v<
                      value_type, Args...> )
        DAW_JSON_CPP23_STATIC_CALL_OP constexpr nullable_type
        operator( )( construct_nullable_with_value_t,
                     Args &&...args ) DAW_JSON_CPP23_STATIC_CALL_OP_CONST
          noexcept( std::is_nothrow_constructible_v<value_type, Args...> ) {
#if not defined( DAW_HAS_AGG_PAREN_INIT )
          if constexpr( std::is_aggregate_v<T> and
                        nullable_impl::is_list_constructible_v<T, Args...> ) {
            return new value_type{ DAW_FWD( args )... };
          } else {
#endif
            return new value_type( DAW_FWD( args )... );
#if not defined( DAW_HAS_AGG_PAREN_INIT )
          }
#endif
        }
 
        constexpr nullable_type DAW_JSON_CPP23_STATIC_CALL_OP operator( )(
          construct_nullable_with_pointer_t,
          value_type *ptr ) DAW_JSON_CPP23_STATIC_CALL_OP_CONST noexcept {
          return ptr;
        }
 
        DAW_JSON_CPP23_STATIC_CALL_OP constexpr nullable_type
        operator( )( construct_nullable_with_empty_t )
          DAW_JSON_CPP23_STATIC_CALL_OP_CONST noexcept {
          return nullptr;
        }
 
        static constexpr bool has_value( nullable_type const &val ) {
          return static_cast<bool>( val );
        }
      };
    } // namespace concepts
  } // namespace DAW_JSON_VER
} // namespace daw::json
#if defined( DAW_HAS_AGG_PAREN_INIT )
#undef DAW_HAS_AGG_PAREN_INIT
#endif