daw_json_apply.h

Go to the documentation of this file.

// 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_link.h"
 
#include <daw/daw_cpp20_concept.h>
#include <daw/daw_cpp_feature_check.h>
#include <daw/daw_enable_requires.h>
#include <daw/daw_function_traits.h>
 
#include <string_view>
#include <tuple>
#include <type_traits>
 
namespace daw::json {
  inline namespace DAW_JSON_VER {
    namespace json_details {
#if defined( DAW_HAS_CPP20_CONCEPTS )
      template<typename T>
      concept has_call_operator = std::is_function_v<T> or requires {
        &std::remove_reference_t<T>::operator( );
      };
#else
      template<typename T, typename = void>
      inline constexpr bool has_call_operator = std::is_function_v<T>;
 
      template<typename T>
      inline constexpr bool has_call_operator<
        T, std::void_t<decltype( &std::remove_reference_t<T>::operator( ) )>> =
        true;
#endif
      template<typename Signature, typename Callable,
               typename... FromJsonParams>
      DAW_ATTRIB_INLINE constexpr auto
      json_apply_impl( Callable &&callable, FromJsonParams &&...params ) {
        using func_t = typename std::conditional_t<
          std::is_same_v<use_default, Signature>,
          daw::traits::identity<daw::func::function_traits<Callable>>,
          daw::traits::identity<daw::func::function_traits<Signature>>>::type;
 
        if constexpr( func_t::arity == 1 ) {
          return DAW_FWD( callable )(
            daw::json::from_json<
              typename func_t::template argument<0>::plain_type>(
              DAW_FWD( params )... ) );
        } else {
          return std::apply(
            DAW_FWD( callable ),
            daw::json::from_json<typename func_t::plain_params_t>(
              DAW_FWD( params )... ) );
        }
      }
    } // namespace json_details
 
    template<typename Signature = use_default, typename String,
             typename Callable DAW_ENABLEIF(
               json_details::has_call_operator<Callable> )>
    DAW_REQUIRES( json_details::has_call_operator<Callable> )
    constexpr auto json_apply( String &&json_doc, Callable &&callable ) {
      return json_details::json_apply_impl<Signature>( DAW_FWD( callable ),
                                                       DAW_FWD( json_doc ) );
    }
 
    template<typename Signature = use_default, typename String,
             typename Callable DAW_ENABLEIF(
               json_details::has_call_operator<Callable> )>
    DAW_REQUIRES( json_details::has_call_operator<Callable> )
    constexpr auto json_apply( String &&json_doc, std::string_view json_path,
                               Callable &&callable ) {
      return json_details::json_apply_impl<Signature>(
        DAW_FWD( callable ), DAW_FWD( json_doc ), json_path );
    }
 
    template<typename Signature = use_default, typename String,
             auto... PolicyFlags,
             typename Callable DAW_ENABLEIF(
               json_details::has_call_operator<Callable> )>
    DAW_REQUIRES( json_details::has_call_operator<Callable> )
    constexpr auto json_apply(
      String &&json_doc, std::string_view json_path,
      daw::json::options::parse_flags_t<PolicyFlags...> flags,
      Callable &&callable ) {
      return json_details::json_apply_impl<Signature>(
        DAW_FWD( callable ), DAW_FWD( json_doc ), json_path, flags );
    }
 
    template<typename Signature = use_default, typename String,
             auto... PolicyFlags,
             typename Callable DAW_ENABLEIF(
               json_details::has_call_operator<Callable> )>
    DAW_REQUIRES( json_details::has_call_operator<Callable> )
    constexpr auto json_apply(
      String &&json_doc,
      daw::json::options::parse_flags_t<PolicyFlags...> flags,
      Callable &&callable ) {
      return json_details::json_apply_impl<Signature>(
        DAW_FWD( callable ), DAW_FWD( json_doc ), flags );
    }
  } // namespace DAW_JSON_VER
} // namespace daw::json