daw_json_parse_class.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 "version.h"
 
#include "daw/json/daw_json_exception.h"
#include "daw/json/impl/daw_json_assert.h"
#include "daw/json/impl/daw_json_location_info.h"
#include "daw/json/impl/daw_json_name.h"
#include "daw/json/impl/daw_json_parse_common.h"
#include "daw/json/impl/daw_json_parse_value.h"
#include "daw/json/impl/daw_json_skip.h"
 
#include <daw/daw_callable.h>
#include <daw/daw_constinit.h>
#include <daw/daw_likely.h>
#include <daw/daw_traits.h>
#include <daw/traits/daw_traits_nth_element.h>
 
#include <cstddef>
#include <type_traits>
 
namespace daw::json {
  inline namespace DAW_JSON_VER {
    namespace json_details {
 
      template<typename JsonMember, typename ParseState>
      [[nodiscard]] DAW_ATTRIB_INLINE static constexpr json_result_t<JsonMember>
      parse_ordered_class_member( std::size_t &member_index,
                                  ParseState &parse_state ) {
 
        using json_member_t = ordered_member_subtype_t<JsonMember>;
 
        parse_state.move_next_member_or_end( );
        if constexpr( is_an_ordered_member_v<JsonMember> ) {
          pocm_details::maybe_skip_members<is_json_nullable_v<json_member_t>>(
            parse_state, member_index, JsonMember::member_index );
        } else {
          daw_json_assert_weak( parse_state.has_more( ),
                                ErrorReason::UnexpectedEndOfData,
                                parse_state );
        }
 
        // this is an out value, get position ready
        ++member_index;
 
        if( DAW_UNLIKELY( parse_state.front( ) == ']' ) ) {
          if constexpr( is_json_nullable_v<json_member_t> ) {
 
            auto loc = ParseState{ };
            return parse_value<json_member_t,
                               true,
                               json_member_t::expected_type>( loc );
          } else {
            daw_json_error(
              true, missing_member( "ordered_class_member" ), parse_state );
          }
        }
        return parse_value<json_member_t, false, json_member_t::expected_type>(
          parse_state );
      }
 
      template<typename JsonMember, bool NeedsClassPositions,
               typename ParseState>
      [[nodiscard]] constexpr json_result_t<JsonMember>
      parse_class_member_impl( ParseState &parse_state,
                               find_result<ParseState> fr ) {
 
        auto [loc, known] = fr;
 
        // If the member was found loc will have it's position
        if( not known ) {
          if constexpr( NeedsClassPositions ) {
            auto const cf = parse_state.class_first;
            auto const cl = parse_state.class_last;
            if constexpr( is_pinned_type_v<
                            json_result_t<without_name<JsonMember>>> ) {
              auto const after_parse = daw::on_scope_exit( [&] {
                parse_state.class_first = cf;
                parse_state.class_last = cl;
              } );
              return parse_value<without_name<JsonMember>,
                                 false,
                                 JsonMember::expected_type>( parse_state );
            } else {
              auto result =
                parse_value<without_name<JsonMember>,
                            false,
                            JsonMember::expected_type>( parse_state );
              parse_state.class_first = cf;
              parse_state.class_last = cl;
              return result;
            }
          } else {
            return parse_value<without_name<JsonMember>,
                               false,
                               JsonMember::expected_type>( parse_state );
          }
        }
        // We cannot find the member, check if the member is nullable
        if( loc.is_null( ) ) {
          if constexpr( is_json_nullable_v<JsonMember> ) {
            return parse_value_null<without_name<JsonMember>, true>( loc );
          } else {
            daw_json_ensure( not loc.is_null( ),
                             missing_member( std::string_view(
                               std::data( JsonMember::name ),
                               std::size( JsonMember::name ) ) ),
                             parse_state );
          }
        }
 
        // Member was previously skipped
        return parse_value<without_name<JsonMember>,
                           true,
                           JsonMember::expected_type>( loc );
      }
 
      template<std::size_t member_position, typename JsonMember,
               AllMembersMustExist must_exist, bool NeedsClassPositions,
               typename ParseState, std::size_t N>
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr json_result_t<JsonMember>
      parse_class_member( ParseState &parse_state,
                          locations_info_t<N, typename ParseState::iterator> &locations ) {
        parse_state.move_next_member_or_end( );
 
        daw_json_assert_weak( not parse_state.empty( ) and
                                parse_state.is_at_next_class_member( ),
                              ErrorReason::MissingMemberNameOrEndOfClass,
                              parse_state );
 
        return parse_class_member_impl<JsonMember, NeedsClassPositions>(
          parse_state,
          find_class_member<member_position, must_exist>(
            parse_state,
            locations,
            is_json_nullable_v<JsonMember>,
            JsonMember::name ) );
      }
 
      template<bool IsExactClass, typename ParseState, typename OldClassPos>
      DAW_ATTRIB_INLINE static constexpr void
      class_cleanup_now( ParseState &parse_state,
                         OldClassPos const &old_class_pos ) {
        daw_json_assert_weak( parse_state.has_more( ),
                              ErrorReason::UnexpectedEndOfData,
                              parse_state );
        parse_state.move_next_member_or_end( );
        // If we fulfill the contract before all values are parses
        parse_state.move_to_next_class_member( );
        if constexpr( IsExactClass ) {
          daw_json_assert_weak( parse_state.front( ) == '}',
                                ErrorReason::UnknownMember,
                                parse_state );
          parse_state.remove_prefix( );
        } else {
          // Usually every member has been parsed and we are at the end
          if( parse_state.has_more( ) and parse_state.front( ) == '}' ) {
            parse_state.remove_prefix( );
          } else {
            (void)parse_state.skip_class( );
          }
          // Yes this must be checked.  We maybe at the end of document. After
          // the 2nd try, give up
        }
        parse_state.trim_left_checked( );
        parse_state.set_class_position( old_class_pos );
      }
 
      template<typename JsonClass, typename... JsonMembers, typename ParseState,
               std::size_t... Is>
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr json_result_t<JsonClass>
      parse_json_class( ParseState &parse_state, std::index_sequence<Is...> ) {
        static_assert( is_a_json_type_v<JsonClass> );
        using T = json_result_t<JsonClass>;
        using Constructor = json_constructor_t<JsonClass>;
        static_assert( has_json_data_contract_trait_v<T>, "Unexpected type" );
        using must_exist =
          daw::constant<( all_json_members_must_exist_v<T, ParseState>
                            ? AllMembersMustExist::yes
                            : AllMembersMustExist::no )>;
 
        parse_state.trim_left( );
        // TODO, use member name
        daw_json_assert_weak( parse_state.is_opening_brace_checked( ),
                              ErrorReason::InvalidClassStart,
                              parse_state );
 
        auto const old_class_pos = parse_state.get_class_position( );
        parse_state.set_class_position( );
        parse_state.remove_prefix( );
        parse_state.trim_left( );
 
        if constexpr( sizeof...( JsonMembers ) == 0 ) {
          // Clang-CL with MSVC has issues if we don't do empties this way
          class_cleanup_now<all_json_members_must_exist_v<T, ParseState>>(
            parse_state, old_class_pos );
 
          if constexpr( should_construct_explicitly_v<Constructor,
                                                      T,
                                                      ParseState> ) {
            return T{ };
          } else {
            return construct_value_tp<T, Constructor>( parse_state,
                                                       fwd_pack{ } );
          }
        } else {
          using NeedClassPositions = std::bool_constant<(
            ( must_be_class_member_v<typename JsonMembers::without_name> or
              ... ) )>;
 
#if defined( DAW_JSON_BUGFIX_MSVC_KNOWN_LOC_ICE_003 )
          auto known_locations =
            make_locations_info<ParseState, JsonMembers...>( );
#else
          auto known_locations = DAW_AS_CONSTANT(
            ( make_locations_info<ParseState, JsonMembers...>( ) ) );
#endif
 
          if constexpr( is_pinned_type_v<json_result_t<JsonClass>> ) {
            auto const run_after_parse = daw::on_exit_success( [&] {
              class_cleanup_now<all_json_members_must_exist_v<T, ParseState>>(
                parse_state, old_class_pos );
            } );
            (void)run_after_parse;
 
            if constexpr( should_construct_explicitly_v<Constructor,
                                                        T,
                                                        ParseState> ) {
              return T{
                parse_class_member<Is,
                                   daw::traits::nth_element<Is, JsonMembers...>,
                                   must_exist::value,
                                   NeedClassPositions::value>(
                  parse_state, known_locations )... };
            } else {
              return construct_value_tp<T, Constructor>(
                parse_state,
                fwd_pack{ parse_class_member<
                  Is,
                  daw::traits::nth_element<Is, JsonMembers...>,
                  must_exist::value,
                  NeedClassPositions::value>( parse_state,
                                              known_locations )... } );
            }
          } else {
            if constexpr( should_construct_explicitly_v<Constructor,
                                                        T,
                                                        ParseState> ) {
              auto result = T{
                parse_class_member<Is,
                                   daw::traits::nth_element<Is, JsonMembers...>,
                                   must_exist::value,
                                   NeedClassPositions::value>(
                  parse_state, known_locations )... };
 
              class_cleanup_now<all_json_members_must_exist_v<T, ParseState>>(
                parse_state, old_class_pos );
              return result;
            } else {
              auto result = construct_value_tp<T, Constructor>(
                parse_state,
                fwd_pack{ parse_class_member<
                  Is,
                  daw::traits::nth_element<Is, JsonMembers...>,
                  must_exist::value,
                  NeedClassPositions::value>( parse_state,
                                              known_locations )... } );
 
              class_cleanup_now<all_json_members_must_exist_v<T, ParseState>>(
                parse_state, old_class_pos );
              return result;
            }
          }
        }
      }
#if defined( DAW_JSON_HAS_REFLECTION )
      template<typename JsonClass, typename... JsonMembers, typename ParseState,
               std::size_t... Is>
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr json_result_t<JsonClass>
      parse_json_reflected_class( ParseState &parse_state,
                                  std::index_sequence<Is...> ) {
        static_assert( sizeof...( JsonMembers ) > 0 );
        using T = json_result_t<JsonClass>;
        static_assert( refl_details::PotentiallyReflectable<T> );
 
        static constexpr auto must_exist =
          all_json_members_must_exist_v<T, ParseState>
            ? AllMembersMustExist::yes
            : AllMembersMustExist::no;
 
        parse_state.trim_left( );
 
        daw_json_assert_weak( parse_state.is_opening_brace_checked( ),
                              ErrorReason::InvalidClassStart,
                              parse_state );
 
        auto const old_class_pos = parse_state.get_class_position( );
        parse_state.set_class_position( );
        parse_state.remove_prefix( );
        parse_state.trim_left( );
 
        static constexpr auto NeedClassPositions =
          ( must_be_class_member_v<typename JsonMembers::without_name> or ... );
 
        auto known_locations =
          make_locations_info<ParseState, JsonMembers...>( );
 
        auto result = T{ parse_class_member<Is,
                                            JsonMembers...[Is],
                                            must_exist,
                                            NeedClassPositions>(
          parse_state, known_locations )... };
 
        class_cleanup_now<all_json_members_must_exist_v<T, ParseState>>(
          parse_state, old_class_pos );
        return result;
      }
#endif
      template<typename JsonClass, typename... JsonMembers, typename ParseState>
      [[nodiscard]] static constexpr json_result_t<JsonClass>
      parse_json_tuple_class( ParseState &parse_state ) {
        static_assert( is_a_json_type_v<JsonClass> );
        using T = json_base_type_t<JsonClass>;
        using Constructor = json_constructor_t<JsonClass>;
        static_assert( has_json_data_contract_trait_v<T>, "Unexpected type" );
        static_assert(
          daw::is_callable_v<Constructor, json_result_t<JsonMembers>...>,
          "Supplied types cannot be used for construction of this type" );
 
        parse_state.trim_left( ); // Move to array start '['
        daw_json_assert_weak( parse_state.is_opening_bracket_checked( ),
                              ErrorReason::InvalidArrayStart,
                              parse_state );
        auto const old_class_pos = parse_state.get_class_position( );
        parse_state.set_class_position( );
        parse_state.remove_prefix( );
        parse_state.trim_left( );
 
        std::size_t current_idx = 0;
 
        if constexpr( is_pinned_type_v<json_result_t<JsonClass>> ) {
          auto const run_after_parse = daw::on_exit_success( [&] {
            ordered_class_cleanup<all_json_members_must_exist_v<T, ParseState>,
                                  ParseState,
                                  decltype( old_class_pos )>( parse_state,
                                                              old_class_pos );
          } );
          (void)run_after_parse;
          if constexpr( should_construct_explicitly_v<Constructor,
                                                      T,
                                                      ParseState> ) {
            return T{ parse_ordered_class_member<JsonMembers>(
              current_idx, parse_state )... };
          } else {
            return construct_value_tp<T, Constructor>(
              parse_state,
              fwd_pack{ parse_ordered_class_member<JsonMembers>(
                current_idx, parse_state )... } );
          }
        } else {
          auto result = [&] {
            if constexpr( should_construct_explicitly_v<Constructor,
                                                        T,
                                                        ParseState> ) {
              return T{ parse_ordered_class_member<JsonMembers>(
                current_idx, parse_state )... };
            } else {
              return construct_value_tp<T, Constructor>(
                parse_state,
                fwd_pack{ parse_ordered_class_member<JsonMembers>(
                  current_idx, parse_state )... } );
            }
          }( );
          if constexpr( all_json_members_must_exist_v<T, ParseState> ) {
            parse_state.trim_left( );
            daw_json_assert_weak( parse_state.front( ) == ']',
                                  ErrorReason::UnknownMember,
                                  parse_state );
            parse_state.remove_prefix( );
            parse_state.trim_left( );
          } else {
            (void)parse_state.skip_array( );
          }
          parse_state.set_class_position( old_class_pos );
          return result;
        }
      }
    } // namespace json_details
  } // namespace DAW_JSON_VER
} // namespace daw::json