daw_json_location_info.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/impl/daw_json_assert.h"
#include "daw/json/impl/daw_json_find_result.h"
#include "daw/json/impl/daw_murmur3.h"
 
#include <daw/algorithms/daw_algorithm_adjacent_find.h>
#include <daw/daw_consteval.h>
#include <daw/daw_likely.h>
#include <daw/daw_logic.h>
#include <daw/daw_sort_n.h>
#include <daw/daw_string_view.h>
#include <daw/daw_traits.h>
#include <daw/daw_uint_buffer.h>
 
#include <cstddef>
#include <daw/stdinc/data_access.h>
 
#if defined( DAW_JSON_PARSER_DIAGNOSTICS )
#include <cmath>
#include <iostream>
#endif
 
namespace daw::json {
  inline namespace DAW_JSON_VER {
    namespace json_details {
      struct location_info_t {
        daw::string_view name;
        char const *first = nullptr;
        char const *last = nullptr;
        char const *class_first = nullptr;
        char const *class_last = nullptr;
        std::size_t counter = 0;
 
        [[nodiscard]] constexpr bool missing( ) const {
          return first == nullptr;
        }
 
        template<typename ParseState>
        constexpr void set_range( ParseState const &parse_state ) {
          first = parse_state.first;
          last = parse_state.last;
          class_first = parse_state.class_first;
          class_last = parse_state.class_last;
          counter = parse_state.counter;
        }
 
        template<typename ParseState>
        constexpr auto get_range( ) const {
          using range_t = typename ParseState::without_allocator_type;
          return range_t( first, last, class_first, class_last, counter );
        }
      };
 
      /***
       * Contains an array of member location_info mapped in a json_class
       * @tparam MemberCount Number of mapped members from json_class
       */
      template<std::size_t MemberCount, bool DoFullNameMatch = true>
      struct locations_info_t {
        using value_type = location_info_t;
        using reference = value_type &;
        using const_reference = value_type const &;
        static constexpr bool do_full_name_match = DoFullNameMatch;
        json_name_hash_t hashes[MemberCount];
        value_type names[MemberCount];
 
        constexpr const_reference operator[]( std::size_t idx ) const {
          daw_json_ensure( idx < MemberCount, ErrorReason::NumberOutOfRange );
          return names[idx];
        }
 
        constexpr reference operator[]( std::size_t idx ) {
          daw_json_ensure( idx < MemberCount, ErrorReason::NumberOutOfRange );
          return names[idx];
        }
 
        static constexpr std::size_t size( ) {
          return MemberCount;
        }
 
        template<bool expect_long_strings, std::size_t start_pos>
        [[nodiscard]] DAW_ATTRIB_INLINE constexpr std::size_t
        find_name( daw::string_view key ) const {
          auto const hash = name_hash<expect_long_strings>( key );
#if defined( DAW_JSON_BUGFIX_MSVC_EVAL_ORDER_002 )
          (void)start_pos;
          for( std::size_t n = 0; n < MemberCount; ++n ) {
#else
          for( std::size_t n = start_pos; n < MemberCount; ++n ) {
#endif
            if( hashes[n] == hash and names[n].name.size( ) == key.size( ) ) {
              if constexpr( do_full_name_match ) {
                if( DAW_UNLIKELY( key != names[n].name ) ) {
                  continue;
                }
              }
              return n;
            }
          }
          return MemberCount;
        }
      };
 
      // Should never be called outside a consteval context
      template<typename... MemberNames>
      static DAW_CONSTEVAL bool do_hashes_collide( ) {
        json_name_hash_t hashes[sizeof...( MemberNames )]{
          name_hash<false>( MemberNames::name )... };
 
        daw::sort( std::data( hashes ), daw::data_end( hashes ) );
        return daw::algorithm::adjacent_find( std::data( hashes ),
                                              daw::data_end( hashes ),
                                              []( auto l, auto r )
                                                DAW_JSON_CPP23_STATIC_CALL_OP {
                                                  return l == r;
                                                } ) != daw::data_end( hashes );
      }
 
      // Should never be called outside a consteval context
      template<typename ParseState, typename... JsonMembers>
      DAW_ATTRIB_FLATINLINE static DAW_JSON_MAKE_LOC_INFO_CONSTEVAL auto
      make_locations_info( ) {
#if defined( DAW_JSON_ALWAYS_FULL_NAME_MATCH )
        using do_full_name_match = std::true_type;
#else
        using do_full_name_match =
          std::bool_constant<ParseState::force_name_equal_check or
                             do_hashes_collide<JsonMembers...>( )>;
#endif
        return locations_info_t<sizeof...( JsonMembers ),
                                do_full_name_match::value>{
          /*hashes*/ { daw::name_hash<false>( JsonMembers::name )... },
          /*names*/ { location_info_t{ JsonMembers::name }... } };
      }
 
      /***
       * Get the position from already seen JSON members or move the parser
       * forward until we reach the end of the class or the member.
       * @tparam N Number of members in json_class
       * @tparam ParseState see IteratorRange
       * @param locations members location and names
       * @param parse_state Current JSON data
       * @return IteratorRange with begin( ) being start of value
       */
      enum class AllMembersMustExist { yes, no };
 
      template<std::size_t pos, AllMembersMustExist must_exist,
               bool from_start = false, std::size_t N, typename ParseState,
               bool B>
      [[nodiscard]] DAW_ATTRIB_INLINE static constexpr find_result<ParseState>
      find_class_member( ParseState &parse_state,
                         locations_info_t<N, B> &locations,
                         bool is_nullable, daw::string_view member_name ) {
 
        // silencing gcc9 warning as these are selectively used
        (void)is_nullable;
        (void)member_name;
 
        daw_json_assert_weak(
          nsc_or( is_nullable,
                  ( not locations[pos].missing( ) ),
                  ( not parse_state.is_closing_brace_checked( ) ) ),
          missing_member( member_name ),
          parse_state );
 
        parse_state.trim_left_unchecked( );
        bool known = not locations[pos].missing( );
        while( nsc_and(
          locations[pos].missing( ),
          ( not parse_state.empty( ) and parse_state.front( ) != '}' ) ) ) {
          // TODO: fully unescape name
          // parse_name checks if we have more and are quotes
          auto const name = parse_name( parse_state );
          auto const name_pos =
            locations.template find_name<ParseState::expect_long_strings,
                                         ( from_start ? 0 : pos )>( name );
          if constexpr( must_exist == AllMembersMustExist::yes ) {
            daw_json_assert_weak( name_pos < std::size( locations ),
                                  ErrorReason::UnknownMember,
                                  parse_state );
          } else {
#if defined( DAW_JSON_PARSER_DIAGNOSTICS )
            std::cerr << "DEBUG: Unknown member '" << name << '\n';
#endif
            if( name_pos >= std::size( locations ) ) {
              // This is not a member we are concerned with
              (void)skip_value( parse_state );
              parse_state.move_next_member_or_end( );
              continue;
            }
          }
          if( name_pos == pos ) {
            locations[pos].set_range( parse_state );
            break;
          } else {
#if defined( DAW_JSON_PARSER_DIAGNOSTICS )
            std::cerr << "DEBUG:  Out of order member '"
                      << locations.names[name_pos].name
                      << "' found, looking for '" << locations.names[pos].name
                      << ". It is "
                      << std::abs( static_cast<long long>( pos ) -
                                   static_cast<long long>( name_pos ) )
                      << " members ahead in constructor\n";
#endif
            // We are out of order, store position for later
            // OLDTODO: use type knowledge to speed up skip
            // OLDTODO: on skipped classes see if way to store
            //        member positions so that we don't have to
            //        re-parse them after
            // RESULT: storing preparsed is slower, don't try 3 times
            // it also limits the type of things we can parse potentially
            // Using locations to switch on BaseType is slower too
            locations[name_pos].set_range( skip_value( parse_state ) );
 
            if constexpr( ParseState::is_unchecked_input ) {
              if( name_pos + 1 < std::size( locations ) ) {
                parse_state.move_next_member( );
              } else {
                parse_state.move_next_member_or_end( );
              }
            } else {
              parse_state.move_next_member_or_end( );
            }
          }
        }
        if( locations[pos].missing( ) ) {
          known = true;
        }
        if constexpr( ParseState::has_allocator ) {
          return find_result{
            locations[pos].template get_range<ParseState>( ).with_allocator(
              parse_state ),
            known };
        } else {
          return find_result<ParseState>{
            locations[pos].template get_range<ParseState>( ), known };
        }
      }
    } // namespace json_details
  } // namespace DAW_JSON_VER
} // namespace daw::json