daw_json_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/daw_json_data_contract.h"
#include "daw/json/impl/daw_json_arrow_proxy.h"
#include "daw/json/impl/daw_json_assert.h"
#include "daw/json/impl/daw_json_parse_name.h"
#include "daw/json/impl/daw_json_parse_policy.h"
#include "daw/json/impl/daw_json_parse_unsigned_int.h"
#include "daw/json/impl/daw_json_parse_value_fwd.h"
#include "daw/json/impl/daw_json_skip.h"
#include "daw/json/impl/daw_json_traits.h"
#include "daw/json/impl/daw_json_value_fwd.h"
 
#include <daw/daw_algorithm.h>
#include <daw/daw_move.h>
#include <daw/daw_utility.h>
 
#include <cassert>
#include <cstddef>
#include <daw/stdinc/tuple_traits.h>
#include <optional>
#include <string_view>
 
namespace daw::json {
  inline namespace DAW_JSON_VER {
    template<json_options_t PolicyFlags = json_details::default_policy_flag,
             typename Allocator = json_details::NoAllocator>
    struct basic_json_pair {
      using ParseState =
        TryDefaultParsePolicy<BasicParsePolicy<PolicyFlags, Allocator>>;
 
      std::optional<std::string_view> name;
      basic_json_value<PolicyFlags, Allocator> value;
    };
 
    template<std::size_t Idx, json_options_t PolicyFlags, typename Allocator>
    constexpr decltype( auto )
    get( basic_json_pair<PolicyFlags, Allocator> const &parse_state ) {
      static_assert(
        Idx < 2,
        "Invalid index. Valid values are 0 for name, and 1 for value" );
      if constexpr( Idx == 0 ) {
        return parse_state.name;
      } else {
        return parse_state.value;
      }
    }
 
    template<std::size_t Idx, json_options_t PolicyFlags, typename Allocator>
    constexpr decltype( auto )
    get( basic_json_pair<PolicyFlags, Allocator> &parse_state ) {
      static_assert(
        Idx < 2,
        "Invalid index. Valid values are 0 for name, and 1 for value" );
      if constexpr( Idx == 0 ) {
        return parse_state.name;
      } else {
        return parse_state.value;
      }
    }
 
    template<std::size_t Idx, json_options_t PolicyFlags, typename Allocator>
    constexpr decltype( auto )
    get( basic_json_pair<PolicyFlags, Allocator> &&parse_state ) {
      static_assert(
        Idx < 2,
        "Invalid index. Valid values are 0 for name, and 1 for value" );
      if constexpr( Idx == 0 ) {
        return std::move( parse_state.name );
      } else {
        return std::move( parse_state.value );
      }
    }
  } // namespace DAW_JSON_VER
} // namespace daw::json
 
namespace std {
  template<daw::json::json_options_t PolicyFlags, typename Allocator>
  class tuple_element<0, daw::json::basic_json_pair<PolicyFlags, Allocator>> {
  public:
    using type = std::optional<std::string_view>;
  };
 
  template<daw::json::json_options_t PolicyFlags, typename Allocator>
  class tuple_element<1, daw::json::basic_json_pair<PolicyFlags, Allocator>> {
  public:
    using type = daw::json::basic_json_value<PolicyFlags, Allocator>;
  };
 
  template<daw::json::json_options_t PolicyFlags, typename Allocator>
  inline constexpr std::size_t
    tuple_size_v<daw::json::basic_json_pair<PolicyFlags, Allocator>> = 2;
 
  template<daw::json::json_options_t PolicyFlags, typename Allocator>
  class tuple_size<daw::json::basic_json_pair<PolicyFlags, Allocator>> {
    static constexpr std::size_t value = 2;
  };
} // namespace std
 
namespace daw::json {
  inline namespace DAW_JSON_VER {
    template<json_options_t PolicyFlags = json_details::default_policy_flag,
             typename Allocator = json_details::NoAllocator>
    struct basic_json_value_iterator {
      using key_type = std::string_view;
      using mapped_type = basic_json_value<PolicyFlags, Allocator>;
 
      using json_pair = basic_json_pair<PolicyFlags, Allocator>;
      using value_type = json_pair;
      using reference = value_type;
      using pointer = json_details::arrow_proxy<value_type>;
      using difference_type = std::ptrdiff_t;
      using iterator_category = std::forward_iterator_tag;
      using parse_policy =
        TryDefaultParsePolicy<BasicParsePolicy<PolicyFlags, Allocator>>;
 
    private:
      using ParseState = parse_policy;
      ParseState m_state{ };
 
    public:
      explicit basic_json_value_iterator( ) = default;
 
      explicit constexpr basic_json_value_iterator(
        parse_policy const &parse_state )
        : m_state( parse_state ) {}
 
      explicit basic_json_value_iterator( daw::string_view json_doc )
        : m_state( std::data( json_doc ), daw::data_end( json_doc ) ) {}
 
      explicit basic_json_value_iterator( daw::string_view json_doc,
                                          Allocator const &alloc )
        : m_state( std::data( json_doc ), daw::data_end( json_doc ),
                   std::data( json_doc ), daw::data_end( json_doc ), alloc ) {}
 
      explicit basic_json_value_iterator(
        basic_json_value<PolicyFlags, Allocator> const &jv )
        : m_state( jv.get_raw_state( ) ) {}
 
      [[nodiscard]] constexpr std::optional<std::string_view> name( ) const {
        if( is_array( ) ) {
          return { };
        }
        auto parse_state = m_state;
        auto result = json_details::parse_name( parse_state );
        return std::string_view( std::data( result ), std::size( result ) );
      }
 
      [[nodiscard]] constexpr basic_json_value<PolicyFlags, Allocator>
      value( ) const {
        if( is_array( ) ) {
          return ParseState( m_state );
        }
        auto parse_state = m_state;
        (void)json_details::parse_name( parse_state );
        return ParseState( parse_state.first,
                           parse_state.last,
                           parse_state.first,
                           parse_state.last,
                           parse_state.get_allocator( ) );
      }
 
      [[nodiscard]] constexpr basic_json_pair<PolicyFlags, Allocator>
      operator*( ) {
        if( is_array( ) ) {
          return { { },
                   basic_json_value( ParseState( m_state.first,
                                                 m_state.last,
                                                 m_state.first,
                                                 m_state.last,
                                                 m_state.get_allocator( ) ) ) };
        }
        auto parse_state = m_state;
        auto name = json_details::parse_name( parse_state );
        return {
          std::string_view( std::data( name ), std::size( name ) ),
          basic_json_value( ParseState( parse_state.first,
                                        parse_state.last,
                                        parse_state.first,
                                        parse_state.last,
                                        parse_state.get_allocator( ) ) ) };
      }
 
      [[nodiscard]] constexpr pointer operator->( ) {
        return { operator*( ) };
      }
 
      constexpr basic_json_value_iterator &operator++( ) {
        if( good( ) ) {
          if( is_class( ) ) {
            (void)json_details::parse_name( m_state );
          }
          (void)json_details::skip_value( m_state );
          m_state.move_next_member_or_end( );
        }
        return *this;
      }
 
      constexpr void operator++( int ) & {
        operator++( );
      }
 
      [[nodiscard]] constexpr bool is_array( ) const {
        return *m_state.class_first == '[';
      }
 
      [[nodiscard]] constexpr bool is_class( ) const {
        return *m_state.class_first == '{';
      }
 
      [[nodiscard]] constexpr bool good( ) const {
        if( m_state.is_null( ) or not m_state.has_more( ) ) {
          return false;
        }
        switch( m_state.front( ) ) {
        case '[':
        case '{':
        case '"':
        case '-':
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
        case 't':
        case 'f':
        case 'n':
          return true;
        case '}':
        case ']':
          return false;
        default:
          DAW_UNLIKELY_BRANCH
          daw_json_error( ErrorReason::ExpectedTokenNotFound, m_state );
        }
      }
 
      [[nodiscard]] constexpr explicit operator bool( ) const {
        return good( );
      }
 
      [[nodiscard]] constexpr parse_policy const &get_raw_state( ) const {
        return m_state;
      }
 
      template<json_options_t P, typename A>
      [[nodiscard]] constexpr bool
      operator==( basic_json_value_iterator<P, A> const &rhs ) const {
        if( good( ) ) {
          if( rhs.good( ) ) {
            return m_state.first == rhs.m_state.first;
          }
          return false;
        }
        return not rhs.good( );
      }
 
      template<json_options_t P, typename A>
      [[nodiscard]] constexpr bool
      operator!=( basic_json_value_iterator<P, A> const &rhs ) const {
        return not operator==( rhs );
      }
    };
 
    template<json_options_t PolicyFlags, typename Allocator>
    basic_json_value_iterator(
      BasicParsePolicy<PolicyFlags, Allocator> const & )
      -> basic_json_value_iterator<PolicyFlags, Allocator>;
 
    basic_json_value_iterator( daw::string_view )
      -> basic_json_value_iterator<>;
 
    template<typename Allocator>
    basic_json_value_iterator( daw::string_view, Allocator const & )
      -> basic_json_value_iterator<daw::json::json_details::default_policy_flag,
                                   Allocator>;
 
    template<json_options_t PolicyFlags, typename Allocator>
    basic_json_value_iterator(
      basic_json_value<PolicyFlags, Allocator> const & )
      -> basic_json_value_iterator<PolicyFlags, Allocator>;
 
    template<json_options_t PolicyFlags = json_details::default_policy_flag,
             typename Allocator = json_details::NoAllocator>
    struct basic_json_value_iterator_range {
      using iterator = basic_json_value_iterator<PolicyFlags, Allocator>;
      iterator first;
      iterator last;
 
      [[nodiscard]] constexpr iterator begin( ) {
        return first;
      }
      [[nodiscard]] constexpr iterator end( ) {
        return last;
      }
    };
 
    template<json_options_t PolicyFlags, typename Allocator>
    basic_json_value_iterator_range(
      basic_json_value_iterator<PolicyFlags, Allocator>,
      basic_json_value_iterator<PolicyFlags, Allocator> )
      -> basic_json_value_iterator_range<PolicyFlags, Allocator>;
 
    template<json_options_t PolicyFlags, typename Allocator>
    struct basic_json_value {
      using ParseState =
        TryDefaultParsePolicy<BasicParsePolicy<PolicyFlags, Allocator>>;
      ParseState m_parse_state{ };
      using iterator = basic_json_value_iterator<PolicyFlags, Allocator>;
      using value_type = basic_json_pair<PolicyFlags, Allocator>;
      using size_type = std::size_t;
      using difference_type = std::ptrdiff_t;
 
      basic_json_value( ) = default;
 
      template<json_options_t P, typename A>
      explicit constexpr basic_json_value( BasicParsePolicy<P, A> parse_state )
        : m_parse_state( std::move( parse_state ) ) {
        // Ensure we are at the actual value.
        m_parse_state.trim_left( );
      }
 
      explicit constexpr basic_json_value( daw::string_view sv )
        : m_parse_state( std::data( sv ), daw::data_end( sv ) ) {
        m_parse_state.trim_left( );
      }
 
      explicit constexpr basic_json_value( char const *first, std::size_t sz )
        : m_parse_state( first, first + static_cast<std::ptrdiff_t>( sz ) ) {
        m_parse_state.trim_left( );
      }
 
      explicit constexpr basic_json_value( char const *first, char const *last )
        : m_parse_state( first, last ) {
        m_parse_state.trim_left( );
      }
 
      [[nodiscard]] constexpr ParseState get_raw_state( ) const {
        return m_parse_state;
      }
 
      [[nodiscard]] constexpr std::string_view get_raw_json_document( ) const {
        return std::string_view( m_parse_state.first, m_parse_state.size( ) );
      }
 
      [[nodiscard]] constexpr iterator begin( ) const {
        auto parse_state = ParseState( m_parse_state.first,
                                       m_parse_state.last,
                                       m_parse_state.first,
                                       m_parse_state.last,
                                       m_parse_state.get_allocator( ) );
        parse_state.remove_prefix( );
        parse_state.trim_left( );
        return iterator( parse_state );
      }
 
      [[nodiscard]] constexpr iterator end( ) const {
        return iterator( );
      }
 
      [[nodiscard]] constexpr basic_json_value
      find_class_member( daw::string_view name ) const {
        if( type( ) != JsonBaseParseTypes::Class ) {
          return basic_json_value{ };
        }
        bool const has_escape = name.contains( '\\' );
        auto pos = [&] {
          if( has_escape ) {
            return daw::algorithm::find_if(
              begin( ), end( ), [name]( auto const &jp ) {
                assert( jp.name );
                auto f0 = std::data( name );
                auto const l0 = daw::data_end( name );
                auto f1 = std::data( *jp.name );
                auto const l1 = daw::data_end( *jp.name );
                while( f0 != l0 and f1 != l1 ) {
                  if( *f0 == '\\' ) {
                    ++f0;
                    continue;
                  }
                  if( *f0 != *f1 ) {
                    return false;
                  }
                  ++f0;
                  ++f1;
                }
                return f0 == l0 and f1 == l1;
              } );
          } else {
            return daw::algorithm::find_if(
              begin( ), end( ), [name]( auto const &jp ) {
                assert( jp.name );
                return jp.name == name;
              } );
          }
        }( );
 
        if( pos == end( ) ) {
          return basic_json_value( );
        }
        return ( *pos ).value;
      }
 
      [[nodiscard]] constexpr basic_json_value
      find_member( daw::string_view json_path ) const {
        auto jv = *this;
        while( not json_path.empty( ) and jv ) {
          auto member = [&] {
            if( json_path.front( ) == '[' ) {
              return json_path.pop_front_until( ']' );
            }
            return json_path.pop_front_until( escaped_any_of<'.', '['>{ },
                                              nodiscard );
          }( );
          if( not json_path.empty( ) and json_path.front( ) == '.' ) {
            json_path.remove_prefix( );
          }
          if( member.front( ) == '[' ) {
            member.remove_prefix( );
            auto index_ps =
              TryDefaultParsePolicy<BasicParsePolicy<PolicyFlags>>(
                std::data( member ), daw::data_end( member ) )
                .with_allocator( m_parse_state.get_allocator( ) );
            auto const index =
              json_details::unsigned_parser<std::size_t,
                                            options::JsonRangeCheck::Never,
                                            true>( index_ps );
 
            jv = jv.find_element( index );
            if( not json_path.empty( ) and json_path.front( ) == '.' ) {
              json_path.remove_prefix( );
            }
            continue;
          }
          jv = jv.find_class_member( member );
        }
        return jv;
      }
 
      template<typename Result>
      [[nodiscard]] constexpr auto as( ) const {
        using result_t = json_details::json_deduced_type<Result>;
        auto state = m_parse_state;
        return json_details::
          parse_value<result_t, false, result_t::expected_type>( state );
      }
 
      template<typename Result>
      [[nodiscard]] explicit operator Result( ) const {
        return as<Result>( );
      }
 
      [[nodiscard]] constexpr basic_json_value
      operator[]( daw::string_view json_path ) const {
        return find_member( json_path );
      }
 
      [[nodiscard]] constexpr basic_json_value
      find_element( std::size_t index ) const {
        auto first = begin( );
        auto const last = end( );
        while( nsc_and( index > 0, first != last ) ) {
          --index;
          ++first;
        }
        if( index == 0 ) {
          return ( *first ).value;
        }
        return basic_json_value( );
      }
 
      [[nodiscard]] constexpr basic_json_value
      find_array_element( std::size_t index ) const {
        assert( type( ) == JsonBaseParseTypes::Array );
        return find_element( index );
      }
 
      [[nodiscard]] constexpr basic_json_value
      operator[]( std::size_t index ) const {
        return find_element( index );
      }
 
      [[nodiscard]] constexpr JsonBaseParseTypes type( ) const {
        if( m_parse_state.empty( ) ) {
          return JsonBaseParseTypes::None;
        }
        switch( m_parse_state.front( ) ) {
        case '"':
          return JsonBaseParseTypes::String;
        case '{':
          return JsonBaseParseTypes::Class;
        case '[':
          return JsonBaseParseTypes::Array;
        case '-':
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
          return JsonBaseParseTypes::Number;
        case 't':
          if constexpr( not ParseState::is_unchecked_input ) {
            if( m_parse_state.starts_with( "true" ) ) {
              return JsonBaseParseTypes::Bool;
            }
            return JsonBaseParseTypes::None;
          } else {
            return JsonBaseParseTypes::Bool;
          }
        case 'f':
          if constexpr( not ParseState::is_unchecked_input ) {
            if( m_parse_state.starts_with( "false" ) ) {
              return JsonBaseParseTypes::Bool;
            }
            return JsonBaseParseTypes::None;
          } else {
            return JsonBaseParseTypes::Bool;
          }
        case 'n':
          daw_json_assert_weak( m_parse_state.starts_with( "null" ),
                                ErrorReason::InvalidNull,
                                m_parse_state );
          return JsonBaseParseTypes::Null;
        }
        return JsonBaseParseTypes::None;
      }
 
      [[nodiscard]] constexpr ParseState get_state( ) const {
        auto parse_state = m_parse_state;
        auto result = json_details::skip_value( parse_state );
        if( is_string( ) ) {
          --result.first;
          ++result.last;
        }
        return result;
      }
 
      [[nodiscard]] constexpr std::string_view get_string_view( ) const {
        auto parse_state = m_parse_state;
        auto result = json_details::skip_value( parse_state );
        return { std::data( result ), std::size( result ) };
      }
 
      template<typename Alloc = std::allocator<char>,
               typename Traits = std::char_traits<char>>
      [[nodiscard]] std::basic_string<char, Traits, Alloc>
      get_string( Alloc const &alloc = Alloc( ) ) const {
        auto parse_state = m_parse_state;
        auto result = json_details::skip_value( parse_state );
        return { std::data( result ), std::size( result ), alloc };
      }
 
      [[nodiscard]] constexpr bool is_null( ) const {
        return type( ) == JsonBaseParseTypes::Null;
      }
 
      [[nodiscard]] constexpr bool is_class( ) const {
        return type( ) == JsonBaseParseTypes::Class;
      }
 
      [[nodiscard]] constexpr bool is_array( ) const {
        return type( ) == JsonBaseParseTypes::Array;
      }
 
      [[nodiscard]] constexpr bool is_number( ) const {
        return type( ) == JsonBaseParseTypes::Number;
      }
 
      [[nodiscard]] constexpr bool is_string( ) const {
        return type( ) == JsonBaseParseTypes::String;
      }
 
      [[nodiscard]] constexpr bool is_bool( ) const {
        return type( ) == JsonBaseParseTypes::Bool;
      }
 
      [[nodiscard]] constexpr bool is_unknown( ) const {
        return type( ) == JsonBaseParseTypes::None;
      }
 
      template<json_options_t P, typename A>
      [[nodiscard]] constexpr
      operator basic_json_value<P, A>( ) const noexcept {
        auto new_range =
          BasicParsePolicy<P, A>( m_parse_state.first, m_parse_state.last );
        new_range.class_first = m_parse_state.class_first;
        new_range.class_last = m_parse_state.class_last;
        return basic_json_value<P, A>( std::move( new_range ) );
      }
 
      [[nodiscard]] explicit constexpr operator bool( ) const {
        return type( ) != JsonBaseParseTypes::None;
      }
    };
 
    template<json_options_t PolicyFlags, typename Allocator>
    basic_json_value( BasicParsePolicy<PolicyFlags, Allocator> )
      -> basic_json_value<PolicyFlags, Allocator>;
 
    basic_json_value( daw::string_view ) -> basic_json_value<>;
 
    basic_json_value( char const *first, std::size_t sz ) -> basic_json_value<>;
 
    basic_json_value( char const *first, char const *last )
      -> basic_json_value<>;
 
    template<typename Result, json_options_t PolicyFlags, typename Allocator>
    [[nodiscard]] constexpr Result
    as( basic_json_value<PolicyFlags, Allocator> const &jv ) {
      return jv.template as<Result>( );
    }
 
    namespace json_details {
      // Will be specialized
      template<typename>
      inline constexpr bool is_json_value = false;
 
      template<json_options_t PolicyFlags, typename Allocator>
      inline constexpr bool
        is_json_value<basic_json_value<PolicyFlags, Allocator>> = true;
 
      template<json_options_t PolicyFlags, typename Allocator>
      inline constexpr bool
        is_string_view_like_v<basic_json_value<PolicyFlags, Allocator>> = false;
    } // namespace json_details
  } // namespace DAW_JSON_VER
} // namespace daw::json