daw_json_parse_policy.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/impl/version.h"
 
#include "daw/json/impl/daw_json_allocator_wrapper.h"
#include "daw/json/impl/daw_json_assert.h"
#include "daw/json/impl/daw_json_parse_common.h"
#include "daw/json/impl/daw_json_parse_options_impl.h"
#include "daw/json/impl/daw_json_parse_policy_cpp_comments.h"
#include "daw/json/impl/daw_json_parse_policy_hash_comments.h"
#include "daw/json/impl/daw_json_parse_policy_no_comments.h"
#include "daw/json/impl/daw_json_parse_policy_policy_details.h"
#include "daw/json/impl/daw_json_string_util.h"
 
#include <daw/cpp_17.h>
#include <daw/daw_attributes.h>
#include <daw/daw_likely.h>
#include <daw/daw_not_null.h>
#include <daw/daw_rw_ref.h>
#include <daw/daw_traits.h>
 
#include <cassert>
#include <cstddef>
#include <iterator>
#include <type_traits>
 
namespace daw::json {
  inline namespace DAW_JSON_VER {
    template<json_options_t PolicyFlags = json_details::default_policy_flag,
             typename Allocator = json_details::NoAllocator>
    struct BasicParsePolicy : json_details::AllocatorWrapper<Allocator> {
 
      using i_am_a_parse_policy = void;
      static constexpr bool is_default_parse_policy =
        PolicyFlags == json_details::default_policy_flag and
        std::is_same_v<Allocator, json_details::NoAllocator>;
 
      static DAW_CONSTEVAL json_options_t policy_flags( ) {
        return PolicyFlags;
      }
 
      using iterator = char const *;
 
      /***
       * see options::CheckedParseMode
       */
      static constexpr bool is_unchecked_input =
        json_details::get_bits_for<options::CheckedParseMode>( PolicyFlags ) ==
        options::CheckedParseMode::no;
 
      /***
       * See options::ExecModeTypes
       */
      using exec_tag_t = switch_t<
        json_details::get_bits_for<options::ExecModeTypes, std::size_t>(
          PolicyFlags ),
        default_exec_tag, constexpr_exec_tag, runtime_exec_tag, simd_exec_tag>;
 
      static constexpr auto exec_tag = exec_tag_t{ };
 
      /***
       * see options::AllowEscapedNames
       */
      static constexpr bool allow_escaped_names =
        json_details::get_bits_for<options::AllowEscapedNames>( PolicyFlags ) ==
        options::AllowEscapedNames::yes;
 
      /***
       * see options::ForceFullNameCheck
       */
      static constexpr bool force_name_equal_check =
        json_details::get_bits_for<options::ForceFullNameCheck>(
          PolicyFlags ) == options::ForceFullNameCheck::yes;
 
      /***
       * see options::ZeroTerminatedString
       */
      static constexpr bool is_zero_terminated_string =
        json_details::get_bits_for<options::ZeroTerminatedString>(
          PolicyFlags ) == options::ZeroTerminatedString::yes;
 
      /***
       * See options::IEEE754Precise
       */
      static constexpr bool precise_ieee754 =
        json_details::get_bits_for<options::IEEE754Precise>( PolicyFlags ) ==
        options::IEEE754Precise::yes;
 
      /***
       * See options::MinifiedDocument
       */
      static constexpr bool minified_document =
        json_details::get_bits_for<options::MinifiedDocument>( PolicyFlags ) ==
        options::MinifiedDocument::yes;
 
      /***
       * See options::ExcludeSpecialEscapes
       */
      static constexpr bool exclude_special_escapes =
        json_details::get_bits_for<options::ExcludeSpecialEscapes>(
          PolicyFlags ) == options::ExcludeSpecialEscapes::yes;
 
      static constexpr bool allow_leading_zero_plus = true;
 
      static constexpr bool use_exact_mappings_by_default =
        json_details::get_bits_for<options::UseExactMappingsByDefault>(
          PolicyFlags ) == options::UseExactMappingsByDefault::yes;
 
      static constexpr bool must_verify_end_of_data_is_valid =
        json_details::get_bits_for<options::MustVerifyEndOfDataIsValid>(
          PolicyFlags ) == options::MustVerifyEndOfDataIsValid::yes;
 
      static constexpr bool expect_long_strings =
        json_details::get_bits_for<options::ExpectLongNames>( PolicyFlags ) ==
        options::ExpectLongNames::yes;
 
      using CommentPolicy =
        switch_t<json_details::get_bits_for<options::PolicyCommentTypes,
                                            std::size_t>( PolicyFlags ),
                 NoCommentSkippingPolicy, CppCommentSkippingPolicy,
                 HashCommentSkippingPolicy>;
 
      iterator first{ };
      iterator last{ };
      iterator class_first{ };
      iterator class_last{ };
      std::size_t counter = 0;
 
      template<auto... PolicyOptions>
      using SetPolicyOptions = BasicParsePolicy<
        json_details::set_bits( PolicyFlags, PolicyOptions... ), Allocator>;
 
      explicit BasicParsePolicy( ) = default;
 
      explicit constexpr BasicParsePolicy( iterator f, iterator l )
        : first( f )
        , last( l )
        , class_first( f )
        , class_last( l ) {}
 
      explicit constexpr BasicParsePolicy( iterator f, iterator l,
                                           Allocator &alloc )
        : json_details::AllocatorWrapper<Allocator>( alloc )
        , first( f )
        , last( l )
        , class_first( f )
        , class_last( l ) {}
 
      explicit constexpr BasicParsePolicy( iterator f, iterator l, iterator cf,
                                           iterator cl )
        : first( f )
        , last( l )
        , class_first( cf )
        , class_last( cl ) {}
 
      explicit constexpr BasicParsePolicy( iterator f, iterator l, iterator cf,
                                           iterator cl, std::size_t cnter )
        : first( f )
        , last( l )
        , class_first( cf )
        , class_last( cl )
        , counter( cnter ) {}
 
      explicit constexpr BasicParsePolicy( iterator f, iterator l, iterator cf,
                                           iterator cl, Allocator const &alloc )
        : json_details::AllocatorWrapper<Allocator>( alloc )
        , first( f )
        , last( l )
        , class_first( cf )
        , class_last( cl ) {}
 
      [[nodiscard]] constexpr BasicParsePolicy
      copy( iterator f = iterator{ }, iterator l = iterator{ },
            iterator cf = iterator{ }, iterator cl = iterator{ } ) const {
        BasicParsePolicy result = *this;
        if( f ) {
          result.first = f;
        }
        if( l ) {
          result.last = l;
        }
        if( cf ) {
          result.class_first = cf;
        }
        if( cl ) {
          result.class_last = cl;
        }
        return result;
      }
 
      DAW_ATTRIB_INLINE constexpr decltype( auto ) get_allocator( ) const {
        return json_details::AllocatorWrapper<Allocator>::get_allocator( );
      }
 
      template<typename Alloc>
      using with_allocator_type = BasicParsePolicy<PolicyFlags, Alloc>;
 
      template<typename Alloc>
      [[nodiscard]] static constexpr with_allocator_type<Alloc>
      with_allocator( iterator f, iterator l, iterator cf, iterator cl,
                      Alloc const &alloc ) {
        return with_allocator_type<Alloc>{ f, l, cf, cl, alloc };
      }
 
      [[nodiscard]] static constexpr BasicParsePolicy
      with_allocator( iterator f, iterator l, iterator cf, iterator cl,
                      json_details::NoAllocator const & ) {
        return BasicParsePolicy( f, l, cf, cl );
      }
 
      template<typename Alloc>
      [[nodiscard]] constexpr auto
      with_allocator( BasicParsePolicy<PolicyFlags, Alloc> p ) const {
        if constexpr( std::is_same_v<Alloc, json_details::NoAllocator> ) {
          return *this;
        } else {
          auto result = with_allocator(
            first, last, class_first, class_last, p.get_allocator( ) );
          result.counter = p.counter;
          return result;
        }
      }
 
      template<typename Alloc>
      [[nodiscard]] constexpr with_allocator_type<Alloc>
      with_allocator( Alloc const &alloc ) const {
        auto result =
          with_allocator( first, last, class_first, class_last, alloc );
        result.counter = counter;
        return result;
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr auto
      with_allocator( json_details::NoAllocator const & ) const {
        return *this;
      }
 
      using without_allocator_type =
        BasicParsePolicy<PolicyFlags, json_details::NoAllocator>;
 
      template<typename Alloc>
      [[nodiscard]] static constexpr with_allocator_type<Alloc>
      with_allocator( iterator f, iterator l, Alloc const &alloc ) {
        return with_allocator_type<Alloc>{ f, l, f, l, alloc };
      }
 
      template<typename Alloc>
      [[nodiscard]] static constexpr BasicParsePolicy
      with_allocator( iterator f, iterator l,
                      json_details::NoAllocator const & ) {
        return BasicParsePolicy{ f, l, f, l };
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr iterator data( ) const {
        return first;
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr iterator data_end( ) const {
        return last;
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr iterator begin( ) const {
        return first;
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr iterator end( ) const {
        return last;
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr bool empty( ) const {
        if( not first ) {
          return true;
        }
        if constexpr( is_zero_terminated_string ) {
          return first >= last or *first == '\0';
        } else {
          return first >= last;
        }
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr bool has_more( ) const {
#if not defined( NDEBUG )
        daw_json_ensure( first != nullptr and last != nullptr,
                         ErrorReason::InvalidNull );
#endif
        return first < last;
      }
 
      template<std::size_t N>
      DAW_ATTRIB_NONNULL( )
      constexpr bool starts_with( char const ( &rhs )[N] ) const {
        static_assert( N > 0 );
        if( size( ) < ( N - 1 ) ) {
          return false;
        }
        bool result = true;
        for( std::size_t n = 0; n < ( N - 1 ); ++n ) {
          result = result & ( first[n] == rhs[n] );
        }
        return result;
      }
 
      template<std::size_t N>
      constexpr bool starts_with_skip( char const ( &rhs )[N] ) {
        if( not starts_with( rhs ) ) {
          return false;
        }
        first += static_cast<std::ptrdiff_t>( N - 1 );
        return true;
      }
 
      template<char c>
      DAW_ATTRIB_INLINE constexpr void move_to_next_of_unchecked( ) {
        first =
          json_details::memchr_unchecked<c, exec_tag_t, expect_long_strings>(
            daw::not_null{ daw::never_null, first },
            daw::not_null{ daw::never_null, last } );
      }
 
      template<char c>
      DAW_ATTRIB_INLINE constexpr void move_to_next_of_checked( ) {
        first =
          json_details::memchr_checked<c, exec_tag_t, expect_long_strings>(
            daw::not_null{ first }, daw::not_null{ last } );
      }
 
      template<char c>
      DAW_ATTRIB_INLINE constexpr void move_to_next_of( ) {
        if( is_unchecked_input ) {
          move_to_next_of_unchecked<c>( );
        } else {
          move_to_next_of_checked<c>( );
        }
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr char front( ) const {
        return *first;
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr char front_checked( ) const {
        daw_json_ensure(
          first < last, ErrorReason::UnexpectedEndOfData, *this );
        return *first;
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr std::size_t size( ) const {
        assert( last >= first );
        return static_cast<std::size_t>( last - first );
      }
 
      [[nodiscard]] constexpr bool is_null( ) const {
        return first == nullptr;
      }
 
      DAW_ATTRIB_INLINE constexpr void remove_prefix( ) {
        ++first;
      }
 
      DAW_ATTRIB_INLINE constexpr void remove_prefix( std::size_t n ) {
        first += static_cast<std::ptrdiff_t>( n );
      }
 
      constexpr void set_class_position( ) {
        class_first = first;
        class_last = last;
      }
 
      struct class_pos_t {
        char const *f;
        char const *l;
      };
 
      constexpr void set_class_position( class_pos_t new_pos ) {
        class_first = new_pos.f;
        class_last = new_pos.l;
      }
 
      [[nodiscard]] constexpr class_pos_t get_class_position( ) const {
        return { class_first, class_last };
      }
 
      constexpr void trim_left_checked( ) {
        return CommentPolicy::trim_left_checked( *this );
      }
 
      constexpr void trim_left_unchecked( ) {
        return CommentPolicy::trim_left_unchecked( *this );
      }
 
      [[nodiscard]] constexpr bool is_literal_end( ) const {
        return CommentPolicy::is_literal_end( *first );
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr bool
      is_space_unchecked( ) const {
        return ( static_cast<unsigned>( static_cast<unsigned char>( *first ) ) -
                 1U ) <= 0x1FU;
      }
 
      [[nodiscard]] constexpr bool is_opening_bracket_checked( ) const {
        return DAW_LIKELY( first < last ) and *first == '[';
      }
 
      [[nodiscard]] constexpr bool is_opening_brace_checked( ) const {
        return DAW_LIKELY( first < last ) and *first == '{';
      }
 
      [[nodiscard]] constexpr bool is_closing_brace_checked( ) const {
        return DAW_LIKELY( first < last ) and *first == '}';
      }
 
      [[nodiscard]] constexpr bool is_quotes_checked( ) const {
        return DAW_LIKELY( first < last ) and *first == '"';
      }
 
      DAW_ATTRIB_INLINE constexpr void trim_left( ) {
        if constexpr( is_unchecked_input ) {
          trim_left_unchecked( );
        } else {
          trim_left_checked( );
        }
      }
 
      constexpr void move_next_member_or_end_unchecked( ) {
        trim_left_unchecked( );
        if( *first == ',' ) {
          ++first;
          trim_left_unchecked( );
        }
      }
 
      DAW_ATTRIB_FLATINLINE constexpr void move_next_member_or_end_checked( ) {
        trim_left_checked( );
        if constexpr( is_zero_terminated_string ) {
          if( *first == ',' ) {
            ++first;
            trim_left( );
          }
        } else {
          if( DAW_LIKELY( first < last ) and *first == ',' ) {
            ++first;
            trim_left( );
          }
        }
      }
 
      DAW_ATTRIB_INLINE constexpr void move_next_member_or_end( ) {
        if constexpr( is_unchecked_input ) {
          move_next_member_or_end_unchecked( );
        } else {
          move_next_member_or_end_checked( );
        }
      }
 
      DAW_ATTRIB_INLINE constexpr void move_next_member( ) {
        if constexpr( is_unchecked_input ) {
          CommentPolicy::move_next_member_unchecked( *this );
        } else {
          // We have no guarantee that all members are available
          move_next_member_or_end_checked( );
        }
      }
 
      constexpr void move_to_next_class_member( ) {
        CommentPolicy::template move_to_next_of<'"', '}'>( *this );
      }
 
      [[nodiscard]] constexpr bool is_at_next_class_member( ) const {
        return parse_policy_details::in<'"', '}'>( *first );
      }
 
      [[nodiscard]] constexpr bool is_at_next_array_element( ) const {
        return parse_policy_details::in<',', ']'>( *first );
      }
 
      [[nodiscard]] constexpr bool is_at_token_after_value( ) const {
        return parse_policy_details::in<',', '}', ']'>( *first );
      }
 
      template<char PrimLeft>
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr BasicParsePolicy
      skip_bracketed_item_checked( ) {
        return CommentPolicy::template skip_bracketed_item_checked<PrimLeft>(
          *this );
      }
 
      template<char PrimLeft>
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr BasicParsePolicy
      skip_bracketed_item_unchecked( ) {
        return CommentPolicy::template skip_bracketed_item_unchecked<PrimLeft>(
          *this );
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr BasicParsePolicy skip_class( ) {
        if constexpr( is_unchecked_input ) {
          return skip_bracketed_item_unchecked<'{'>( );
        } else {
          return skip_bracketed_item_checked<'{'>( );
        }
      }
 
      [[nodiscard]] DAW_ATTRIB_INLINE constexpr BasicParsePolicy skip_array( ) {
        if constexpr( is_unchecked_input ) {
          return skip_bracketed_item_unchecked<'['>( );
        } else {
          return skip_bracketed_item_checked<'['>( );
        }
      }
    };
 
    BasicParsePolicy( ) -> BasicParsePolicy<>;
 
    BasicParsePolicy( char const *, char const * ) -> BasicParsePolicy<>;
 
    template<typename Allocator>
    BasicParsePolicy( char const *, char const *, Allocator const & )
      -> BasicParsePolicy<json_details::default_policy_flag, Allocator>;
 
    BasicParsePolicy( char const *, char const *, char const *, char const * )
      -> BasicParsePolicy<>;
 
    template<typename Allocator>
    BasicParsePolicy( char const *, char const *, char const *, char const *,
                      Allocator const & )
      -> BasicParsePolicy<json_details::default_policy_flag, Allocator>;
 
    struct DefaultParsePolicy
      : BasicParsePolicy<json_details::default_policy_flag,
                         json_details::NoAllocator> {
 
      using BasicParsePolicy::BasicParsePolicy;
 
      constexpr DefaultParsePolicy( BasicParsePolicy const &other ) noexcept
        : BasicParsePolicy( other ) {}
      constexpr DefaultParsePolicy( BasicParsePolicy &&other ) noexcept
        : BasicParsePolicy( std::move( other ) ) {}
    };
 
    template<json_options_t PolicyFlags = json_details::default_policy_flag,
             typename Allocator = json_details::NoAllocator>
    using GetParsePolicy =
      daw::conditional_t<(PolicyFlags == json_details::default_policy_flag and
                          std::is_same_v<Allocator, json_details::NoAllocator>),
                         DefaultParsePolicy,
                         BasicParsePolicy<PolicyFlags, Allocator>>;
    template<typename ParsePolicy>
    using TryDefaultParsePolicy =
      daw::conditional_t<ParsePolicy::is_default_parse_policy,
                         DefaultParsePolicy, ParsePolicy>;
 
    namespace options {
      /***
       * @brief Specify parse policy flags in to_json calls.  See cookbook item
       * parse_options.md
       */
      template<auto... PolicyFlags>
      struct parse_flags_t {
        static_assert(
          json_details::are_option_flags<decltype( PolicyFlags )...>,
          "Only registered policy types are allowed" );
        static constexpr json_options_t value = parse_options( PolicyFlags... );
      };
      template<>
      struct parse_flags_t<> {
        static constexpr json_options_t value =
          json_details::default_policy_flag;
      };
 
      namespace details {
        template<typename... Ts>
        std::false_type is_policy_flag( Ts... );
 
        template<auto... PolicyFlags>
        std::true_type is_policy_flag( parse_flags_t<PolicyFlags...> );
 
        template<auto... PolicyFlags>
        DAW_CONSTEVAL auto make_parse_flags( ) {
          if constexpr( decltype( details::is_policy_flag(
                          PolicyFlags... ) )::value ) {
            static_assert( sizeof...( PolicyFlags ) == 1 );
            // We know there is only one but need to unpack
            return ( PolicyFlags, ... );
          } else {
            return parse_flags_t<PolicyFlags...>{ };
          }
        }
      } // namespace details
      template<auto... PolicyFlags>
      inline constexpr auto parse_flags =
        details::make_parse_flags<PolicyFlags...>( );
    } // namespace options
 
#define DAW_JSON_CONFORMANCE_FLAGS                       \
  daw::json::options::AllowEscapedNames::yes,            \
    daw::json::options::MustVerifyEndOfDataIsValid::yes, \
    daw::json::options::IEEE754Precise::yes,             \
    daw::json::options::ExcludeSpecialEscapes::yes
 
    inline constexpr auto ConformancePolicy =
      options::parse_flags<DAW_JSON_CONFORMANCE_FLAGS>;
 
  } // namespace DAW_JSON_VER
} // namespace daw::json