Class parser

native/thirdpart/json/json.hpp:8684–9147

*/
template<typename BasicJsonType>
class parser
{
    using number_integer_t = typename BasicJsonType::number_integer_t;
    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
    using number_float_t = typename BasicJsonType::number_float_t;
    using string_t = typename BasicJsonType::string_t;
    using lexer_t = lexer<BasicJsonType>;
    using token_type = typename lexer_t::token_type;

  public:
    enum class parse_event_t : uint8_t
    {
        /// the parser read `{` and started to process a JSON object
        object_start,
        /// the parser read `}` and finished processing a JSON object
        object_end,
        /// the parser read `[` and started to process a JSON array
        array_start,
        /// the parser read `]` and finished processing a JSON array
        array_end,
        /// the parser read a key of a value in an object
        key,
        /// the parser finished reading a JSON value
        value
    };

    using parser_callback_t =
        std::function<bool(int depth, parse_event_t event, BasicJsonType& parsed)>;

    /// a parser reading from an input adapter
    explicit parser(detail::input_adapter_t&& adapter,
                    const parser_callback_t cb = nullptr,
                    const bool allow_exceptions_ = true)
        : callback(cb), m_lexer(std::move(adapter)), allow_exceptions(allow_exceptions_)
    {
        // read first token
        get_token();
    }

    /*!
    @brief public parser interface

    @param[in] strict      whether to expect the last token to be EOF
    @param[in,out] result  parsed JSON value

    @throw parse_error.101 in case of an unexpected token
    @throw parse_error.102 if to_unicode fails or surrogate error
    @throw parse_error.103 if to_unicode fails
    */
    void parse(const bool strict, BasicJsonType& result)
    {
        if (callback)
        {
            json_sax_dom_callback_parser<BasicJsonType> sdp(result, callback, allow_exceptions);
            sax_parse_internal(&sdp);
            result.assert_invariant();

            // in strict mode, input must be completely read