Function scan

3rd/nlohmann_json/single_include/nlohmann/json.hpp:8129–8215

    }

    token_type scan()
    {
        // initially, skip the BOM
        if (position.chars_read_total == 0 && !skip_bom())
        {
            error_message = "invalid BOM; must be 0xEF 0xBB 0xBF if given";
            return token_type::parse_error;
        }

        // read next character and ignore whitespace
        skip_whitespace();

        // ignore comments
        while (ignore_comments && current == '/')
        {
            if (!scan_comment())
            {
                return token_type::parse_error;
            }

            // skip following whitespace
            skip_whitespace();
        }

        switch (current)
        {
            // structural characters
            case '[':
                return token_type::begin_array;
            case ']':
                return token_type::end_array;
            case '{':
                return token_type::begin_object;
            case '}':
                return token_type::end_object;
            case ':':
                return token_type::name_separator;
            case ',':
                return token_type::value_separator;

            // literals
            case 't':
            {
                std::array<char_type, 4> true_literal = {{char_type('t'), char_type('r'), char_type('u'), char_type('e')}};
                return scan_literal(true_literal.data(), true_literal.size(), token_type::literal_true);
            }
            case 'f':
            {
                std::array<char_type, 5> false_literal = {{char_type('f'), char_type('a'), char_type('l'), char_type('s'), char_type('e')}};
                return scan_literal(false_literal.data(), false_literal.size(), token_type::literal_false);
            }
            case 'n':
            {
                std::array<char_type, 4> null_literal = {{char_type('n'), char_type('u'), char_type('l'), char_type('l')}};
                return scan_literal(null_literal.data(), null_literal.size(), token_type::literal_null);
            }

            // string