Function operator[]

3rd/nlohmann_json/single_include/nlohmann/json.hpp:12258–12290

! @brief access to successor @pre The iterator is initialized; i.e. `m_object != nullptr`. */

    @pre The iterator is initialized; i.e. `m_object != nullptr`.
    */
    reference operator[](difference_type n) const
    {
        JSON_ASSERT(m_object != nullptr);

        switch (m_object->m_type)
        {
            case value_t::object:
                JSON_THROW(invalid_iterator::create(208, "cannot use operator[] for object iterators", *m_object));

            case value_t::array:
                return *std::next(m_it.array_iterator, n);

            case value_t::null:
                JSON_THROW(invalid_iterator::create(214, "cannot get value", *m_object));

            case value_t::string:
            case value_t::boolean:
            case value_t::number_integer:
            case value_t::number_unsigned:
            case value_t::number_float:
            case value_t::binary:
            case value_t::discarded:
            default:
            {
                if (JSON_HEDLEY_LIKELY(m_it.primitive_iterator.get_value() == -n))
                {
                    return *m_object;
                }

                JSON_THROW(invalid_iterator::create(214, "cannot get value", *m_object));
            }
        }
    }

    /*!
    @brief return the key of an object iterator