Function emplace

example/cacheHierarchy/fkYAML/node.hpp:12610–12618

        typename KeyType,
        detail::enable_if_t<detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    std::pair<iterator, bool> emplace(KeyType&& key, const mapped_type& value) noexcept {
        for (auto itr = this->begin(); itr != this->end(); ++itr) {
            if (m_compare(itr->first, key)) {
                return {itr, false};
            }
        }
        this->emplace_back(std::forward<KeyType>(key), value);
        return {std::prev(this->end()), true};
    }

    /// @brief Find a value associated to the given key. Throws an exception if the search fails.
    /// @tparam KeyType A type for the input key.