Class btree_map_container

src/include/cpp-btree/btree_container.h:318–400

// Base class for btree_map.
template <typename Tree>
class btree_map_container : public btree_set_container<Tree> {
  using super_type = btree_set_container<Tree>;
  using params_type = typename Tree::params_type;

 protected:
  template <class K>
  using key_arg = typename super_type::template key_arg<K>;

 public:
  using key_type = typename Tree::key_type;
  using mapped_type = typename params_type::mapped_type;
  using value_type = typename Tree::value_type;
  using key_compare = typename Tree::key_compare;
  using allocator_type = typename Tree::allocator_type;
  using iterator = typename Tree::iterator;
  using const_iterator = typename Tree::const_iterator;

  // Inherit constructors.
  using super_type::super_type;
  btree_map_container() {}

  // Insertion routines.
  template <typename... Args>
  std::pair<iterator, bool> try_emplace(const key_type &k, Args &&... args) {
    return this->tree_.insert_unique(
        k, std::piecewise_construct, std::forward_as_tuple(k),
        std::forward_as_tuple(std::forward<Args>(args)...));
  }
  template <typename... Args>
  std::pair<iterator, bool> try_emplace(key_type &&k, Args &&... args) {
    // Note: `key_ref` exists to avoid a ClangTidy warning about moving from `k`
    // and then using `k` unsequenced. This is safe because the move is into a
    // forwarding reference and insert_unique guarantees that `key` is never
    // referenced after consuming `args`.
    const key_type& key_ref = k;
    return this->tree_.insert_unique(
        key_ref, std::piecewise_construct, std::forward_as_tuple(std::move(k)),
        std::forward_as_tuple(std::forward<Args>(args)...));
  }
  template <typename... Args>
  iterator try_emplace(const_iterator hint, const key_type &k,
                       Args &&... args) {
    return this->tree_
        .insert_hint_unique(iterator(hint), k, std::piecewise_construct,
                            std::forward_as_tuple(k),
                            std::forward_as_tuple(std::forward<Args>(args)...))
        .first;
  }
  template <typename... Args>
  iterator try_emplace(const_iterator hint, key_type &&k, Args &&... args) {
    // Note: `key_ref` exists to avoid a ClangTidy warning about moving from `k`
    // and then using `k` unsequenced. This is safe because the move is into a
    // forwarding reference and insert_hint_unique guarantees that `key` is
    // never referenced after consuming `args`.
    const key_type& key_ref = k;
    return this->tree_
        .insert_hint_unique(iterator(hint), key_ref, std::piecewise_construct,
                            std::forward_as_tuple(std::move(k)),