23 Containers library [containers]

A set is an associative container that supports unique keys (contains at most one of each key value) and provides for fast retrieval of the keys themselves. The set class supports bidirectional iterators.

A set satisfies all of the requirements of a container, of a reversible container ([container.requirements]), of an associative container ([associative.reqmts]), and of an allocator-aware container (Table [tab:containers.allocatoraware]). A set also provides most operations described in ([associative.reqmts]) for unique keys. This means that a set supports the a_uniq operations in ([associative.reqmts]) but not the a_eq operations. For a set<Key> both the key_type and value_type are Key. Descriptions are provided here only for operations on set that are not described in one of these tables and for operations where there is additional semantic information.

namespace std {
  template <class Key, class Compare = less<Key>,
            class Allocator = allocator<Key> >
  class set {
  public:
    // types:
    typedef Key                                   key_type;
    typedef Key                                   value_type;
    typedef Compare                               key_compare;
    typedef Compare                               value_compare;
    typedef Allocator                             allocator_type;
    typedef value_type&                           reference;
    typedef const value_type&                     const_reference;
    typedef implementation-defined                iterator;       // See [container.requirements]
    typedef implementation-defined                const_iterator; // See [container.requirements]
    typedef implementation-defined                size_type;      // See [container.requirements]
    typedef implementation-defined                difference_type;// See [container.requirements]
    typedef typename allocator_traits<Allocator>::pointer           pointer;
    typedef typename allocator_traits<Allocator>::const_pointer     const_pointer;
    typedef std::reverse_iterator<iterator>       reverse_iterator;
    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;

    // [set.cons], construct/copy/destroy:
    explicit set(const Compare& comp = Compare(),
                 const Allocator& = Allocator());
    template <class InputIterator>
      set(InputIterator first, InputIterator last,
          const Compare& comp = Compare(), const Allocator& = Allocator());
    set(const set<Key,Compare,Allocator>& x);
    set(set<Key,Compare,Allocator>&& x);
    explicit set(const Allocator&);
    set(const set&, const Allocator&);
    set(set&&, const Allocator&);
    set(initializer_list<value_type>,
      const Compare& = Compare(),
      const Allocator& = Allocator());
   ~set();
    set<Key,Compare,Allocator>& operator=
      (const set<Key,Compare,Allocator>& x);
    set<Key,Compare,Allocator>& operator=
      (set<Key,Compare,Allocator>&& x);
    set& operator=(initializer_list<value_type>);
    allocator_type get_allocator() const noexcept;

    // iterators:
    iterator               begin() noexcept;
    const_iterator         begin() const noexcept;
    iterator               end() noexcept;
    const_iterator         end() const noexcept;

    reverse_iterator       rbegin() noexcept;
    const_reverse_iterator rbegin() const noexcept;
    reverse_iterator       rend() noexcept;
    const_reverse_iterator rend() const noexcept;

    const_iterator         cbegin() const noexcept;
    const_iterator         cend() const noexcept;
    const_reverse_iterator crbegin() const noexcept;
    const_reverse_iterator crend() const noexcept;

    // capacity:
    bool          empty() const noexcept;
    size_type     size() const noexcept;
    size_type     max_size() const noexcept;

    // modifiers:
    template <class... Args> pair<iterator, bool> emplace(Args&&... args);
    template <class... Args> iterator emplace_hint(const_iterator position, Args&&... args);
    pair<iterator,bool> insert(const value_type& x);
    pair<iterator,bool> insert(value_type&& x);
    iterator insert(const_iterator position, const value_type& x);
    iterator insert(const_iterator position, value_type&& x);
    template <class InputIterator>
      void insert(InputIterator first, InputIterator last);
    void insert(initializer_list<value_type>);

    iterator  erase(const_iterator position);
    size_type erase(const key_type& x);
    iterator  erase(const_iterator first, const_iterator last);
    void swap(set<Key,Compare,Allocator>&);
    void clear() noexcept;

    // observers:
    key_compare   key_comp() const;
    value_compare value_comp() const;

    // set operations:
    iterator        find(const key_type& x);
    const_iterator  find(const key_type& x) const;

    size_type count(const key_type& x) const;

    iterator        lower_bound(const key_type& x);
    const_iterator  lower_bound(const key_type& x) const;

    iterator        upper_bound(const key_type& x);
    const_iterator  upper_bound(const key_type& x) const;

    pair<iterator,iterator>             equal_range(const key_type& x);
    pair<const_iterator,const_iterator> equal_range(const key_type& x) const;
  };

  template <class Key, class Compare, class Allocator>
    bool operator==(const set<Key,Compare,Allocator>& x,
                    const set<Key,Compare,Allocator>& y);
  template <class Key, class Compare, class Allocator>
    bool operator< (const set<Key,Compare,Allocator>& x,
                    const set<Key,Compare,Allocator>& y);
  template <class Key, class Compare, class Allocator>
    bool operator!=(const set<Key,Compare,Allocator>& x,
                    const set<Key,Compare,Allocator>& y);
  template <class Key, class Compare, class Allocator>
    bool operator> (const set<Key,Compare,Allocator>& x,
                    const set<Key,Compare,Allocator>& y);
  template <class Key, class Compare, class Allocator>
    bool operator>=(const set<Key,Compare,Allocator>& x,
                    const set<Key,Compare,Allocator>& y);
  template <class Key, class Compare, class Allocator>
    bool operator<=(const set<Key,Compare,Allocator>& x,
                    const set<Key,Compare,Allocator>& y);

  // specialized algorithms:
  template <class Key, class Compare, class Allocator>
    void swap(set<Key,Compare,Allocator>& x,
              set<Key,Compare,Allocator>& y);
}