Improving flat containers interface.

base/containers/flat_set.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_CONTAINERS_FLAT_SET_H_
 #define BASE_CONTAINERS_FLAT_SET_H_
 
-#include <functional>
-
 #include "base/containers/flat_tree.h"
+#include "base/functional.h"
 
 namespace base {
 
 // flat_set is a container with a std::set-like interface that stores its
 // contents in a sorted vector.
 //
 // Please see //base/containers/README.md for an overview of which container
 // to select.
 //
 // PROS
 //
 //  - Good memory locality.
 //  - Low overhead, especially for smaller sets.
 //  - Performance is good for more workloads than you might expect (see
 //    overview link above).
+//  - Supports C++14 set interface.
+//  - Uses base::less which allows for an easy use with smart pointers.
 //
 // CONS
 //
 //  - Inserts and removals are O(n).
 //
 // IMPORTANT NOTES
 //
 //  - Iterators are invalidated across mutations.
 //  - If possible, construct a flat_set in one operation by inserting into
 //    a std::vector and moving that vector into the flat_set constructor.
@@ skipping 39 matching lines @@
 //   const_iterator         end() const;
 //   const_iterator         cend() const;
 //   reverse_iterator       rbegin();
 //   const reverse_iterator rbegin() const;
 //   const_reverse_iterator crbegin() const;
 //   reverse_iterator       rend();
 //   const_reverse_iterator rend() const;
 //   const_reverse_iterator crend() const;
 //
 // Insert and accessor functions:
-//   pair<iterator, bool> insert(const Key&);
-//   pair<iterator, bool> insert(Key&&);
+//   pair<iterator, bool> insert(const key_type&);
+//   pair<iterator, bool> insert(key_type&&);
 //   void                 insert(InputIterator first, InputIterator last,
 //                               FlatContainerDupes);
+//   template <typename ...Args>
 //   pair<iterator, bool> emplace(Args&&...);
+//   template <typename ...Args>
 //   iterator             emplace_hint(const_iterator, Args&&...);
 //
 // Erase functions:
+//   iterator erase(iterator);
 //   iterator erase(const_iterator);
 //   iterator erase(const_iterator first, const_iterator& last);
-//   size_t   erase(const Key& key)
+//   template <typename K>
+//   size_t   erase(const K& key)
 //
 // Comparators (see std::set documentation).
 //   key_compare   key_comp() const;
 //   value_compare value_comp() const;
 //
 // Search functions:
-//   size_t                   count(const Key&) const;
-//   iterator                 find(const Key&);
-//   const_iterator           find(const Key&) const;
-//   pair<iterator, iterator> equal_range(Key&)
-//   iterator                 lower_bound(const Key&);
-//   const_iterator           lower_bound(const Key&) const;
-//   iterator                 upper_bound(const Key&);
-//   const_iterator           upper_bound(const Key&) const;
+//   template <typename K>
+//   size_t                   count(const K&) const;
+//   template <typename K>
+//   iterator                 find(const K&);
+//   template <typename K>
+//   const_iterator           find(const K&) const;
+//   template <typename K>
+//   pair<iterator, iterator> equal_range(K&)
+//   template <typename K>
+//   iterator                 lower_bound(const K&);
+//   template <typename K>
+//   const_iterator           lower_bound(const K&) const;
+//   template <typename K>
+//   iterator                 upper_bound(const K&);
+//   template <typename K>
+//   const_iterator           upper_bound(const K&) const;
 //
 // General functions:
 //   void swap(flat_set&&)
 //
 // Non-member operators:
 //   bool operator==(const flat_set&, const flat_set);
 //   bool operator!=(const flat_set&, const flat_set);
 //   bool operator<(const flat_set&, const flat_set);
 //   bool operator>(const flat_set&, const flat_set);
 //   bool operator>=(const flat_set&, const flat_set);
 //   bool operator<=(const flat_set&, const flat_set);
 //
-template <class Key, class Compare = std::less<Key>>
+template <class Key, class Compare = less>
 using flat_set = typename ::base::internal::flat_tree<
     Key,
     Key,
     ::base::internal::GetKeyFromValueIdentity<Key>,
     Compare>;
 
 }  // namespace base
 
 #endif  // BASE_CONTAINERS_FLAT_SET_H_