Move base to DEPS

base/containers/linked_list.h

-// Copyright (c) 2009 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_LINKED_LIST_H_
-#define BASE_CONTAINERS_LINKED_LIST_H_
-
-#include "base/macros.h"
-
-// Simple LinkedList type. (See the Q&A section to understand how this
-// differs from std::list).
-//
-// To use, start by declaring the class which will be contained in the linked
-// list, as extending LinkNode (this gives it next/previous pointers).
-//
-//   class MyNodeType : public LinkNode<MyNodeType> {
-//     ...
-//   };
-//
-// Next, to keep track of the list's head/tail, use a LinkedList instance:
-//
-//   LinkedList<MyNodeType> list;
-//
-// To add elements to the list, use any of LinkedList::Append,
-// LinkNode::InsertBefore, or LinkNode::InsertAfter:
-//
-//   LinkNode<MyNodeType>* n1 = ...;
-//   LinkNode<MyNodeType>* n2 = ...;
-//   LinkNode<MyNodeType>* n3 = ...;
-//
-//   list.Append(n1);
-//   list.Append(n3);
-//   n3->InsertBefore(n3);
-//
-// Lastly, to iterate through the linked list forwards:
-//
-//   for (LinkNode<MyNodeType>* node = list.head();
-//        node != list.end();
-//        node = node->next()) {
-//     MyNodeType* value = node->value();
-//     ...
-//   }
-//
-// Or to iterate the linked list backwards:
-//
-//   for (LinkNode<MyNodeType>* node = list.tail();
-//        node != list.end();
-//        node = node->previous()) {
-//     MyNodeType* value = node->value();
-//     ...
-//   }
-//
-// Questions and Answers:
-//
-// Q. Should I use std::list or base::LinkedList?
-//
-// A. The main reason to use base::LinkedList over std::list is
-//    performance. If you don't care about the performance differences
-//    then use an STL container, as it makes for better code readability.
-//
-//    Comparing the performance of base::LinkedList<T> to std::list<T*>:
-//
-//    * Erasing an element of type T* from base::LinkedList<T> is
-//      an O(1) operation. Whereas for std::list<T*> it is O(n).
-//      That is because with std::list<T*> you must obtain an
-//      iterator to the T* element before you can call erase(iterator).
-//
-//    * Insertion operations with base::LinkedList<T> never require
-//      heap allocations.
-//
-// Q. How does base::LinkedList implementation differ from std::list?
-//
-// A. Doubly-linked lists are made up of nodes that contain "next" and
-//    "previous" pointers that reference other nodes in the list.
-//
-//    With base::LinkedList<T>, the type being inserted already reserves
-//    space for the "next" and "previous" pointers (base::LinkNode<T>*).
-//    Whereas with std::list<T> the type can be anything, so the implementation
-//    needs to glue on the "next" and "previous" pointers using
-//    some internal node type.
-
-namespace base {
-
-template <typename T>
-class LinkNode {
- public:
-  LinkNode() : previous_(NULL), next_(NULL) {}
-  LinkNode(LinkNode<T>* previous, LinkNode<T>* next)
-      : previous_(previous), next_(next) {}
-
-  // Insert |this| into the linked list, before |e|.
-  void InsertBefore(LinkNode<T>* e) {
-    this->next_ = e;
-    this->previous_ = e->previous_;
-    e->previous_->next_ = this;
-    e->previous_ = this;
-  }
-
-  // Insert |this| into the linked list, after |e|.
-  void InsertAfter(LinkNode<T>* e) {
-    this->next_ = e->next_;
-    this->previous_ = e;
-    e->next_->previous_ = this;
-    e->next_ = this;
-  }
-
-  // Remove |this| from the linked list.
-  void RemoveFromList() {
-    this->previous_->next_ = this->next_;
-    this->next_->previous_ = this->previous_;
-    // next() and previous() return non-NULL if and only this node is not in any
-    // list.
-    this->next_ = NULL;
-    this->previous_ = NULL;
-  }
-
-  LinkNode<T>* previous() const {
-    return previous_;
-  }
-
-  LinkNode<T>* next() const {
-    return next_;
-  }
-
-  // Cast from the node-type to the value type.
-  const T* value() const {
-    return static_cast<const T*>(this);
-  }
-
-  T* value() {
-    return static_cast<T*>(this);
-  }
-
- private:
-  LinkNode<T>* previous_;
-  LinkNode<T>* next_;
-
-  DISALLOW_COPY_AND_ASSIGN(LinkNode);
-};
-
-template <typename T>
-class LinkedList {
- public:
-  // The "root" node is self-referential, and forms the basis of a circular
-  // list (root_.next() will point back to the start of the list,
-  // and root_->previous() wraps around to the end of the list).
-  LinkedList() : root_(&root_, &root_) {}
-
-  // Appends |e| to the end of the linked list.
-  void Append(LinkNode<T>* e) {
-    e->InsertBefore(&root_);
-  }
-
-  LinkNode<T>* head() const {
-    return root_.next();
-  }
-
-  LinkNode<T>* tail() const {
-    return root_.previous();
-  }
-
-  const LinkNode<T>* end() const {
-    return &root_;
-  }
-
-  bool empty() const { return head() == end(); }
-
- private:
-  LinkNode<T> root_;
-
-  DISALLOW_COPY_AND_ASSIGN(LinkedList);
-};
-
-}  // namespace base
-
-#endif  // BASE_CONTAINERS_LINKED_LIST_H_