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 // Copyright 2005, Google Inc.

 // All rights reserved.

 //

 // Redistribution and use in source and binary forms, with or without

 // modification, are permitted provided that the following conditions are

 // met:

 //

 //     * Redistributions of source code must retain the above copyright

 // notice, this list of conditions and the following disclaimer.

 //     * Redistributions in binary form must reproduce the above

 // copyright notice, this list of conditions and the following disclaimer

 // in the documentation and/or other materials provided with the

 // distribution.

 //     * Neither the name of Google Inc. nor the names of its

 // contributors may be used to endorse or promote products derived from

 // this software without specific prior written permission.

 //

 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 // A sample program demonstrating using Google C++ testing framework.

 //

 // Author: wan@google.com (Zhanyong Wan)

 #ifndef GTEST_SAMPLES_SAMPLE3_INL_H_

 #define GTEST_SAMPLES_SAMPLE3_INL_H_

 #include <stddef.h>

 // Queue is a simple queue implemented as a singled-linked list.

 //

 // The element type must support copy constructor.

 template <typename E>  // E is the element type

 class Queue;

 // QueueNode is a node in a Queue, which consists of an element of

 // type E and a pointer to the next node.

 template <typename E>  // E is the element type

 class QueueNode {

   friend class Queue<E>;

  public:

   // Gets the element in this node.

   const E& element() const { return element_; }

   // Gets the next node in the queue.

   QueueNode* next() { return next_; }

   const QueueNode* next() const { return next_; }

  private:

   // Creates a node with a given element value.  The next pointer is

   // set to NULL.

   explicit QueueNode(const E& an_element) : element_(an_element), next_(NULL) {}

   // We disable the default assignment operator and copy c'tor.

   const QueueNode& operator = (const QueueNode&);

   QueueNode(const QueueNode&);

   E element_;

   QueueNode* next_;

 };

 template <typename E>  // E is the element type.

 class Queue {

  public:

   // Creates an empty queue.

   Queue() : head_(NULL), last_(NULL), size_(0) {}

   // D'tor.  Clears the queue.

   ~Queue() { Clear(); }

   // Clears the queue.

   void Clear() {

     if (size_ > 0) {

       // 1. Deletes every node.

       QueueNode<E>* node = head_;

       QueueNode<E>* next = node->next();

       for (; ;) {

         delete node;

         node = next;

         if (node == NULL) break;

         next = node->next();

       }

       // 2. Resets the member variables.

       head_ = last_ = NULL;

       size_ = 0;

     }

   }

   // Gets the number of elements.

   size_t Size() const { return size_; }

   // Gets the first element of the queue, or NULL if the queue is empty.

   QueueNode<E>* Head() { return head_; }

   const QueueNode<E>* Head() const { return head_; }

   // Gets the last element of the queue, or NULL if the queue is empty.

   QueueNode<E>* Last() { return last_; }

   const QueueNode<E>* Last() const { return last_; }

   // Adds an element to the end of the queue.  A copy of the element is

   // created using the copy constructor, and then stored in the queue.

   // Changes made to the element in the queue doesn't affect the source

   // object, and vice versa.

   void Enqueue(const E& element) {

     QueueNode<E>* new_node = new QueueNode<E>(element);

     if (size_ == 0) {

       head_ = last_ = new_node;

       size_ = 1;

     } else {

       last_->next_ = new_node;

       last_ = new_node;

       size_++;

     }

   }

   // Removes the head of the queue and returns it.  Returns NULL if

   // the queue is empty.

   E* Dequeue() {

     if (size_ == 0) {

       return NULL;

     }

     const QueueNode<E>* const old_head = head_;

     head_ = head_->next_;

     size_--;

     if (size_ == 0) {

       last_ = NULL;

     }

     E* element = new E(old_head->element());

     delete old_head;

     return element;

   }

   // Applies a function/functor on each element of the queue, and

   // returns the result in a new queue.  The original queue is not

   // affected.

   template <typename F>

   Queue* Map(F function) const {

     Queue* new_queue = new Queue();

     for (const QueueNode<E>* node = head_; node != NULL; node = node->next_) {

       new_queue->Enqueue(function(node->element()));

     }

     return new_queue;

   }

  private:

   QueueNode<E>* head_;  // The first node of the queue.

   QueueNode<E>* last_;  // The last node of the queue.

   size_t size_;  // The number of elements in the queue.

   // We disallow copying a queue.

   Queue(const Queue&);

   const Queue& operator = (const Queue&);

 };

 #endif  // GTEST_SAMPLES_SAMPLE3_INL_H_