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1 // Copyright 2005, Google Inc.
2 // All rights reserved.
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29 
30 // A sample program demonstrating using Google C++ testing framework.
31 //
32 // Author: wan@google.com (Zhanyong Wan)
33 
34 #ifndef GTEST_SAMPLES_SAMPLE3_INL_H_
35 #define GTEST_SAMPLES_SAMPLE3_INL_H_
36 
37 #include <stddef.h>
38 
39 
40 // Queue is a simple queue implemented as a singled-linked list.
41 //
42 // The element type must support copy constructor.
43 template <typename E>  // E is the element type
44 class Queue;
45 
46 // QueueNode is a node in a Queue, which consists of an element of
47 // type E and a pointer to the next node.
48 template <typename E>  // E is the element type
49 class QueueNode {
50   friend class Queue<E>;
51 
52  public:
53   // Gets the element in this node.
element()54   const E & element() const { return element_; }
55 
56   // Gets the next node in the queue.
next()57   QueueNode * next() { return next_; }
next()58   const QueueNode * next() const { return next_; }
59 
60  private:
61   // Creates a node with a given element value.  The next pointer is
62   // set to NULL.
QueueNode(const E & element)63   QueueNode(const E & element) : element_(element), next_(NULL) {}
64 
65   // We disable the default assignment operator and copy c'tor.
66   const QueueNode & operator = (const QueueNode &);
67   QueueNode(const QueueNode &);
68 
69   E element_;
70   QueueNode * next_;
71 };
72 
73 template <typename E>  // E is the element type.
74 class Queue {
75 public:
76 
77   // Creates an empty queue.
Queue()78   Queue() : head_(NULL), last_(NULL), size_(0) {}
79 
80   // D'tor.  Clears the queue.
~Queue()81   ~Queue() { Clear(); }
82 
83   // Clears the queue.
Clear()84   void Clear() {
85     if (size_ > 0) {
86       // 1. Deletes every node.
87       QueueNode<E> * node = head_;
88       QueueNode<E> * next = node->next();
89       for (; ;) {
90         delete node;
91         node = next;
92         if (node == NULL) break;
93         next = node->next();
94       }
95 
96       // 2. Resets the member variables.
97       head_ = last_ = NULL;
98       size_ = 0;
99     }
100   }
101 
102   // Gets the number of elements.
Size()103   size_t Size() const { return size_; }
104 
105   // Gets the first element of the queue, or NULL if the queue is empty.
Head()106   QueueNode<E> * Head() { return head_; }
Head()107   const QueueNode<E> * Head() const { return head_; }
108 
109   // Gets the last element of the queue, or NULL if the queue is empty.
Last()110   QueueNode<E> * Last() { return last_; }
Last()111   const QueueNode<E> * Last() const { return last_; }
112 
113   // Adds an element to the end of the queue.  A copy of the element is
114   // created using the copy constructor, and then stored in the queue.
115   // Changes made to the element in the queue doesn't affect the source
116   // object, and vice versa.
Enqueue(const E & element)117   void Enqueue(const E & element) {
118     QueueNode<E> * new_node = new QueueNode<E>(element);
119 
120     if (size_ == 0) {
121       head_ = last_ = new_node;
122       size_ = 1;
123     } else {
124       last_->next_ = new_node;
125       last_ = new_node;
126       size_++;
127     }
128   }
129 
130   // Removes the head of the queue and returns it.  Returns NULL if
131   // the queue is empty.
Dequeue()132   E * Dequeue() {
133     if (size_ == 0) {
134       return NULL;
135     }
136 
137     const QueueNode<E> * const old_head = head_;
138     head_ = head_->next_;
139     size_--;
140     if (size_ == 0) {
141       last_ = NULL;
142     }
143 
144     E * element = new E(old_head->element());
145     delete old_head;
146 
147     return element;
148   }
149 
150   // Applies a function/functor on each element of the queue, and
151   // returns the result in a new queue.  The original queue is not
152   // affected.
153   template <typename F>
Map(F function)154   Queue * Map(F function) const {
155     Queue * new_queue = new Queue();
156     for (const QueueNode<E> * node = head_; node != NULL; node = node->next_) {
157       new_queue->Enqueue(function(node->element()));
158     }
159 
160     return new_queue;
161   }
162 
163  private:
164   QueueNode<E> * head_;  // The first node of the queue.
165   QueueNode<E> * last_;  // The last node of the queue.
166   size_t size_;  // The number of elements in the queue.
167 
168   // We disallow copying a queue.
169   Queue(const Queue &);
170   const Queue & operator = (const Queue &);
171  };
172 
173 #endif  // GTEST_SAMPLES_SAMPLE3_INL_H_
174