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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 & an_element)63   explicit QueueNode(const E& an_element) : element_(an_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   // Creates an empty queue.
Queue()77   Queue() : head_(NULL), last_(NULL), size_(0) {}
78 
79   // D'tor.  Clears the queue.
~Queue()80   ~Queue() { Clear(); }
81 
82   // Clears the queue.
Clear()83   void Clear() {
84     if (size_ > 0) {
85       // 1. Deletes every node.
86       QueueNode<E>* node = head_;
87       QueueNode<E>* next = node->next();
88       for (; ;) {
89         delete node;
90         node = next;
91         if (node == NULL) break;
92         next = node->next();
93       }
94 
95       // 2. Resets the member variables.
96       head_ = last_ = NULL;
97       size_ = 0;
98     }
99   }
100 
101   // Gets the number of elements.
Size()102   size_t Size() const { return size_; }
103 
104   // Gets the first element of the queue, or NULL if the queue is empty.
Head()105   QueueNode<E>* Head() { return head_; }
Head()106   const QueueNode<E>* Head() const { return head_; }
107 
108   // Gets the last element of the queue, or NULL if the queue is empty.
Last()109   QueueNode<E>* Last() { return last_; }
Last()110   const QueueNode<E>* Last() const { return last_; }
111 
112   // Adds an element to the end of the queue.  A copy of the element is
113   // created using the copy constructor, and then stored in the queue.
114   // Changes made to the element in the queue doesn't affect the source
115   // object, and vice versa.
Enqueue(const E & element)116   void Enqueue(const E& element) {
117     QueueNode<E>* new_node = new QueueNode<E>(element);
118 
119     if (size_ == 0) {
120       head_ = last_ = new_node;
121       size_ = 1;
122     } else {
123       last_->next_ = new_node;
124       last_ = new_node;
125       size_++;
126     }
127   }
128 
129   // Removes the head of the queue and returns it.  Returns NULL if
130   // the queue is empty.
Dequeue()131   E* Dequeue() {
132     if (size_ == 0) {
133       return NULL;
134     }
135 
136     const QueueNode<E>* const old_head = head_;
137     head_ = head_->next_;
138     size_--;
139     if (size_ == 0) {
140       last_ = NULL;
141     }
142 
143     E* element = new E(old_head->element());
144     delete old_head;
145 
146     return element;
147   }
148 
149   // Applies a function/functor on each element of the queue, and
150   // returns the result in a new queue.  The original queue is not
151   // affected.
152   template <typename F>
Map(F function)153   Queue* Map(F function) const {
154     Queue* new_queue = new Queue();
155     for (const QueueNode<E>* node = head_; node != NULL; node = node->next_) {
156       new_queue->Enqueue(function(node->element()));
157     }
158 
159     return new_queue;
160   }
161 
162  private:
163   QueueNode<E>* head_;  // The first node of the queue.
164   QueueNode<E>* last_;  // The last node of the queue.
165   size_t size_;  // The number of elements in the queue.
166 
167   // We disallow copying a queue.
168   Queue(const Queue&);
169   const Queue& operator = (const Queue&);
170 };
171 
172 #endif  // GTEST_SAMPLES_SAMPLE3_INL_H_
173