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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.
43template <typename E>  // E is the element type
44class 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.
48template <typename E>  // E is the element type
49class QueueNode {
50  friend class Queue<E>;
51
52 public:
53  // Gets the element in this node.
54  const E& element() const { return element_; }
55
56  // Gets the next node in the queue.
57  QueueNode* next() { return 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.
63  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
73template <typename E>  // E is the element type.
74class Queue {
75public:
76
77  // Creates an empty queue.
78  Queue() : head_(NULL), last_(NULL), size_(0) {}
79
80  // D'tor.  Clears the queue.
81  ~Queue() { Clear(); }
82
83  // Clears the queue.
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.
103  size_t Size() const { return size_; }
104
105  // Gets the first element of the queue, or NULL if the queue is empty.
106  QueueNode<E>* Head() { return 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.
110  QueueNode<E>* Last() { return 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.
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.
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>
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