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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  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
73template <typename E>  // E is the element type.
74class Queue {
75 public:
76  // Creates an empty queue.
77  Queue() : head_(NULL), last_(NULL), size_(0) {}
78
79  // D'tor.  Clears the queue.
80  ~Queue() { Clear(); }
81
82  // Clears the queue.
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.
102  size_t Size() const { return size_; }
103
104  // Gets the first element of the queue, or NULL if the queue is empty.
105  QueueNode<E>* Head() { return 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.
109  QueueNode<E>* Last() { return 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.
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.
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>
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