test/gtest-1.6.0/samples/sample3-inl.h

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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.
  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
  73 template <typename E>  // E is the element type.
  74 class Queue {
  75 public:
  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_