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sample3-inl.h
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29
30// A sample program demonstrating using Google C++ testing framework.
31
32#ifndef GOOGLETEST_SAMPLES_SAMPLE3_INL_H_
33#define GOOGLETEST_SAMPLES_SAMPLE3_INL_H_
34
35#include <stddef.h>
36
37// Queue is a simple queue implemented as a singled-linked list.
38//
39// The element type must support copy constructor.
40template <typename E> // E is the element type
41class Queue;
42
43// QueueNode is a node in a Queue, which consists of an element of
44// type E and a pointer to the next node.
45template <typename E> // E is the element type
46class QueueNode {
47 friend class Queue<E>;
48
49 public:
50 // Gets the element in this node.
51 const E& element() const { return element_; }
52
53 // Gets the next node in the queue.
54 QueueNode* next() { return next_; }
55 const QueueNode* next() const { return next_; }
56
57 private:
58 // Creates a node with a given element value. The next pointer is
59 // set to NULL.
60 explicit QueueNode(const E& an_element)
61 : element_(an_element), next_(nullptr) {}
62
63 // We disable the default assignment operator and copy c'tor.
64 const QueueNode& operator=(const QueueNode&);
65 QueueNode(const QueueNode&);
66
67 E element_;
68 QueueNode* next_;
69};
70
71template <typename E> // E is the element type.
72class Queue {
73 public:
74 // Creates an empty queue.
75 Queue() : head_(nullptr), last_(nullptr), size_(0) {}
76
77 // D'tor. Clears the queue.
78 ~Queue() { Clear(); }
79
80 // Clears the queue.
81 void Clear() {
82 if (size_ > 0) {
83 // 1. Deletes every node.
84 QueueNode<E>* node = head_;
85 QueueNode<E>* next = node->next();
86 for (;;) {
87 delete node;
88 node = next;
89 if (node == nullptr) break;
90 next = node->next();
91 }
92
93 // 2. Resets the member variables.
94 head_ = last_ = nullptr;
95 size_ = 0;
96 }
97 }
98
99 // Gets the number of elements.
100 size_t Size() const { return size_; }
101
102 // Gets the first element of the queue, or NULL if the queue is empty.
103 QueueNode<E>* Head() { return head_; }
104 const QueueNode<E>* Head() const { return head_; }
105
106 // Gets the last element of the queue, or NULL if the queue is empty.
107 QueueNode<E>* Last() { return last_; }
108 const QueueNode<E>* Last() const { return last_; }
109
110 // Adds an element to the end of the queue. A copy of the element is
111 // created using the copy constructor, and then stored in the queue.
112 // Changes made to the element in the queue doesn't affect the source
113 // object, and vice versa.
114 void Enqueue(const E& element) {
115 QueueNode<E>* new_node = new QueueNode<E>(element);
116
117 if (size_ == 0) {
118 head_ = last_ = new_node;
119 size_ = 1;
120 } else {
121 last_->next_ = new_node;
122 last_ = new_node;
123 size_++;
124 }
125 }
126
127 // Removes the head of the queue and returns it. Returns NULL if
128 // the queue is empty.
129 E* Dequeue() {
130 if (size_ == 0) {
131 return nullptr;
132 }
133
134 const QueueNode<E>* const old_head = head_;
135 head_ = head_->next_;
136 size_--;
137 if (size_ == 0) {
138 last_ = nullptr;
139 }
140
141 E* element = new E(old_head->element());
142 delete old_head;
143
144 return element;
145 }
146
147 // Applies a function/functor on each element of the queue, and
148 // returns the result in a new queue. The original queue is not
149 // affected.
150 template <typename F>
151 Queue* Map(F function) const {
152 Queue* new_queue = new Queue();
153 for (const QueueNode<E>* node = head_; node != nullptr;
154 node = node->next_) {
155 new_queue->Enqueue(function(node->element()));
156 }
157
158 return new_queue;
159 }
160
161 private:
162 QueueNode<E>* head_; // The first node of the queue.
163 QueueNode<E>* last_; // The last node of the queue.
164 size_t size_; // The number of elements in the queue.
165
166 // We disallow copying a queue.
167 Queue(const Queue&);
168 const Queue& operator=(const Queue&);
169};
170
171#endif // GOOGLETEST_SAMPLES_SAMPLE3_INL_H_
const QueueNode< E > * Head() const
E * Dequeue()
Queue * Map(F function) const
const QueueNode< E > * Last() const
QueueNode< E > * Last()
void Enqueue(const E &element)
size_t Size() const
void Clear()
Definition sample3-inl.h:81
QueueNode< E > * Head()
const QueueNode * next() const
Definition sample3-inl.h:55
QueueNode * next()
Definition sample3-inl.h:54
const E & element() const
Definition sample3-inl.h:51