模板与泛型编程
--类模板成员[续2]
六、完整的Queue类
Queue的完整定义：
templateclass Queue; template ostream &operator<<(ostream &,const Queue &); template class QueueItem { friend class Queue ; friend ostream & operator<< (ostream &,const Queue &); QueueItem(const Type &t):item(t),next(0) {} Type item; QueueItem *next; }; template class Queue { friend ostream & operator<< (ostream &,const Queue &); public: Queue():head(0),tail(0) {} template Queue(Iter beg,Iter end):head(0),tail(0) { copy_elems(beg,end); } Queue(const Queue &Q):head(0),tail(0) { copy_elems(Q); } Queue &operator=(const Queue &); ~Queue() { destroy(); } template void assign(Iter,Iter); Type &front() { return head -> item; } const Type &front() const { return head -> item; } void push(const Type &); void pop(); bool empty() const { return head == 0; } private: QueueItem *head; QueueItem *tail; void destroy(); void copy_elems(const Queue &); template void copy_elems(Iter,Iter); }; #include “Queue.cpp”
//P559 习题16.43 + P551习题16.34 templateclass List; template class ListItem { friend class List ; ListItem(Type &t):item(t),next(0) {} Type item; ListItem *next; }; template class List { public: List():front(0),end(0) {} List(const List &rhs):front(0),end(0) { copy_elems(rhs); } template List(Iter first,Iter last):front(first),end(last) { copy_elems(first,last); } List &operator=(const List &rhs); ~List() { destroy(); } void insert(ListItem *ptr,Type &value); void del(ListItem *ptr); ListItem *find(const Type &value); ListItem *first() const { return front; } ListItem *last() const { return end; } bool empty() const { return front == 0; } Type &getElem(ListItem *ptr) { return ptr -> item; } template void assign(Iter,Iter); private: ListItem *front,*end; void destroy(); void copy_elems(List &); template void copy_elems(Iter,Iter); }; template void List ::destroy() { while (!empty()) del(front); } template void List ::del(ListItem *ptr) { ListItem *p = front; while (p != 0 && p != ptr && p -> next != ptr) { p = p -> next; } if (p != 0) { if (p == ptr) { front = ptr -> next; } else { p -> next = ptr -> next; } if (ptr == end) { end = ptr -> next; } delete ptr; } else { throw out_of_range("no such element"); } } template void List ::insert(ListItem *ptr,Type &val) { ListItem *pt = new ListItem (val); if (empty()) { front = pt; } else { pt -> next = ptr -> next; ptr -> next = pt; } if (ptr == end) { end = pt; } } template void List ::copy_elems(List &rhs) { for (ListItem *pt = rhs.front; pt ; pt = pt -> next) { insert(end,pt -> item); } } template template void List ::copy_elems(Iter first,Iter last) { while (first != last) { insert(end,first -> item); first = first -> next; } insert(end,first -> item); } template List &List ::operator=(const List &rhs) { destroy(); copy_elems(rhs); } template ListItem *List ::find(const Type &value) { ListItem *pt = front; while (pt && pt -> item != value) { pt = pt -> next; } return pt; } template template void List ::assign(Iter first,Iter last) { destroy(); copy_elems(first,last); }
//习题16.44 templateclass Queue; template ostream &operator<<(ostream &os,const Queue &); template class Queue { friend ostream &operator<< (ostream &os,const Queue &); public: Queue() {} template Queue(Iter beg,Iter end):items(beg,end) {} template void assign(Iter beg,Iter end) { items.assign(beg,end); } Type &front() { return items.front(); } const Type &f