JavaScript 数据结构（6）：双端链表 FirstLastList

/**
* 双端链表(FirstLastList)
*/

/* Link 链表节点 */
function Link (data) {
this.data = data;
this.next = null;
}

Link.prototype.displayLink = function(){
console.log(this.data);
};

/* FirstLastList 双端链表 */
function FirstLastList () {
var first = null,		// 链表中的第一个链结点
last = null,		// 链表中的最后一个链结点
size = 0;

return {
insertFirst: function(data){		// 在表头插入一个结点
var link = new Link(data);
link.next = first;
first = link;
if(last === null){
last = link;
}
size++;
},
insertLast: function(data){
var link = new Link(data);
if(last === null){
first = last = link;
}else{
last.next = link;
last = link;
}
size++;
},
deleteFirst: function(){		// 删除表头结点
var link = null;

if(size > 1){
link = first;
first = first.next;
size--;
}else if(size == 1){
link = first;
first = last = null;
size--;
}

return link.data;
},
search: function(key){		// 根据指定值查找结点
var current = first;

while(current !== null){
if(current.data === key){
console.log('Find it!');
return current.data;
}
current = current.next;
}
console.log('Can not find such a Link.');
return null;
},
delete: function(key){		// 根据指定值删除结点
var previous = null,
current = first;

while(current !== null){
if(current.data === key){
size--;

console.log('Find and delete it!');
if(current === first){
first = current.next;
return current.data;
}else{
previous.next = current.next;
return current.data;
}

if(current === last){
last = previous;
}
}

previous = current;
current = current.next;
}
console.log('Can not delete such a Link.');
return null;
},
displayList: function(){		// 显示整个链表
console.log('List(first --> last):')
var current = first;
while(current !== null){
current.displayLink();
current = current.next;
}
},
size: function() {		// 链表长度
return size;
},
isEmpty: function(){		// 判断链表是否为空
return size === 0;
}
}
}

// 测试

var list = new FirstLastList();

list.insertLast(5);
list.insertLast(6);
list.insertLast(7);
list.displayList();

list.insertFirst(4);
list.displayList();

console.log(list.delete(6));
list.displayList();

console.log('Delete till list is empty:');
while(!list.isEmpty()){
console.log(list.deleteFirst());
}