/// <summary>
/// 在尾节点前插入新节点
/// </summary>
/// <param name="value"></param>
public void AddBefore(T value)
{
DbNode <T> dbNode = new DbNode <T>(value);
if (this.head == null)
{
this.head = dbNode;
}
else if (this.head.NextNode == null)
{
dbNode.NextNode = this.head;
this.head.PrevNode = dbNode;
this.head = dbNode;
}
else
{
DbNode <T> lastNode = GetNodeByIndex(this.count - 1);
DbNode <T> lastSecondNode = lastNode.PrevNode;//倒数第二个
//调整倒数第二个节点
lastSecondNode.NextNode = dbNode;
dbNode.PrevNode = lastSecondNode;
//调整倒数第一个节点
lastNode.PrevNode = dbNode;
dbNode.NextNode = lastNode;
}
this.count++;
}
/// <summary>
/// 在指定位置前插入新节点
/// </summary>
/// <param name="index">索引</param>
/// <param name="value"></param>
public void InsertBefore(int index, T value)
{
DbNode <T> dbNode = new DbNode <T>(value);
if (index < 0 || index > this.count)
{
throw new ArgumentOutOfRangeException("index", "索引超出范围");
}
else if (index == 0)
{
if (this.head == null)
{
this.head = dbNode;
}
else
{
this.head.PrevNode = dbNode;
dbNode.NextNode = this.head;
this.head = dbNode;
}
}
else
{
DbNode <T> currNode = GetNodeByIndex(index);
DbNode <T> prevNode = currNode.PrevNode;
currNode.PrevNode = dbNode;
prevNode.NextNode = dbNode;
dbNode.PrevNode = prevNode;
dbNode.NextNode = currNode;
}
this.count++;
}
private DbNode <T> GetNodeByIndex(int index)
{
if (index < 0 || index > this.count)
{
throw new ArgumentOutOfRangeException("index", "索引超出范围");
}
DbNode <T> dbNode = this.head;
for (int i = 0; i < index; i++)
{
dbNode = dbNode.NextNode;
}
return(dbNode);
}
/// <summary>
/// 在末尾添加节点
/// </summary>
/// <param name="value"></param>
public void AddAfter(T value)
{
DbNode <T> dbNode = new DbNode <T>(value);
if (this.head == null)
{
this.head = dbNode;
}
else
{
DbNode <T> lastNode = GetNodeByIndex(this.count - 1);
lastNode.NextNode = dbNode;
dbNode.PrevNode = lastNode;
}
this.count++;
}
/// <summary>
/// 移除指定位置节点
/// </summary>
/// <param name="index"></param>
public void RemoveAt(int index)
{
if (index < 0 || index > this.count)
{
throw new ArgumentOutOfRangeException("index", "索引超出范围");
}
else if (index == 0)
{
this.head = this.head?.NextNode;
}
else
{
DbNode <T> delNode = GetNodeByIndex(index);
DbNode <T> nextNode = delNode.NextNode;
DbNode <T> prevNode = delNode.PrevNode;
prevNode.NextNode = nextNode;
if (nextNode != null)
{
nextNode.PrevNode = prevNode;
}
delNode = null;
}
this.count--;
}
public MyDoubleLinkedList()
{
count = 0;
head = null;
}
