/// <summary>
/// 根据索引获取结点
/// </summary>
/// <param name="index"></param>
/// <returns></returns>
public DbNode <T> GetNodeByIndex(int index)
{
//首先判断index是否超出界限
if (index < 0 || index > count - 1)
{
throw new ArgumentOutOfRangeException("index", "索引超出界限");
}
//先把头结点赋值
DbNode <T> tempNode = head;
for (int i = 0; i < index; i++)
{
tempNode = tempNode.Next;
}
return(tempNode);
}
/// <summary>
/// 在尾结点之前插入结点
/// </summary>
/// <param name="value"></param>
public void AddBefore(T value)
{
DbNode <T> newNode = new DbNode <T>(value);
if (head == null)
{
head = newNode;
}
else
{
DbNode <T> lastNode = GetNodeByIndex(count - 1);
lastNode.Prev.Next = newNode;
newNode.Prev = lastNode.Prev;
newNode.Next = lastNode;
lastNode.Prev = newNode;
}
count++;
}
/// <summary>
/// 在尾结点之后插入新结点
/// </summary>
/// <param name="value"></param>
public void AddAfter(T value)
{
DbNode <T> newNode = new DbNode <T>(value);
//这里判断当前链表是否存在结点
if (head == null)
{
//插入头结点
head = newNode;
}
else
{
//根据索引获取尾结点
DbNode <T> lastNode = GetNodeByIndex(count - 1);
lastNode.Next = newNode;
newNode.Prev = lastNode;
newNode.Next = null;
}
count++;
}
/// <summary>
/// 指定位置后插入新结点
/// </summary>
/// <param name="index"></param>
/// <param name="value"></param>
public void InsertAfter(int index, T value)
{
//先判断index是否合法
if (index < 0 || index > count - 1)
{
throw new ArgumentOutOfRangeException("index", "索引超出界限");
}
//根据Value值拿到结点
DbNode <T> newNode = new DbNode <T>(value);
//拿到当前索引对应的结点
DbNode <T> currentNode = GetNodeByIndex(index);
//拿到当前索引下一个结点
DbNode <T> nextNode = GetNodeByIndex(index + 1);
if (index == 0)
{
if (head == null)
{
//插入头结点
head = newNode;
}
else
{
head.Next = newNode;
newNode.Prev = head;
newNode.Next = nextNode;
nextNode.Prev = newNode;
}
}
else
{
currentNode.Next = newNode;
newNode.Prev = currentNode;
newNode.Next = nextNode;
newNode.Prev = newNode;
}
count++;
}