/// <summary>
/// 从指定的流初始化树
/// </summary>
/// <param name="fromFile">指定的流</param>
/// <param name="seekStart">流起始查询点</param>
/// <param name="keyLength">键长度</param>
/// <param name="nodeCapacity">节点容量</param>
/// <returns>树</returns>
public static BPlusTree InitializeInStream(Stream fromFile, long seekStart, int keyLength, int nodeCapacity)
{
if (fromFile == null)
{
throw new ArgumentNullException("fromFile");
}
if (fromFile.Length > seekStart)
{
throw new BPlusTreeException("Cannot initialize tree inside written area of stream.");
}
BPlusTree tree = new BPlusTree(fromFile, seekStart, keyLength, nodeCapacity, (byte)1);
tree.WriteHeader();
tree.BlockFile = BlockFile.InitializeInStream(
fromFile, seekStart + HeaderSize, StorageConstants.BlockFileHeaderPrefix, tree.BlockSize);
return(tree);
}
public static BPlusTreeNode BinaryRoot(
BPlusTreeNode oldRoot, string splitFirstKey,
BPlusTreeNode splitNode, BPlusTree tree)
{
if (oldRoot == null)
{
throw new ArgumentNullException("oldRoot");
}
if (splitNode == null)
{
throw new ArgumentNullException("splitNode");
}
BPlusTreeNode newRoot = MakeRoot(tree, false);
newRoot._childKeys[0] = splitFirstKey;
oldRoot.ResetParent(newRoot, 0);
splitNode.ResetParent(newRoot, 1);
return(newRoot);
}
/// <summary>
/// 为树构造一个根节点
/// </summary>
/// <param name="tree">指定树</param>
/// <param name="isLeaf">是否为叶节点</param>
/// <returns>根节点</returns>
public static BPlusTreeNode MakeRoot(BPlusTree tree, bool isLeaf)
{
return(new BPlusTreeNode(tree, null, -1, isLeaf));
}