private IEnumerable <T> EnumerateRecords(BTree2Node <T> node, ushort nodeLevel)
{
// This method could be rearranged to accept a BTree2NodePointer (instead of the root node).
// In that case it would be possible to simplify the double check for internal/leaf node.
// internal node
var internalNode = node as BTree2InternalNode <T>;
if (internalNode is not null)
{
var records = node.Records
.Cast <T>()
.ToList();
var nodePointers = internalNode.NodePointers;
for (int i = 0; i < nodePointers.Length; i++)
{
// there is one more node pointer than records
if (i < records.Count)
{
yield return(records[i]);
}
var nodePointer = nodePointers[i];
this.Reader.Seek((long)nodePointer.Address, SeekOrigin.Begin);
var childNodeLevel = (ushort)(nodeLevel - 1);
IEnumerable <T> childRecords;
// internal node
if (childNodeLevel > 0)
{
var childNode = new BTree2InternalNode <T>(this.Reader, _superblock, this, nodePointer.RecordCount, childNodeLevel, _decodeKey);
childRecords = this.EnumerateRecords(childNode, childNodeLevel);
}
// leaf node
else
{
var childNode = new BTree2LeafNode <T>(this.Reader, this, nodePointer.RecordCount, _decodeKey);
childRecords = childNode.Records;
}
foreach (var record in childRecords)
{
yield return(record);
}
}
}
// leaf node
else
{
foreach (var record in node.Records)
{
yield return(record);
}
}
}
public bool TryFindRecord(out T result, Func <T, int> compare)
{
/* H5B2.c (H5B2_find) */
int cmp;
uint index = 0;
BTree2NodePosition curr_pos;
result = default;
/* Make copy of the root node pointer to start search with */
var currentNodePointer = this.RootNodePointer;
/* Check for empty tree */
if (currentNodePointer.RecordCount == 0)
{
return(false);
}
#warning Optimizations missing.
/* Current depth of the tree */
var depth = this.Depth;
/* Walk down B-tree to find record or leaf node where record is located */
cmp = -1;
curr_pos = BTree2NodePosition.Root;
while (depth > 0)
{
this.Reader.Seek((long)currentNodePointer.Address, SeekOrigin.Begin);
var internalNode = new BTree2InternalNode <T>(this.Reader, _superblock, this, currentNodePointer.RecordCount, depth, _decodeKey);
if (internalNode is null)
{
throw new Exception("Unable to load B-tree internal node.");
}
/* Locate node pointer for child */
(index, cmp) = this.LocateRecord(internalNode.Records, compare);
if (cmp > 0)
{
index++;
}
if (cmp != 0)
{
/* Get node pointer for next node to search */
var nextNodePointer = internalNode.NodePointers[index];
/* Set the position of the next node */
if (curr_pos != BTree2NodePosition.Middle)
{
if (index == 0)
{
if (curr_pos == BTree2NodePosition.Left || curr_pos == BTree2NodePosition.Root)
{
curr_pos = BTree2NodePosition.Left;
}
else
{
curr_pos = BTree2NodePosition.Middle;
}
}
else if (index == internalNode.Records.Length)
{
if (curr_pos == BTree2NodePosition.Right || curr_pos == BTree2NodePosition.Root)
{
curr_pos = BTree2NodePosition.Right;
}
else
{
curr_pos = BTree2NodePosition.Middle;
}
}
else
{
curr_pos = BTree2NodePosition.Middle;
}
}
currentNodePointer = nextNodePointer;
}
else
{
result = internalNode.Records[index];
return(true);
}
/* Decrement depth we're at in B-tree */
depth--;
}
{
this.Reader.Seek((long)currentNodePointer.Address, SeekOrigin.Begin);
var leafNode = new BTree2LeafNode <T>(this.Reader, this, currentNodePointer.RecordCount, _decodeKey);
/* Locate record */
(index, cmp) = this.LocateRecord(leafNode.Records, compare);
if (cmp == 0)
{
result = leafNode.Records[index];
return(true);
#warning Optimizations missing.
}
}
return(false);
}