public override IMemTreeNode Free(int offset, int blocks)
{
if (leftChild.LastBlock > offset) // is this offset contained in the left subtree?
{
leftChild = leftChild.Free(offset, blocks);
contiguousBlocks = (leftChild.ContiguousBlocks < rightChild.ContiguousBlocks) ? rightChild.ContiguousBlocks : leftChild.ContiguousBlocks;
if (leftChild.LastBlock + 1 == rightChild.FirstBlock)
{ // left and right nodes have become contiguous, so merge them
return(Merge());
}
return(this);
}
else if (rightChild.FirstBlock < offset) //is this offset contained in the right subtree?
{
rightChild = rightChild.Free(offset, blocks);
contiguousBlocks = (leftChild.ContiguousBlocks < rightChild.ContiguousBlocks) ? rightChild.ContiguousBlocks : leftChild.ContiguousBlocks;
if (leftChild.LastBlock + 1 == rightChild.FirstBlock)
{ // left and right nodes have become contiguous, so merge them
return(Merge());
}
return(this);
}
else
{
// oh crap, not in either of them. Guess we'll have to handle this ourselves.
// does the block to free lie adjacent ot the leftchild or rightchild?
bool leftAdjacent, rightAdjacent;
leftAdjacent = (offset - 1 == leftChild.LastBlock);
rightAdjacent = (offset + blocks == rightChild.FirstBlock);
if (leftAdjacent)
{
if (rightAdjacent)
{ // Adjacent to both right and left, so merge them into one.
return(Merge());
}
else
{ // Adjacent to left only, expand left
leftChild.ExpandRightLeaf(blocks);
contiguousBlocks = (leftChild.ContiguousBlocks < rightChild.ContiguousBlocks) ? rightChild.ContiguousBlocks : leftChild.ContiguousBlocks;
return(this);
}
}
else if (rightAdjacent)
{ // adjacent to right only, expand right;
rightChild.ExpandLeftLeaf(blocks);
contiguousBlocks = (leftChild.ContiguousBlocks < rightChild.ContiguousBlocks) ? rightChild.ContiguousBlocks : leftChild.ContiguousBlocks;
return(this);
}
else
{
// adjacent to nothing, create new contentnode for the freed space, and a new index node to contain it.
ContentNode newContentNode = new ContentNode()
{
FirstBlock = offset, LastBlock = offset + blocks - 1
};
IndexNode newIndexNode = null;
if (IMemTreeNode.MergeDirection)
{
newIndexNode = new IndexNode(newContentNode, rightChild); // merging it into right subtree
return(new IndexNode(leftChild, newIndexNode));
}
else
{
newIndexNode = new IndexNode(leftChild, newContentNode); // merging it into left subtree
return(new IndexNode(newIndexNode, rightChild));
}
}
}
}
public override IMemTreeNode ExpandLeftLeaf(int blocks)
{
leftChild.ExpandLeftLeaf(blocks);
contiguousBlocks = (leftChild.ContiguousBlocks < rightChild.ContiguousBlocks) ? rightChild.ContiguousBlocks : leftChild.ContiguousBlocks;
return(this);
}
