public static void Write(BNode x)
{
file.Position = x.offset * size;
byte[] bytes = NodeToBytes(x);
foreach (byte b in bytes)
file.WriteByte(b);
}
private static BNode BytesToNode(byte[] bytes)
{
BNode result = new BNode();
result.length = BitConverter.ToInt32(bytes, 0);
result.isALeaf = BitConverter.ToInt32(bytes, 4) == 1;
for (int i = 0; i < result.length; i++)
result.keys[i] = BitConverter.ToInt32(bytes, 4 * (i + 2));
if (!result.isALeaf)
for (int i = 0; i < result.length + 1; i++)
result.childOffsets[i] = BitConverter.ToInt32(bytes, 4 * (i + 2 + result.length));
result.isLoaded = true;
return result;
}
public static BNode Read(BNode x, int offset)
{
if (x == null)
x = new BNode();
if (x.isLoaded)
return x;
x.offset = offset;
file.Position = size * offset;
byte[] bytes = new byte[size];
for (int i = 0; i < size; i++)
bytes[i] = (byte)file.ReadByte();
return BytesToNode(bytes);
}
private static byte[] NodeToBytes(BNode x)
{
int[] array;
if (!x.isALeaf)
array = new int[2 + 2 * x.length + 1];
else
array = new int[2 + x.length];
array[0] = x.length;
array[1] = x.isALeaf? 1:0;
for (int i = 0; i < x.length; i++)
array[i + 2] = x.keys[i];
if (!x.isALeaf)
for (int i = 0; i < x.length + 1; i++)
array[i + 2 + (x.length)] = x.childOffsets[i];
byte[] bytes = new byte[(2 + 2 * x.length + 1) * 4];
List<byte[]> byt = new List<byte[]>();
foreach (int a in array)
byt.Add(BitConverter.GetBytes(a));
for (int j = 0; j < byt.Count; j++)
for (int i = 0; i < 4; i++)
bytes[i + j * 4] = byt[j][i];
return bytes;
}
public void Insert(int key)
{
if (root.length == 2 * t - 1)
{
BNode r = root;
BNode s = new BNode(false);
root = s;
s.length = 0;
s.childOffsets[0] = r.offset;
s.children[0] = r;
s.offset = BNode.generalOffset;
BNode.generalOffset += 1;
s.isLoaded = true;
s.SplitChild(0, r);
int i = 0;
if (s.keys[0] < key)
i++;
s.children[i].InsertNonFull(key);
root = s;
}
else
root.InsertNonFull(key);
}
public BTree()
{
root = new BNode(true);
root.offset = BNode.generalOffset;
BNode.generalOffset++;
Disk.Write(root);
root.isLoaded = true;
}
internal void SplitChild(int i, BNode y)
{
BNode z = new BNode(y.isALeaf);
z.length = t - 1;
z.offset = generalOffset++;
z.isLoaded = true;
for (int j = 0; j < t - 1; j++)
z.keys[j] = y.keys[j + t];
if (!y.isALeaf)
{
for (int j = 0; j < t; j++)
z.childOffsets[j] = y.childOffsets[j + t];
}
y.length = t - 1;
for (int j = length; j >= i + 1; j--)
{
childOffsets[j + 1] = childOffsets[j];
children[j + 1] = children[j];
}
childOffsets[i + 1] = z.offset;
children[i + 1] = z;
for (int j = length - 1; j >= i; j--)
keys[j + 1] = keys[j];
keys[i] = y.keys[t-1];
length++;
Disk.Write(y);
Disk.Write(z);
Disk.Write(this);
}
