public int Rank(int symbol, int position)
{
var coderstream = new BitStream32 ();
this.Coder.Encode (coderstream, symbol);
//this.CoderStream.Seek (0);
var ctx = new BitStreamCtx (0);
int numbits = (int)coderstream.CountBits;
var node = this.Root;
for (int i = 0; i < numbits; i++) {
bool b = coderstream.Read (ctx);
if (b) {
position = node.B.Rank1 (position) - 1;
if (i + 1 < numbits) {
node = node.Right as WT_Inner;
}
} else {
position = node.B.Rank0 (position) - 1;
if (i + 1 < numbits) {
node = node.Left as WT_Inner;
}
}
if (node == null) {
return 0;
}
}
return position + 1;
}
