public override string Encode(string str)
{
_decoded = string.Concat(str, '\0');
var nodes = new List <Node>();
var buffer = new Buffer();
var position = 0;
while (position < _decoded.Length)
{
var pair = FindMatching(buffer, position);
var offset = pair.Key;
var length = pair.Value;
buffer.Shift(length + 1);
position += length;
nodes.Add(new Node(offset, length, _decoded[position]));
position++;
}
return(BuildNodes(nodes));
}
private KeyValuePair <int, int> FindMatching(Buffer buffer, int position)
{
int mod = buffer.Length, pos = buffer.Length;
var buffered = buffer.GetBufferedString(_decoded);
var optimal = new KeyValuePair <int, int>(0, 0);
while (pos > 0)
{
pos--;
var start = FindStartPosition(buffered, position, pos);
pos = start;
if (start < 0)
{
continue;
}
var currentLen = 0;
var currentPosition = position;
while (currentPosition < _decoded.Length && buffered[start] == _decoded[currentPosition])
{
start = (start + 1) % mod;
currentPosition++;
currentLen++;
}
if (currentLen > optimal.Value)
{
var offset = position - (buffer.Position + pos);
optimal = new KeyValuePair <int, int>(offset, currentLen);
}
}
return(optimal);
}
