//
// This Add method attach an object "data" to a node "n" using
// the BitVector key as path.
//
private void Add(Node n, BitVector key, string data)
{
if (n.Key == null)
{
AddAsChildren(n, key, data);
return;
}
//
// First, calculate the longest common prefix for the key
// and the BitVector stored in this node.
//
var longest = key.LongestCommonPrefix(n.Key);
//System.Diagnostics.Debug.Assert(longest != 0);
if (longest == n.Key.Length)
{
//
// If the current node is a perfect prefix of the
// key, then remove the prefix from the key, and
// we continue our walk on the children.
//
key = key.Range(longest, key.Length - longest);
AddAsChildren(n, key, data);
return;
}
//
// Here, n.Key and key share a common prefix. So we:
//
// - Create a new node with this common prefix
// held there,
//
// - make n.Key and a new node with key as
// children of this new node.
var common = n.Key.Range(0, longest);
var c1 = new Node
{
Key = n.Key.Range(longest, n.Key.Length - longest),
Data = n.Data,
Children = n.Children
};
var c2 = new Node {
Key = key.Range(longest, key.Length - longest), Data = data
};
n.Key = common;
n.Data = null;
// initialize the list with a capacity: we save ourself
// a few ms
n.Children = new List <Node>(2)
{
c1, c2
};
}
//
// Returns the object held in the node that best matches our
// key.
//
internal string GetBest(BitVector key)
{
var curnode = root;
while (curnode != null)
{
if (curnode.Children == null)
{
return(curnode.Data);
}
// Get the best fitting index
var bestindex = -1;
var bestlength = 0;
for (var i = 0; i < curnode.Children.Count; i++)
{
var b = curnode.Children[i].Key.LongestCommonPrefix(key);
if (b <= bestlength)
{
continue;
}
bestlength = b;
bestindex = i;
}
if (bestindex == -1)
{
return(curnode.Data);
}
key = key.Range(bestlength, key.Length - bestlength);
curnode = curnode.Children[bestindex];
if (key.Length == 0)
{
return(curnode.Data);
}
}
return(null);
}
//
// Returns the object held in the node that best matches our
// key.
//
internal string GetBest(BitVector key)
{
var curnode = root;
while (curnode != null)
{
if (curnode.Children == null)
return curnode.Data;
// Get the best fitting index
var bestindex = -1;
var bestlength = 0;
for (var i = 0; i < curnode.Children.Count; i++)
{
var b = curnode.Children[i].Key.LongestCommonPrefix(key);
if (b <= bestlength) continue;
bestlength = b;
bestindex = i;
}
if (bestindex == -1)
{
return curnode.Data;
}
key = key.Range(bestlength, key.Length - bestlength);
curnode = curnode.Children[bestindex];
if (key.Length == 0)
{
return curnode.Data;
}
}
return null;
}
//
// This Add method attach an object "data" to a node "n" using
// the BitVector key as path.
//
private void Add(Node n, BitVector key, string data)
{
if (n.Key == null)
{
AddAsChildren(n, key, data);
return;
}
//
// First, calculate the longest common prefix for the key
// and the BitVector stored in this node.
//
var longest = key.LongestCommonPrefix(n.Key);
//System.Diagnostics.Debug.Assert(longest != 0);
if (longest == n.Key.Length)
{
//
// If the current node is a perfect prefix of the
// key, then remove the prefix from the key, and
// we continue our walk on the children.
//
key = key.Range(longest, key.Length - longest);
AddAsChildren(n, key, data);
return;
}
//
// Here, n.Key and key share a common prefix. So we:
//
// - Create a new node with this common prefix
// held there,
//
// - make n.Key and a new node with key as
// children of this new node.
var common = n.Key.Range(0, longest);
var c1 = new Node
{
Key = n.Key.Range(longest, n.Key.Length - longest),
Data = n.Data,
Children = n.Children
};
var c2 = new Node { Key = key.Range(longest, key.Length - longest), Data = data };
n.Key = common;
n.Data = null;
// initialize the list with a capacity: we save ourself
// a few ms
n.Children = new List<Node>(2) { c1, c2 };
}