void enum_objects(ArrayList o, RadixNode n)
{
if (n.Object != null)
{
o.Add(n.Object);
}
foreach (RadixNode nc in n.SubNodes)
{
enum_objects(o, nc);
}
}
/// <summary>
/// look for a word in the tree begining at the current node
/// </summary>
/// <param name="wordPart"></param>
/// <param name="curNode"></param>
/// <returns></returns>
private RadixNode?LookupRec(byte[] word, int pos, RadixNode curNode)
{
int matches = MatchingConsecutiveCharacters(word, pos, curNode);
if ((matches == 0) || (curNode == Root) ||
((matches > 0) && (matches < (word.Length - pos)) && (matches >= curNode.Label.Length)))
{
RadixNode?ret = null;
int new_pos = pos + matches;
foreach (RadixNode child in curNode.SubNodes)
{
if (child.Label[0] == word[new_pos])
{
ret = LookupRec(word, new_pos, child);
if (ret != null)
{
break;
}
}
}
if (ret == null)
{
ret = curNode;
}
return(ret);
}
else if (matches == curNode.Label.Length)
{
return(curNode);
}
else
{
return(null);
}
}
/// <summary>
/// given a string and a node the number of characters that the string and the node's label have
/// in common starting from the first character in each is returned
/// </summary>
/// <param name="word">a string that is to be compared with the node's label</param>
/// <param name="curNode">a node</param>
/// <returns></returns>
private int MatchingConsecutiveCharacters(byte[] word, int word_pos, RadixNode curNode)
{
int matches = 0;
int minLength = 0;
//see which string is smaller and save it's lenght
//when cycling throught the two strings we won't go any further than that
if (curNode.Label.Length >= (word.Length - word_pos))
{
minLength = word.Length - word_pos;
}
else if (curNode.Label.Length < (word.Length - word_pos))
{
minLength = curNode.Label.Length;
}
if (minLength > 0)
{
//go throught the two streams
for (int i = 0; i < minLength; i++)
{
//if two characters at the same position have the same value we have one more match
if (word[i + word_pos] == curNode.Label[i])
{
matches++;
}
else
{
//if at any position the two strings have different characters break the cycle
break;
}
}
}
//and return the current number of matches
return(matches);
}
/// <summary>
/// recursively traverse the tree
/// carry the word you want inserted until a proper place for it is found and it can be inserted there
/// if a node already stores a substring of the word(substrnig with the same first letter as the word itself)
/// then that substring must be removed from the word and it's children checked out next
/// hence the name wordPart - part of a word
/// </summary>
/// <param name="wordPart">the part of the word that is to be inserted that is not already included in any of the tree's nodes</param>
/// <param name="curNode">the node currently traversed</param>
private RadixNode?InsertRec(byte[] wordPart, RadixNode curNode)
{
RadixNode?ret = null;
//get the number of characters that the word part that is to be inserted and the current node's label have
//in common starting from the first position of both strings
//matching characters in the two strings = have the same value at the same position in both strings
int matches = MatchingConsecutiveCharacters(wordPart, 0, curNode);
//if we are at the root node
//OR
//the number of characters from the two strings that match is
//bigger than 0
//smaller than the the part of the word that is to be inserted
//bigger than the the label of the current node
if ((matches == 0) || (curNode == Root) ||
((matches > 0) && (matches < wordPart.Length) && (matches >= curNode.Label.Length)))
{
//remove the current node's label from the word part
bool inserted = false;
byte[] newWordPart = Util.CopyByte(wordPart, matches);
//search the node's subnodes and if the subnode label's first character matches
//the word part's first character then insert the word part after this node(call the
//current method recursively)
foreach (RadixNode child in curNode.SubNodes)
{
if (child.Label[0] == newWordPart[0])
{
inserted = true;
ret = InsertRec(newWordPart, child);
}
}
if (inserted == false)
{
ret = new RadixNode(curNode, newWordPart);
curNode.SubNodes.Add(ret);
this.Count++;
}
}
else if (matches < wordPart.Length)
{
//in this case we have to nodes that we must add to the tree
//one is the node that has a label extracted from the current node's label without the string of
//matching characters(common characters)
//the other is the node that has it's label extracted from the current word part minus the string
//of matching characters
byte[] commonRoot = Util.CopyByte(wordPart, 0, matches);
byte[] branchPreviousLabel = Util.CopyByte(curNode.Label, matches);
byte[] branchNewLabel = Util.CopyByte(wordPart, matches);
curNode.Label = commonRoot;
RadixNode newNodePreviousLabel = new RadixNode(curNode, branchPreviousLabel);
newNodePreviousLabel.Object = curNode.Object;
newNodePreviousLabel.SubNodes.AddRange(curNode.SubNodes);
foreach (RadixNode n in curNode.SubNodes)
{
n.Parent = newNodePreviousLabel;
}
curNode.SubNodes.Clear();
curNode.SubNodes.Add(newNodePreviousLabel);
curNode.Object = null;
RadixNode newNodeNewLabel = new RadixNode(curNode, branchNewLabel);
curNode.SubNodes.Add(newNodeNewLabel);
ret = newNodeNewLabel;
this.Count++;
}
else if (matches == curNode.Label.Length)
{
//in this case we don't do anything because the word is already added
}
else if (matches > curNode.Label.Length)
{
//add the current word part minus the common characters after the current node
byte[] newNodeLabel = Util.CopyByte(curNode.Label, curNode.Label.Length, wordPart.Length);
RadixNode newNode = new RadixNode(curNode, newNodeLabel);
curNode.SubNodes.Add(newNode);
ret = newNode;
this.Count++;
}
return(ret);
}
public RadixTrie(RadixNode root)
{
Root = root;
}
/// <summary>
/// construct a new tree with it's root
/// </summary>
public RadixTrie()
{
Root = new RadixNode(null, new byte[0]);
}