private void InsertRec(string wordPart, Node curNode)
{
//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
var matches = MatchingConsecutiveCharacters(wordPart, 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;
var newWordPart = wordPart.Substring(matches, wordPart.Length - 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(var child in curNode.SubNodes)
if (child.Label.StartsWith(newWordPart[0].ToString()))
{
inserted = true;
InsertRec(newWordPart, child);
}
if (inserted == false)
{
curNode.SubNodes.Add(new Node(newWordPart));
}
}
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
string commonRoot = wordPart.Substring(0, matches);
string branchPreviousLabel = curNode.Label.Substring(matches, curNode.Label.Length - matches);
string branchNewLabel = wordPart.Substring(matches, wordPart.Length - matches);
curNode.Label = commonRoot;
var newNodePreviousLabel = new Node(branchPreviousLabel);
newNodePreviousLabel.SubNodes.AddRange(curNode.SubNodes);
curNode.SubNodes.Clear();
curNode.SubNodes.Add(newNodePreviousLabel);
var newNodeNewLabel = new Node(branchNewLabel);
curNode.SubNodes.Add(newNodeNewLabel);
}
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
string newNodeLabel = curNode.Label.Substring(curNode.Label.Length, wordPart.Length);
var newNode = new Node(newNodeLabel);
curNode.SubNodes.Add(newNode);
}
}
