/// <summary>
/// Adds word to Trei
/// </summary>
/// <param name="word">Word to add</param>
/// <returns>true if word was added, false otherwise, returns false if word already exists</returns>
internal bool AddWord(string word)
{
//Cannot add empty or null string
if ((word?.Length ?? 0) == 0)
{
throw new ArgumentException("Word canot be empty or null");
}
var curNode = root;
var isNewWord = false;
//Used to keep track of nodes traversed. We want to keep track of how
//many words go through a particular node.
//We will increment number of words in the end
//if new word was created
var traversedNodes = new List <TreiNode>();
traversedNodes.Add(root);
//loop through each character in the string
foreach (var c in word.ToLower())
{
//Check if child node for character exists
if (!curNode.Children.TryGetValue(c, out TreiNode node))
{
//Add new character if it does not currently exist
node = new TreiNode(c);
curNode.Children[c] = node;
//if a new node is created this is a new word
isNewWord = true;
}
//traverse down to new or existing node that represents the next character.
curNode = node;
//Add node to list of traversed nodes
traversedNodes.Add(curNode);
}
//Update word count for each traversed node if this is a new word.
//If an existing word is added isNewWord will remain false
if (isNewWord)
{
traversedNodes.ForEach(t => t.WordCount++);
}
//Mark last node as IsWord. This is required
//Example: When we add word "cat" we don't want the FindWord to return
//true if we search for "ca". By setting IsWord on last node only
//we can determine that if we end up on node representing character "a"
//from "ca" it is not a word
traversedNodes[traversedNodes.Count - 1].IsWord = true;
return(isNewWord);
}
/// <summary>
/// Create a Trei
/// </summary>
internal Trei()
{
root = new TreiNode((char)0);
}
