/// <summary>
/// Adds the given string to the trie rooted at this node.
/// If the string contains any characters other than lower-case English letters,
/// throws an ArgumentException.
/// </summary>
/// <param name="s">The string to add.</param>
/// <returns>The resulting trie.</returns>
public ITrie Add(string s)
{
if (s == "")
{
_hasEmptyString = true;
}
else if (s[0] < 'a' || s[0] > 'z')
{
throw new ArgumentException();
}
else
{
int loc = s[0] - 'a';
if (_children[loc] == null)
{
_children[loc] = new TrieWithNoChildren();
}
_children[loc] = _children[loc].Add(s.Substring(1));
}
return(this);
}
/// <summary>
/// Adds the given string to the trie rooted at this node.
/// If the string contains a character that is not a lower-case English
/// letter, throws an ArgumentException.
/// </summary>
/// <param name="s">The string to add.</param>
public ITrie Add(string s)
{
if (s == "")
{
_hasEmptyString = true;
}
else
{
int loc = s[0] - 'a';
if (loc < 0 || loc >= _children.Length)
{
throw new ArgumentException();
}
if (_children[loc] == null)
{
_children[loc] = new TrieWithNoChildren();
}
_children[loc] = _children[loc].Add(s.Substring(1));
}
return this;
}