private void AddNewPalindromeNode(PalindromeNode longestPalindromePrefix, Insertion insertion)
{
var nextNodeIndex = _tree.Count; //todo: change null-suffix to smth
var newNode = new PalindromeNode(nextNodeIndex);
if (longestPalindromePrefix.IsImaginaryStringPalindromeNode)
{
newNode.Label = insertion.Letter.ToString();
}
else
{
newNode.Label = insertion.Letter + longestPalindromePrefix.Label + insertion.Letter;
}
_tree.Add(newNode);
longestPalindromePrefix.OutgoingNodes.Add(insertion.Letter, newNode);
if (longestPalindromePrefix.IsImaginaryStringPalindromeNode)
{
newNode = _tree[EmptyStringPalindromeNode.INDEX_EMPTY_STRING];
}
else
{
var suffixForNewNode =
GetLongestPalindromeSuffixForNewNode(insertion, longestPalindromePrefix);
newNode.LongestPalindromeSuffix = suffixForNewNode;
}
_currentLongestPalindromeSuffixNodeIndex = newNode.Index;
}
private PalindromeNode GetLongestPalindromeSuffixForNewNode(Insertion insertion,
PalindromeNode longestPalindromePrefix)
{
var suffixForNewNode = longestPalindromePrefix.LongestPalindromeSuffix;
while (isNecessaryToKeepTraversingTheSuffixChain(insertion, suffixForNewNode))
{
suffixForNewNode = suffixForNewNode.LongestPalindromeSuffix;
}
suffixForNewNode = suffixForNewNode.OutgoingNodes[insertion.Letter];
return(suffixForNewNode);
}
private bool isNecessaryToKeepTraversingTheSuffixChain(Insertion insertion, PalindromeNode currentSuffix)
{
if (currentSuffix.IsImaginaryStringPalindromeNode)
{
return(false);
}
var indexOfLetterPrecedingTheCurrentSuffix =
insertion.LetterIndex - currentSuffix.GetPalindromeLength - 1;
return(indexOfLetterPrecedingTheCurrentSuffix < 0 ||
insertion.Letter != _storedString[indexOfLetterPrecedingTheCurrentSuffix]);
}
private bool IsDuplicatePalindrome(char letter, PalindromeNode longestPalindromeSuffixForNextPalindrome)
{
return(longestPalindromeSuffixForNextPalindrome.OutgoingNodes.ContainsKey(letter));
}