/// <summary>
/// Adds the rest of the word to the dfa.
/// </summary>
/// <param name="parent">The state to attack the suffix to.</param>
/// <param name="word">The current word.</param>
/// <param name="wordPos">The index of the first letter of the suffix.</param>
private void AddSuffix(State parent, WordWithValue word, int wordPos)
{
var states = new Stack <State>();
states.Push(parent);
// Create new States.
var i = wordPos;
while (i < WordLength - 1)
{
var prevState = states.Peek();
var newState = new State(AlphabetSize);
prevState.CreateOutTransition(newState, word.Word[i]);
states.Push(newState);
i += 1;
}
// Connect to final State.
var final = _stateManager.GetOrCreateFinalState(word.Value);
states.Peek().CreateOutTransition(final, word.Word[WordLength - 1]);
// Merge new States with unique States.
i -= 1;
MergeStates(word.Word, i, states);
}
/// <summary>
/// Adds a word to the dfa and minimizes the dfa.
/// </summary>
private void MergeWord(WordWithValue word)
{
if (HasBeenAdded(word.Word))
{
return;
}
var curUnique = _stateManager.StartingState;
var i = 0;
var monofluentStates = new Stack <State>();
// We need the previous state for each state.
monofluentStates.Push(curUnique);
// Traverse common prefix before the first confluence state.
while (i < WordLength - 1 && curUnique.HasTransition(word.Word[i]) && !curUnique.Advance(word.Word[i]) !.IsConfluenceState)
{
curUnique = curUnique.Advance(word.Word[i]) !;
monofluentStates.Push(curUnique);
i += 1;
}
// Here curUnique points to the last State before the first confluence State,
// or the last state in the common prefix if there is no confluence state.
// Here i is the index of the character of the transition away from curUnique.
if (curUnique != _stateManager.StartingState)
{
// This state will have an outgoing transition changed.
// It has to be reinserted.
// Have to remove it before changing because the transitions are the dictionary key.
_stateManager.RemoveUniqueState(curUnique, GetHeight(i - 1));
}
// Clone rest of common prefix.
var lastAdded = curUnique;
var clones = new Stack <State>();
// We need the previous state for each clone.
clones.Push(lastAdded);
while (i < WordLength - 1 && curUnique.HasTransition(word.Word[i]))
{
curUnique = curUnique.Advance(word.Word[i]) !;
var clone = curUnique.Clone(AlphabetSize);
lastAdded.RedirectOutTransition(clone, word.Word[i]);
lastAdded = clone;
clones.Push(clone);
i += 1;
}
// Here curUnique points to the last state in the common prefix if continued on the unique path.
// Here lastAdded points to the last state in the common prefix if continued on the cloned path.
// Here i is the index of the character of the transition away from lastAdded.
// Add the rest of the word to the dfa.
AddSuffix(lastAdded, word, i);
// Merge clones into the state machine.
i -= 1;
i = MergeStates(word.Word, i, clones);
// Fix monofluent States:
// remove them from the dfa and either insert them back in or merge them with an equivalent state.
while (monofluentStates.Count > 1)
{
var curState = monofluentStates.Pop();
var prevState = monofluentStates.Peek();
var uniqueState = _stateManager.TryGetEquivalentUniqueState(curState, GetHeight(i));
if (uniqueState == null)
{
_stateManager.InsertUniqueState(curState, GetHeight(i));
break;
}
if (prevState != _stateManager.StartingState)
{
_stateManager.RemoveUniqueState(prevState, GetHeight(i - 1));
}
prevState.RedirectOutTransition(uniqueState, word.Word[i]);
i -= 1;
}
}
