void UnionSet(Set S1, Set S2, Set *S3)
{
int i;
CopySet(S1,&*S3);
for (i=1;i<=SetNbElmt(S2);i++)
{
InsertSet(&*S3,S2.T[i]);
}
}
void SetDifference (Set S1, Set S2, Set *S3)
{
int i;
CopySet(S1,&*S3);
for (i=1;i<=SetNbElmt(S2);i++)
{
if (IsSetMember(*S3,S2.T[i]))
DeleteSet(&*S3,S2.T[i]);
}
}
// Subset Construction for converting a Nondeterministic Finite Automaton (NFA) to a Deterministic Finite Automaton (DFA)
// algorithm from book Compilers Principles and Tools: by Alfred V.Aho, Ravi Sethi and Jeffrey D. Ullman
void dDeterministicFiniteAutonata::CreateDeterministicFiniteAutomaton (const dNonDeterministicFiniteAutonata& nfa)
{
if (nfa.IsValid()) {
dTree<int, int> symbolsList;
dList<dAutomataState*> stateArray;
nfa.GetStartState()->GetStateArray(stateArray);
for (dList<dAutomataState*>::dListNode* node = stateArray.GetFirst(); node; node = node->GetNext()) {
dAutomataState* const state = node->GetInfo();
for (dList<dAutomataState::dTransition>::dListNode* transitionNode = state->m_transtions.GetFirst(); transitionNode; transitionNode = transitionNode->GetNext()) {
dAutomataState::dTransition& transition = transitionNode->GetInfo();
dAutomataState::dCharacter ch (transition.GetCharater());
if (ch.m_symbol) {
symbolsList.Insert(ch.m_symbol, ch.m_symbol);
}
}
}
dTree<dAutomataState*,dAutomataState*> NFAmap;
dTree<dAutomataState*,dAutomataState*> subSet;
int stateID = 0;
NFAmap.Insert(nfa.GetStartState(), nfa.GetStartState());
dAutomataState* stackPool[2048];
EmptyTransitionClosure (NFAmap, subSet);
// dAutomataState* const startState = new dAutomataState(subSet, stateID ++);
dAutomataState* const startState = CreateTargetState(subSet, stateID ++);
dList<dAutomataState*> newStatesList;
int stack = 1;
stackPool[0] = startState;
newStatesList.Append(startState);
while (stack) {
stack --;
dAutomataState* const state = stackPool[stack];
dTree<int, int>::Iterator iter (symbolsList);
for (iter.Begin(); iter; iter ++) {
int ch = iter.GetNode()->GetInfo();
dTree<dAutomataState*,dAutomataState*> moveSet;
MoveSymbol (ch, state, moveSet);
if (moveSet.GetCount()) {
dTree<dAutomataState*,dAutomataState*> subSet;
EmptyTransitionClosure (moveSet, subSet);
dAutomataState* foundState = NULL;
for (dList<dAutomataState*>::dListNode* node = newStatesList.GetFirst(); node; node = node->GetNext()) {
dAutomataState* const state = node->GetInfo();
dAssert (state);
if (CompareSets(state->m_myNFANullStates, subSet)) {
foundState = state;
break;
}
}
if (foundState) {
state->m_transtions.Append(dAutomataState::dTransition(ch, foundState));
} else {
dAutomataState* const targetState = CreateTargetState(subSet, stateID ++);
stackPool[stack] = targetState;
stack ++;
dAssert (stack < sizeof (stackPool)/sizeof (stackPool[0]));
newStatesList.Append(targetState);
state->m_transtions.Append(dAutomataState::dTransition(ch, targetState));
}
}
}
}
m_startState = startState;
CopySet (nfa);
}
}
