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/*
* NfaSimulator
* Simulate a NFA with a word. Check if regular expression produces word.
*/
function NfaSimulator(nfa) {
this.startState = nfa.getStartState();
this.finalState = nfa.getFinalState();
};
// Accessor functions.
NfaSimulator.prototype.getStartState = function() { return this.startState; };
NfaSimulator.prototype.getFinalState = function() { return this.finalState; };
// Main simulate function.
NfaSimulator.prototype.simulate = function(word) {
var a, accepted = false;
this.p = new Stack();
this.q = new Stack();
this.getStartState().mark(true);
this.q.push(this.getStartState());
word += REDELIMITER;
for (var i = 0; i < word.length; i++) {
accepted = this.epsclosure();
a = word.substring(i, i+1);
this.move(a);
};
return accepted;
};
// Get reachable states through epsilon transitions.
NfaSimulator.prototype.epsclosure = function() {
var s, t, accepted = false;
while(!this.q.isEmpty()) {
s = this.q.pop();
this.p.push(s);
accepted = accepted || s == this.getFinalState();
if(s.symbol == EPSILON) {
for (var i = 0; i < 2; i++) {
t = s.getFollowUp(i);
if (t!=null) {
if(!t.marked) {
t.mark(true);
this.q.push(t);
};
};
};
};
};
return accepted;
};
// Get reachable states through transitions with symbol.
NfaSimulator.prototype.move = function(symbol) {
var s;
while(!this.p.isEmpty()) {
s = this.p.pop();
s.mark(false);
if (s.symbol == symbol) {
s.getFollowUp(0).mark(true);
this.q.push(s.getFollowUp(0));
};
};
};
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