package dk.brics.string.stringoperations;
import dk.brics.automaton.Automaton;
import dk.brics.automaton.State;
import dk.brics.automaton.StatePair;
import dk.brics.string.charset.CharSet;
import java.util.HashSet;
import java.util.Set;
/**
* Automaton operation for {@link StringBuffer#substring(int,int)}.
*/
public class Substring extends UnaryOperation {
/**
* Constructs new operation object.
*/
public Substring() {
}
/**
* Automaton operation.
* Constructs new automaton as copy of <tt>a</tt> with a new initial state <i>p</i> and a new accept state <i>s</i>.
* Epsilon transitions are added from <i>p</i> to every other state and from all those to <i>s</i>.
*
* @param a input automaton
* @return resulting automaton
*/
@Override
public Automaton op(Automaton a) {
Automaton b = a.clone();
State initial = new State();
State accept = new State();
accept.setAccept(true);
Set<StatePair> epsilons = new HashSet<StatePair>();
for (State s : b.getStates()) {
epsilons.add(new StatePair(initial, s));
epsilons.add(new StatePair(s, accept));
}
b.setInitialState(initial);
b.addEpsilons(epsilons);
b.minimize();
return b;
}
@Override
public String toString() {
return "substring";
}
@Override
public int getPriority() {
return 4;
}
@Override
public CharSet charsetTransfer(CharSet a) {
return a;
}
@Override
public int hashCode() {
return getClass().hashCode();
}
@Override
public boolean equals(Object obj) {
return obj instanceof Substring;
}
}