package dk.brics.string.stringoperations;
import dk.brics.automaton.Automaton;
import dk.brics.automaton.State;
import dk.brics.automaton.StatePair;
import dk.brics.automaton.Transition;
import dk.brics.string.charset.CharSet;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* Automaton operation for {@link StringBuffer#delete(int,int)}.
*/
public class Delete extends UnaryOperation {
/**
* Constructs new operation object.
*/
public Delete() {
}
/**
* Automaton operation.
* Constructs new automaton from two copies, <i>a1</i> and <i>a2</i>, of <tt>a</tt>.
* The initial state is the one from <i>a1</i>, and the accept states are those from <i>a2</i>.
* From each state <i>q</i> in <i>a1</i>, epsilon transitions are added from <i>q</i> to all states
* in <i>a2</i> that are reachable from the one corresponding to <i>q</i>.
*
* @param a input automaton
* @return resulting automaton
*/
@Override
public Automaton op(Automaton a) {
Automaton a1 = a.clone();
Map<State, State> map = new HashMap<State, State>();
Set<State> a1s = a1.getStates();
for (State s : a1s) {
State p = new State();
map.put(s, p);
if (s.isAccept()) {
p.setAccept(true);
s.setAccept(false);
}
}
for (State s : a1s) {
State p = map.get(s);
for (Transition t : s.getTransitions()) {
p.addTransition(new Transition(t.getMin(), t.getMax(), map.get(t.getDest())));
}
}
a1.setDeterministic(false);
Set<StatePair> epsilons = new HashSet<StatePair>();
for (State s : a1s) {
Set<State> reachable = Basic.findReachableStates(map.get(s));
for (State p : reachable) {
epsilons.add(new StatePair(s, p));
}
}
a1.addEpsilons(epsilons);
a1.minimize();
return a1;
}
@Override
public String toString() {
return "delete";
}
@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 Delete;
}
}