@Override
public Node visit(Sequence node) {
// Node result = new Sequence( node.a.accept(this), node.b);
Node result =
Sequence.getInstance(
new SequenceChild(node.sequenceChild.a.accept(this), node.sequenceChild.b));
// Dc(AB) = Dc(A)B if A does not contain the empty string
if (!node.sequenceChild.a.accept(nullable)) {
return result;
// Dc(AB) = Dc(A)B | Dc(B) if A contains the empty string
} else {
/* return new Or(
result, // Dc(AB)
node.sequenceChild.b.accept(this) // Dc(B)
);
*/
return Or.getInstance(
new OrChild(
result, // Dc(AB)
node.sequenceChild.b.accept(this)) // Dc(B)
);
}
}
@Override
public Node visit(OrChild node) {
// Dc(A | B) = Dc(A) | Dc(B)
// return new Or(node.a.accept(this), node.b.accept(this));
return Or.getInstance(new OrChild(node.a.accept(this), node.b.accept(this)));
}
