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Functional Java is an open source library that supports closures for the Java programming language
package fj.data.fingertrees;
import fj.P;
import fj.P2;
import fj.P3;
import fj.data.Option;
import fj.data.vector.V2;
import fj.F;
import static fj.data.Option.none;
import static fj.data.Option.some;
import static fj.data.fingertrees.FingerTree.mkTree;
/**
* A two-element prefix or suffix of a finger tree.
*/
public final class Two extends Digit {
private final V2 as;
Two(final Measured m, final V2 as) {
super(m);
this.as = as;
}
public B foldRight(final F> aff, final B z) {
return aff.f(as._1()).f(aff.f(as._2()).f(z));
}
public B foldLeft(final F> bff, final B z) {
return as.toStream().foldLeft(bff, z);
}
@Override public B match(
final F, B> one, final F, B> two, final F, B> three,
final F, B> four) {
return two.f(this);
}
/**
* Returns the elements of this digit as a vector.
*
* @return the elements of this digit as a vector.
*/
public V2 values() {
return as;
}
@Override P3>, A, Option>> split1(final F predicate, final V acc) {
final Measured m = measured();
final MakeTree mk = mkTree(m);
if (predicate.f(m.sum(acc, m.measure().f(as._1())))) {
return P.p(none(), as._1(), some(mk.one(as._2())));
} else {
return P.p(some(mk.one(as._1())), as._2(), none());
}
}
@Override public P2 lookup(F o, int i) {
final F m = measured().measure();
final int s1 = o.f(m.f(as._1()));
if (i < s1) {
return P.p(i, as._1());
} else {
return P.p(i - s1, as._2());
}
}
}