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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.V4;
import fj.F;
import static fj.data.Option.none;
import static fj.data.Option.some;
import static fj.data.fingertrees.FingerTree.mkTree;
/**
* A four-element prefix or suffix of a finger tree.
*/
public final class Four extends Digit {
private final V4 as;
Four(final Measured m, final V4 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(aff.f(as._3()).f(aff.f(as._4()).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 four.f(this);
}
/**
* Returns the elements of this digit as a vector.
*
* @return the elements of this digit as a vector.
*/
public V4 values() {
return as;
}
@Override P3>, A, Option>> split1(final F predicate, final V acc) {
final Measured m = measured();
final MakeTree mk = mkTree(m);
final F measure = m.measure();
final V acc1 = m.sum(acc, measure.f(as._1()));
if (predicate.f(acc1)) {
return P.p(none(), as._1(), some(mk.three(as._2(), as._3(), as._4())));
} else {
final V acc2 = m.sum(acc1, measure.f(as._2()));
if (predicate.f(acc2)) {
return P.p(some(mk.one(as._1())), as._2(), some(mk.two(as._3(), as._4())));
} else if (predicate.f(m.sum(acc2, measure.f(as._3())))) {
return P.p(some(mk.two(as._1(), as._2())), as._3(), some(mk.one(as._4())));
} else {
return P.p(some(mk.three(as._1(), as._2(), as._3())), as._4(), none());
}
}
}
@Override public P2 lookup(final F o, final 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 {
final int s2 = s1 + o.f(m.f(as._2()));
if (i < s2) {
return P.p(i - s1, as._2());
} else {
final int s3 = s2 + o.f(m.f(as._3()));
if (i < s3) {
return P.p(i - s2, as._3());
} else {
return P.p(i - s3, as._4());
}
}
}
}
}