yield in Java

BinaryExprOfSize.java

import java.util.Iterator;

import com.google.common.collect.AbstractIterator;

/*
i = 1;
j = n - 2;
while (i <= j) {
    e1 = Main.exprOfSize(i);
    while (e1.hasNext()) {
        _e1 = e1.next();
        e2 = Main.exprOfSize(j);
        while (e2.hasNext()) {
            yield construct(_e1, e2.next());
        }
    }
    i++;
    j--;
}
*/
public abstract class BinaryExprOfSize extends AbstractIterator<BvExpr> {

    private int i, j;
    private Iterator<BvExpr> e1, e2;
    private BvExpr _e1;

    public BinaryExprOfSize(int n) {
        i = 1;
        j = n - 2;
        e1 = Main.exprOfSize(i);
        _e1 = e1.next();
        e2 = Main.exprOfSize(j);
    }

    protected abstract BvExpr construct(BvExpr e1, BvExpr e2);

    @Override
    protected BvExpr computeNext() {
        loop_e2: while (true) {
            if (e2.hasNext()) {
                return construct(_e1, e2.next());
            }
            loop_e1: while (true) {
                if (e1.hasNext()) {
                    _e1 = e1.next();
                    e2 = Main.exprOfSize(j);
                    continue loop_e2;
                }
                i++;
                j--;
                if (i <= j) {
                    e1 = Main.exprOfSize(i);
                    continue loop_e1;
                }
                return endOfData();
            }
        }
    }
}