public Iterator reverseIterator()

in utils/src/main/java/jetbrains/exodus/core/dataStructures/persistent/AbstractPersistent23Tree.java [236:302]
62 lines of code
13 McCabe index (conditional complexity)

    public Iterator<K> reverseIterator() {
        if (isEmpty()) {
            return Collections.EMPTY_LIST.iterator();
        }
        final RootNode<K> root = getRoot();
        final TreePosRev<K>[] stack = new TreePosRev[MathUtil.integerLogarithm(root.getSize()) + 1];
        for (int i = 0; i < stack.length; ++i) {
            stack[i] = new TreePosRev<>(root);
        }
        return new Iterator<K>() {

            private int i = 0;
            private boolean hasNext;
            private boolean hasNextValid;

            @Override
            public boolean hasNext() {
                if (hasNextValid) {
                    return hasNext;
                }
                hasNextValid = true;
                TreePosRev<K> treePos = stack[i];
                if (treePos.node.isLeaf()) {
                    while (treePos.pos <= 1) {
                        if (--i < 0) {
                            hasNext = false;
                            return false;
                        }
                        treePos = stack[i];
                    }
                } else {
                    TreePosRev<K> newPos = stack[++i];
                    if (treePos.pos == 1) {
                        newPos.setNode(treePos.node.getFirstChild());
                    } else if (treePos.pos == 2) {
                        newPos.setNode(treePos.node.getSecondChild());
                    } else {
                        newPos.setNode(treePos.node.getThirdChild());
                    }
                    treePos = newPos;
                    while (!treePos.node.isLeaf()) {
                        newPos = stack[++i];
                        newPos.setNode(treePos.node.isTernary() ? treePos.node.getThirdChild() : treePos.node.getSecondChild());
                        treePos = newPos;
                    }
                }
                treePos.pos--;
                return hasNext = true;
            }

            @Override
            public K next() {
                if (!hasNext()) {
                    throw new NoSuchElementException();
                }
                hasNextValid = false;
                final TreePosRev<K> treePos = stack[i];
                // treePos.pos must be 1 or 2 here
                return treePos.pos == 1 ? treePos.node.getFirstKey() : treePos.node.getSecondKey();
            }

            @Override
            public void remove() {
                throw new UnsupportedOperationException();
            }
        };
    }