private void doPut()

in src/main/java/org/apache/commons/collections4/bidimap/TreeBidiMap.java [498:551]
42 lines of code
7 McCabe index (conditional complexity)

    private void doPut(final K key, final V value) {
        checkKeyAndValue(key, value);

        // store previous and remove previous mappings
        doRemoveKey(key);
        doRemoveValue(value);

        Node<K, V> node = rootNode[KEY.ordinal()];
        if (node == null) {
            // map is empty
            final Node<K, V> root = new Node<>(key, value);
            rootNode[KEY.ordinal()] = root;
            rootNode[VALUE.ordinal()] = root;
            grow();

        } else {
            // add new mapping
            while (true) {
                final int cmp = compare(key, node.getKey());

                if (cmp == 0) {
                    // shouldn't happen
                    throw new IllegalArgumentException("Cannot store a duplicate key (\"" + key + "\") in this Map");
                }
                if (cmp < 0) {
                    if (node.getLeft(KEY) == null) {
                        final Node<K, V> newNode = new Node<>(key, value);

                        insertValue(newNode);
                        node.setLeft(newNode, KEY);
                        newNode.setParent(node, KEY);
                        doRedBlackInsert(newNode, KEY);
                        grow();

                        break;
                    }
                    node = node.getLeft(KEY);
                } else { // cmp > 0
                    if (node.getRight(KEY) == null) {
                        final Node<K, V> newNode = new Node<>(key, value);

                        insertValue(newNode);
                        node.setRight(newNode, KEY);
                        newNode.setParent(node, KEY);
                        doRedBlackInsert(newNode, KEY);
                        grow();

                        break;
                    }
                    node = node.getRight(KEY);
                }
            }
        }
    }