Method dec

chapter21/src/test/java/com/seaofnodes/simple/Eval2.java:29–39

()

        // Dec ref count
        void dec() {
            assert _refcnt>0;
            if( --_refcnt == 0 ) {
                Frame prior = _prior;
                _prior = null;
                _data.clear();
                // TODO: FREE LIST?
                if( prior!=null )
                    prior.dec();
            }
        }

        // Put a mapping from Node->Object
        Node put(Node n, Object d) {