public void getGarbageElements()

in stetho/src/main/java/com/facebook/stetho/inspector/elements/ShadowDocument.java [299:337]
26 lines of code
9 McCabe index (conditional complexity)

    public void getGarbageElements(Accumulator<Object> accumulator) {
      // This queue stores pairs of elements, [element, expectedParent]
      // When we dequeue, we look at element's parentElement in the new view to see if it matches
      // expectedParent. If it does, then it's garbage. For enqueueing roots, whose parents are
      // null, since we can't enqueue null we instead enqueue the element twice.
      Queue<Object> queue = new ArrayDeque<>();

      // Initialize the queue with all disconnected tree roots (parentElement == null) which
      // aren't the DOM root.
      for (Object element : mRootElementChangesSet) {
        ElementInfo newElementInfo = getElementInfo(element);
        if (element != mRootElement && newElementInfo.parentElement == null) {
          queue.add(element);
          queue.add(element);
        }
      }

      // BFS traversal from those elements in the old view of the tree and test each element
      // to see if it's still within a disconnected sub-tree. We can tell if it's garbage if its
      // parent element in the new view of the tree hasn't changed.
      while (!queue.isEmpty()) {
        final Object element = queue.remove();
        final Object expectedParent0 = queue.remove();
        final Object expectedParent = (element == expectedParent0) ? null : expectedParent0;
        final ElementInfo newElementInfo = getElementInfo(element);

        if (newElementInfo.parentElement == expectedParent) {
          accumulator.store(element);

          ElementInfo oldElementInfo = ShadowDocument.this.getElementInfo(element);
          if (oldElementInfo != null) {
            for (int i = 0, N = oldElementInfo.children.size(); i < N; ++i) {
              queue.add(oldElementInfo.children.get(i));
              queue.add(element);
            }
          }
        }
      }
    }