/** Removes a node and all its dependents from the graph. */
void removeDependencyPath (const T &key) {
auto it = _nodeMap.find(key);
if (it != _nodeMap.end()) {
for (GraphNode *node = it->second.get(); node;) {
GraphNode *dependent = node->dependent;
node->unlinkDependees();
if (dependent)
dependent->unlinkDependee(node);
_nodeMap.erase(node->key);
node = dependent;
}
}
}
