CollectingPass

A pass base class that allows the node processing to be done in a depth first hierarchical order by calling:

• openContainer at the start of container's processing

• processLeaf for any leaf node

• closeContainer after all the container's contents have been processed This kind of Pass allows the processing to follow the AST hierarchy so that container nodes can run before all their content (openContainer) and also after all its content (closeContainer). This is necessary for passes that must maintain the hierarchical structure of the AST model in their processing