Local Contexts

→ stack-based data structure for hierarchically storing generic key-value pair collections used by processors on different AST levels

• used to orchestrate extraction processes over multiple processors working on different levels of the AST
• the local contexts stack is part of the processing context

Implementation

classDiagram
	class LocalContexts {
		+Stack~Map~ contexts
		+currentContexts() Map
		+parentContexts() Map
		+getNextContext() Tuple~Object, int~
		+pushContexts() void
		+popContexts() Map
	}

• the maps should use strings or numbers as keys, that are defined as constants in the processor class that registers a given context, or at a central location within the code base
• map values can be of any type
• the contexts field may also have a private visibility to limit the complexity of local context usage
• the methods proposed above serve as guideline for various utility functions that ease the interaction with the local contexts stacks
  • currentContexts(): returns a reference to the context map on top of the stack (i.e. for the current level of the AST)
  • parentContexts(): returns a reference to the context map on level below the stack top (i.e. for the parent level of the AST)
  • getNextContext(): returns the closest-to-stack-top context map value, along with an integer denoting the depth where it was found (0 for the top of the stack)
  • pushContexts(): pushes a new, empty context map on top of the stack
  • popContexts(): removes the top context map of the stack and returns it (if possible)