Traversers

→ LCE traversers are implemented as a modified visitor pattern

• The abstract Traverser base class provides the implementation that orchestrates the execution of the other components
  • only the traverseChildren method that delegates the traversal of potential child nodes to other traversers is abstract and has to be implemented by sub types
• for each AST node type (provided via @typescript-eslint/utils) that should be processed, a separate Traverser implementation has to be provided
  • note that skipping nodes in the ESLint AST through a simplified Traverser implementation (e.g. via nested node access: runTraverserForNodes(node.body.body, ...)) must be avoided as it leads to an incorrectly set parent property on the traversed child nodes
• all traverser implementations are located under typescript/src/core/traversers
  • all files end with .traverser.ts
  • may export one or more traverser classes each

Notes for creating new traversers:

• each traverser class must inherit from Traverser
• all traversers need to be registered in the TRAVERSERS feature collection in features.ts
  • before implementing a new traverser check if there already exists one in the collection
  • existing traversers may not trigger the traversal for all their child nodes: expand where needed
  • for nodes that don’t have any children that should be traversed the SimpleTraverser default implementation can be specified in TRAVERSERS for the corresponding node type
• use runTraverserForNode(s) utility function to easily delegate the traversal process
• parent property names should be declared as public static readonly members of the implementing class