Class: ASTTransform::AbstractTransformation

Inherits:
AbstractProcessor
  • Object
show all
Defined in:
lib/ast_transform/abstract_transformation.rb

Overview

Base class for structural transformations: subclass and write on_* handlers to rewrite a pattern wherever it occurs in the tree. This is one of three authoring shapes — pick by how the rewrite site is found:

  • Structural (this class): the pattern alone identifies the site, so on_* handlers rewrite it anywhere in the tree.
  • Positional (node builders): a plain object with run(node) → node, including only TransformationHelper. The caller owns traversal and applies the builder at a site it already located; the builder never walks. Anything with that duck type composes with Transformer and other passes — deriving from this class is just one way to implement it.
  • Sibling-annotation: the pattern is a marker statement plus its NEXT sibling, matched in process_node where the child list is visible — an on_* handler sees one node, never its siblings, and cannot delete itself from its parent. See ASTTransform::Transformation (the transform! detector) for the canonical example.

For read-only passes that harvest information instead of rewriting, see ASTTransform::AbstractAnalysis.

Direct Known Subclasses

Transformation

Instance Method Summary collapse

Methods inherited from AbstractProcessor

#on_ast_thunk, #process

Methods included from TransformationHelper

included

Instance Method Details

#run(node) ⇒ Parser::AST::Node

Runs this transformation on node and returns the rebuilt tree. Note: If you want to add one-time checks to the transformation, override this, then call super.

Parameters:

  • node (Parser::AST::Node) —

    The node to be transformed.

Returns:

  • (Parser::AST::Node) —

    The transformed node.



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# File 'lib/ast_transform/abstract_transformation.rb', line 27

def run(node)
  process(node)
end