@FunctionalInterface
public interface ExpressionTransformer

Functional interface for transforming Expression nodes during AST traversal and manipulation.

This transformer interface enables expression-level transformations in AST processing. Implementations typically take an input expression and return a (possibly modified) expression. This can be used for:

• Code generation and transformation passes
• Expression normalization or optimization
• Type-driven transformation in static type checking
• Custom DSL implementation and metaprogramming

Transformers may return:

• The same expression instance unchanged
• A new expression of the same type with modified properties
• A completely different expression type
• Null if the expression should be removed (usage-dependent)

This is a functional interface and can be implemented as a lambda expression.

See Also:

for abstract transformer base class

for visitor using transformers