Package org.apache.groovy.contracts.ast

Class MethodVariantASTTransformation

java.lang.Object
org.apache.groovy.contracts.ast.MethodVariantASTTransformation
All Implemented Interfaces:
ASTTransformation
public class MethodVariantASTTransformation extends Object implements ASTTransformation
Handles a Decreases annotation placed on a method (the loop case is handled by LoopVariantASTTransformation). The closure is a termination measure over the method's parameters that must strictly decrease, and stay non-negative, on every recursive re-entry.

The method body is wrapped so that, conceptually: 

 def $m   = <measure>
 def $prev = MethodVariantSupport.enter("<key>", $m)   // checks decrease vs the enclosing frame
 try { <original body> } finally { MethodVariantSupport.exit("<key>", $prev) }
The check is pure entry/exit bookkeeping keyed by method signature, so no static analysis of recursive call sites is needed.
Since:
6.0.0
See Also:

  • Constructor Details

    • MethodVariantASTTransformation

      public MethodVariantASTTransformation()

  • Method Details

    • visit

      public void visit(ASTNode[] nodes, SourceUnit source)
      Description copied from interface: ASTTransformation
      The method is invoked when an AST Transformation is active. For local transformations, it is invoked once each time the local annotation is encountered. For global transformations, it is invoked once for every source unit, which is typically a source file.
      Specified by:
      visit in interface ASTTransformation
      Parameters:
      nodes - The ASTnodes when the call was triggered. Element 0 is the AnnotationNode that triggered this annotation to be activated. Element 1 is the AnnotatedNode decorated, such as a MethodNode or ClassNode. For global transformations it is usually safe to ignore this parameter.
      source - The source unit being compiled. The source unit may contain several classes. For global transformations, information about the AST can be retrieved from this object.