Groovy example source code file (LoggingASTTransformation.groovy)

This example Groovy source code file (LoggingASTTransformation.groovy) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Groovy tags/keywords

annotation, argumentlistexpression, constantexpression, constantexpression, ending, expressionstatement, list, list, methodcallexpression, methodnode, sourceunit, starting, statement, statement, variableexpression

The Groovy LoggingASTTransformation.groovy source code

package transforms.global

import org.codehaus.groovy.transform.ASTTransformation
import org.codehaus.groovy.ast.ASTNode
import org.codehaus.groovy.control.SourceUnit
import org.codehaus.groovy.transform.GroovyASTTransformation
import org.codehaus.groovy.control.CompilePhase
import org.codehaus.groovy.ast.MethodNode
import org.codehaus.groovy.ast.AnnotationNode
import org.codehaus.groovy.ast.expr.ConstantExpression
import org.codehaus.groovy.ast.expr.MethodCallExpression
import org.codehaus.groovy.ast.expr.VariableExpression
import org.codehaus.groovy.ast.expr.ArgumentListExpression
import org.codehaus.groovy.ast.stmt.BlockStatement
import java.lang.annotation.Annotation
import org.codehaus.groovy.ast.expr.Expression
import org.codehaus.groovy.ast.stmt.Statement
import org.codehaus.groovy.ast.stmt.ExpressionStatement

/**
* This ASTTransformation adds a start and stop message to every single method call. 
*
* @author Hamlet D'Arcy
*/ 
@GroovyASTTransformation(phase=CompilePhase.CONVERSION)
public class LoggingASTTransformation implements ASTTransformation {


    public void visit(ASTNode[] astNodes, SourceUnit sourceUnit) {
        List methods = sourceUnit.getAST()?.getMethods()
        methods?.each { MethodNode method ->
            Statement startMessage = createPrintlnAst("Starting $method.name")
            Statement endMessage = createPrintlnAst("Ending $method.name")

            List existingStatements = method.getCode().getStatements()
            existingStatements.add(0, startMessage)
            existingStatements.add(endMessage)
        }
    }

    /**
    * Creates the AST for a println invocation. 
    */ 
    private Statement createPrintlnAst(String message) {
        return new ExpressionStatement(
            new MethodCallExpression(
                new VariableExpression("this"),
                new ConstantExpression("println"),
                new ArgumentListExpression(
                    new ConstantExpression(message)
                )
            )
        )
    }
}