play.template2.compile.GTGroovyVariableScopeTransformer Maven / Gradle / Ivy

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package play.template2.compile;

import org.codehaus.groovy.ast.ASTNode;
import org.codehaus.groovy.ast.ClassCodeExpressionTransformer;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.expr.BinaryExpression;
import org.codehaus.groovy.ast.expr.DeclarationExpression;
import org.codehaus.groovy.ast.expr.Expression;
import org.codehaus.groovy.control.CompilePhase;
import org.codehaus.groovy.control.SourceUnit;
import org.codehaus.groovy.transform.ASTTransformation;
import org.codehaus.groovy.transform.GroovyASTTransformation;

@GroovyASTTransformation(phase = CompilePhase.CONVERSION)
public class GTGroovyVariableScopeTransformer implements ASTTransformation {

    static class Trans extends ClassCodeExpressionTransformer {

        final SourceUnit sourceUnit;

        Trans(SourceUnit sourceUnit) {
            this.sourceUnit = sourceUnit;
        }

        @Override
        protected SourceUnit getSourceUnit() {
            return sourceUnit;
        }

        @Override
        public Expression transform(Expression exp) {
            
            if (exp instanceof DeclarationExpression) {
                // info: http://stackoverflow.com/questions/8158637/using-asttransformation-to-remove-def-to-change-scope-in-groovy-script
                // DeclarationExpression is used when something is declared like this:
                // def a = "hi";
                // Long b = 1;
                //
                // When we change it to use BinaryExpression, we "remove" the def or Long, making it "behave" like this:
                // a = "hi";
                // b = 1;
                // This changes the scope

                BinaryExpression e = new BinaryExpression(((DeclarationExpression) exp).getLeftExpression(), ((DeclarationExpression) exp).getOperation(), ((DeclarationExpression) exp).getRightExpression());
                // setting source position
                e.setSourcePosition( exp);
                return e.transformExpression(this);
            } else {
                return super.transform(exp);
            }
        }
    }

    @Override 
    public void visit(ASTNode[] nodes, SourceUnit source) {
            for (ClassNode classNode : source.getAST().getClasses() ) {
                classNode.visitContents(new Trans(source));
            }
        }
}