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Groovy: A powerful, dynamic language for the JVM
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.codehaus.groovy.transform.sc.transformers;
import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.GroovyCodeVisitor;
import org.codehaus.groovy.ast.expr.BinaryExpression;
import org.codehaus.groovy.ast.expr.Expression;
import org.codehaus.groovy.ast.expr.ExpressionTransformer;
import org.codehaus.groovy.classgen.AsmClassGenerator;
import org.codehaus.groovy.classgen.asm.WriterController;
import org.codehaus.groovy.syntax.Token;
import org.codehaus.groovy.syntax.Types;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
/**
* Compares two objects using identity comparison.
* This expression will generate bytecode using the IF_ACMPNE instruction, instead of
* using the "equals" method that is currently mapped to "==" in Groovy.
*
* This expression should only be used to compare to objects, not primitives, and only
* in the context of reference equality check.
*
* @author Cedric Champeau
*/
public class CompareIdentityExpression extends BinaryExpression implements Opcodes {
private final Expression leftExpression;
private final Expression rightExpression;
public CompareIdentityExpression(final Expression leftExpression, final Expression rightExpression) {
super(leftExpression, new Token(Types.COMPARE_TO, "==", -1, -1), rightExpression);
this.leftExpression = leftExpression;
this.rightExpression = rightExpression;
}
@Override
public Expression transformExpression(final ExpressionTransformer transformer) {
return this;
}
@Override
public void visit(final GroovyCodeVisitor visitor) {
if (visitor instanceof AsmClassGenerator) {
AsmClassGenerator acg = (AsmClassGenerator) visitor;
WriterController controller = acg.getController();
ClassNode leftType = controller.getTypeChooser().resolveType(leftExpression, controller.getClassNode());
ClassNode rightType = controller.getTypeChooser().resolveType(rightExpression, controller.getClassNode());
MethodVisitor mv = controller.getMethodVisitor();
leftExpression.visit(acg);
controller.getOperandStack().box();
rightExpression.visit(acg);
controller.getOperandStack().box();
Label l1 = new Label();
mv.visitJumpInsn(IF_ACMPNE, l1);
mv.visitInsn(ICONST_1);
Label l2 = new Label();
mv.visitJumpInsn(GOTO, l2);
mv.visitLabel(l1);
mv.visitInsn(ICONST_0);
mv.visitLabel(l2);
controller.getOperandStack().replace(ClassHelper.boolean_TYPE, 2);
} else {
super.visit(visitor);
}
}
}