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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.ConstantExpression;
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;
public class CompareToNullExpression extends BinaryExpression implements Opcodes {
private final boolean equalsNull;
private final Expression objectExpression;
public CompareToNullExpression(final Expression objectExpression, final boolean compareToNull) {
super(objectExpression, new Token(Types.COMPARE_TO, compareToNull ? "==" : "!=", -1, -1), ConstantExpression.NULL);
this.objectExpression = objectExpression;
this.equalsNull = compareToNull;
}
public Expression getObjectExpression() {
return objectExpression;
}
@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();
MethodVisitor mv = controller.getMethodVisitor();
objectExpression.visit(acg);
ClassNode top = controller.getOperandStack().getTopOperand();
if (ClassHelper.isPrimitiveType(top)) {
controller.getOperandStack().pop();
mv.visitInsn(equalsNull ? ICONST_0 : ICONST_1);
controller.getOperandStack().push(ClassHelper.boolean_TYPE);
return;
}
Label zero = new Label();
mv.visitJumpInsn(equalsNull ? IFNONNULL : IFNULL, zero);
mv.visitInsn(ICONST_1);
Label end = new Label();
mv.visitJumpInsn(GOTO, end);
mv.visitLabel(zero);
mv.visitInsn(ICONST_0);
mv.visitLabel(end);
controller.getOperandStack().replace(ClassHelper.boolean_TYPE);
} else {
super.visit(visitor);
}
}
}