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/*
* Copyright 2003-2009 the original author or authors.
*
* Licensed 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();
ClassNode objectType = controller.getTypeChooser().resolveType(objectExpression, controller.getClassNode());
MethodVisitor mv = controller.getMethodVisitor();
if (ClassHelper.isPrimitiveType(objectType)) {
// we're in a primitive == null comparison, which *always* return false
mv.visitInsn(ICONST_0);
controller.getOperandStack().push(ClassHelper.boolean_TYPE);
} else {
objectExpression.visit(acg);
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);
}
}
}