/*
* Copyright 2002-2014 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.springframework.expression.spel.ast;
import org.springframework.asm.Label;
import org.springframework.asm.MethodVisitor;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.spel.CodeFlow;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelEvaluationException;
import org.springframework.expression.spel.SpelMessage;
import org.springframework.expression.spel.support.BooleanTypedValue;
/**
* Represents a NOT operation.
*
* @author Andy Clement
* @author Mark Fisher
* @author Oliver Becker
* @since 3.0
*/
public class OperatorNot extends SpelNodeImpl { // Not is a unary operator so does not extend BinaryOperator
public OperatorNot(int pos, SpelNodeImpl operand) {
super(pos, operand);
this.exitTypeDescriptor = "Z";
}
@Override
public BooleanTypedValue getValueInternal(ExpressionState state) throws EvaluationException {
try {
Boolean value = this.children[0].getValue(state, Boolean.class);
if (value == null) {
throw new SpelEvaluationException(SpelMessage.TYPE_CONVERSION_ERROR, "null", "boolean");
}
return BooleanTypedValue.forValue(!value);
}
catch (SpelEvaluationException ex) {
ex.setPosition(getChild(0).getStartPosition());
throw ex;
}
}
@Override
public String toStringAST() {
return "!" + getChild(0).toStringAST();
}
@Override
public boolean isCompilable() {
SpelNodeImpl child = this.children[0];
return (child.isCompilable() && CodeFlow.isBooleanCompatible(child.exitTypeDescriptor));
}
@Override
public void generateCode(MethodVisitor mv, CodeFlow cf) {
this.children[0].generateCode(mv, cf);
cf.unboxBooleanIfNecessary(mv);
Label elseTarget = new Label();
Label endOfIf = new Label();
mv.visitJumpInsn(IFNE,elseTarget);
mv.visitInsn(ICONST_1); // TRUE
mv.visitJumpInsn(GOTO,endOfIf);
mv.visitLabel(elseTarget);
mv.visitInsn(ICONST_0); // FALSE
mv.visitLabel(endOfIf);
cf.pushDescriptor(this.exitTypeDescriptor);
}
}