/*
* Copyright 2002-2009 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.springframework.expression.spel.ast;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.TypedValue;
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;
/**
* The operator 'instanceof' checks if an object is of the class specified in the right hand operand,
* in the same way that <code>instanceof</code> does in Java.
*
* @author Andy Clement
* @since 3.0
*/
public class OperatorInstanceof extends Operator {
public OperatorInstanceof(int pos, SpelNodeImpl... operands) {
super("instanceof", pos, operands);
}
/**
* Compare the left operand to see it is an instance of the type specified as the right operand.
* The right operand must be a class.
* @param state the expression state
* @return true if the left operand is an instanceof of the right operand, otherwise false
* @throws EvaluationException if there is a problem evaluating the expression
*/
@Override
public BooleanTypedValue getValueInternal(ExpressionState state) throws EvaluationException {
TypedValue left = getLeftOperand().getValueInternal(state);
TypedValue right = getRightOperand().getValueInternal(state);
Object leftValue = left.getValue();
Object rightValue = right.getValue();
if (leftValue == null) {
return BooleanTypedValue.FALSE; // null is not an instanceof anything
}
if (rightValue == null || !(rightValue instanceof Class<?>)) {
throw new SpelEvaluationException(getRightOperand().getStartPosition(),
SpelMessage.INSTANCEOF_OPERATOR_NEEDS_CLASS_OPERAND,
(rightValue == null ? "null" : rightValue.getClass().getName()));
}
Class<?> rightClass = (Class<?>) rightValue;
return BooleanTypedValue.forValue(rightClass.isAssignableFrom(leftValue.getClass()));
}
}
|