/*
* 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;
/**
* Represents the elvis operator ?:. For an expression "a?:b" if a is not null, the value of the expression
* is "a", if a is null then the value of the expression is "b".
*
* @author Andy Clement
* @since 3.0
*/
public class Elvis extends SpelNodeImpl {
public Elvis(int pos, SpelNodeImpl... args) {
super(pos,args);
}
/**
* Evaluate the condition and if not null, return it. If it is null return the other value.
* @param state the expression state
* @throws EvaluationException if the condition does not evaluate correctly to a boolean or there is a problem
* executing the chosen alternative
*/
@Override
public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
TypedValue value = children[0].getValueInternal(state);
if (value.getValue()!=null && !((value.getValue() instanceof String) && ((String)value.getValue()).length()==0)) {
return value;
} else {
return children[1].getValueInternal(state);
}
}
@Override
public String toStringAST() {
return new StringBuilder().append(getChild(0).toStringAST()).append(" ?: ").append(getChild(1).toStringAST()).toString();
}
}
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