/*
* 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.TypedValue;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelEvaluationException;
/**
* Represents a variable reference, eg. #someVar. Note this is different to a *local* variable like $someVar
*
* @author Andy Clement
* @since 3.0
*/
public class VariableReference extends SpelNodeImpl {
// Well known variables:
private final static String THIS = "this"; // currently active context object
private final static String ROOT = "root"; // root context object
private final String name;
public VariableReference(String variableName, int pos) {
super(pos);
name = variableName;
}
@Override
public TypedValue getValueInternal(ExpressionState state) throws SpelEvaluationException {
if (this.name.equals(THIS)) {
return state.getActiveContextObject();
}
if (this.name.equals(ROOT)) {
return state.getRootContextObject();
}
TypedValue result = state.lookupVariable(this.name);
// a null value will mean either the value was null or the variable was not found
return result;
}
@Override
public void setValue(ExpressionState state, Object value) throws SpelEvaluationException {
state.setVariable(this.name, value);
}
@Override
public String toStringAST() {
return "#" + this.name;
}
@Override
public boolean isWritable(ExpressionState expressionState) throws SpelEvaluationException {
return !(this.name.equals(THIS) || this.name.equals(ROOT));
}
}
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