/*
* 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.common;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.Expression;
/**
* A very simple hardcoded implementation of the Expression interface that represents a string literal.
* It is used with CompositeStringExpression when representing a template expression which is made up
* of pieces - some being real expressions to be handled by an EL implementation like Spel, and some
* being just textual elements.
*
* @author Andy Clement
* @since 3.0
*/
public class LiteralExpression implements Expression {
/** Fixed literal value of this expression */
private final String literalValue;
public LiteralExpression(String literalValue) {
this.literalValue = literalValue;
}
public final String getExpressionString() {
return this.literalValue;
}
public String getValue() {
return this.literalValue;
}
public String getValue(EvaluationContext context) {
return this.literalValue;
}
public String getValue(Object rootObject) {
return this.literalValue;
}
public Class getValueType(EvaluationContext context) {
return String.class;
}
public TypeDescriptor getValueTypeDescriptor(EvaluationContext context) {
return TypeDescriptor.valueOf(String.class);
}
public TypeDescriptor getValueTypeDescriptor() {
return TypeDescriptor.valueOf(String.class);
}
public void setValue(EvaluationContext context, Object value) throws EvaluationException {
throw new EvaluationException(literalValue, "Cannot call setValue() on a LiteralExpression");
}
public <T> T getValue(EvaluationContext context, Class<T> expectedResultType) throws EvaluationException {
Object value = getValue(context);
return ExpressionUtils.convert(context, value, expectedResultType);
}
public <T> T getValue(Class<T> expectedResultType) throws EvaluationException {
Object value = getValue();
return ExpressionUtils.convert(null, value, expectedResultType);
}
public boolean isWritable(EvaluationContext context) {
return false;
}
public Class getValueType() {
return String.class;
}
public <T> T getValue(Object rootObject, Class<T> desiredResultType) throws EvaluationException {
Object value = getValue(rootObject);
return ExpressionUtils.convert(null, value, desiredResultType);
}
public String getValue(EvaluationContext context, Object rootObject) throws EvaluationException {
return this.literalValue;
}
public <T> T getValue(EvaluationContext context, Object rootObject, Class<T> desiredResultType) throws EvaluationException {
Object value = getValue(context, rootObject);
return ExpressionUtils.convert(null, value, desiredResultType);
}
public Class getValueType(Object rootObject) throws EvaluationException {
return String.class;
}
public Class getValueType(EvaluationContext context, Object rootObject) throws EvaluationException {
return String.class;
}
public TypeDescriptor getValueTypeDescriptor(Object rootObject) throws EvaluationException {
return TypeDescriptor.valueOf(String.class);
}
public TypeDescriptor getValueTypeDescriptor(EvaluationContext context, Object rootObject) throws EvaluationException {
return TypeDescriptor.valueOf(String.class);
}
public boolean isWritable(EvaluationContext context, Object rootObject) throws EvaluationException {
return false;
}
public void setValue(EvaluationContext context, Object rootObject, Object value) throws EvaluationException {
throw new EvaluationException(literalValue, "Cannot call setValue() on a LiteralExpression");
}
public boolean isWritable(Object rootObject) throws EvaluationException {
return false;
}
public void setValue(Object rootObject, Object value) throws EvaluationException {
throw new EvaluationException(literalValue, "Cannot call setValue() on a LiteralExpression");
}
}
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