/*
* Copyright 2002-2012 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.standard;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.Expression;
import org.springframework.expression.TypedValue;
import org.springframework.expression.common.ExpressionUtils;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelNode;
import org.springframework.expression.spel.SpelParserConfiguration;
import org.springframework.expression.spel.ast.SpelNodeImpl;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.util.Assert;
/**
* A {@code SpelExpression} represents a parsed (valid) expression that is ready
* to be evaluated in a specified context. An expression can be evaluated
* standalone or in a specified context. During expression evaluation the context
* may be asked to resolve references to types, beans, properties, and methods.
*
* @author Andy Clement
* @since 3.0
*/
public class SpelExpression implements Expression {
private final String expression;
private final SpelNodeImpl ast;
private final SpelParserConfiguration configuration;
// the default context is used if no override is supplied by the user
private EvaluationContext defaultContext;
/**
* Construct an expression, only used by the parser.
*/
public SpelExpression(String expression, SpelNodeImpl ast, SpelParserConfiguration configuration) {
this.expression = expression;
this.ast = ast;
this.configuration = configuration;
}
// implementing Expression
public Object getValue() throws EvaluationException {
ExpressionState expressionState = new ExpressionState(getEvaluationContext(), configuration);
return ast.getValue(expressionState);
}
public Object getValue(Object rootObject) throws EvaluationException {
ExpressionState expressionState = new ExpressionState(getEvaluationContext(), toTypedValue(rootObject), configuration);
return ast.getValue(expressionState);
}
public <T> T getValue(Class<T> expectedResultType) throws EvaluationException {
ExpressionState expressionState = new ExpressionState(getEvaluationContext(), configuration);
TypedValue typedResultValue = ast.getTypedValue(expressionState);
return ExpressionUtils.convertTypedValue(expressionState.getEvaluationContext(), typedResultValue, expectedResultType);
}
public <T> T getValue(Object rootObject, Class<T> expectedResultType) throws EvaluationException {
ExpressionState expressionState = new ExpressionState(getEvaluationContext(), toTypedValue(rootObject), configuration);
TypedValue typedResultValue = ast.getTypedValue(expressionState);
return ExpressionUtils.convertTypedValue(expressionState.getEvaluationContext(), typedResultValue, expectedResultType);
}
public Object getValue(EvaluationContext context) throws EvaluationException {
Assert.notNull(context, "The EvaluationContext is required");
return ast.getValue(new ExpressionState(context, configuration));
}
public Object getValue(EvaluationContext context, Object rootObject) throws EvaluationException {
Assert.notNull(context, "The EvaluationContext is required");
return ast.getValue(new ExpressionState(context, toTypedValue(rootObject), configuration));
}
public <T> T getValue(EvaluationContext context, Class<T> expectedResultType) throws EvaluationException {
TypedValue typedResultValue = ast.getTypedValue(new ExpressionState(context, configuration));
return ExpressionUtils.convertTypedValue(context, typedResultValue, expectedResultType);
}
public <T> T getValue(EvaluationContext context, Object rootObject, Class<T> expectedResultType) throws EvaluationException {
TypedValue typedResultValue = ast.getTypedValue(new ExpressionState(context, toTypedValue(rootObject), configuration));
return ExpressionUtils.convertTypedValue(context, typedResultValue, expectedResultType);
}
public Class<?> getValueType() throws EvaluationException {
return getValueType(getEvaluationContext());
}
public Class<?> getValueType(Object rootObject) throws EvaluationException {
return getValueType(getEvaluationContext(), rootObject);
}
public Class<?> getValueType(EvaluationContext context) throws EvaluationException {
Assert.notNull(context, "The EvaluationContext is required");
ExpressionState eState = new ExpressionState(context, configuration);
TypeDescriptor typeDescriptor = ast.getValueInternal(eState).getTypeDescriptor();
return typeDescriptor != null ? typeDescriptor.getType() : null;
}
public Class<?> getValueType(EvaluationContext context, Object rootObject) throws EvaluationException {
ExpressionState eState = new ExpressionState(context, toTypedValue(rootObject), configuration);
TypeDescriptor typeDescriptor = ast.getValueInternal(eState).getTypeDescriptor();
return typeDescriptor != null ? typeDescriptor.getType() : null;
}
public TypeDescriptor getValueTypeDescriptor() throws EvaluationException {
return getValueTypeDescriptor(getEvaluationContext());
}
public TypeDescriptor getValueTypeDescriptor(Object rootObject) throws EvaluationException {
ExpressionState eState = new ExpressionState(getEvaluationContext(), toTypedValue(rootObject), configuration);
return ast.getValueInternal(eState).getTypeDescriptor();
}
public TypeDescriptor getValueTypeDescriptor(EvaluationContext context) throws EvaluationException {
Assert.notNull(context, "The EvaluationContext is required");
ExpressionState eState = new ExpressionState(context, configuration);
return ast.getValueInternal(eState).getTypeDescriptor();
}
public TypeDescriptor getValueTypeDescriptor(EvaluationContext context, Object rootObject) throws EvaluationException {
Assert.notNull(context, "The EvaluationContext is required");
ExpressionState eState = new ExpressionState(context, toTypedValue(rootObject), configuration);
return ast.getValueInternal(eState).getTypeDescriptor();
}
public String getExpressionString() {
return expression;
}
public boolean isWritable(EvaluationContext context) throws EvaluationException {
Assert.notNull(context, "The EvaluationContext is required");
return ast.isWritable(new ExpressionState(context, configuration));
}
public boolean isWritable(Object rootObject) throws EvaluationException {
return ast.isWritable(new ExpressionState(getEvaluationContext(), toTypedValue(rootObject), configuration));
}
public boolean isWritable(EvaluationContext context, Object rootObject) throws EvaluationException {
Assert.notNull(context, "The EvaluationContext is required");
return ast.isWritable(new ExpressionState(context, toTypedValue(rootObject), configuration));
}
public void setValue(EvaluationContext context, Object value) throws EvaluationException {
Assert.notNull(context, "The EvaluationContext is required");
ast.setValue(new ExpressionState(context, configuration), value);
}
public void setValue(Object rootObject, Object value) throws EvaluationException {
ast.setValue(new ExpressionState(getEvaluationContext(), toTypedValue(rootObject), configuration), value);
}
public void setValue(EvaluationContext context, Object rootObject, Object value) throws EvaluationException {
Assert.notNull(context, "The EvaluationContext is required");
ast.setValue(new ExpressionState(context, toTypedValue(rootObject), configuration), value);
}
// impl only
/**
* @return return the Abstract Syntax Tree for the expression
*/
public SpelNode getAST() {
return ast;
}
/**
* Produce a string representation of the Abstract Syntax Tree for the expression, this should ideally look like the
* input expression, but properly formatted since any unnecessary whitespace will have been discarded during the
* parse of the expression.
* @return the string representation of the AST
*/
public String toStringAST() {
return ast.toStringAST();
}
/**
* Return the default evaluation context that will be used if none is supplied on an evaluation call
* @return the default evaluation context
*/
public EvaluationContext getEvaluationContext() {
if (defaultContext == null) {
defaultContext = new StandardEvaluationContext();
}
return defaultContext;
}
/**
* Set the evaluation context that will be used if none is specified on an evaluation call.
* @param context an evaluation context
*/
public void setEvaluationContext(EvaluationContext context) {
this.defaultContext = context;
}
private TypedValue toTypedValue(Object object) {
if (object == null) {
return TypedValue.NULL;
}
else {
return new TypedValue(object);
}
}
}