/*
* 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.ast;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.TypedValue;
import org.springframework.expression.common.ExpressionUtils;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelEvaluationException;
import org.springframework.expression.spel.SpelMessage;
import org.springframework.expression.spel.SpelNode;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.util.Assert;
/**
* The common supertype of all AST nodes in a parsed Spring Expression Language format expression.
*
* @author Andy Clement
* @since 3.0
*/
public abstract class SpelNodeImpl implements SpelNode {
private static SpelNodeImpl[] NO_CHILDREN = new SpelNodeImpl[0];
protected int pos; // start = top 16bits, end = bottom 16bits
protected SpelNodeImpl[] children = SpelNodeImpl.NO_CHILDREN;
private SpelNodeImpl parent;
public SpelNodeImpl(int pos, SpelNodeImpl... operands) {
this.pos = pos;
// pos combines start and end so can never be zero because tokens cannot be zero length
Assert.isTrue(pos != 0);
if (operands != null && operands.length > 0) {
this.children = operands;
for (SpelNodeImpl childnode : operands) {
childnode.parent = this;
}
}
}
protected SpelNodeImpl getPreviousChild() {
SpelNodeImpl result = null;
if (parent != null) {
for (SpelNodeImpl child : parent.children) {
if (this==child) break;
result = child;
}
}
return result;
}
/**
* @return true if the next child is one of the specified classes
*/
protected boolean nextChildIs(Class... clazzes) {
if (parent!=null) {
SpelNodeImpl[] peers = parent.children;
for (int i=0,max=peers.length;i<max;i++) {
if (peers[i]==this) {
if ((i+1)>=max) {
return false;
} else {
Class clazz = peers[i+1].getClass();
for (Class desiredClazz: clazzes) {
if (clazz.equals(desiredClazz)) {
return true;
}
}
return false;
}
}
}
}
return false;
}
public final Object getValue(ExpressionState expressionState) throws EvaluationException {
if (expressionState != null) {
return getValueInternal(expressionState).getValue();
} else {
// configuration not set - does that matter?
return getValue(new ExpressionState(new StandardEvaluationContext()));
}
}
public final TypedValue getTypedValue(ExpressionState expressionState) throws EvaluationException {
if (expressionState != null) {
return getValueInternal(expressionState);
} else {
// configuration not set - does that matter?
return getTypedValue(new ExpressionState(new StandardEvaluationContext()));
}
}
// by default Ast nodes are not writable
public boolean isWritable(ExpressionState expressionState) throws EvaluationException {
return false;
}
public void setValue(ExpressionState expressionState, Object newValue) throws EvaluationException {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.SETVALUE_NOT_SUPPORTED, getClass());
}
public SpelNode getChild(int index) {
return children[index];
}
public int getChildCount() {
return children.length;
}
public Class<?> getObjectClass(Object obj) {
if (obj == null) {
return null;
}
return (obj instanceof Class ? ((Class<?>) obj) : obj.getClass());
}
protected final <T> T getValue(ExpressionState state, Class<T> desiredReturnType) throws EvaluationException {
return ExpressionUtils.convertTypedValue(state.getEvaluationContext(), getValueInternal(state), desiredReturnType);
}
public abstract TypedValue getValueInternal(ExpressionState expressionState) throws EvaluationException;
public abstract String toStringAST();
public int getStartPosition() {
return (pos>>16);
}
public int getEndPosition() {
return (pos&0xffff);
}
protected ValueRef getValueRef(ExpressionState state) throws EvaluationException {
throw new SpelEvaluationException(pos,SpelMessage.NOT_ASSIGNABLE,toStringAST());
}
}