/*
* Copyright 2002-2010 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 java.util.Collection;
import java.util.List;
import java.util.Map;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.expression.AccessException;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.PropertyAccessor;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelEvaluationException;
import org.springframework.expression.spel.SpelMessage;
import org.springframework.expression.spel.support.ReflectivePropertyAccessor;
/**
* An Indexer can index into some proceeding structure to access a particular piece of it.
* Supported structures are: strings/collections (lists/sets)/arrays
*
* @author Andy Clement
* @since 3.0
*/
// TODO support multidimensional arrays
// TODO support correct syntax for multidimensional [][][] and not [,,,]
public class Indexer extends SpelNodeImpl {
// These fields are used when the indexer is being used as a property read accessor. If the name and
// target type match these cached values then the cachedReadAccessor is used to read the property.
// If they do not match, the correct accessor is discovered and then cached for later use.
private String cachedReadName;
private Class<?> cachedReadTargetType;
private PropertyAccessor cachedReadAccessor;
// These fields are used when the indexer is being used as a property write accessor. If the name and
// target type match these cached values then the cachedWriteAccessor is used to write the property.
// If they do not match, the correct accessor is discovered and then cached for later use.
private String cachedWriteName;
private Class<?> cachedWriteTargetType;
private PropertyAccessor cachedWriteAccessor;
public Indexer(int pos, SpelNodeImpl expr) {
super(pos, expr);
}
@Override
public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
TypedValue context = state.getActiveContextObject();
Object targetObject = context.getValue();
TypeDescriptor targetObjectTypeDescriptor = context.getTypeDescriptor();
TypedValue indexValue = null;
Object index = null;
// This first part of the if clause prevents a 'double dereference' of the property (SPR-5847)
if (targetObject instanceof Map && (children[0] instanceof PropertyOrFieldReference)) {
PropertyOrFieldReference reference = (PropertyOrFieldReference)children[0];
index = reference.getName();
indexValue = new TypedValue(index);
}
else {
// In case the map key is unqualified, we want it evaluated against the root object so
// temporarily push that on whilst evaluating the key
try {
state.pushActiveContextObject(state.getRootContextObject());
indexValue = children[0].getValueInternal(state);
index = indexValue.getValue();
}
finally {
state.popActiveContextObject();
}
}
// Indexing into a Map
if (targetObject instanceof Map) {
if (targetObject == null) {
// Current decision: attempt to index into null map == exception and does not just return null
throw new SpelEvaluationException(getStartPosition(),SpelMessage.CANNOT_INDEX_INTO_NULL_VALUE);
}
Object possiblyConvertedKey = index;
if (targetObjectTypeDescriptor.isMapEntryTypeKnown()) {
possiblyConvertedKey = state.convertValue(index,TypeDescriptor.valueOf(targetObjectTypeDescriptor.getMapKeyType()));
}
Object o = ((Map<?, ?>) targetObject).get(possiblyConvertedKey);
if (targetObjectTypeDescriptor.isMapEntryTypeKnown()) {
return new TypedValue(o, targetObjectTypeDescriptor.getMapValueTypeDescriptor());
} else {
return new TypedValue(o);
}
}
if (targetObject == null) {
throw new SpelEvaluationException(getStartPosition(),SpelMessage.CANNOT_INDEX_INTO_NULL_VALUE);
}
// if the object is something that looks indexable by an integer, attempt to treat the index value as a number
if ((targetObject instanceof Collection ) || targetObject.getClass().isArray() || targetObject instanceof String) {
int idx = (Integer)state.convertValue(index, TypeDescriptor.valueOf(Integer.class));
if (targetObject.getClass().isArray()) {
return new TypedValue(accessArrayElement(targetObject, idx), targetObjectTypeDescriptor.getElementTypeDescriptor());
} else if (targetObject instanceof Collection) {
Collection c = (Collection) targetObject;
if (idx >= c.size()) {
if (!growCollection(state, targetObjectTypeDescriptor.getElementType(), idx, c)) {
throw new SpelEvaluationException(getStartPosition(),SpelMessage.COLLECTION_INDEX_OUT_OF_BOUNDS, c.size(), idx);
}
}
int pos = 0;
for (Object o : c) {
if (pos == idx) {
return new TypedValue(o, targetObjectTypeDescriptor.getElementTypeDescriptor());
}
pos++;
}
} else if (targetObject instanceof String) {
String ctxString = (String) targetObject;
if (idx >= ctxString.length()) {
throw new SpelEvaluationException(getStartPosition(),SpelMessage.STRING_INDEX_OUT_OF_BOUNDS, ctxString.length(), idx);
}
return new TypedValue(String.valueOf(ctxString.charAt(idx)));
}
}
// Try and treat the index value as a property of the context object
// TODO could call the conversion service to convert the value to a String
if (indexValue.getTypeDescriptor().getType()==String.class) {
Class<?> targetObjectRuntimeClass = getObjectClass(targetObject);
String name = (String)indexValue.getValue();
EvaluationContext eContext = state.getEvaluationContext();
try {
if (cachedReadName!=null && cachedReadName.equals(name) && cachedReadTargetType!=null && cachedReadTargetType.equals(targetObjectRuntimeClass)) {
// it is OK to use the cached accessor
return cachedReadAccessor.read(eContext, targetObject, name);
}
List<PropertyAccessor> accessorsToTry = AstUtils.getPropertyAccessorsToTry(targetObjectRuntimeClass, state);
if (accessorsToTry != null) {
for (PropertyAccessor accessor : accessorsToTry) {
if (accessor.canRead(eContext, targetObject, name)) {
if (accessor instanceof ReflectivePropertyAccessor) {
accessor = ((ReflectivePropertyAccessor)accessor).createOptimalAccessor(eContext, targetObject, name);
}
this.cachedReadAccessor = accessor;
this.cachedReadName = name;
this.cachedReadTargetType = targetObjectRuntimeClass;
return accessor.read(eContext, targetObject, name);
}
}
}
} catch (AccessException e) {
throw new SpelEvaluationException(getStartPosition(), e, SpelMessage.INDEXING_NOT_SUPPORTED_FOR_TYPE, targetObjectTypeDescriptor.asString());
}
}
throw new SpelEvaluationException(getStartPosition(),SpelMessage.INDEXING_NOT_SUPPORTED_FOR_TYPE, targetObjectTypeDescriptor.asString());
}
@Override
public boolean isWritable(ExpressionState expressionState) throws SpelEvaluationException {
return true;
}
@SuppressWarnings("unchecked")
@Override
public void setValue(ExpressionState state, Object newValue) throws EvaluationException {
TypedValue contextObject = state.getActiveContextObject();
Object targetObject = contextObject.getValue();
TypeDescriptor targetObjectTypeDescriptor = contextObject.getTypeDescriptor();
TypedValue index = children[0].getValueInternal(state);
if (targetObject == null) {
throw new SpelEvaluationException(SpelMessage.CANNOT_INDEX_INTO_NULL_VALUE);
}
// Indexing into a Map
if (targetObjectTypeDescriptor.isMap()) {
Map map = (Map)targetObject;
Object possiblyConvertedKey = index;
Object possiblyConvertedValue = newValue;
if (targetObjectTypeDescriptor.isMapEntryTypeKnown()) {
possiblyConvertedKey = state.convertValue(index.getValue(),TypeDescriptor.valueOf(targetObjectTypeDescriptor.getMapKeyType()));
possiblyConvertedValue = state.convertValue(newValue,TypeDescriptor.valueOf(targetObjectTypeDescriptor.getMapValueType()));
}
map.put(possiblyConvertedKey,possiblyConvertedValue);
return;
}
if (targetObjectTypeDescriptor.isArray()) {
int idx = (Integer)state.convertValue(index, TypeDescriptor.valueOf(Integer.class));
setArrayElement(state, contextObject.getValue(), idx, newValue, targetObjectTypeDescriptor.getElementType());
return;
}
else if (targetObjectTypeDescriptor.isCollection()) {
int idx = (Integer)state.convertValue(index, TypeDescriptor.valueOf(Integer.class));
Collection c = (Collection) targetObject;
if (idx >= c.size()) {
if (!growCollection(state, targetObjectTypeDescriptor.getElementType(), idx, c)) {
throw new SpelEvaluationException(getStartPosition(),SpelMessage.COLLECTION_INDEX_OUT_OF_BOUNDS, c.size(), idx);
}
}
if (targetObject instanceof List) {
List list = (List)targetObject;
Object possiblyConvertedValue = state.convertValue(newValue, targetObjectTypeDescriptor.getElementTypeDescriptor());
list.set(idx,possiblyConvertedValue);
return;
}
else {
throw new SpelEvaluationException(getStartPosition(),SpelMessage.INDEXING_NOT_SUPPORTED_FOR_TYPE, targetObjectTypeDescriptor.asString());
}
}
// Try and treat the index value as a property of the context object
// TODO could call the conversion service to convert the value to a String
if (index.getTypeDescriptor().getType()==String.class) {
Class<?> contextObjectClass = getObjectClass(contextObject.getValue());
String name = (String)index.getValue();
EvaluationContext eContext = state.getEvaluationContext();
try {
if (cachedWriteName!=null && cachedWriteName.equals(name) && cachedWriteTargetType!=null && cachedWriteTargetType.equals(contextObjectClass)) {
// it is OK to use the cached accessor
cachedWriteAccessor.write(eContext, targetObject, name,newValue);
return;
}
List<PropertyAccessor> accessorsToTry = AstUtils.getPropertyAccessorsToTry(contextObjectClass, state);
if (accessorsToTry != null) {
for (PropertyAccessor accessor : accessorsToTry) {
if (accessor.canWrite(eContext, contextObject.getValue(), name)) {
this.cachedWriteName = name;
this.cachedWriteTargetType = contextObjectClass;
this.cachedWriteAccessor = accessor;
accessor.write(eContext, contextObject.getValue(), name, newValue);
return;
}
}
}
} catch (AccessException ae) {
throw new SpelEvaluationException(getStartPosition(), ae, SpelMessage.EXCEPTION_DURING_PROPERTY_WRITE,
name, ae.getMessage());
}
}
throw new SpelEvaluationException(getStartPosition(),SpelMessage.INDEXING_NOT_SUPPORTED_FOR_TYPE, targetObjectTypeDescriptor.asString());
}
/**
* Attempt to grow the specified collection so that the specified index is valid.
*
* @param state the expression state
* @param elementType the type of the elements in the collection
* @param index the index into the collection that needs to be valid
* @param collection the collection to grow with elements
* @return true if collection growing succeeded, otherwise false
*/
@SuppressWarnings("unchecked")
private boolean growCollection(ExpressionState state, Class<?> elementType, int index,
Collection collection) {
if (state.getConfiguration().isAutoGrowCollections()) {
Object newCollectionElement = null;
try {
int newElements = index-collection.size();
if (elementType == null || elementType == Object.class) {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.UNABLE_TO_GROW_COLLECTION_UNKNOWN_ELEMENT_TYPE);
}
while (newElements>0) {
collection.add(elementType.newInstance());
newElements--;
}
newCollectionElement = elementType.newInstance();
}
catch (Exception ex) {
throw new SpelEvaluationException(getStartPosition(), ex, SpelMessage.UNABLE_TO_GROW_COLLECTION);
}
collection.add(newCollectionElement);
return true;
}
return false;
}
@Override
public String toStringAST() {
StringBuilder sb = new StringBuilder();
sb.append("[");
for (int i = 0; i < getChildCount(); i++) {
if (i > 0)
sb.append(",");
sb.append(getChild(i).toStringAST());
}
sb.append("]");
return sb.toString();
}
private void setArrayElement(ExpressionState state, Object ctx, int idx, Object newValue, Class clazz) throws EvaluationException {
Class<?> arrayComponentType = clazz;
if (arrayComponentType == Integer.TYPE) {
int[] array = (int[]) ctx;
checkAccess(array.length, idx);
array[idx] = (Integer)state.convertValue(newValue, TypeDescriptor.valueOf(Integer.class));
} else if (arrayComponentType == Boolean.TYPE) {
boolean[] array = (boolean[]) ctx;
checkAccess(array.length, idx);
array[idx] = (Boolean)state.convertValue(newValue, TypeDescriptor.valueOf(Boolean.class));
} else if (arrayComponentType == Character.TYPE) {
char[] array = (char[]) ctx;
checkAccess(array.length, idx);
array[idx] = (Character)state.convertValue(newValue, TypeDescriptor.valueOf(Character.class));
} else if (arrayComponentType == Long.TYPE) {
long[] array = (long[]) ctx;
checkAccess(array.length, idx);
array[idx] = (Long)state.convertValue(newValue, TypeDescriptor.valueOf(Long.class));
} else if (arrayComponentType == Short.TYPE) {
short[] array = (short[]) ctx;
checkAccess(array.length, idx);
array[idx] = (Short)state.convertValue(newValue, TypeDescriptor.valueOf(Short.class));
} else if (arrayComponentType == Double.TYPE) {
double[] array = (double[]) ctx;
checkAccess(array.length, idx);
array[idx] = (Double)state.convertValue(newValue, TypeDescriptor.valueOf(Double.class));
} else if (arrayComponentType == Float.TYPE) {
float[] array = (float[]) ctx;
checkAccess(array.length, idx);
array[idx] = (Float)state.convertValue(newValue, TypeDescriptor.valueOf(Float.class));
} else if (arrayComponentType == Byte.TYPE) {
byte[] array = (byte[]) ctx;
checkAccess(array.length, idx);
array[idx] = (Byte)state.convertValue(newValue, TypeDescriptor.valueOf(Byte.class));
} else {
Object[] array = (Object[]) ctx;
checkAccess(array.length, idx);
array[idx] = state.convertValue(newValue, TypeDescriptor.valueOf(clazz));
}
}
private Object accessArrayElement(Object ctx, int idx) throws SpelEvaluationException {
Class<?> arrayComponentType = ctx.getClass().getComponentType();
if (arrayComponentType == Integer.TYPE) {
int[] array = (int[]) ctx;
checkAccess(array.length, idx);
return array[idx];
} else if (arrayComponentType == Boolean.TYPE) {
boolean[] array = (boolean[]) ctx;
checkAccess(array.length, idx);
return array[idx];
} else if (arrayComponentType == Character.TYPE) {
char[] array = (char[]) ctx;
checkAccess(array.length, idx);
return array[idx];
} else if (arrayComponentType == Long.TYPE) {
long[] array = (long[]) ctx;
checkAccess(array.length, idx);
return array[idx];
} else if (arrayComponentType == Short.TYPE) {
short[] array = (short[]) ctx;
checkAccess(array.length, idx);
return array[idx];
} else if (arrayComponentType == Double.TYPE) {
double[] array = (double[]) ctx;
checkAccess(array.length, idx);
return array[idx];
} else if (arrayComponentType == Float.TYPE) {
float[] array = (float[]) ctx;
checkAccess(array.length, idx);
return array[idx];
} else if (arrayComponentType == Byte.TYPE) {
byte[] array = (byte[]) ctx;
checkAccess(array.length, idx);
return array[idx];
} else {
Object[] array = (Object[]) ctx;
checkAccess(array.length, idx);
return array[idx];
}
}
private void checkAccess(int arrayLength, int index) throws SpelEvaluationException {
if (index > arrayLength) {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.ARRAY_INDEX_OUT_OF_BOUNDS, arrayLength, index);
}
}
}
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