/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 jakarta.el;
import java.lang.reflect.Array;
import java.util.Objects;
/**
* Standard ELResolver for working with arrays.
*/
public class ArrayELResolver extends ELResolver {
private static final String LENGTH_PROPERTY_NAME = "length";
private final boolean readOnly;
/**
* Creates a writable instance of the standard array resolver.
*/
public ArrayELResolver() {
this.readOnly = false;
}
/**
* Creates an instance of the standard array resolver.
*
* @param readOnly {@code true} if the created instance should be read-only otherwise false.
*/
public ArrayELResolver(boolean readOnly) {
this.readOnly = readOnly;
}
@Override
public Class<?> getType(ELContext context, Object base, Object property) {
Objects.requireNonNull(context);
if (base != null && base.getClass().isArray()) {
context.setPropertyResolved(base, property);
if (LENGTH_PROPERTY_NAME.equals(property)) {
// Always read-only
return null;
}
try {
int idx = coerce(property);
checkBounds(base, idx);
} catch (IllegalArgumentException e) {
// ignore
}
/*
* The resolver may have been created in read-only mode but the array and its elements will always be
* read-write.
*/
if (readOnly) {
return null;
}
return base.getClass().getComponentType();
}
return null;
}
@Override
public Object getValue(ELContext context, Object base, Object property) {
Objects.requireNonNull(context);
if (base != null && base.getClass().isArray()) {
context.setPropertyResolved(base, property);
if (LENGTH_PROPERTY_NAME.equals(property)) {
return Integer.valueOf(Array.getLength(base));
}
int idx = coerce(property);
if (idx < 0 || idx >= Array.getLength(base)) {
return null;
}
return Array.get(base, idx);
}
return null;
}
@Override
public void setValue(ELContext context, Object base, Object property, Object value) {
Objects.requireNonNull(context);
if (base != null && base.getClass().isArray()) {
context.setPropertyResolved(base, property);
if (LENGTH_PROPERTY_NAME.equals(property)) {
throw new PropertyNotWritableException(
Util.message(context, "propertyNotWritable", base.getClass().getName(), property));
}
if (this.readOnly) {
throw new PropertyNotWritableException(
Util.message(context, "resolverNotWritable", base.getClass().getName()));
}
int idx = coerce(property);
checkBounds(base, idx);
if (value != null && !Util.isAssignableFrom(value.getClass(), base.getClass().getComponentType())) {
throw new ClassCastException(Util.message(context, "objectNotAssignable", value.getClass().getName(),
base.getClass().getComponentType().getName()));
}
Array.set(base, idx, value);
}
}
@Override
public boolean isReadOnly(ELContext context, Object base, Object property) {
Objects.requireNonNull(context);
if (base != null && base.getClass().isArray()) {
context.setPropertyResolved(base, property);
if (LENGTH_PROPERTY_NAME.equals(property)) {
// Always read-only
return true;
}
try {
int idx = coerce(property);
checkBounds(base, idx);
} catch (IllegalArgumentException e) {
// ignore
}
}
return this.readOnly;
}
@Override
public Class<?> getCommonPropertyType(ELContext context, Object base) {
if (base != null && base.getClass().isArray()) {
return Integer.class;
}
return null;
}
private static void checkBounds(Object base, int idx) {
if (idx < 0 || idx >= Array.getLength(base)) {
throw new PropertyNotFoundException(new ArrayIndexOutOfBoundsException(idx).getMessage());
}
}
private static int coerce(Object property) {
if (property instanceof Number) {
return ((Number) property).intValue();
}
if (property instanceof Character) {
return ((Character) property).charValue();
}
if (property instanceof Boolean) {
return ((Boolean) property).booleanValue() ? 1 : 0;
}
if (property instanceof String) {
return Integer.parseInt((String) property);
}
throw new IllegalArgumentException(property != null ? property.toString() : "null");
}
}