org.apache.bval.util.IndexedAccess Maven / Gradle / Ivy
/**
* 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 org.apache.bval.util;
import java.lang.annotation.ElementType;
import java.lang.reflect.Array;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.List;
import java.util.Map;
import org.apache.commons.lang3.reflect.TypeUtils;
/**
* {@link AccessStrategy} to get an indexed member of an {@link Iterable} or
* array object.
*/
public class IndexedAccess extends AccessStrategy {
private static final TypeVariable ITERABLE_TYPE = Iterable.class.getTypeParameters()[0];
/**
* Get the Java element type of a particular container type.
*
* @param containerType
* @return Type or null if containerType is not
* some type of {@link Iterable} or array
*/
public static Type getJavaElementType(Type containerType) {
if (TypeUtils.isArrayType(containerType)) {
return TypeUtils.getArrayComponentType(containerType);
}
if (TypeUtils.isAssignable(containerType, Iterable.class)) {
Map, Type> typeArguments = TypeUtils.getTypeArguments(containerType, Iterable.class);
return typeArguments.containsKey(ITERABLE_TYPE) ? typeArguments.get(ITERABLE_TYPE) : Object.class;
}
return null;
}
private Type containerType;
private Integer index;
/**
* Create a new IndexedAccessStrategy instance.
*
* @param containerType
* @param index
*/
public IndexedAccess(Type containerType, Integer index) {
super();
this.containerType = containerType;
this.index = index;
}
/**
* {@inheritDoc}
*/
@Override
public Object get(Object instance) {
if (index == null) {
throw new UnsupportedOperationException("Cannot read null index");
}
if (instance != null && instance.getClass().isArray()) {
if (Array.getLength(instance) - index > 0) {
return Array.get(instance, index);
}
} else if (instance instanceof List) {
List list = (List) instance;
if (list.size() - index > 0) {
return list.get(index);
}
} else if (instance instanceof Iterable) {
int i = 0;
for (Object o : (Iterable) instance) {
if (++i == index) {
return o;
}
}
}
return null;
}
/**
* {@inheritDoc}
*/
@Override
public ElementType getElementType() {
return ElementType.METHOD;
}
/**
* {@inheritDoc}
*/
@Override
public Type getJavaType() {
return getJavaElementType(containerType);
}
/**
* {@inheritDoc}
*/
@Override
public String getPropertyName() {
return String.format("[%d]", index);
}
}