/*
* Copyright 2002-2011 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.core.convert;
import java.lang.annotation.Annotation;
import java.util.Collection;
import java.util.Map;
import org.springframework.util.Assert;
/**
* @author Keith Donald
* @since 2.0
*/
abstract class AbstractDescriptor {
private final Class<?> type;
protected AbstractDescriptor(Class<?> type) {
Assert.notNull(type, "Type must not be null");
this.type = type;
}
public Class<?> getType() {
return this.type;
}
public TypeDescriptor getElementTypeDescriptor() {
if (isCollection()) {
Class<?> elementType = resolveCollectionElementType();
return (elementType != null ? new TypeDescriptor(nested(elementType, 0)) : null);
}
else if (isArray()) {
Class<?> elementType = getType().getComponentType();
return new TypeDescriptor(nested(elementType, 0));
}
else {
return null;
}
}
public TypeDescriptor getMapKeyTypeDescriptor() {
if (isMap()) {
Class<?> keyType = resolveMapKeyType();
return keyType != null ? new TypeDescriptor(nested(keyType, 0)) : null;
}
else {
return null;
}
}
public TypeDescriptor getMapValueTypeDescriptor() {
if (isMap()) {
Class<?> valueType = resolveMapValueType();
return valueType != null ? new TypeDescriptor(nested(valueType, 1)) : null;
}
else {
return null;
}
}
public AbstractDescriptor nested() {
if (isCollection()) {
Class<?> elementType = resolveCollectionElementType();
return (elementType != null ? nested(elementType, 0) : null);
}
else if (isArray()) {
return nested(getType().getComponentType(), 0);
}
else if (isMap()) {
Class<?> mapValueType = resolveMapValueType();
return (mapValueType != null ? nested(mapValueType, 1) : null);
}
else if (Object.class.equals(getType())) {
// could be a collection type but we don't know about its element type,
// so let's just assume there is an element type of type Object
return this;
}
else {
throw new IllegalStateException("Not a collection, array, or map: cannot resolve nested value types");
}
}
// subclassing hooks
public abstract Annotation[] getAnnotations();
protected abstract Class<?> resolveCollectionElementType();
protected abstract Class<?> resolveMapKeyType();
protected abstract Class<?> resolveMapValueType();
protected abstract AbstractDescriptor nested(Class<?> type, int typeIndex);
// internal helpers
private boolean isCollection() {
return Collection.class.isAssignableFrom(getType());
}
private boolean isArray() {
return getType().isArray();
}
private boolean isMap() {
return Map.class.isAssignableFrom(getType());
}
}