/**
*
* Copyright (c) 2006-2017, Speedment, Inc. All Rights Reserved.
*
* 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 com.speedment.runtime.config.util;
import com.speedment.runtime.config.Document;
import com.speedment.runtime.config.trait.HasMainInterface;
import java.util.Map;
/**
* An utility class with methods that traits can use to produce a view of the
* document that satisfies exactly that trait.
*
* @author Emil Forslund
* @since 3.0.1
*/
public final class TraitUtil {
/**
* Returns a view of the specified document that implements the specified
* trait. The returned document might or might not be the same instance as
* was inputted to this method. If not, the instance will be initialized
* using the specified constructor.
*
* @param <TRAIT> the trait class
* @param document the document to create a view of
* @param trait the trait type
* @param constructor constructor to use for documents that lack the trait
* @return the view of the trait
*/
public static <TRAIT extends Document> TRAIT viewOf(
Document document,
Class<TRAIT> trait,
TraitViewConstructor<? extends TRAIT> constructor) {
if (trait.isInstance(document)) {
return trait.cast(document);
} else {
final Class<? extends Document> mainInterface;
if (document instanceof HasMainInterface) {
mainInterface = ((HasMainInterface) document).mainInterface();
} else {
mainInterface = trait;
}
return constructor.create(
document.getParent().orElse(null),
document.getData(),
mainInterface
);
}
}
/**
* A functional interface describing the constructor for a class that
* implements a specific trait.
*
* @param <TRAIT> the trait to construct an implementation of
*/
@FunctionalInterface
public interface TraitViewConstructor<TRAIT> {
TRAIT create(Document parent, Map<String, Object> data, Class<? extends Document> mainInterface);
}
/**
* Utility classes should not be instantiated.
*/
private TraitUtil() {
throw new UnsupportedOperationException();
}
}