com.getperka.flatpack.ext.Walkers Maven / Gradle / Ivy
package com.getperka.flatpack.ext;
/*
* #%L
* FlatPack serialization code
* %%
* Copyright (C) 2012 - 2013 Perka Inc.
* %%
* 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.
* #L%
*/
import java.util.List;
import javax.inject.Inject;
import com.getperka.flatpack.Visitors;
import com.getperka.flatpack.visitors.ArrayContext;
import com.getperka.flatpack.visitors.ImmutableContext;
import com.getperka.flatpack.visitors.IterableContext;
import com.getperka.flatpack.visitors.ListContext;
import com.getperka.flatpack.visitors.NullableContext;
import com.getperka.flatpack.visitors.SingletonContext;
import com.google.inject.Injector;
/**
* A utility class for constructing {@link Acceptor} instances that operate on a variety of common
* collection types.
*
* @see Visitors#getWalkers()
*/
public class Walkers {
private Injector injector;
/**
* Requires injection.
*/
protected Walkers() {}
/**
* Construct an acceptor to apply a walker to the elements of an array.
*/
public Acceptor walkArray(Walker element) {
return create(ArrayContext.class, element);
}
/**
* Construct an acceptor to apply a walker to a single immutable entry.
*/
public Acceptor walkImmutable(Walker element) {
return create(ImmutableContext.class, element);
}
/**
* Construct an acceptor to apply a walker to the elements of a collection.
*/
public Acceptor> walkIterable(Walker element) {
return create(IterableContext.class, element);
}
/**
* Construct an acceptor to apply a walker to the elements of a list.
*/
public Acceptor> walkList(Walker element) {
return create(ListContext.class, element);
}
/**
* Construct an acceptor to apply a walker to a single element that may be nullified.
*/
public Acceptor walkNullable(Walker element) {
return create(NullableContext.class, element);
}
/**
* Construct an acceptor to apply a walker to the value of an entity property. This method will
* select as appropriate {@link Acceptor} based on the property's metadata.
*/
public Acceptor walkProperty(Property property, Walker element) {
if (property.getSetter() == null) {
return walkImmutable(element);
} else if (property.getSetter().getParameterTypes()[0].isPrimitive()) {
return walkSingleton(element);
} else {
return walkNullable(element);
}
}
/**
* Construct an acceptor that allows a single value to be replaced.
*/
public Acceptor walkSingleton(Walker element) {
return create(SingletonContext.class, element);
}
@Inject
void inject(Injector injector) {
this.injector = injector;
}
@SuppressWarnings("unchecked")
private , E> A create(Class clazz, Walker walker) {
A toReturn = (A) injector.getInstance(clazz);
VisitorContext visitorContext = (VisitorContext) toReturn;
visitorContext.setWalker(walker);
return toReturn;
}
}