ProviderClassSatisfaction.java

/*
 * Grapht, an open source dependency injector.
 * Copyright 2014-2015 various contributors (see CONTRIBUTORS.txt)
 * Copyright 2010-2014 Regents of the University of Minnesota
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */
package org.grouplens.grapht.reflect.internal;

import org.grouplens.grapht.*;
import org.grouplens.grapht.reflect.*;
import org.grouplens.grapht.util.ClassProxy;
import org.grouplens.grapht.util.Preconditions;
import org.grouplens.grapht.util.Types;

import javax.inject.Provider;
import javax.inject.Singleton;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.ObjectStreamException;
import java.io.Serializable;
import java.lang.reflect.Modifier;
import java.lang.reflect.Type;
import java.util.List;
import java.util.Map;

/**
 * ProviderClassSatisfaction is a satisfaction implementation that satisfies a
 * type given a {@link Provider} class capable of providing that type.
 * 
 * @author <a href="http://grouplens.org">GroupLens Research</a>
 */
public class ProviderClassSatisfaction implements Satisfaction, Serializable {
    private static final long serialVersionUID = -1L;
    private final transient Class<? extends Provider<?>> providerType;

    /**
     * Create a ProviderClassSatisfaction that wraps a given provider type.
     * 
     * @param providerType The provider class type
     * @throws NullPointerException if providerType is null
     * @throws IllegalArgumentException if the class is not a Provider, or is not instantiable
     */
    public ProviderClassSatisfaction(Class<? extends Provider<?>> providerType) {
        Preconditions.notNull("provider type", providerType);
        Preconditions.isAssignable(Provider.class, providerType);
        int mods = providerType.getModifiers();
        if (Modifier.isAbstract(mods) || Modifier.isInterface(mods)) {
            throw new IllegalArgumentException("Provider satisfaction " + providerType + " is abstract");
        }
        if (!Types.isInstantiable(providerType)) {
            throw new IllegalArgumentException("Provider satisfaction " + providerType + " is not instantiable");
        }
        
        this.providerType = providerType;
    }
    
    @Override
    public CachePolicy getDefaultCachePolicy() {
        return (getErasedType().getAnnotation(Singleton.class) != null ? CachePolicy.MEMOIZE : CachePolicy.NO_PREFERENCE);
    }
    
    /**
     * @return The Provider class that provides instances satisfying this
     *         satisfaction
     */
    public Class<? extends Provider<?>> getProviderType() {
        return providerType;
    }
    
    @Override
    public List<Desire> getDependencies() {
        return ReflectionDesire.getDesires(providerType);
    }

    @Override
    public Type getType() {
        return Types.getProvidedType(providerType);
    }

    @Override
    public Class<?> getErasedType() {
        return Types.erase(getType());
    }

    @Override
    public boolean hasInstance() {
        return false;
    }

    @Override
    public <T> T visit(SatisfactionVisitor<T> visitor) {
        return visitor.visitProviderClass(providerType);
    }

    @Override
    @SuppressWarnings({ "unchecked", "rawtypes" })
    public Instantiator makeInstantiator(Map<Desire,Instantiator> dependencies,
                                         LifecycleManager lm) {
        // we have to use the raw type because we don't have enough information,
        // but we can assume correctly that it will build a provider
        ClassInstantiator providerBuilder = new ClassInstantiator(providerType, getDependencies(),
                                                                  dependencies, lm);
        return Instantiators.ofProviderInstantiator(providerBuilder);
    }
    
    @Override
    public boolean equals(Object o) {
        if (!(o instanceof ProviderClassSatisfaction)) {
            return false;
        }
        return ((ProviderClassSatisfaction) o).providerType.equals(providerType);
    }
    
    @Override
    public int hashCode() {
        return providerType.hashCode();
    }
    
    @Override
    public String toString() {
        return "Provider(" + providerType.getName() + ")";
    }

    private Object writeReplace() {
        return new SerialProxy(providerType);
    }

    private void readObject(ObjectInputStream stream) throws ObjectStreamException {
        throw new InvalidObjectException("must use serialization proxy");
    }

    private static class SerialProxy implements Serializable {
        private static final long serialVersionUID = 1L;

        private final ClassProxy providerType;

        public SerialProxy(Class<?> cls) {
            providerType = ClassProxy.of(cls);
        }

        @SuppressWarnings("unchecked")
        private Object readResolve() throws ObjectStreamException {
            try {
                return new ProviderClassSatisfaction((Class<? extends Provider<?>>) providerType.resolve().asSubclass(Provider.class));
            } catch (ClassNotFoundException e) {
                InvalidObjectException ex = new InvalidObjectException("cannot resolve " + providerType);
                ex.initCause(e);
                throw ex;
            } catch (ClassCastException e) {
                InvalidObjectException ex = new InvalidObjectException("class " + providerType + " is not a provider");
                ex.initCause(e);
                throw ex;
            }
        }
    }
}