Key.java

/*
 * Copyright 2013 eXo Platform SAS
 *
 * 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 juzu.impl.metamodel;

import juzu.impl.common.JSON;

import java.io.Serializable;

/** @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a> */
public abstract class Key<O extends MetaModelObject> implements Serializable {

  public static <O extends MetaModelObject> Key<O> of(Object value, Class<O> type) {
    return new Wrapper<O>(value, type);
  }

  public static <O extends MetaModelObject> Key<O> of(Class<O> type) {
    return new Literal<O>(type);
  }

  public abstract JSON toJSON();

  protected abstract Class<O> getType();

  @Override
  public abstract boolean equals(Object obj);

  @Override
  public abstract int hashCode();

  private static final class Literal<O extends MetaModelObject> extends Key<O> {

    /** . */
    private final Class<O> type;

    private Literal(Class<O> type) throws NullPointerException {
      if (type == null) {
        throw new NullPointerException("No null type accepted");
      }

      //
      this.type = type;
    }

    @Override
    public JSON toJSON() {
      return new JSON().set("type", type.getName());
    }

    @Override
    protected Class<O> getType() {
      return type;
    }

    @Override
    public boolean equals(Object obj) {
      if (obj == this) {
        return true;
      }
      if (obj instanceof Literal<?>) {
        Literal<?> that = (Literal<?>)obj;
        return type.equals(that.type);
      }
      return false;
    }

    @Override
    public int hashCode() {
      return type.hashCode();
    }

    @Override
    public String toString() {
      return getClass().getSimpleName() + "[" + type.getName() + "]";
    }
  }

  private static final class Wrapper<O extends MetaModelObject> extends Key<O> {

    /** . */
    private final Object value;

    /** . */
    private final Class<O> type;

    private Wrapper(Object value, Class<O> type) throws NullPointerException {
      if (value == null) {
        throw new NullPointerException("No null value accepted");
      }
      if (type == null) {
        throw new NullPointerException("No null type accepted");
      }

      //
      this.value = value;
      this.type = type;
    }

    @Override
    protected Class<O> getType() {
      return type;
    }

    @Override
    public JSON toJSON() {
      return new JSON().set("value", value).set("type", type.getName());
    }

    @Override
    public boolean equals(Object obj) {
      if (obj == this) {
        return true;
      }
      if (obj instanceof Wrapper<?>) {
        Wrapper<?> that = (Wrapper<?>)obj;
        return value.equals(that.value) && type.equals(that.type);
      }
      return false;
    }

    @Override
    public int hashCode() {
      return value.hashCode() ^ type.hashCode();
    }

    @Override
    public String toString() {
      return getClass().getSimpleName() + "[value=" + value + ",type=" + type.getName() + "]";
    }
  }
}