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    • it.tidalwave.util.spi.AsSupport Maven / Gradle / Ivy

    There is a newer version: 3.2-ALPHA-24
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    /*
 * #%L
 * *********************************************************************************************************************
 *
 * These Foolish Things - Miscellaneous utilities
 * http://thesefoolishthings.java.net - hg clone https://bitbucket.org/tidalwave/thesefoolishthings-src
 * %%
 * Copyright (C) 2009 - 2013 Tidalwave s.a.s. (http://tidalwave.it)
 * %%
 * *********************************************************************************************************************
 *
 * 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.
 *
 * *********************************************************************************************************************
 *
 * $Id$
 *
 * *********************************************************************************************************************
 * #L%
 */
package it.tidalwave.util.spi;

import javax.annotation.Nonnull;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import it.tidalwave.util.As;
import it.tidalwave.util.RoleFactory;

/***********************************************************************************************************************
 *
 * @author  Fabrizio Giudici
 * @version $Id$
 *
 **********************************************************************************************************************/
public class AsSupport implements As
  {
    @Nonnull
    private final AsDelegate delegate;

    @Nonnull
    private final Object owner;

    @Nonnull
    private final List roles = new ArrayList();

    /*******************************************************************************************************************
     *
     * Constructor for use in subclassing.
     *
     ******************************************************************************************************************/
    protected AsSupport()
      {
        owner = this;
        delegate = AsDelegateProvider.Locator.find().createAsDelegate(this);
      }

    /*******************************************************************************************************************
     *
     * Constructor for use in composition. In addition to the mandatory owner, it's possible to pass a collection of
     * pre-instantiated roles, or instances of {@link RoleFactory} that will be invoked to create additional roles.
     *
     * @param  owner             the owner
     * @param  rolesOrFactories  a collection of roles or factories for roles
     *
     ******************************************************************************************************************/
    public AsSupport (final @Nonnull Object owner, final @Nonnull Object ... rolesOrFactories)
      {
        delegate = AsDelegateProvider.Locator.find().createAsDelegate(owner);
        this.owner = owner;
        roles.addAll(resolveFactories(Arrays.asList(rolesOrFactories)));
      }

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     ******************************************************************************************************************/
    @Nonnull
    public  T as (final @Nonnull Class type)
      {
        return as(type, As.Defaults.throwAsException(type));
      }

    /*******************************************************************************************************************
     *
     * {@inheritDoc}
     *
     * First, local roles are probed; then the owner, in case it directly implements the required role; at last,
     * the delegate is invoked.
     *
     ******************************************************************************************************************/
    @Nonnull
    public  T as (final @Nonnull Class type, final @Nonnull As.NotFoundBehaviour notFoundBehaviour)
      {
        for (final Object role : roles)
          {
            if (type.isAssignableFrom(role.getClass()))
              {
                return type.cast(role);
              }
          }

        return delegate.as(type, notFoundBehaviour);
      }

    /*******************************************************************************************************************
     *
     * Resolve the factories: if found, they are invoked and the produced role is added to the list.
     *
     * @param  rolesOrFactories  the list of roles or factory roles
     * @return                   a list of roles
     *
     ******************************************************************************************************************/
    @Nonnull
    private List resolveFactories (final @Nonnull List rolesOrFactories)
      {
        final List result = new ArrayList();

        for (final Object roleOrFactory : rolesOrFactories)
          {
            if (roleOrFactory instanceof RoleFactory)
              {
                result.add(((RoleFactory)roleOrFactory).createRoleFor(owner));
              }
            else
              {
                result.add(roleOrFactory);
              }
          }

        return result;
      }
  }
    
    
    
    

    




    
    
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