Source code: javax/ide/model/spi/ModelAdapterFactory.java

   package javax.ide.model.spi;
   
   import java.util.ArrayList;
   import java.util.Collection;
   
   import java.util.Collections;
   import java.util.Iterator;
   import java.util.List;
   import javax.ide.model.Element;
  import javax.ide.spi.LookupProvider;
  import javax.ide.spi.ProviderNotFoundException;
  
  /**
   * A model apapter factory is responsible for creating the best possible 
   * adapter for a given element. The adapter is responsible for managing the 
   * communication between JSR model objects and IDE specific model objects.
   */
  public abstract class ModelAdapterFactory
  {
    private static ModelAdapterFactory _impl;
  
    /**
     * Creates an instance of an adapter that will delegate requests to IDE 
     * specific model objects.
     * 
     * @param element the element that the newly created adapter adapts.
     * @return an adapter instance.
     */
    public abstract ElementImpl getImpl( Element element );
  
    /**
     * Get the ModelAdpaterFactory implementation for this IDE.
     * 
     * @return the DocumentFactory implementation for this IDE.
     */
    public static ModelAdapterFactory getModelAdapterFactory()
    {
      try
      {
        if ( _impl == null )
        {
          Collection impls = LookupProvider.lookupAll(
            Thread.currentThread().getContextClassLoader(), 
            ModelAdapterFactory.class
          );
          if ( impls.size() == 1 )
          {
            _impl = (ModelAdapterFactory) impls.iterator().next();
          }
          else
          {
            List copy = new ArrayList( impls );
            Collections.reverse( copy );
            _impl = new ChainedFactories( copy );
          }
        }
      }
      catch ( ProviderNotFoundException pnfe )
      {
        throw new IllegalStateException( "No model adapter factory." );
      }
      
      return _impl;
    }
    
    
    private static final class ChainedFactories extends ModelAdapterFactory
    {
      private final List _factories;
      
      ChainedFactories( List factories )
      {
        _factories = factories;
      }
    
      public ElementImpl getImpl( Element element )
      {
        for ( Iterator i = _factories.iterator(); i.hasNext(); )
        {
          ModelAdapterFactory f = (ModelAdapterFactory) i.next();
          ElementImpl result = f.getImpl( element );
          if ( result != null )
          {
            return result;
          }
        }
        return null;
      }
    }
    
  }