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/*******************************************************************************
* Copyright (c) 2009, 2012 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.e4.core.di.suppliers;
import java.lang.ref.WeakReference;
/**
* The base class for an "object supplier" - something that knows how to
* instantiate objects corresponding to the object descriptor.
* <p>
* If supplier is asked to track changes, it should notify requestor whenever
* any of the objects produced by the
* {@link #get(IObjectDescriptor[], Object[], IRequestor, boolean, boolean, boolean)}
* method change. The supplier can do this by performing calls to the
* {@link IRequestor#resolveArguments(boolean)} and
* {@link IRequestor#execute()}.
* </p>
*
* @see IRequestor#resolveArguments(boolean)
* @see IRequestor#execute()
* @since 1.7
*/
abstract public class PrimaryObjectSupplier {
/**
* Default constructor
*/
public PrimaryObjectSupplier() {
// placeholder
}
/**
* This method is called by the dependency injection mechanism to obtain objects corresponding
* to the object descriptors. If the supplier is asked to track changes, it should notify requestor
* whenever it detects a change that would result in a different result produced by this method.
* @param descriptors descriptors to the objects requested by the requestor
* @param actualValues the values of actual arguments computed so far for the descriptors (in/out)
* @param requestor the requestor originating this request
* @param initial <code>true</code> true if this is the initial request from the requestor
* @param track <code>true</code> if the object suppliers should notify requestor of
* changes to the returned objects; <code>false</code> otherwise
* @param group <code>true</code> if the change notifications can be grouped;
* <code>false</code> otherwise
*/
abstract public void get(IObjectDescriptor[] descriptors, Object[] actualValues, IRequestor requestor, boolean initial, boolean track, boolean group);
/**
* Pause tracking access to the supplier's objects.
*/
abstract public void pauseRecording();
/**
* Resume tracking access to the supplier's objects.
*/
abstract public void resumeRecording();
/**
* Creates a new reference to the object.
* <p>
* Suppliers may override to provide improved memory management, for instance, by
* to tracking references with reference queues.
* </p>
* @param object the referred object
* @return a new weak reference to the object
*/
public WeakReference<Object> makeReference(Object object) {
return new WeakReference<>(object);
}
}
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