EGLPathContainerInitializer.java example

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/*******************************************************************************
 * Copyright © 2000, 2013 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.edt.ide.core.model;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IProgressMonitor;

/**
 * Abstract base implementation of all eglpath container initializer.
 * EGLPath variable containers are used in conjunction with the
 * "org.eclipse.jdt.core.classpathContainerInitializer" extension point.
 * <p>
 * Clients should subclass this class to implement a specific eglpath
 * container initializer. The subclass must have a public 0-argument
 * constructor and a concrete implementation of <code>resolve</code>.
 * <p>
 * Multiple eglpath containers can be registered, each of them declares
 * the container ID they can handle, so as to narrow the set of containers they
 * can resolve, in other words, a container initializer is guaranteed to only be 
 * activated to resolve containers which match the ID they registered onto.
 * <p>
 * In case multiple container initializers collide on the same container ID, the first
 * registered one will be invoked.
 * 
 * @see IEGLPathEntry
 * @see IEGLPathContainer
 * @since 2.0
 */

public abstract class EGLPathContainerInitializer {
	
   /**
     * Creates a new eglpath container initializer.
     */
    public EGLPathContainerInitializer() {
    }

    /**
     * Binds a eglpath container to a <code>IEGLPathContainer</code> for a given project,
     * or silently fails if unable to do so.
     * <p>
     * A container is identified by a container path, which must be formed of two segments.
     * The first segment is used as a unique identifier (which this initializer did register onto), and
     * the second segment can be used as an additional hint when performing the resolution.
     * <p>
     * The initializer is invoked if a container path needs to be resolved for a given project, and no
     * value for it was recorded so far. The implementation of the initializer can set the corresponding 
     * container using <code>EGLCore#setEGLPathContainer</code>.
     * <p>
     * @param containerPath a two-segment path (ID/hint) identifying the container that needs 
     * 	to be resolved
     * @param project the EGL project in which context the container is to be resolved.
     *    This allows generic containers to be bound with project specific values.
     * 
     * @see EGLCore#getEGLPathContainer(IPath, IEGLProject)
     * @see EGLCore#setEGLPathContainer(IPath, IEGLProject[], IEGLPathContainer[], IProgressMonitor)
     * @see IEGLPathContainer
     */
    public abstract void initialize(IPath containerPath, IEGLProject project) throws CoreException;
    
    /**
     * Returns <code>true</code> if this container initializer can be requested to perform updates 
     * on its own container values. If so, then an update request will be performed using
     * <code>EGLPathContainerInitializer#requestEGLPathContainerUpdate</code>/
     * <p>
     * @param containerPath the path of the container which requires to be updated
     * @param project the project for which the container is to be updated
     * @return returns <code>true</code> if the container can be updated
     * @since 2.1
     */
    public boolean canUpdateEGLPathContainer(IPath containerPath, IEGLProject project) {
    	
		// By default, eglpath container initializers do not accept updating containers
    	return false; 
    }

	/**
	 * Request a registered container definition to be updated according to a container suggestion. The container suggestion 
	 * only acts as a place-holder to pass along the information to update the matching container definition(s) held by the 
	 * container initializer. In particular, it is not expected to store the container suggestion as is, but rather adjust 
	 * the actual container definition based on suggested changes.
	 * <p>
	 * IMPORTANT: In reaction to receiving an update request, a container initializer will update the corresponding
	 * container definition (after reconciling changes) at its earliest convenience, using 
	 * <code>EGLCore#setEGLPathContainer(IPath, IEGLProject[], IEGLPathContainer[], IProgressMonitor)</code>. 
	 * Until it does so, the update will not be reflected in the EGL Model.
	 * <p>
	 * In order to anticipate whether the container initializer allows to update its containers, the predicate
	 * <code>EGLCore#canUpdateEGLPathContainer</code> should be used.
	 * <p>
	 * @param containerPath the path of the container which requires to be updated
     * @param project the project for which the container is to be updated
	 * @param containerSuggestion a suggestion to update the corresponding container definition
	 * @throws CoreException when <code>EGLCore#setEGLPathContainer</code> would throw any.
	 * @see EGLCore#setEGLPathContainer(IPath, IEGLProject[], IEGLPathContainer[], IProgressMonitor)
	 * @see EGLPathContainerInitializer#canUpdateEGLPathContainer(IPath, IEGLProject)
	 * @since 2.1
	 */
    public void requestEGLPathContainerUpdate(IPath containerPath, IEGLProject project, IEGLPathContainer containerSuggestion) throws CoreException {

		// By default, eglpath container initializers do not accept updating containers
    }

	/**
	 * Returns a readable description for a container path. A readable description for a container path can be
	 * used for improving the display of references to container, without actually needing to resolve them.
	 * A good implementation should answer a description consistent with the description of the associated 
	 * target container (see <code>IEGLPathContainer.getDescription()</code>).
	 * 
	 * @param containerPath the path of the container which requires a readable description
	 * @param project the project from which the container is referenced
	 * @return a string description of the container
	 * @since 2.1
	 */    
    public String getDescription(IPath containerPath, IEGLProject project) {
    	
    	// By default, a container path is the only available description
    	return containerPath.makeRelative().toString();
    }
}