org.eclipse.babel.tapiji.tools.core.ui/src/org/eclipse/babel/tapiji/tools/core/ui/builder/ExtensionManager.java

/*******************************************************************************
 * Copyright (c) 2012 Martin Reiterer.
 * 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:
 *     Martin Reiterer - initial API and implementation
 ******************************************************************************/
package org.eclipse.babel.tapiji.tools.core.ui.builder;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.eclipse.babel.tapiji.tools.core.Activator;
import org.eclipse.babel.tapiji.tools.core.Logger;
import org.eclipse.babel.tapiji.tools.core.ui.analyzer.RBAuditor;
import org.eclipse.babel.tapiji.tools.core.ui.extensions.I18nAuditor;
import org.eclipse.babel.tapiji.tools.core.ui.preferences.TapiJIPreferences;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.Platform;
import org.eclipse.jface.util.IPropertyChangeListener;

public final class ExtensionManager {

	// list of registered extension plug-ins
	private List<I18nAuditor> extensions = null;

	// change listener for builder property change events
	private IPropertyChangeListener propertyChangeListener = null;

	// file-endings supported by the registered extension plug-ins
	private Set<String> supportedFileEndings = new HashSet<String>();

	// singleton instance
	private static ExtensionManager INSTANCE = null;

	private ExtensionManager() {
		initExtensionManager();
	}

	public static ExtensionManager getExtensionManager() {
		if (INSTANCE == null) {
			INSTANCE = new ExtensionManager();
		}

		return INSTANCE;
	}

	private void initExtensionManager() {
		extensions = new ArrayList<I18nAuditor>();

		// init default auditors
		extensions.add(new RBAuditor());

		// lookup registered auditor extensions
		IConfigurationElement[] config = Platform.getExtensionRegistry()
				.getConfigurationElementsFor(Activator.BUILDER_EXTENSION_ID);

		try {
			for (IConfigurationElement e : config) {
				addExtensionPlugIn((I18nAuditor) e
						.createExecutableExtension("class"));
			}
		} catch (CoreException ex) {
			Logger.logError(ex);
		}
	}

	public List<I18nAuditor> getRegisteredI18nAuditors() {

		// init builder property change listener
		if (propertyChangeListener == null) {
			propertyChangeListener = new BuilderPropertyChangeListener();
			TapiJIPreferences.addPropertyChangeListener(propertyChangeListener);
		}

		return extensions;
	}

	public Set<String> getSupportedFileEndings() {
		return supportedFileEndings;
	}

	private void addExtensionPlugIn(I18nAuditor extension) {
		I18nAuditor a = extension;
		extensions.add(a);
		supportedFileEndings.addAll(Arrays.asList(a.getFileEndings()));
	}
}