core/plugins/org.eclipse.dltk.ui/src/org/eclipse/dltk/internal/ui/ModelElementActionFilterAdapter.java

package org.eclipse.dltk.internal.ui;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.dltk.core.PriorityDLTKExtensionManager;
import org.eclipse.dltk.core.DLTKCore;
import org.eclipse.dltk.ui.actions.IActionFilterTester;
import org.eclipse.ui.IActionFilter;

public class ModelElementActionFilterAdapter implements IActionFilter {
	private final static String ACTION_FILTER_TESTER = "org.eclipse.dltk.ui.actionFilterTester";
	private static class IdBasedExtensionManager extends PriorityDLTKExtensionManager {
		private static final String CLASS_ATTR = "class";
		public IdBasedExtensionManager(String extension) {
			super(extension, "id");
		}
		public IActionFilterTester getObject(String id) throws CoreException {
			ElementInfo ext = this.getElementInfo(id);

			return (IActionFilterTester)getInitObject(ext);
		}

		public Object getInitObject(ElementInfo ext) throws CoreException {
			if (ext != null) {
				if (ext.object != null) {
					return ext.object;
				}

				IConfigurationElement cfg = (IConfigurationElement) ext.getConfig();
				Object object = createObject(cfg);
				ext.object = object;
				return object;
			}
			return null;
		}

		protected Object createObject(IConfigurationElement cfg) throws CoreException {
			return cfg.createExecutableExtension(CLASS_ATTR);
		}
	}
	private static IdBasedExtensionManager actionFilterTesters = new IdBasedExtensionManager(ACTION_FILTER_TESTER) {
		
	};
	public boolean testAttribute(Object target, String name, String value) {
		try {
			IActionFilterTester tester = actionFilterTesters.getObject(name);
			if( tester == null ) {
				return false;
			}
			return tester.test(target, name, value);
		} catch (CoreException e) {
			if( DLTKCore.DEBUG ) {
				e.printStackTrace();
			}
		}
		return false;
	}
}