core/plugins/org.eclipse.dltk.ui/src/org/eclipse/dltk/ui/viewsupport/ViewHistory.java

/*******************************************************************************
 * Copyright (c) 2006, 2017 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.dltk.ui.viewsupport;

import java.util.List;

import org.eclipse.jface.action.Action;
import org.eclipse.jface.action.IAction;
import org.eclipse.jface.action.MenuManager;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.swt.widgets.Shell;

/**
 * History support for a view.
 *
 * @param <E>
 *            the type of elements managed by this history
 */
public abstract class ViewHistory<E> {

	/**
	 * Configure the history List action. Clients typically want to set a text
	 * and an image.
	 *
	 * @param action
	 *            the action
	 */
	public abstract void configureHistoryListAction(IAction action);

	/**
	 * Configure the history drop down action. Clients typically want to set a
	 * tooltip and an image.
	 *
	 * @param action
	 *            the action
	 */
	public abstract void configureHistoryDropDownAction(IAction action);

	/**
	 * @return action to clear history entries, or <code>null</code>
	 */
	public abstract Action getClearAction();

	public abstract String getHistoryListDialogTitle();

	public abstract String getHistoryListDialogMessage();

	public abstract Shell getShell();

	/**
	 * @return An unmodifiable list of history entries, can be empty. The list
	 *         is sorted by age, youngest first.
	 */
	public abstract List<E> getHistoryEntries();

	/**
	 * @return the active entry from the history
	 */
	public abstract E getCurrentEntry();

	/**
	 * @param entry
	 *            the entry to activate, or <code>null</code> if none should be
	 *            active
	 */
	public abstract void setActiveEntry(E entry);

	/**
	 * @param remainingEntries
	 *            all the remaining history entries, can be empty
	 * @param activeEntry
	 *            the entry to activate, or <code>null</code> if none should be
	 *            active
	 */
	public abstract void setHistoryEntries(List<E> remainingEntries,
			E activeEntry);

	/**
	 * @param element
	 *            the element to render
	 * @return the image descriptor for the given element, or <code>null</code>
	 */
	public abstract ImageDescriptor getImageDescriptor(E element);

	/**
	 * @param element
	 *            the element to render
	 * @return the label text for the given element
	 */
	public abstract String getText(E element);

	/**
	 * @return a history drop down action, ready for inclusion in a view toolbar
	 */
	public final IAction createHistoryDropDownAction() {
		return new HistoryDropDownAction<>(this);
	}

	public abstract void addMenuEntries(MenuManager manager);

	public abstract String getMaxEntriesMessage();

	public abstract int getMaxEntries();

	public abstract void setMaxEntries(int maxEntries);

}