ItemsProvider.java

/*******************************************************************************
 * Copyright (c) 2012-2017 Codenvy, S.A.
 * 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:
 *   Codenvy, S.A. - initial API and implementation
 *******************************************************************************/
package org.eclipse.che.ide.ui.menubutton;

import org.eclipse.che.commons.annotation.Nullable;
import org.eclipse.che.ide.util.Pair;

import java.util.List;
import java.util.Optional;

/** Provides {@link MenuItem}s for {@link MenuButton}. */
public interface ItemsProvider {

    /**
     * Returns an {@code Optional} with a default {@link MenuItem} which should be passed
     * to {@link ActionHandler#onAction(MenuItem)}
     * when user makes a short click on a {@link MenuButton}.
     * <p>Returns an empty {@code Optional} if no default {@link MenuItem}.
     */
    Optional<MenuItem> getDefaultItem();

    /** Returns top level items. */
    List<MenuItem> getItems();

    /**
     * Checks whether the given {@code item} is a group.
     * Group item cannot be selected.
     */
    boolean isGroup(MenuItem item);

    /** Returns the pair of the given {@code parent} children and their labels. */
    @Nullable
    Pair<List<MenuItem>, String> getChildren(MenuItem parent);

    /** Sets the {@link DataChangedHandler}. */
    void setDataChangedHandler(DataChangedHandler handler);

    interface DataChangedHandler {
        /** Should be called when provided by {@link ItemsProvider} data has been changed. */
        void onDataChanged();
    }
}