org.eclipse.osbp.xtext.action/src/org/eclipse/osbp/xtext/action/common/E4Helper.java

package org.eclipse.osbp.xtext.action.common;

import org.eclipse.e4.ui.model.application.ui.MElementContainer;
import org.eclipse.e4.ui.model.application.ui.MUIElement;
import org.eclipse.e4.ui.model.application.ui.basic.MPart;

public class E4Helper {
	private E4Helper() {
	}

	public static final MUIElement getPart(boolean next, MUIElement element, boolean wasActive) {
		int direction = +1;
		if(!next) {
			direction = -1;
		}
		MElementContainer<MUIElement> parent = element.getParent();
		MUIElement child = null;
		if (wasActive) {
			int index = parent.getChildren().size() - 1;
			if(!next) {
				index = 0;
			}
			if (parent.getChildren().indexOf(element) == index) {
				return getPart(next, parent, wasActive);
			} else {
				child = parent.getChildren().get(parent.getChildren().indexOf(element) + direction);
			}
		} else {
			child = parent.getChildren().get(parent.getChildren().indexOf(element));
		}
		if (child instanceof MPart) {
			return child;
		}
		if (child instanceof MElementContainer<?> && !((MElementContainer<?>) child).getChildren().isEmpty()) {
			int index = 0;
			if(!next) {
				index = ((MElementContainer<?>) child).getChildren().size() - 1;
			}
			return getPart(next, (MUIElement) ((MElementContainer<?>) child).getChildren().get(index), false);
		}
		if (parent instanceof MElementContainer<?> && !parent.getChildren().isEmpty()) {
			int index = 0;
			if(!next) {
				index = parent.getChildren().size() - 1;
			}
			return getPart(next, (MUIElement) parent.getChildren().get(index), false);
		}
		return null;
	}
}