| /* |
| * Copyright 2011 Google Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| * use this file except in compliance with the License. You may obtain a copy of |
| * the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| * License for the specific language governing permissions and limitations under |
| * the License. |
| */ |
| package com.google.gwt.user.client.ui; |
| |
| import java.util.Iterator; |
| import java.util.NoSuchElementException; |
| |
| /** |
| * Iterator over a finite number of widgets, which are stored in a delegate |
| * class (usually a widget panel). |
| * |
| * <p> |
| * In order to use this class, assign each widget in the panel an arbitrary |
| * index. For example, {@link HeaderPanel} defines the header as index 0, the |
| * content as index 1, and the footer as index 2. Construct a new |
| * {@link FiniteWidgetIterator} with a {@link WidgetProvider} that provides the |
| * child widgets. |
| */ |
| class FiniteWidgetIterator implements Iterator<Widget> { |
| |
| /** |
| * Provides widgets to the iterator. |
| */ |
| public static interface WidgetProvider { |
| IsWidget get(int index); |
| } |
| |
| private int index = -1; |
| private final WidgetProvider provider; |
| private final int widgetCount; |
| |
| /** |
| * Construct a new {@link FiniteWidgetIterator}. |
| * |
| * <p> |
| * The widget count is the number of child widgets that the panel supports, |
| * regardless of whether or not they are set. |
| * |
| * @param provider the widget provider |
| * @param widgetCount the finite number of widgets that can be provided |
| */ |
| public FiniteWidgetIterator(WidgetProvider provider, int widgetCount) { |
| this.provider = provider; |
| this.widgetCount = widgetCount; |
| } |
| |
| public boolean hasNext() { |
| // Iterate over the remaining widgets until we find one. |
| for (int i = index + 1; i < widgetCount; i++) { |
| IsWidget w = provider.get(i); |
| if (w != null) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| public Widget next() { |
| // Iterate over the remaining widgets until we find one. |
| for (int i = index + 1; i < widgetCount; i++) { |
| index = i; |
| IsWidget w = provider.get(i); |
| if (w != null) { |
| return w.asWidget(); |
| } |
| } |
| throw new NoSuchElementException(); |
| } |
| |
| public void remove() { |
| if (index < 0 || index >= widgetCount) { |
| throw new IllegalStateException(); |
| } |
| IsWidget w = provider.get(index); |
| if (w == null) { |
| throw new IllegalStateException("Widget was already removed."); |
| } |
| w.asWidget().removeFromParent(); |
| } |
| } |