com.google.gwt.user.client.ui.WidgetIterators Maven / Gradle / Ivy
/*
* Copyright 2007 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;
/**
* A collection of convenience factories for creating iterators for widgets.
* This mostly helps developers support {@link HasWidgets} without having to
* implement their own {@link Iterator}.
*/
class WidgetIterators {
private static Widget[] copyWidgetArray(final Widget[] widgets) {
final Widget[] clone = new Widget[widgets.length];
for (int i = 0; i < widgets.length; i++) {
clone[i] = widgets[i];
}
return clone;
}
/**
* Wraps an array of widgets to be returned during iteration.
* null is allowed in the array and will be skipped during
* iteration.
*
* @param container the container of the widgets in contained
* @param contained the array of widgets
* @return the iterator
*/
static final Iterator createWidgetIterator(final HasWidgets container,
final Widget[] contained) {
return new Iterator() {
int index = -1, last = -1;
boolean widgetsWasCopied = false;
Widget[] widgets = contained;
{
gotoNextIndex();
}
private void gotoNextIndex() {
++index;
while (index < contained.length) {
if (contained[index] != null) {
return;
}
++index;
}
}
public boolean hasNext() {
return (index < contained.length);
}
public Widget next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
last = index;
final Widget w = contained[index];
gotoNextIndex();
return w;
}
public void remove() {
if (last < 0) {
throw new IllegalStateException();
}
if (!widgetsWasCopied) {
widgets = copyWidgetArray(widgets);
widgetsWasCopied = true;
}
container.remove(contained[last]);
last = -1;
}
};
}
private WidgetIterators() {
// Not instantiable.
}
}