/*
* Copyright 2014 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 java.util;
import javaemul.internal.InternalPreconditions;
import javaemul.internal.JsUtils;
/**
* A helper to detect concurrent modifications to collections. This is implemented as a helper
* utility so that we could remove the checks easily by a flag.
*/
class ConcurrentModificationDetector {
private static final boolean API_CHECK = InternalPreconditions.isApiChecked();
private static final String MOD_COUNT_PROPERTY = "_gwt_modCount";
public static void structureChanged(Object map) {
if (!API_CHECK) {
return;
}
// Ensure that modCount is initialized if it is not already.
int modCount = JsUtils.getIntProperty(map, MOD_COUNT_PROPERTY) | 0;
JsUtils.setIntProperty(map, MOD_COUNT_PROPERTY, modCount + 1);
}
public static void recordLastKnownStructure(Object host, Iterator<?> iterator) {
if (!API_CHECK) {
return;
}
int modCount = JsUtils.getIntProperty(host, MOD_COUNT_PROPERTY);
JsUtils.setIntProperty(iterator, MOD_COUNT_PROPERTY, modCount);
}
public static void checkStructuralChange(Object host, Iterator<?> iterator) {
if (!API_CHECK) {
return;
}
if (JsUtils.getIntProperty(iterator, MOD_COUNT_PROPERTY)
!= JsUtils.getIntProperty(host, MOD_COUNT_PROPERTY)) {
throw new ConcurrentModificationException();
}
}
}