// Copyright (C) 2016 The Android Open Source Project
//
// 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.gerrit.reviewdb.server;
import com.google.common.collect.Ordering;
import com.google.gwtorm.client.IntKey;
/** Static utilities for ReviewDb types. */
public class ReviewDbUtil {
private static final Ordering<? extends IntKey<?>> INT_KEY_ORDERING =
Ordering.natural().nullsFirst().<IntKey<?>>onResultOf(IntKey::get).nullsFirst();
/**
* Null-safe ordering over arbitrary subclass of {@code IntKey}.
*
* <p>In some cases, {@code Comparator.comparing(Change.Id::get)} may be shorter and cleaner.
* However, this method may be preferable in some cases:
*
* <ul>
* <li>This ordering is null-safe over both input and the result of {@link IntKey#get()}; {@code
* comparing} is only a good idea if all inputs are obviously non-null.
* <li>{@code intKeyOrdering().sortedCopy(iterable)} is shorter than the stream equivalent.
* <li>Creating derived comparators may be more readable with {@link Ordering} method chaining
* rather than static {@code Comparator} methods.
* </ul>
*/
@SuppressWarnings("unchecked")
public static <K extends IntKey<?>> Ordering<K> intKeyOrdering() {
return (Ordering<K>) INT_KEY_ORDERING;
}
public static ReviewDb unwrapDb(ReviewDb db) {
if (db instanceof DisallowReadFromChangesReviewDbWrapper) {
return ((DisallowReadFromChangesReviewDbWrapper) db).unsafeGetDelegate();
}
return db;
}
private ReviewDbUtil() {}
}