1090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson/* 21d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * Copyright (C) 2007 The Guava Authors 3090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * 4090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * Licensed under the Apache License, Version 2.0 (the "License"); 5090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * you may not use this file except in compliance with the License. 6090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * You may obtain a copy of the License at 7090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * 8090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * http://www.apache.org/licenses/LICENSE-2.0 9090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * 10090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * Unless required by applicable law or agreed to in writing, software 11090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * distributed under the License is distributed on an "AS IS" BASIS, 12090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * See the License for the specific language governing permissions and 14090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson * limitations under the License. 15090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson */ 16090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 17090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilsonpackage com.google.common.collect; 18090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 19090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilsonimport com.google.common.annotations.GwtCompatible; 20090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 21090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilsonimport java.io.Serializable; 22090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 23090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilsonimport javax.annotation.Nullable; 24090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 25090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson/** An ordering that treats {@code null} as greater than all other values. */ 26090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson@GwtCompatible(serializable = true) 27090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilsonfinal class NullsLastOrdering<T> extends Ordering<T> implements Serializable { 28090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson final Ordering<? super T> ordering; 29090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 30090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson NullsLastOrdering(Ordering<? super T> ordering) { 31090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson this.ordering = ordering; 32090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 33090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 341d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert @Override public int compare(@Nullable T left, @Nullable T right) { 35090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson if (left == right) { 36090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson return 0; 37090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 38090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson if (left == null) { 39090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson return LEFT_IS_GREATER; 40090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 41090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson if (right == null) { 42090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson return RIGHT_IS_GREATER; 43090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 44090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson return ordering.compare(left, right); 45090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 46090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 47090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson @Override public <S extends T> Ordering<S> reverse() { 48090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson // ordering.reverse() might be optimized, so let it do its thing 49090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson return ordering.reverse().nullsFirst(); 50090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 51090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 52090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson @Override public <S extends T> Ordering<S> nullsFirst() { 53090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson return ordering.nullsFirst(); 54090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 55090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 56090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson @SuppressWarnings("unchecked") // still need the right way to explain this 57090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson @Override public <S extends T> Ordering<S> nullsLast() { 581d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert return (Ordering<S>) this; 59090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 60090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 61090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson @Override public boolean equals(@Nullable Object object) { 62090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson if (object == this) { 63090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson return true; 64090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 65090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson if (object instanceof NullsLastOrdering) { 66090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson NullsLastOrdering<?> that = (NullsLastOrdering<?>) object; 67090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson return this.ordering.equals(that.ordering); 68090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 69090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson return false; 70090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 71090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 72090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson @Override public int hashCode() { 73090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson return ordering.hashCode() ^ -921210296; // meaningless 74090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 75090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 76090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson @Override public String toString() { 77090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson return ordering + ".nullsLast()"; 78090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson } 79090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson 80090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson private static final long serialVersionUID = 0; 81090f9b4c879985bc747c214f82c62471e60c7742Jesse Wilson} 82