| // Copyright 2015 The Bazel Authors. All rights reserved. |
| // |
| // 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.devtools.build.lib.query2.engine; |
| |
| import com.google.common.collect.ImmutableList; |
| import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe; |
| |
| /** A helper for deduping values. */ |
| @ThreadSafe |
| public interface Uniquifier<T> { |
| /** |
| * Returns whether {@code newElement} has been seen before by {@link #unique(T)} or |
| * {@link #unique(Iterable)}. |
| * |
| * <p>Please note the difference between this method and {@link #unique(T)}! |
| * |
| * <p>This method is inherently racy wrt {@link #unique(T)} and {@link #unique(Iterable)}. Only |
| * use it if you know what you are doing. |
| */ |
| boolean uniquePure(T newElement); |
| |
| /** |
| * Returns whether {@code newElement} has been seen before by {@link #unique(T)} or {@link |
| * #unique(Iterable)}. |
| */ |
| boolean unique(T newElement) throws QueryException; |
| |
| /** |
| * Returns the subset of {@code newElements} that haven't been seen before by {@link #unique(T)} |
| * or {@link #unique(Iterable)}. |
| */ |
| ImmutableList<T> unique(Iterable<T> newElements) throws QueryException; |
| } |