| /* |
| * Copyright 2018, OpenCensus Authors |
| * |
| * 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 io.opencensus.common; |
| |
| /*>>> |
| import org.checkerframework.checker.nullness.qual.Nullable; |
| */ |
| |
| /** |
| * Represents a function that produces a double-valued result. See {@link |
| * io.opencensus.metrics.MetricRegistry} for an example of its use. |
| * |
| * <p>Note: This class is based on the java.util.ToDoubleFunction class added in Java 1.8. We cannot |
| * use the Function from Java 1.8 because this library is Java 1.6 compatible. |
| * |
| * @since 0.16 |
| */ |
| public interface ToDoubleFunction</*@Nullable*/ T> { |
| |
| /** |
| * Applies this function to the given argument. |
| * |
| * @param value the function argument. |
| * @return the function result. |
| */ |
| double applyAsDouble(/*@Nullable*/ T value); |
| } |