1 /* 2 * Copyright 2018, OpenCensus Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package io.opencensus.common; 18 19 /*>>> 20 import org.checkerframework.checker.nullness.qual.Nullable; 21 */ 22 23 /** 24 * Represents a function that produces a long-valued result. See {@link 25 * io.opencensus.metrics.MetricRegistry} for an example of its use. 26 * 27 * <p>Note: This class is based on the java.util.ToLongFunction class added in Java 1.8. We cannot 28 * use the Function from Java 1.8 because this library is Java 1.6 compatible. 29 * 30 * @since 0.16 31 */ 32 public interface ToLongFunction</*@Nullable*/ T> { 33 /** 34 * Applies this function to the given argument. 35 * 36 * @param value the function argument. 37 * @return the function result. 38 */ applyAsLong( T value)39 long applyAsLong(/*@Nullable*/ T value); 40 } 41