1 /* 2 * Copyright 2016-17, 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 * Used to specify matching functions for use encoding tagged unions (i.e. sum types) in Java. See 21 * {@link io.opencensus.trace.AttributeValue#match} for an example of its use. 22 * 23 * <p>Note: This class is based on the java.util.Function class added in Java 1.8. We cannot use the 24 * Function from Java 1.8 because this library is Java 1.6 compatible. 25 * 26 * @since 0.5 27 */ 28 public interface Function<A, B> { 29 30 /** 31 * Applies the function to the given argument. 32 * 33 * @param arg the argument to the function. 34 * @return the result of the function. 35 * @since 0.5 36 */ apply(A arg)37 B apply(A arg); 38 } 39