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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.lang3.function;
19  
20  import java.util.function.ToIntFunction;
21  
22  /**
23   * A functional interface like {@link ToIntFunction} that declares a {@link Throwable}.
24   *
25   * @param <T> the type of the argument to the function
26   * @param <E> The kind of thrown exception or error.
27   * @since 3.11
28   */
29  @FunctionalInterface
30  public interface FailableToIntFunction<T, E extends Throwable> {
31  
32      /** NOP singleton */
33      @SuppressWarnings("rawtypes")
34      FailableToIntFunction NOP = t -> 0;
35  
36      /**
37       * Returns The NOP singleton.
38       *
39       * @param <T> the type of the argument to the function
40       * @param <E> The kind of thrown exception or error.
41       * @return The NOP singleton.
42       */
43      @SuppressWarnings("unchecked")
44      static <T, E extends Throwable> FailableToIntFunction<T, E> nop() {
45          return NOP;
46      }
47  
48      /**
49       * Applies this function to the given arguments.
50       *
51       * @param t the first function argument
52       * @return the function result
53       * @throws E Thrown when the function fails.
54       */
55      int applyAsInt(T t) throws E;
56  }