1 package org.apache.maven.surefire.util;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.util.Iterator;
23 import java.util.NoSuchElementException;
24
25 /**
26 * This iterator is marked as stopped if {@link #isClosed()} returns {@code true}.
27 * If the iterator has been closed before calling {@link #hasNext()} then the method returns {@code false}.
28 * If the iterator was closed after {@link #hasNext() hasNext returns true} but before {@link #next()}, the
29 * method {@link #next()} throws {@link java.util.NoSuchElementException}.
30 * The method {@link #remove()} throws {@link IllegalStateException} if the iterator has been closed.
31 *
32 * @param <T> the type of elements returned by this iterator
33 *
34 * @author <a href="mailto:tibordigana@apache.org">Tibor Digana (tibor17)</a>
35 * @since 2.19.1
36 */
37 public abstract class CloseableIterator<T>
38 implements Iterator<T>
39 {
40 private Boolean finishCurrentIteration;
41
42 protected abstract boolean isClosed();
43 protected abstract boolean doHasNext();
44 protected abstract T doNext();
45 protected abstract void doRemove();
46
47 @Override
48 public boolean hasNext()
49 {
50 popMarker();
51 return !finishCurrentIteration && doHasNext();
52 }
53
54 @Override
55 public T next()
56 {
57 try
58 {
59 if ( popMarker() && finishCurrentIteration )
60 {
61 throw new NoSuchElementException( "iterator closed" );
62 }
63 return doNext();
64 }
65 finally
66 {
67 finishCurrentIteration = null;
68 }
69 }
70
71 @Override
72 public void remove()
73 {
74 try
75 {
76 if ( popMarker() && finishCurrentIteration )
77 {
78 throw new IllegalStateException( "iterator closed" );
79 }
80 doRemove();
81 }
82 finally
83 {
84 finishCurrentIteration = null;
85 }
86 }
87
88 /**
89 * @return {@code true} if marker changed from NULL to anything
90 */
91 private boolean popMarker()
92 {
93 if ( finishCurrentIteration == null )
94 {
95 finishCurrentIteration = isClosed();
96 return true;
97 }
98 return false;
99 }
100 }