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 public boolean hasNext()
48 {
49 popMarker();
50 return !finishCurrentIteration && doHasNext();
51 }
52
53 public T next()
54 {
55 try
56 {
57 if ( popMarker() && finishCurrentIteration )
58 {
59 throw new NoSuchElementException( "iterator closed" );
60 }
61 return doNext();
62 }
63 finally
64 {
65 finishCurrentIteration = null;
66 }
67 }
68
69 public void remove()
70 {
71 try
72 {
73 if ( popMarker() && finishCurrentIteration )
74 {
75 throw new IllegalStateException( "iterator closed" );
76 }
77 doRemove();
78 }
79 finally
80 {
81 finishCurrentIteration = null;
82 }
83 }
84
85 /**
86 * @return {@code true} if marker changed from NULL to anything
87 */
88 private boolean popMarker()
89 {
90 if ( finishCurrentIteration == null )
91 {
92 finishCurrentIteration = isClosed();
93 return true;
94 }
95 return false;
96 }
97 }