Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
PrefixedKeysIterator |
|
| 3.0;3 |
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.configuration; | |
19 | ||
20 | import java.util.Iterator; | |
21 | import java.util.NoSuchElementException; | |
22 | ||
23 | /** | |
24 | * * A specialized iterator implementation used by {@link AbstractConfiguration} | |
25 | * to return an iteration over all keys starting with a specified prefix. | |
26 | * | |
27 | * <p>This class is basically a stripped-down version of the | |
28 | * {@code FilterIterator} class of Commons Collections</p> | |
29 | * | |
30 | * @author <a href="http://commons.apache.org/configuration/team-list.html">Commons Configuration team</a> | |
31 | * @version $Id: PrefixedKeysIterator.java 1205603 2011-11-23 21:17:38Z oheger $ | |
32 | */ | |
33 | 329 | class PrefixedKeysIterator implements Iterator<String> |
34 | { | |
35 | /** Stores the wrapped iterator. */ | |
36 | private final Iterator<String> iterator; | |
37 | ||
38 | /** Stores the prefix. */ | |
39 | private final String prefix; | |
40 | ||
41 | /** Stores the next element in the iteration. */ | |
42 | private String nextElement; | |
43 | ||
44 | /** A flag whether the next element has been calculated. */ | |
45 | private boolean nextElementSet; | |
46 | ||
47 | /** | |
48 | * Creates a new instance of {@code PrefixedKeysIterator} and sets | |
49 | * the wrapped iterator and the prefix for the accepted keys. | |
50 | * | |
51 | * @param wrappedIterator the wrapped iterator | |
52 | * @param keyPrefix the prefix of the allowed keys | |
53 | */ | |
54 | public PrefixedKeysIterator(Iterator<String> wrappedIterator, String keyPrefix) | |
55 | 43 | { |
56 | 43 | iterator = wrappedIterator; |
57 | 43 | prefix = keyPrefix; |
58 | 43 | } |
59 | ||
60 | /** | |
61 | * Returns a flag whether there are more elements in the iteration. | |
62 | * | |
63 | * @return a flag if there is a next element | |
64 | */ | |
65 | public boolean hasNext() | |
66 | { | |
67 | 366 | return nextElementSet || setNextElement(); |
68 | } | |
69 | ||
70 | /** | |
71 | * Returns the next element in the iteration. This is the next key that | |
72 | * matches the specified prefix. | |
73 | * | |
74 | * @return the next element in the iteration | |
75 | * @throws NoSuchElementException if there is no next element | |
76 | */ | |
77 | public String next() | |
78 | { | |
79 | 329 | if (!nextElementSet && !setNextElement()) |
80 | { | |
81 | 0 | throw new NoSuchElementException(); |
82 | } | |
83 | 329 | nextElementSet = false; |
84 | 329 | return nextElement; |
85 | } | |
86 | ||
87 | /** | |
88 | * Removes from the underlying collection of the base iterator the last | |
89 | * element returned by this iterator. This method can only be called if | |
90 | * {@code next()} was called, but not after {@code hasNext()}, | |
91 | * because the {@code hasNext()} call changes the base iterator. | |
92 | * | |
93 | * @throws IllegalStateException if {@code hasNext()} has already | |
94 | * been called. | |
95 | */ | |
96 | public void remove() | |
97 | { | |
98 | 4 | if (nextElementSet) |
99 | { | |
100 | 0 | throw new IllegalStateException("remove() cannot be called"); |
101 | } | |
102 | 4 | iterator.remove(); |
103 | 4 | } |
104 | ||
105 | /** | |
106 | * Determines the next element in the iteration. The return value indicates | |
107 | * whether such an element can be found. | |
108 | * | |
109 | * @return a flag whether a next element exists | |
110 | */ | |
111 | private boolean setNextElement() | |
112 | { | |
113 | 536 | while (iterator.hasNext()) |
114 | { | |
115 | 496 | String key = iterator.next(); |
116 | 496 | if (key.startsWith(prefix + ".") || key.equals(prefix)) |
117 | { | |
118 | 332 | nextElement = key; |
119 | 332 | nextElementSet = true; |
120 | 332 | return true; |
121 | } | |
122 | 164 | } |
123 | 40 | return false; |
124 | } | |
125 | } |