1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.eclipse.aether.util.graph.version;
20
21 import java.util.Iterator;
22
23 import org.eclipse.aether.collection.DependencyCollectionContext;
24 import org.eclipse.aether.collection.VersionFilter;
25 import org.eclipse.aether.version.Version;
26
27 /**
28 * A version filter that excludes any version except the highest one.
29 */
30 public final class HighestVersionFilter implements VersionFilter {
31 private final int count;
32
33 /**
34 * Creates a new instance of this version filter.
35 */
36 public HighestVersionFilter() {
37 this.count = 1;
38 }
39
40 /**
41 * Creates a new instance of this version filter.
42 */
43 public HighestVersionFilter(int count) {
44 if (count < 1) {
45 throw new IllegalArgumentException("Count should be greater or equal to 1");
46 }
47 this.count = count;
48 }
49
50 @Override
51 public void filterVersions(VersionFilterContext context) {
52 if (context.getCount() <= count) {
53 return;
54 }
55 // iterator comes in ascending order, basically we "step over" (remove) first few
56 int stepOver = context.getCount() - count;
57 Iterator<Version> it = context.iterator();
58 while (it.hasNext()) {
59 it.next();
60 stepOver--;
61 if (stepOver >= 0) {
62 it.remove();
63 }
64 }
65 }
66
67 @Override
68 public VersionFilter deriveChildFilter(DependencyCollectionContext context) {
69 return this;
70 }
71
72 @Override
73 public boolean equals(Object obj) {
74 if (this == obj) {
75 return true;
76 } else if (null == obj || !getClass().equals(obj.getClass())) {
77 return false;
78 }
79 return true;
80 }
81
82 @Override
83 public int hashCode() {
84 return getClass().hashCode();
85 }
86 }