1 /*
2 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package org.graalvm.options;
26
27 import java.util.Arrays;
28 import java.util.Collections;
29 import java.util.Iterator;
30 import java.util.LinkedHashMap;
31 import java.util.List;
32 import java.util.Map;
33 import java.util.NoSuchElementException;
34
35 /**
36 * An interface to a set of {@link OptionDescriptor}s.
37 *
38 * @since 1.0
39 */
40 public interface OptionDescriptors extends Iterable<OptionDescriptor> {
41
42 /**
43 * An empty set of option descriptors.
44 *
45 * @since 1.0
46 */
47 OptionDescriptors EMPTY = new OptionDescriptors() {
48
49 public Iterator<OptionDescriptor> iterator() {
50 return Collections.<OptionDescriptor> emptyList().iterator();
51 }
52
53 public OptionDescriptor get(String key) {
54 return null;
55 }
56 };
57
58 /**
59 * Gets the {@link OptionDescriptor} matching a given option name or {@code null} if this option
60 * descriptor set doesn't contain a matching option name.
61 *
62 * @since 1.0
63 */
64 OptionDescriptor get(String optionName);
65
66 /**
67 * Create a union options descriptor out of multiple given descriptors. The operation
68 * descriptors are not checked for duplicate keys. The option descriptors are iterated in
69 * declaration order.
70 *
71 * @since 1.0
72 */
73 static OptionDescriptors createUnion(OptionDescriptors... descriptors) {
74 if (descriptors.length == 0) {
75 return EMPTY;
76 } else if (descriptors.length == 1) {
77 return descriptors[0];
78 } else {
79 return new UnionOptionDescriptors(descriptors);
80 }
81 }
82
83 /**
84 * {@inheritDoc}
85 *
86 * @since 1.0
87 */
88 @Override
89 Iterator<OptionDescriptor> iterator();
90
91 /**
92 * Create an {@link OptionDescriptors} instance from a list. The option descriptors
93 * implementation is backed by a {@link LinkedHashMap} that preserves ordering.
94 *
95 * @since 1.0
96 */
97 static OptionDescriptors create(List<OptionDescriptor> descriptors) {
98 if (descriptors == null || descriptors.isEmpty()) {
99 return EMPTY;
100 }
101 return new OptionDescriptorsMap(descriptors);
102 }
103 }
104
105 class OptionDescriptorsMap implements OptionDescriptors {
106
107 final Map<String, OptionDescriptor> descriptors = new LinkedHashMap<>();
108
109 OptionDescriptorsMap(List<OptionDescriptor> descriptorList) {
110 for (OptionDescriptor descriptor : descriptorList) {
111 descriptors.put(descriptor.getName(), descriptor);
112 }
113 }
114
115 @Override
116 public OptionDescriptor get(String optionName) {
117 return descriptors.get(optionName);
118 }
119
120 @Override
121 public Iterator<OptionDescriptor> iterator() {
122 return descriptors.values().iterator();
123 }
124
125 }
126
127 final class UnionOptionDescriptors implements OptionDescriptors {
128
129 final OptionDescriptors[] descriptorsList;
130
131 UnionOptionDescriptors(OptionDescriptors[] descriptors) {
132 // defensive copy
133 this.descriptorsList = Arrays.copyOf(descriptors, descriptors.length);
134 }
135
136 public Iterator<OptionDescriptor> iterator() {
137 return new Iterator<OptionDescriptor>() {
138
139 Iterator<OptionDescriptor> descriptors = descriptorsList[0].iterator();
140 int descriptorsIndex = 0;
141 OptionDescriptor next = null;
142
143 public boolean hasNext() {
144 return fetchNext() != null;
145 }
146
147 private OptionDescriptor fetchNext() {
148 if (next != null) {
149 return next;
150 }
151 if (descriptors.hasNext()) {
152 next = descriptors.next();
153 return next;
154 } else if (descriptorsIndex < descriptorsList.length - 1) {
155 descriptorsIndex++;
156 descriptors = descriptorsList[descriptorsIndex].iterator();
157 return fetchNext();
158 } else {
159 return null;
160 }
161 }
162
163 public OptionDescriptor next() {
164 OptionDescriptor fetchedNext = fetchNext();
165 if (fetchedNext != null) {
166 // consume next
167 this.next = null;
168 return fetchedNext;
169 } else {
170 throw new NoSuchElementException();
171 }
172 }
173 };
174 }
175
176 public OptionDescriptor get(String value) {
177 for (OptionDescriptors descriptors : descriptorsList) {
178 OptionDescriptor descriptor = descriptors.get(value);
179 if (descriptor != null) {
180 return descriptor;
181 }
182 }
183 return null;
184 }
185
186 }