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 * Create an {@link OptionDescriptors} instance from a list. The option descriptors
85 * implementation is backed by a {@link LinkedHashMap} that preserves ordering.
86 *
87 * @since 1.0
88 */
89 static OptionDescriptors create(List<OptionDescriptor> descriptors) {
90 if (descriptors == null || descriptors.isEmpty()) {
91 return EMPTY;
92 }
93 return new OptionDescriptorsMap(descriptors);
94 }
95 }
96
97 class OptionDescriptorsMap implements OptionDescriptors {
98
99 final Map<String, OptionDescriptor> descriptors = new LinkedHashMap<>();
100
101 OptionDescriptorsMap(List<OptionDescriptor> descriptorList) {
102 for (OptionDescriptor descriptor : descriptorList) {
103 descriptors.put(descriptor.getName(), descriptor);
104 }
105 }
106
107 @Override
108 public OptionDescriptor get(String optionName) {
109 return descriptors.get(optionName);
110 }
111
112 @Override
113 public Iterator<OptionDescriptor> iterator() {
114 return descriptors.values().iterator();
115 }
116
117 }
118
119 final class UnionOptionDescriptors implements OptionDescriptors {
120
121 final OptionDescriptors[] descriptorsList;
122
123 UnionOptionDescriptors(OptionDescriptors[] descriptors) {
124 // defensive copy
125 this.descriptorsList = Arrays.copyOf(descriptors, descriptors.length);
126 }
127
128 public Iterator<OptionDescriptor> iterator() {
129 return new Iterator<OptionDescriptor>() {
130
131 Iterator<OptionDescriptor> descriptors = descriptorsList[0].iterator();
132 int descriptorsIndex = 0;
133 OptionDescriptor next = null;
134
135 public boolean hasNext() {
136 return fetchNext() != null;
137 }
138
139 private OptionDescriptor fetchNext() {
140 if (next != null) {
141 return next;
142 }
143 if (descriptors.hasNext()) {
144 next = descriptors.next();
145 return next;
146 } else if (descriptorsIndex < descriptorsList.length - 1) {
147 descriptorsIndex++;
148 descriptors = descriptorsList[descriptorsIndex].iterator();
149 return fetchNext();
150 } else {
151 return null;
152 }
153 }
154
155 public OptionDescriptor next() {
156 OptionDescriptor fetchedNext = fetchNext();
157 if (fetchedNext != null) {
158 // consume next
159 this.next = null;
160 return fetchedNext;
161 } else {
162 throw new NoSuchElementException();
163 }
164 }
165 };
166 }
167
168 public OptionDescriptor get(String value) {
169 for (OptionDescriptors descriptors : descriptorsList) {
170 OptionDescriptor descriptor = descriptors.get(value);
171 if (descriptor != null) {
172 return descriptor;
173 }
174 }
175 return null;
176 }
177
178 }