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
118 * If the constant cannot be resolved, the sentinel will be returned.
119 * If the constant can (perhaps) be resolved, but has not yet been resolved,
120 * then the sentinel <em>may</em> be returned, at the implementation's discretion.
121 * To force resolution (and a possible exception), call {@link #get(int)}.
122 * @param index the selected constant
123 * @param ifNotPresent the sentinel value to return if the constant is not present
124 * @return the selected constant, if available, else the sentinel value
125 */
126 Object get(int index, Object ifNotPresent);
127
128 /**
129 * Returns an indication of whether a constant may be available.
130 * If it returns {@code true}, it will always return true in the future,
131 * and a call to {@link #get(int)} will never throw an exception.
132 * <p>
133 * After a normal return from {@link #get(int)} or a present
134 * value is reported from {@link #get(int,Object)}, this method
135 * must always return true.
136 * <p>
137 * If this method returns {@code false}, nothing in particular
138 * can be inferred, since the query only concerns the internal
139 * logic of the {@code ConstantGroup} object which ensures that
140 a successful * query to a constant will always remain successful.
141 * The only way to force a permanent decision about whether
142 * a constant is available is to call {@link #get(int)} and
143 * be ready for an exception if the constant is unavailable.
144 * @param index the selected constant
145 * @return {@code true} if the selected constant is known by
146 * this object to be present, {@code false} if it is known
147 * not to be present or
148 */
149 boolean isPresent(int index);
150
151 /// Views
152
153 /**
154 * Create a view on this group as a {@link List} view.
155 * Any request for a constant through this view will
156 * force resolution.
157 * @return a {@code List} view on this group which will force resolution
158 */
159 default List<Object> asList() {
160 return new AbstractConstantGroup.AsList(this, 0, size());
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1 /*
2 * Copyright (c) 2017, 2020, 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
118 * If the constant cannot be resolved, the sentinel will be returned.
119 * If the constant can (perhaps) be resolved, but has not yet been resolved,
120 * then the sentinel <em>may</em> be returned, at the implementation's discretion.
121 * To force resolution (and a possible exception), call {@link #get(int)}.
122 * @param index the selected constant
123 * @param ifNotPresent the sentinel value to return if the constant is not present
124 * @return the selected constant, if available, else the sentinel value
125 */
126 Object get(int index, Object ifNotPresent);
127
128 /**
129 * Returns an indication of whether a constant may be available.
130 * If it returns {@code true}, it will always return true in the future,
131 * and a call to {@link #get(int)} will never throw an exception.
132 * <p>
133 * After a normal return from {@link #get(int)} or a present
134 * value is reported from {@link #get(int,Object)}, this method
135 * must always return true.
136 * <p>
137 * If this method returns {@code false}, nothing in particular
138 * can be inferred, since the query only concerns the internal
139 * logic of the {@code ConstantGroup} object which ensures that
140 * a successful query to a constant will always remain successful.
141 * The only way to force a permanent decision about whether
142 * a constant is available is to call {@link #get(int)} and
143 * be ready for an exception if the constant is unavailable.
144 * @param index the selected constant
145 * @return {@code true} if the selected constant is known by
146 * this object to be present, {@code false} if it is known
147 * not to be present or
148 */
149 boolean isPresent(int index);
150
151 /// Views
152
153 /**
154 * Create a view on this group as a {@link List} view.
155 * Any request for a constant through this view will
156 * force resolution.
157 * @return a {@code List} view on this group which will force resolution
158 */
159 default List<Object> asList() {
160 return new AbstractConstantGroup.AsList(this, 0, size());
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