LazyName.java revision 13264:48566d838608 
1/*
2 * Copyright (c) 2014, 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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23package org.graalvm.compiler.phases;
24
25import org.graalvm.compiler.debug.DebugContext;
26
27/**
28 * A name whose {@link String} value is computed only when it is needed. This is useful in
29 * combination with debugging facilities such as {@link DebugContext#scope(Object)} where the
30 * {@link String} value of a name is only needed if debugging is enabled.
31 */
32public abstract class LazyName implements CharSequence {
33
34    private String value;
35
36    @Override
37    public int length() {
38        return toString().length();
39    }
40
41    @Override
42    public char charAt(int index) {
43        return toString().charAt(index);
44    }
45
46    @Override
47    public CharSequence subSequence(int start, int end) {
48        return toString().subSequence(start, end);
49    }
50
51    @Override
52    public final String toString() {
53        if (value == null) {
54            value = createString();
55        }
56        return value;
57    }
58
59    /**
60     * Creates the {@link String} value of this name.
61     */
62    protected abstract String createString();
63}
64