001/*
002 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package com.oracle.graal.phases;
024
025import com.oracle.graal.debug.*;
026
027/**
028 * A name whose {@link String} value is computed only when it is needed. This is useful in
029 * combination with debugging facilities such as {@link Debug#scope(Object)} where the
030 * {@link String} value of a name is only needed if debugging is enabled.
031 */
032public abstract class LazyName implements CharSequence {
033
034    private String value;
035
036    public int length() {
037        return toString().length();
038    }
039
040    public char charAt(int index) {
041        return toString().charAt(index);
042    }
043
044    public CharSequence subSequence(int start, int end) {
045        return toString().subSequence(start, end);
046    }
047
048    @Override
049    public final String toString() {
050        if (value == null) {
051            value = createString();
052        }
053        return value;
054    }
055
056    /**
057     * Creates the {@link String} value of this name.
058     */
059    protected abstract String createString();
060}