/*
 * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */


package org.graalvm.compiler.phases;

import org.graalvm.compiler.debug.DebugContext;

/**
 * A name whose {@link String} value is computed only when it is needed. This is useful in
 * combination with debugging facilities such as {@link DebugContext#scope(Object)} where the
 * {@link String} value of a name is only needed if debugging is enabled.
 */
public abstract class LazyName implements CharSequence {

    private String value;

    @Override
    public int length() {
        return toString().length();
    }

    @Override
    public char charAt(int index) {
        return toString().charAt(index);
    }

    @Override
    public CharSequence subSequence(int start, int end) {
        return toString().subSequence(start, end);
    }

    @Override
    public final String toString() {
        if (value == null) {
            value = createString();
        }
        return value;
    }

    /**
     * Creates the {@link String} value of this name.
     */
    protected abstract String createString();
}