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  */
  23 package org.graalvm.compiler.phases;
  24 
  25 import org.graalvm.compiler.debug.Debug;
  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 Debug#scope(Object)} where the
  30  * {@link String} value of a name is only needed if debugging is enabled.
  31  */
  32 public 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 }