1 /*
   2  * Copyright (c) 2014, 2018, 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 
  24 
  25 package org.graalvm.compiler.graph;
  26 
  27 import java.util.Iterator;
  28 import java.util.NoSuchElementException;
  29 
  30 class NodeUsageIterator implements Iterator<Node> {
  31 
  32     final Node node;
  33     int index = -1;
  34     Node current;
  35 
  36     void advance() {
  37         current = null;
  38         index++;
  39         if (index == 0) {
  40             current = node.usage0;
  41         } else if (index == 1) {
  42             current = node.usage1;
  43         } else {
  44             int relativeIndex = index - Node.INLINE_USAGE_COUNT;
  45             if (relativeIndex < node.extraUsagesCount) {
  46                 current = node.extraUsages[relativeIndex];
  47             }
  48         }
  49     }
  50 
  51     NodeUsageIterator(Node node) {
  52         this.node = node;
  53         advance();
  54     }
  55 
  56     @Override
  57     public boolean hasNext() {
  58         return current != null;
  59     }
  60 
  61     @Override
  62     public Node next() {
  63         Node result = current;
  64         if (result == null) {
  65             throw new NoSuchElementException();
  66         }
  67         advance();
  68         return result;
  69     }
  70 
  71     @Override
  72     public void remove() {
  73         throw new UnsupportedOperationException();
  74     }
  75 }