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.graph;
  24 
  25 import java.util.Iterator;
  26 
  27 /**
  28  * Iterates over the nodes in a given graph.
  29  */
  30 class GraphNodeIterator implements Iterator<Node> {
  31 
  32     private final Graph graph;
  33     private int index;
  34 
  35     GraphNodeIterator(Graph graph) {
  36         this(graph, 0);
  37     }
  38 
  39     GraphNodeIterator(Graph graph, int index) {
  40         this.graph = graph;
  41         this.index = index - 1;
  42         forward();
  43     }
  44 
  45     private void forward() {
  46         if (index < graph.nodesSize) {
  47             do {
  48                 index++;
  49             } while (index < graph.nodesSize && graph.nodes[index] == null);
  50         }
  51     }
  52 
  53     @Override
  54     public boolean hasNext() {
  55         checkForDeletedNode();
  56         return index < graph.nodesSize;
  57     }
  58 
  59     private void checkForDeletedNode() {
  60         while (index < graph.nodesSize && graph.nodes[index] == null) {
  61             index++;
  62         }
  63     }
  64 
  65     @Override
  66     public Node next() {
  67         try {
  68             return graph.nodes[index];
  69         } finally {
  70             forward();
  71         }
  72     }
  73 
  74     @Override
  75     public void remove() {
  76         throw new UnsupportedOperationException();
  77     }
  78 }