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 
  24 
  25 package org.graalvm.compiler.graph;
  26 
  27 import java.util.Iterator;
  28 
  29 /**
  30  * Iterates over the nodes in a given graph.
  31  */
  32 class GraphNodeIterator implements Iterator<Node> {
  33 
  34     private final Graph graph;
  35     private int index;
  36 
  37     GraphNodeIterator(Graph graph) {
  38         this(graph, 0);
  39     }
  40 
  41     GraphNodeIterator(Graph graph, int index) {
  42         this.graph = graph;
  43         this.index = index - 1;
  44         forward();
  45     }
  46 
  47     private void forward() {
  48         if (index < graph.nodesSize) {
  49             do {
  50                 index++;
  51             } while (index < graph.nodesSize && graph.nodes[index] == null);
  52         }
  53     }
  54 
  55     @Override
  56     public boolean hasNext() {
  57         checkForDeletedNode();
  58         return index < graph.nodesSize;
  59     }
  60 
  61     private void checkForDeletedNode() {
  62         while (index < graph.nodesSize && graph.nodes[index] == null) {
  63             index++;
  64         }
  65     }
  66 
  67     @Override
  68     public Node next() {
  69         try {
  70             return graph.nodes[index];
  71         } finally {
  72             forward();
  73         }
  74     }
  75 
  76     @Override
  77     public void remove() {
  78         throw new UnsupportedOperationException();
  79     }
  80 }