1/*
2 * Copyright (c) 2011, 2017, 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 */
23package org.graalvm.compiler.graph;
24
25import java.util.Iterator;
26import java.util.NoSuchElementException;
27
28class TypedGraphNodeIterator<T extends IterableNodeType> implements Iterator<T> {
29
30    private final Graph graph;
31    private final int[] ids;
32    private final Node[] current;
33
34    private int currentIdIndex;
35    private boolean needsForward;
36
37    TypedGraphNodeIterator(NodeClass<?> clazz, Graph graph) {
38        this.graph = graph;
39        ids = clazz.iterableIds();
40        currentIdIndex = 0;
41        current = new Node[ids.length];
42        needsForward = true;
43    }
44
45    private Node findNext() {
46        if (needsForward) {
47            forward();
48        } else {
49            Node c = current();
50            Node afterDeleted = graph.getIterableNodeNext(c);
51            if (afterDeleted == null) {
52                needsForward = true;
53            } else if (c != afterDeleted) {
54                setCurrent(afterDeleted);
55            }
56        }
57        if (needsForward) {
58            return null;
59        }
60        return current();
61    }
62
63    private void forward() {
64        needsForward = false;
65        int startIdx = currentIdIndex;
66        while (true) {
67            Node next;
68            if (current() == null) {
69                next = graph.getIterableNodeStart(ids[currentIdIndex]);
70            } else {
71                next = graph.getIterableNodeNext(current().typeCacheNext);
72            }
73            if (next == null) {
74                currentIdIndex++;
75                if (currentIdIndex >= ids.length) {
76                    currentIdIndex = 0;
77                }
78                if (currentIdIndex == startIdx) {
79                    needsForward = true;
80                    return;
81                }
82            } else {
83                setCurrent(next);
84                break;
85            }
86        }
87    }
88
89    private Node current() {
90        return current[currentIdIndex];
91    }
92
93    private void setCurrent(Node n) {
94        current[currentIdIndex] = n;
95    }
96
97    @Override
98    public boolean hasNext() {
99        return findNext() != null;
100    }
101
102    @Override
103    @SuppressWarnings("unchecked")
104    public T next() {
105        Node result = findNext();
106        if (result == null) {
107            throw new NoSuchElementException();
108        }
109        needsForward = true;
110        return (T) result;
111    }
112
113    @Override
114    public void remove() {
115        throw new UnsupportedOperationException();
116    }
117}
118