1/*
2 * Copyright (c) 2011, 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 */
23package org.graalvm.compiler.graph;
24
25import java.util.Arrays;
26import java.util.Iterator;
27import java.util.NoSuchElementException;
28
29class TypedGraphNodeIterator<T extends IterableNodeType> implements Iterator<T> {
30
31    private final Graph graph;
32    private final int[] ids;
33    private final Node[] current;
34
35    private int currentIdIndex;
36    private boolean needsForward;
37
38    TypedGraphNodeIterator(NodeClass<?> clazz, Graph graph) {
39        this.graph = graph;
40        ids = clazz.iterableIds();
41        currentIdIndex = 0;
42        current = new Node[ids.length];
43        Arrays.fill(current, Graph.PLACE_HOLDER);
44        needsForward = true;
45    }
46
47    private Node findNext() {
48        if (needsForward) {
49            forward();
50        } else {
51            Node c = current();
52            Node afterDeleted = graph.getIterableNodeNext(c);
53            if (afterDeleted == null) {
54                needsForward = true;
55            } else if (c != afterDeleted) {
56                setCurrent(afterDeleted);
57            }
58        }
59        if (needsForward) {
60            return null;
61        }
62        return current();
63    }
64
65    private void forward() {
66        needsForward = false;
67        int startIdx = currentIdIndex;
68        while (true) {
69            Node next;
70            if (current() == Graph.PLACE_HOLDER) {
71                next = graph.getIterableNodeStart(ids[currentIdIndex]);
72            } else {
73                next = graph.getIterableNodeNext(current().typeCacheNext);
74            }
75            if (next == null) {
76                currentIdIndex++;
77                if (currentIdIndex >= ids.length) {
78                    currentIdIndex = 0;
79                }
80                if (currentIdIndex == startIdx) {
81                    needsForward = true;
82                    return;
83                }
84            } else {
85                setCurrent(next);
86                break;
87            }
88        }
89    }
90
91    private Node current() {
92        return current[currentIdIndex];
93    }
94
95    private void setCurrent(Node n) {
96        current[currentIdIndex] = n;
97    }
98
99    @Override
100    public boolean hasNext() {
101        return findNext() != null;
102    }
103
104    @Override
105    @SuppressWarnings("unchecked")
106    public T next() {
107        Node result = findNext();
108        if (result == null) {
109            throw new NoSuchElementException();
110        }
111        needsForward = true;
112        return (T) result;
113    }
114
115    @Override
116    public void remove() {
117        throw new UnsupportedOperationException();
118    }
119}
120