1/*
2 * Copyright 2012, Google Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met:
8 *
9 *     * Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *     * Redistributions in binary form must reproduce the above
12 * copyright notice, this list of conditions and the following disclaimer
13 * in the documentation and/or other materials provided with the
14 * distribution.
15 *     * Neither the name of Google Inc. nor the names of its
16 * contributors may be used to endorse or promote products derived from
17 * this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32package org.jf.dexlib2.dexbacked.util;
33
34import org.jf.dexlib2.dexbacked.DexBackedDexFile;
35import org.jf.dexlib2.dexbacked.DexReader;
36import org.jf.dexlib2.dexbacked.value.DexBackedEncodedValue;
37import org.jf.dexlib2.iface.value.EncodedValue;
38
39import javax.annotation.Nonnull;
40import javax.annotation.Nullable;
41
42public abstract class StaticInitialValueIterator {
43    public static final StaticInitialValueIterator EMPTY = new StaticInitialValueIterator() {
44        @Nullable @Override public EncodedValue getNextOrNull() { return null; }
45        @Override public void skipNext() {}
46    };
47
48    @Nullable public abstract EncodedValue getNextOrNull();
49    public abstract void skipNext();
50
51    @Nonnull
52    public static StaticInitialValueIterator newOrEmpty(@Nonnull DexBackedDexFile dexFile, int offset) {
53        if (offset == 0) {
54            return EMPTY;
55        }
56        return new StaticInitialValueIteratorImpl(dexFile, offset);
57    }
58
59    private static class StaticInitialValueIteratorImpl extends StaticInitialValueIterator {
60        @Nonnull private final DexReader reader;
61        private final int size;
62        private int index = 0;
63
64        public StaticInitialValueIteratorImpl(@Nonnull DexBackedDexFile dexFile, int offset) {
65            this.reader = dexFile.readerAt(offset);
66            this.size = reader.readSmallUleb128();
67        }
68
69        @Nullable
70        public EncodedValue getNextOrNull() {
71            if (index < size) {
72                index++;
73                return DexBackedEncodedValue.readFrom(reader);
74            }
75            return null;
76        }
77
78        public void skipNext() {
79            if (index < size) {
80                index++;
81                DexBackedEncodedValue.skipFrom(reader);
82            }
83        }
84    }
85}
86