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;
36
37import javax.annotation.Nonnull;
38import java.util.ListIterator;
39import java.util.NoSuchElementException;
40
41public abstract class VariableSizeListIterator<T> implements ListIterator<T> {
42    @Nonnull private DexReader reader;
43    protected final int size;
44    private final int startOffset;
45
46    private int index;
47
48    protected VariableSizeListIterator(@Nonnull DexBackedDexFile dexFile, int offset, int size) {
49        this.reader = dexFile.readerAt(offset);
50        this.startOffset = offset;
51        this.size = size;
52    }
53
54    /**
55     * Reads the next item from reader.
56     *
57     * @param reader The {@code DexReader} to read the next item from
58     * @param index The index of the item being read. This is guaranteed to be less than {@code size}
59     * @return The item that was read
60     */
61    protected abstract T readNextItem(@Nonnull DexReader reader, int index);
62
63    public int getReaderOffset() {
64        return reader.getOffset();
65    }
66
67    @Override
68    public boolean hasNext() {
69        return index < size;
70    }
71
72    @Override
73    public T next() {
74        if (index >= size) {
75            throw new NoSuchElementException();
76        }
77        return readNextItem(reader, index++);
78    }
79
80    @Override
81    public boolean hasPrevious() {
82        return index > 0;
83    }
84
85    @Override
86    public T previous() {
87        int targetIndex = index-1;
88        reader.setOffset(startOffset);
89        index = 0;
90        while (index < targetIndex) {
91            readNextItem(reader, index++);
92        }
93        return readNextItem(reader, index++);
94    }
95
96    @Override
97    public int nextIndex() {
98        return index;
99    }
100
101    @Override
102    public int previousIndex() {
103        return index - 1;
104    }
105
106    @Override public void remove() { throw new UnsupportedOperationException(); }
107    @Override public void set(T t) { throw new UnsupportedOperationException(); }
108    @Override public void add(T t) { throw new UnsupportedOperationException(); }
109}
110