VariableSizeList.java revision 779bf9bccba5e27317e9b50a059fa1bae73decbb 
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.DexFile;
35import org.jf.dexlib2.dexbacked.DexFileReader;
36import org.jf.util.AbstractListIterator;
37
38import javax.annotation.Nonnull;
39import java.util.AbstractSequentialList;
40import java.util.NoSuchElementException;
41
42/**
43 * Provides a base class for a list that is backed by variable size items in a dex file
44 * @param <T> The type of the item that this list contains
45 */
46public abstract class VariableSizeList<T> extends AbstractSequentialList<T> {
47    @Nonnull private final DexFile dexFile;
48    private final int offset;
49
50    public VariableSizeList(@Nonnull DexFile dexFile, int offset) {
51        this.dexFile = dexFile;
52        this.offset = offset;
53    }
54
55    @Nonnull
56    protected abstract T readItem(DexFileReader dexFileReader, int index);
57
58    protected void skipItem(DexFileReader dexFileReader, int index) {
59        readItem(dexFileReader, index);
60    }
61
62    @Nonnull
63    @Override
64    public Iterator listIterator(int startIndex) {
65        Iterator iterator = listIterator();
66        if (startIndex < 0 || startIndex >= size()) {
67            throw new IndexOutOfBoundsException();
68        }
69        for (int i=0; i<startIndex; i++) {
70            iterator.skip();
71        }
72        return iterator;
73    }
74
75    @Nonnull
76    @Override
77    public Iterator listIterator() {
78        return new Iterator();
79    }
80
81    public class Iterator extends AbstractListIterator<T> {
82        private int index = 0;
83        @Nonnull private final DexFileReader dexFileReader = dexFile.readerAt(offset);
84
85        @Override public boolean hasNext() { return index < size(); }
86        @Override public int nextIndex() { return index; }
87
88        @Nonnull
89        @Override
90        public T next() {
91            if (index >= size()) {
92                throw new NoSuchElementException();
93            }
94            return readItem(dexFileReader, index++);
95        }
96
97        public void skip() {
98            if (index >= size()) {
99                throw new NoSuchElementException();
100            }
101            skipItem(dexFileReader, index++);
102        }
103    }
104}
105