Section.java revision cb83d271e5485aa85ec7b8b3dc7b6e01417e1e43 
1/*
2 * [The "BSD licence"]
3 * Copyright (c) 2009 Ben Gruver
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 *    derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29package org.jf.dexlib;
30
31import org.jf.dexlib.Util.AnnotatedOutput;
32import org.jf.dexlib.Util.Input;
33
34import java.util.ArrayList;
35import java.util.HashMap;
36
37public abstract class Section<T extends Item> {
38    protected ArrayList<T> items;
39    protected HashMap<T, T> uniqueItems = null;
40
41    /**
42     * When offset > -1, this section is "placed" at the specified offset. All
43     * items should have sequential indexes, and be placed appropriately.
44     *
45     * To unplace the section, set offset to -1, and set the offset of all
46     * items to -1
47     */
48    protected int offset = -1;
49
50    public Section() {
51        items = new ArrayList<T>();
52    }
53
54    public int place(int offset) {
55        this.offset = offset;
56        for (int i=0; i < items.size(); i++) {
57            T item = items.get(i);
58            if (item == null) {
59                throw new RuntimeException("This section contains a null item");
60            }
61            offset = item.place(i, offset);
62            if (i == 0) {
63                /**
64                 * if this item type has an alignment requirement,
65                 * then item.getOffset() may be different than the
66                 * offset that was passed in to this method, so we have
67                 * to initialize the section offset to the actual
68                 * (post-alignment) offset of the first item
69                 */
70                this.offset = item.getOffset();
71            }
72        }
73
74        return offset;
75    }
76
77    public void writeTo(AnnotatedOutput out) {
78        for (int i = 0; i < size(); i++) {
79            T item = items.get(i);
80            if (item == null) {
81                throw new RuntimeException("Cannot write section because all items haven't been initialized");
82            }
83            item.writeTo(out);
84            out.annotate(0, " ");
85        }
86        out.annotate(0, " ");
87    }
88
89    public abstract void readFrom(int size, Input in);
90
91    protected void setSize(int size) {
92        if (items.size() > size) {
93            throw new RuntimeException("There are references elsewhere to items in this section, that are " +
94                    "beyond the end of the section");
95        }
96
97        items.ensureCapacity(size);
98        for (int i = items.size(); i < size; i++) {
99            items.add(null);
100        }
101    }
102
103    public int size() {
104        return items.size();
105    }
106
107    public boolean isPlaced() {
108        return offset > -1;
109    }
110
111    public int getOffset() {
112        return offset;
113    }
114
115    protected T getInternedItem(T item) {
116        if (uniqueItems == null) {
117            buildInternedItemMap();
118        }
119        return uniqueItems.get(item);
120    }
121
122    protected void buildInternedItemMap() {
123        uniqueItems = new HashMap<T,T>();
124        for (T item: items) {
125            uniqueItems.put(item, item);
126        }
127    }
128
129    public abstract T intern(DexFile dexFile, T item);
130}
131