1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.dx.merge;
18
19import com.android.dx.io.ClassDef;
20import com.android.dx.io.DexBuffer;
21import java.util.Comparator;
22
23/**
24 * Name and structure of a type. Used to order types such that each type is
25 * preceded by its supertype and implemented interfaces.
26 */
27final class SortableType {
28    public static final Comparator<SortableType> NULLS_LAST_ORDER = new Comparator<SortableType>() {
29        public int compare(SortableType a, SortableType b) {
30            if (a == b) {
31                return 0;
32            }
33            if (b == null) {
34                return -1;
35            }
36            if (a == null) {
37                return 1;
38            }
39            if (a.depth != b.depth) {
40                return a.depth - b.depth;
41            }
42            return a.getTypeIndex() - b.getTypeIndex();
43        }
44    };
45
46    private final DexBuffer buffer;
47    private ClassDef classDef;
48    private int depth = -1;
49
50    public SortableType(DexBuffer buffer, ClassDef classDef) {
51        this.buffer = buffer;
52        this.classDef = classDef;
53    }
54
55    public DexBuffer getBuffer() {
56        return buffer;
57    }
58
59    public ClassDef getClassDef() {
60        return classDef;
61    }
62
63    public int getTypeIndex() {
64        return classDef.getTypeIndex();
65    }
66
67    /**
68     * Assigns this type's depth if the depths of its supertype and implemented
69     * interfaces are known. Returns false if the depth couldn't be computed
70     * yet.
71     */
72    public boolean tryAssignDepth(SortableType[] types) {
73        int max;
74        if (classDef.getSupertypeIndex() == ClassDef.NO_INDEX) {
75            max = 0; // this is Object.class or an interface
76        } else {
77            SortableType sortableSupertype = types[classDef.getSupertypeIndex()];
78            if (sortableSupertype == null) {
79                max = 1; // unknown, so assume it's a root.
80            } else if (sortableSupertype.depth == -1) {
81                return false;
82            } else {
83                max = sortableSupertype.depth;
84            }
85        }
86
87        for (short interfaceIndex : classDef.getInterfaces()) {
88            SortableType implemented = types[interfaceIndex];
89            if (implemented == null) {
90                max = Math.max(max, 1); // unknown, so assume it's a root.
91            } else if (implemented.depth == -1) {
92                return false;
93            } else {
94                max = Math.max(max, implemented.depth);
95            }
96        }
97
98        depth = max + 1;
99        return true;
100    }
101
102    public boolean isDepthAssigned() {
103        return depth != -1;
104    }
105}
106