SymbolTable.h revision ce5e56e243d262a9b65459c3bd0bb9eaadd40628 
1/*
2 * Copyright (C) 2015 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
17#ifndef AAPT_PROCESS_SYMBOLTABLE_H
18#define AAPT_PROCESS_SYMBOLTABLE_H
19
20#include <algorithm>
21#include <memory>
22#include <vector>
23
24#include "android-base/macros.h"
25#include "androidfw/AssetManager.h"
26#include "utils/JenkinsHash.h"
27#include "utils/LruCache.h"
28
29#include "Resource.h"
30#include "ResourceTable.h"
31#include "ResourceValues.h"
32#include "util/Util.h"
33
34namespace aapt {
35
36inline android::hash_t hash_type(const ResourceName& name) {
37  std::hash<std::string> str_hash;
38  android::hash_t hash = 0;
39  hash = android::JenkinsHashMix(hash, (uint32_t)str_hash(name.package));
40  hash = android::JenkinsHashMix(hash, (uint32_t)name.type);
41  hash = android::JenkinsHashMix(hash, (uint32_t)str_hash(name.entry));
42  return hash;
43}
44
45inline android::hash_t hash_type(const ResourceId& id) {
46  return android::hash_type(id.id);
47}
48
49class ISymbolSource;
50
51class SymbolTable {
52 public:
53  struct Symbol {
54    Symbol() : Symbol(Maybe<ResourceId>{}) {}
55
56    explicit Symbol(const Maybe<ResourceId>& i) : Symbol(i, nullptr) {}
57
58    Symbol(const Maybe<ResourceId>& i, const std::shared_ptr<Attribute>& attr)
59        : Symbol(i, attr, false) {}
60
61    Symbol(const Maybe<ResourceId>& i, const std::shared_ptr<Attribute>& attr,
62           bool pub)
63        : id(i), attribute(attr), is_public(pub) {}
64
65    Symbol(const Symbol&) = default;
66    Symbol(Symbol&&) = default;
67    Symbol& operator=(const Symbol&) = default;
68    Symbol& operator=(Symbol&&) = default;
69
70    Maybe<ResourceId> id;
71    std::shared_ptr<Attribute> attribute;
72    bool is_public = false;
73  };
74
75  SymbolTable() : cache_(200), id_cache_(200) {}
76
77  void AppendSource(std::unique_ptr<ISymbolSource> source);
78  void PrependSource(std::unique_ptr<ISymbolSource> source);
79
80  /**
81   * Never hold on to the result between calls to FindByName or FindById. The
82   * results stored in a cache which may evict entries.
83   */
84  const Symbol* FindByName(const ResourceName& name);
85  const Symbol* FindById(const ResourceId& id);
86
87  /**
88   * Let's the ISymbolSource decide whether looking up by name or ID is faster,
89   * if both are available.
90   */
91  const Symbol* FindByReference(const Reference& ref);
92
93 private:
94  std::vector<std::unique_ptr<ISymbolSource>> sources_;
95
96  // We use shared_ptr because unique_ptr is not supported and
97  // we need automatic deletion.
98  android::LruCache<ResourceName, std::shared_ptr<Symbol>> cache_;
99  android::LruCache<ResourceId, std::shared_ptr<Symbol>> id_cache_;
100
101  DISALLOW_COPY_AND_ASSIGN(SymbolTable);
102};
103
104/**
105 * An interface that a symbol source implements in order to surface symbol
106 * information
107 * to the symbol table.
108 */
109class ISymbolSource {
110 public:
111  virtual ~ISymbolSource() = default;
112
113  virtual std::unique_ptr<SymbolTable::Symbol> FindByName(
114      const ResourceName& name) = 0;
115  virtual std::unique_ptr<SymbolTable::Symbol> FindById(ResourceId id) = 0;
116
117  /**
118   * Default implementation tries the name if it exists, else the ID.
119   */
120  virtual std::unique_ptr<SymbolTable::Symbol> FindByReference(
121      const Reference& ref) {
122    if (ref.name) {
123      return FindByName(ref.name.value());
124    } else if (ref.id) {
125      return FindById(ref.id.value());
126    }
127    return {};
128  }
129};
130
131/**
132 * Exposes the resources in a ResourceTable as symbols for SymbolTable.
133 * Instances of this class must outlive the encompassed ResourceTable.
134 * Lookups by ID are ignored.
135 */
136class ResourceTableSymbolSource : public ISymbolSource {
137 public:
138  explicit ResourceTableSymbolSource(ResourceTable* table) : table_(table) {}
139
140  std::unique_ptr<SymbolTable::Symbol> FindByName(
141      const ResourceName& name) override;
142
143  std::unique_ptr<SymbolTable::Symbol> FindById(ResourceId id) override {
144    return {};
145  }
146
147 private:
148  ResourceTable* table_;
149
150  DISALLOW_COPY_AND_ASSIGN(ResourceTableSymbolSource);
151};
152
153class AssetManagerSymbolSource : public ISymbolSource {
154 public:
155  AssetManagerSymbolSource() = default;
156
157  bool AddAssetPath(const StringPiece& path);
158
159  std::unique_ptr<SymbolTable::Symbol> FindByName(
160      const ResourceName& name) override;
161  std::unique_ptr<SymbolTable::Symbol> FindById(ResourceId id) override;
162  std::unique_ptr<SymbolTable::Symbol> FindByReference(
163      const Reference& ref) override;
164
165 private:
166  android::AssetManager assets_;
167
168  DISALLOW_COPY_AND_ASSIGN(AssetManagerSymbolSource);
169};
170
171}  // namespace aapt
172
173#endif /* AAPT_PROCESS_SYMBOLTABLE_H */
174