1 /*
2 * Copyright (C) 2016 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 #include "optimize/VersionCollapser.h"
18
19 #include <algorithm>
20 #include <vector>
21
22 #include "ResourceTable.h"
23
24 namespace aapt {
25
26 template <typename Iterator, typename Pred>
27 class FilterIterator {
28 public:
FilterIterator(Iterator begin,Iterator end,Pred pred=Pred ())29 FilterIterator(Iterator begin, Iterator end, Pred pred = Pred())
30 : current_(begin), end_(end), pred_(pred) {
31 Advance();
32 }
33
HasNext()34 bool HasNext() { return current_ != end_; }
35
NextIter()36 Iterator NextIter() {
37 Iterator iter = current_;
38 ++current_;
39 Advance();
40 return iter;
41 }
42
Next()43 typename Iterator::reference Next() { return *NextIter(); }
44
45 private:
Advance()46 void Advance() {
47 for (; current_ != end_; ++current_) {
48 if (pred_(*current_)) {
49 return;
50 }
51 }
52 }
53
54 Iterator current_, end_;
55 Pred pred_;
56 };
57
58 template <typename Iterator, typename Pred>
make_filter_iterator(Iterator begin,Iterator end=Iterator (),Pred pred=Pred ())59 FilterIterator<Iterator, Pred> make_filter_iterator(Iterator begin,
60 Iterator end = Iterator(),
61 Pred pred = Pred()) {
62 return FilterIterator<Iterator, Pred>(begin, end, pred);
63 }
64
65 /**
66 * Every Configuration with an SDK version specified that is less than minSdk
67 * will be removed.
68 * The exception is when there is no exact matching resource for the minSdk. The
69 * next smallest
70 * one will be kept.
71 */
CollapseVersions(int min_sdk,ResourceEntry * entry)72 static void CollapseVersions(int min_sdk, ResourceEntry* entry) {
73 // First look for all sdks less than minSdk.
74 for (auto iter = entry->values.rbegin(); iter != entry->values.rend();
75 ++iter) {
76 // Check if the item was already marked for removal.
77 if (!(*iter)) {
78 continue;
79 }
80
81 const ConfigDescription& config = (*iter)->config;
82 if (config.sdkVersion <= min_sdk) {
83 // This is the first configuration we've found with a smaller or equal SDK
84 // level
85 // to the minimum. We MUST keep this one, but remove all others we find,
86 // which get
87 // overridden by this one.
88
89 ConfigDescription config_without_sdk = config.CopyWithoutSdkVersion();
90 auto pred = [&](const std::unique_ptr<ResourceConfigValue>& val) -> bool {
91 // Check that the value hasn't already been marked for removal.
92 if (!val) {
93 return false;
94 }
95
96 // Only return Configs that differ in SDK version.
97 config_without_sdk.sdkVersion = val->config.sdkVersion;
98 return config_without_sdk == val->config &&
99 val->config.sdkVersion <= min_sdk;
100 };
101
102 // Remove the rest that match.
103 auto filter_iter =
104 make_filter_iterator(iter + 1, entry->values.rend(), pred);
105 while (filter_iter.HasNext()) {
106 filter_iter.Next() = {};
107 }
108 }
109 }
110
111 // Now erase the nullptr values.
112 entry->values.erase(
113 std::remove_if(entry->values.begin(), entry->values.end(),
114 [](const std::unique_ptr<ResourceConfigValue>& val)
115 -> bool { return val == nullptr; }),
116 entry->values.end());
117
118 // Strip the version qualifiers for every resource with version <= minSdk.
119 // This will ensure
120 // that the resource entries are all packed together in the same ResTable_type
121 // struct
122 // and take up less space in the resources.arsc table.
123 bool modified = false;
124 for (std::unique_ptr<ResourceConfigValue>& config_value : entry->values) {
125 if (config_value->config.sdkVersion != 0 &&
126 config_value->config.sdkVersion <= min_sdk) {
127 // Override the resource with a Configuration without an SDK.
128 std::unique_ptr<ResourceConfigValue> new_value =
129 util::make_unique<ResourceConfigValue>(
130 config_value->config.CopyWithoutSdkVersion(),
131 config_value->product);
132 new_value->value = std::move(config_value->value);
133 config_value = std::move(new_value);
134
135 modified = true;
136 }
137 }
138
139 if (modified) {
140 // We've modified the keys (ConfigDescription) by changing the sdkVersion to
141 // 0. We MUST re-sort to ensure ordering guarantees hold.
142 std::sort(entry->values.begin(), entry->values.end(),
143 [](const std::unique_ptr<ResourceConfigValue>& a,
144 const std::unique_ptr<ResourceConfigValue>& b) -> bool {
145 return a->config.compare(b->config) < 0;
146 });
147 }
148 }
149
Consume(IAaptContext * context,ResourceTable * table)150 bool VersionCollapser::Consume(IAaptContext* context, ResourceTable* table) {
151 const int min_sdk = context->GetMinSdkVersion();
152 for (auto& package : table->packages) {
153 for (auto& type : package->types) {
154 for (auto& entry : type->entries) {
155 CollapseVersions(min_sdk, entry.get());
156 }
157 }
158 }
159 return true;
160 }
161
162 } // namespace aapt
163