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