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: 32 FilterIterator(Iterator begin, Iterator end, Pred pred = Pred()) 33 : current_(begin), end_(end), pred_(pred) { 34 Advance(); 35 } 36 37 bool HasNext() { return current_ != end_; } 38 39 Iterator NextIter() { 40 Iterator iter = current_; 41 ++current_; 42 Advance(); 43 return iter; 44 } 45 46 typename Iterator::reference Next() { return *NextIter(); } 47 48 private: 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> 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 */ 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 } 146 147 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
