Implement filter-product

filter-product option is added to aapt2 compile, which filters values
with a given product and removes all other values (including default).
The motivation of this change is to generate product-specific RRO
automatically, making a main resource APK (e.g. framework-res.apk)
identical in all targets.

Bug: 294799593
Test: build
Change-Id: I42eb3e134c7aa120f6bbe2d26d311bd46b586595

3 files changed, 428 insertions, 0 deletions

diff --git a/tools/aapt2/process/ProductFilter.cpp b/tools/aapt2/process/ProductFilter.cpp
new file mode 100644
index 000000000000..0b1c0a6adb51
--- /dev/null
+++ b/tools/aapt2/process/ProductFilter.cpp
@@ -0,0 +1,155 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "process/ProductFilter.h"
+
+#include <algorithm>
+
+#include "ResourceTable.h"
+#include "trace/TraceBuffer.h"
+
+namespace aapt {
+
+std::optional<ProductFilter::ResourceConfigValueIter> ProductFilter::SelectProductToKeep(
+    const ResourceNameRef& name, ResourceConfigValueIter begin, ResourceConfigValueIter end,
+    android::IDiagnostics* diag) {
+  ResourceConfigValueIter default_product_iter = end;
+  ResourceConfigValueIter selected_product_iter = end;
+
+  for (ResourceConfigValueIter iter = begin; iter != end; ++iter) {
+    ResourceConfigValue* config_value = iter->get();
+    if (products_.find(config_value->product) != products_.end()) {
+      if (selected_product_iter != end) {
+        // We have two possible values for this product!
+        diag->Error(android::DiagMessage(config_value->value->GetSource())
+                    << "selection of product '" << config_value->product << "' for resource "
+                    << name << " is ambiguous");
+
+        ResourceConfigValue* previously_selected_config_value = selected_product_iter->get();
+        diag->Note(android::DiagMessage(previously_selected_config_value->value->GetSource())
+                   << "product '" << previously_selected_config_value->product
+                   << "' is also a candidate");
+        return std::nullopt;
+      }
+
+      // Select this product.
+      selected_product_iter = iter;
+    }
+
+    if (config_value->product.empty() || config_value->product == "default") {
+      if (default_product_iter != end) {
+        // We have two possible default values.
+        diag->Error(android::DiagMessage(config_value->value->GetSource())
+                    << "multiple default products defined for resource " << name);
+
+        ResourceConfigValue* previously_default_config_value = default_product_iter->get();
+        diag->Note(android::DiagMessage(previously_default_config_value->value->GetSource())
+                   << "default product also defined here");
+        return std::nullopt;
+      }
+
+      // Mark the default.
+      default_product_iter = iter;
+    }
+  }
+
+  if (remove_default_config_values_) {
+    // If we are leaving only a specific product, return early here instead of selecting the default
+    // value. Returning end here will cause this value set to be skipped, and will be removed with
+    // ClearEmptyValues method.
+    return selected_product_iter;
+  }
+
+  if (default_product_iter == end) {
+    diag->Error(android::DiagMessage() << "no default product defined for resource " << name);
+    return std::nullopt;
+  }
+
+  if (selected_product_iter == end) {
+    selected_product_iter = default_product_iter;
+  }
+  return selected_product_iter;
+}
+
+bool ProductFilter::Consume(IAaptContext* context, ResourceTable* table) {
+  TRACE_NAME("ProductFilter::Consume");
+  bool error = false;
+  for (auto& pkg : table->packages) {
+    for (auto& type : pkg->types) {
+      for (auto& entry : type->entries) {
+        std::vector<std::unique_ptr<ResourceConfigValue>> new_values;
+
+        ResourceConfigValueIter iter = entry->values.begin();
+        ResourceConfigValueIter start_range_iter = iter;
+        while (iter != entry->values.end()) {
+          ++iter;
+          if (iter == entry->values.end() || (*iter)->config != (*start_range_iter)->config) {
+            // End of the array, or we saw a different config,
+            // so this must be the end of a range of products.
+            // Select the product to keep from the set of products defined.
+            ResourceNameRef name(pkg->name, type->named_type, entry->name);
+            auto value_to_keep =
+                SelectProductToKeep(name, start_range_iter, iter, context->GetDiagnostics());
+            if (!value_to_keep.has_value()) {
+              // An error occurred, we could not pick a product.
+              error = true;
+            } else if (auto val = value_to_keep.value(); val != iter) {
+              // We selected a product to keep. Move it to the new array.
+              if (remove_default_config_values_) {
+                // We are filtering values with the given product. The selected value here will be
+                // a new default value, and all other values will be removed.
+                new_values.push_back(
+                    std::make_unique<ResourceConfigValue>((*val)->config, android::StringPiece{}));
+                new_values.back()->value = std::move((*val)->value);
+              } else {
+                new_values.push_back(std::move(*val));
+              }
+            }
+
+            // Start the next range of products.
+            start_range_iter = iter;
+          }
+        }
+
+        // Now move the new values in to place.
+        entry->values = std::move(new_values);
+      }
+    }
+  }
+
+  if (remove_default_config_values_) {
+    ClearEmptyValues(table);
+  }
+
+  return !error;
+}
+
+void ProductFilter::ClearEmptyValues(ResourceTable* table) {
+  // Clear any empty packages/types/entries, as remove_default_config_values_ may remove an entire
+  // value set.
+  CHECK(remove_default_config_values_)
+      << __func__ << " should only be called when remove_default_config_values_ is set";
+
+  for (auto& pkg : table->packages) {
+    for (auto& type : pkg->types) {
+      std::erase_if(type->entries, [](auto& entry) { return entry->values.empty(); });
+    }
+    std::erase_if(pkg->types, [](auto& type) { return type->entries.empty(); });
+  }
+  std::erase_if(table->packages, [](auto& package) { return package->types.empty(); });
+}
+
+}  // namespace aapt
diff --git a/tools/aapt2/process/ProductFilter.h b/tools/aapt2/process/ProductFilter.h
new file mode 100644
index 000000000000..0ec2f00863fc
--- /dev/null
+++ b/tools/aapt2/process/ProductFilter.h
@@ -0,0 +1,65 @@
+#pragma once
+
+#include <memory>
+#include <optional>
+#include <string>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
+#include "Resource.h"
+#include "android-base/macros.h"
+#include "androidfw/ConfigDescription.h"
+#include "androidfw/IDiagnostics.h"
+#include "process/IResourceTableConsumer.h"
+
+namespace aapt {
+
+class ResourceConfigValue;
+
+class ProductFilter : public IResourceTableConsumer {
+ public:
+  using ResourceConfigValueIter = std::vector<std::unique_ptr<ResourceConfigValue>>::iterator;
+
+  // Setting remove_default_config_values will remove all values other than
+  // specified product, including default. For example, if the following table
+  //
+  //     <string name="foo" product="default">foo_default</string>
+  //     <string name="foo" product="tablet">foo_tablet</string>
+  //     <string name="bar">bar</string>
+  //
+  // is consumed with tablet, it will result in
+  //
+  //     <string name="foo">foo_tablet</string>
+  //
+  // removing foo_default and bar. This option is to generate an RRO package
+  // with given product.
+  explicit ProductFilter(std::unordered_set<std::string> products,
+                         bool remove_default_config_values)
+      : products_(std::move(products)),
+        remove_default_config_values_(remove_default_config_values) {
+  }
+
+  bool Consume(IAaptContext* context, ResourceTable* table) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ProductFilter);
+
+  // SelectProductToKeep returns an iterator for the selected value.
+  //
+  // Returns std::nullopt in case of failure (e.g. ambiguous values, missing or duplicated default
+  // values).
+  // Returns `end` if keep_as_default_product is set and no value for the specified product was
+  // found.
+  std::optional<ResourceConfigValueIter> SelectProductToKeep(const ResourceNameRef& name,
+                                                             ResourceConfigValueIter begin,
+                                                             ResourceConfigValueIter end,
+                                                             android::IDiagnostics* diag);
+
+  void ClearEmptyValues(ResourceTable* table);
+
+  std::unordered_set<std::string> products_;
+  bool remove_default_config_values_;
+};
+
+}  // namespace aapt
diff --git a/tools/aapt2/process/ProductFilter_test.cpp b/tools/aapt2/process/ProductFilter_test.cpp
new file mode 100644
index 000000000000..27a82dcc3453
--- /dev/null
+++ b/tools/aapt2/process/ProductFilter_test.cpp
@@ -0,0 +1,208 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "process/ProductFilter.h"
+
+#include "test/Test.h"
+
+using ::android::ConfigDescription;
+
+namespace aapt {
+
+TEST(ProductFilterTest, SelectTwoProducts) {
+  std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();
+
+  const ConfigDescription land = test::ParseConfigOrDie("land");
+  const ConfigDescription port = test::ParseConfigOrDie("port");
+
+  ResourceTable table;
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("land/default.xml")).Build(),
+                    land)
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("land/tablet.xml")).Build(),
+                    land, "tablet")
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("port/default.xml")).Build(),
+                    port)
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("port/tablet.xml")).Build(),
+                    port, "tablet")
+          .Build(),
+      context->GetDiagnostics()));
+
+  ProductFilter filter({"tablet"}, /* remove_default_config_values = */ false);
+  ASSERT_TRUE(filter.Consume(context.get(), &table));
+
+  EXPECT_EQ(nullptr, test::GetValueForConfigAndProduct<Id>(&table, "android:string/one", land, ""));
+  EXPECT_NE(nullptr,
+            test::GetValueForConfigAndProduct<Id>(&table, "android:string/one", land, "tablet"));
+  EXPECT_EQ(nullptr, test::GetValueForConfigAndProduct<Id>(&table, "android:string/one", port, ""));
+  EXPECT_NE(nullptr,
+            test::GetValueForConfigAndProduct<Id>(&table, "android:string/one", port, "tablet"));
+}
+
+TEST(ProductFilterTest, SelectDefaultProduct) {
+  std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();
+
+  ResourceTable table;
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("default.xml")).Build())
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("tablet.xml")).Build(), {},
+                    "tablet")
+          .Build(),
+      context->GetDiagnostics()));
+  ;
+
+  ProductFilter filter(std::unordered_set<std::string>{},
+                       /* remove_default_config_values = */ false);
+  ASSERT_TRUE(filter.Consume(context.get(), &table));
+
+  EXPECT_NE(nullptr, test::GetValueForConfigAndProduct<Id>(&table, "android:string/one",
+                                                           ConfigDescription::DefaultConfig(), ""));
+  EXPECT_EQ(nullptr,
+            test::GetValueForConfigAndProduct<Id>(&table, "android:string/one",
+                                                  ConfigDescription::DefaultConfig(), "tablet"));
+}
+
+TEST(ProductFilterTest, FailOnAmbiguousProduct) {
+  std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();
+
+  ResourceTable table;
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("default.xml")).Build())
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("tablet.xml")).Build(), {},
+                    "tablet")
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("no-sdcard.xml")).Build(),
+                    {}, "no-sdcard")
+          .Build(),
+      context->GetDiagnostics()));
+
+  ProductFilter filter({"tablet", "no-sdcard"}, /* remove_default_config_values = */ false);
+  ASSERT_FALSE(filter.Consume(context.get(), &table));
+}
+
+TEST(ProductFilterTest, FailOnMultipleDefaults) {
+  std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();
+
+  ResourceTable table;
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source(".xml")).Build())
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("default.xml")).Build(), {},
+                    "default")
+          .Build(),
+      context->GetDiagnostics()));
+
+  ProductFilter filter(std::unordered_set<std::string>{},
+                       /* remove_default_config_values = */ false);
+  ASSERT_FALSE(filter.Consume(context.get(), &table));
+}
+
+TEST(ProductFilterTest, RemoveDefaultConfigValues) {
+  std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();
+
+  const ConfigDescription land = test::ParseConfigOrDie("land");
+  const ConfigDescription port = test::ParseConfigOrDie("port");
+
+  ResourceTable table;
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("land/default.xml")).Build(),
+                    land)
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("land/tablet.xml")).Build(),
+                    land, "tablet")
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/two"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("land/default.xml")).Build(),
+                    land)
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("port/default.xml")).Build(),
+                    port)
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/one"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("port/tablet.xml")).Build(),
+                    port, "tablet")
+          .Build(),
+      context->GetDiagnostics()));
+
+  ASSERT_TRUE(table.AddResource(
+      NewResourceBuilder(test::ParseNameOrDie("android:string/two"))
+          .SetValue(test::ValueBuilder<Id>().SetSource(android::Source("port/default.xml")).Build(),
+                    port)
+          .Build(),
+      context->GetDiagnostics()));
+
+  ProductFilter filter({"tablet"}, /* remove_default_config_values = */ true);
+  ASSERT_TRUE(filter.Consume(context.get(), &table));
+
+  EXPECT_NE(nullptr, test::GetValueForConfigAndProduct<Id>(&table, "android:string/one", land, ""));
+  EXPECT_EQ(nullptr, test::GetValueForConfigAndProduct<Id>(&table, "android:string/two", land, ""));
+  EXPECT_NE(nullptr, test::GetValueForConfigAndProduct<Id>(&table, "android:string/one", port, ""));
+  EXPECT_EQ(nullptr, test::GetValueForConfigAndProduct<Id>(&table, "android:string/two", port, ""));
+}
+
+}  // namespace aapt