libs/androidfw/include/androidfw/AssetManager2.h - platform/frameworks/base - Git at Google

 /*
  * 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.
  */

 #ifndef ANDROIDFW_ASSETMANAGER2_H_
 #define ANDROIDFW_ASSETMANAGER2_H_

 #include "android-base/macros.h"

 #include <array>
 #include <limits>
 #include <set>
 #include <unordered_map>

 #include "androidfw/ApkAssets.h"
 #include "androidfw/Asset.h"
 #include "androidfw/AssetManager.h"
 #include "androidfw/ResourceTypes.h"
 #include "androidfw/Util.h"

 namespace android {

 class Theme;

 using ApkAssetsCookie = int32_t;

 enum : ApkAssetsCookie {
   kInvalidCookie = -1,
 };

 // Holds a bag that has been merged with its parent, if one exists.
 struct ResolvedBag {
   // A single key-value entry in a bag.
   struct Entry {
     // The key, as described in ResTable_map::name.
     uint32_t key;

     Res_value value;

     // Which ApkAssets this entry came from.
     ApkAssetsCookie cookie;

     ResStringPool* key_pool;
     ResStringPool* type_pool;
   };

   // Denotes the configuration axis that this bag varies with.
   // If a configuration changes with respect to one of these axis,
   // the bag should be reloaded.
   uint32_t type_spec_flags;

   // The number of entries in this bag. Access them by indexing into `entries`.
   uint32_t entry_count;

   // The array of entries for this bag. An empty array is a neat trick to force alignment
   // of the Entry structs that follow this structure and avoids a bunch of casts.
   Entry entries[0];
 };

 // AssetManager2 is the main entry point for accessing assets and resources.
 // AssetManager2 provides caching of resources retrieved via the underlying ApkAssets.
 class AssetManager2 {
  public:
   struct ResourceName {
     const char* package = nullptr;
     size_t package_len = 0u;

     const char* type = nullptr;
     const char16_t* type16 = nullptr;
     size_t type_len = 0u;

     const char* entry = nullptr;
     const char16_t* entry16 = nullptr;
     size_t entry_len = 0u;
   };

   AssetManager2();

   // Sets/resets the underlying ApkAssets for this AssetManager. The ApkAssets
   // are not owned by the AssetManager, and must have a longer lifetime.
   //
   // Only pass invalidate_caches=false when it is known that the structure
   // change in ApkAssets is due to a safe addition of resources with completely
   // new resource IDs.
   bool SetApkAssets(const std::vector<const ApkAssets*>& apk_assets, bool invalidate_caches = true);

   inline const std::vector<const ApkAssets*> GetApkAssets() const {
     return apk_assets_;
   }

   // Returns the string pool for the given asset cookie.
   // Use the string pool returned here with a valid Res_value object of type Res_value::TYPE_STRING.
   const ResStringPool* GetStringPoolForCookie(ApkAssetsCookie cookie) const;

   // Returns the DynamicRefTable for the given package ID.
   // This may be nullptr if the APK represented by `cookie` has no resource table.
   const DynamicRefTable* GetDynamicRefTableForPackage(uint32_t package_id) const;

   // Returns the DynamicRefTable for the ApkAssets represented by the cookie.
   // This may be nullptr if the APK represented by `cookie` has no resource table.
   const DynamicRefTable* GetDynamicRefTableForCookie(ApkAssetsCookie cookie) const;

   // Sets/resets the configuration for this AssetManager. This will cause all
   // caches that are related to the configuration change to be invalidated.
   void SetConfiguration(const ResTable_config& configuration);

   inline const ResTable_config& GetConfiguration() const {
     return configuration_;
   }

   // Returns all configurations for which there are resources defined. This includes resource
   // configurations in all the ApkAssets set for this AssetManager.
   // If `exclude_system` is set to true, resource configurations from system APKs
   // ('android' package, other libraries) will be excluded from the list.
   // If `exclude_mipmap` is set to true, resource configurations defined for resource type 'mipmap'
   // will be excluded from the list.
   std::set<ResTable_config> GetResourceConfigurations(bool exclude_system = false,
                                                       bool exclude_mipmap = false);

   // Returns all the locales for which there are resources defined. This includes resource
   // locales in all the ApkAssets set for this AssetManager.
   // If `exclude_system` is set to true, resource locales from system APKs
   // ('android' package, other libraries) will be excluded from the list.
   // If `merge_equivalent_languages` is set to true, resource locales will be canonicalized
   // and de-duped in the resulting list.
   std::set<std::string> GetResourceLocales(bool exclude_system = false,
                                            bool merge_equivalent_languages = false);

   // Searches the set of APKs loaded by this AssetManager and opens the first one found located
   // in the assets/ directory.
   // `mode` controls how the file is opened.
   //
   // NOTE: The loaded APKs are searched in reverse order.
   std::unique_ptr<Asset> Open(const std::string& filename, Asset::AccessMode mode);

   // Opens a file within the assets/ directory of the APK specified by `cookie`.
   // `mode` controls how the file is opened.
   std::unique_ptr<Asset> Open(const std::string& filename, ApkAssetsCookie cookie,
                               Asset::AccessMode mode);

   // Opens the directory specified by `dirname`. The result is an AssetDir that is the combination
   // of all directories matching `dirname` under the assets/ directory of every ApkAssets loaded.
   // The entries are sorted by their ASCII name.
   std::unique_ptr<AssetDir> OpenDir(const std::string& dirname);

   // Searches the set of APKs loaded by this AssetManager and opens the first one found.
   // `mode` controls how the file is opened.
   // `out_cookie` is populated with the cookie of the APK this file was found in.
   //
   // NOTE: The loaded APKs are searched in reverse order.
   std::unique_ptr<Asset> OpenNonAsset(const std::string& filename, Asset::AccessMode mode,
                                       ApkAssetsCookie* out_cookie = nullptr);

   // Opens a file in the APK specified by `cookie`. `mode` controls how the file is opened.
   // This is typically used to open a specific AndroidManifest.xml, or a binary XML file
   // referenced by a resource lookup with GetResource().
   std::unique_ptr<Asset> OpenNonAsset(const std::string& filename, ApkAssetsCookie cookie,
                                       Asset::AccessMode mode);

   // Populates the `out_name` parameter with resource name information.
   // Utf8 strings are preferred, and only if they are unavailable are
   // the Utf16 variants populated.
   // Returns false if the resource was not found or the name was missing/corrupt.
   bool GetResourceName(uint32_t resid, ResourceName* out_name);

   // Populates `out_flags` with the bitmask of configuration axis that this resource varies with.
   // See ResTable_config for the list of configuration axis.
   // Returns false if the resource was not found.
   bool GetResourceFlags(uint32_t resid, uint32_t* out_flags);

   // Finds the resource ID assigned to `resource_name`.
   // `resource_name` must be of the form '[package:][type/]entry'.
   // If no package is specified in `resource_name`, then `fallback_package` is used as the package.
   // If no type is specified in `resource_name`, then `fallback_type` is used as the type.
   // Returns 0x0 if no resource by that name was found.
   uint32_t GetResourceId(const std::string& resource_name, const std::string& fallback_type = {},
                          const std::string& fallback_package = {});

   // Retrieves the best matching resource with ID `resid`. The resource value is filled into
   // `out_value` and the configuration for the selected value is populated in `out_selected_config`.
   // `out_flags` holds the same flags as retrieved with GetResourceFlags().
   // If `density_override` is non-zero, the configuration to match against is overridden with that
   // density.
   //
   // Returns a valid cookie if the resource was found. If the resource was not found, or if the
   // resource was a map/bag type, then kInvalidCookie is returned. If `may_be_bag` is false,
   // this function logs if the resource was a map/bag type before returning kInvalidCookie.
   ApkAssetsCookie GetResource(uint32_t resid, bool may_be_bag, uint16_t density_override,
                               Res_value* out_value, ResTable_config* out_selected_config,
                               uint32_t* out_flags);

   // Resolves the resource reference in `in_out_value` if the data type is
   // Res_value::TYPE_REFERENCE.
   // `cookie` is the ApkAssetsCookie of the reference in `in_out_value`.
   // `in_out_value` is the reference to resolve. The result is placed back into this object.
   // `in_out_flags` is the type spec flags returned from calls to GetResource() or
   // GetResourceFlags(). Configuration flags of the values pointed to by the reference
   // are OR'd together with `in_out_flags`.
   // `in_out_config` is populated with the configuration for which the resolved value was defined.
   // `out_last_reference` is populated with the last reference ID before resolving to an actual
   // value. This is only initialized if the passed in `in_out_value` is a reference.
   // Returns the cookie of the APK the resolved resource was defined in, or kInvalidCookie if
   // it was not found.
   ApkAssetsCookie ResolveReference(ApkAssetsCookie cookie, Res_value* in_out_value,
                                    ResTable_config* in_out_selected_config, uint32_t* in_out_flags,
                                    uint32_t* out_last_reference);

   // Retrieves the best matching bag/map resource with ID `resid`.
   // This method will resolve all parent references for this bag and merge keys with the child.
   // To iterate over the keys, use the following idiom:
   //
   //  const AssetManager2::ResolvedBag* bag = asset_manager->GetBag(id);
   //  if (bag != nullptr) {
   //    for (auto iter = begin(bag); iter != end(bag); ++iter) {
   //      ...
   //    }
   //  }
   const ResolvedBag* GetBag(uint32_t resid);

   // Creates a new Theme from this AssetManager.
   std::unique_ptr<Theme> NewTheme();

   template <typename Func>
   void ForEachPackage(Func func) {
     for (const PackageGroup& package_group : package_groups_) {
       func(package_group.packages_.front()->GetPackageName(),
            package_group.dynamic_ref_table.mAssignedPackageId);
     }
   }

   void DumpToLog() const;

  private:
   DISALLOW_COPY_AND_ASSIGN(AssetManager2);

   // Finds the best entry for `resid` from the set of ApkAssets. The entry can be a simple
   // Res_value, or a complex map/bag type. If successful, it is available in `out_entry`.
   // Returns kInvalidCookie on failure. Otherwise, the return value is the cookie associated with
   // the ApkAssets in which the entry was found.
   //
   // `density_override` overrides the density of the current configuration when doing a search.
   //
   // When `stop_at_first_match` is true, the first match found is selected and the search
   // terminates. This is useful for methods that just look up the name of a resource and don't
   // care about the value. In this case, the value of `FindEntryResult::type_flags` is incomplete
   // and should not be used.
   //
   // NOTE: FindEntry takes care of ensuring that structs within FindEntryResult have been properly
   // bounds-checked. Callers of FindEntry are free to trust the data if this method succeeds.
   ApkAssetsCookie FindEntry(uint32_t resid, uint16_t density_override, bool stop_at_first_match,
                             FindEntryResult* out_entry);

   // Assigns package IDs to all shared library ApkAssets.
   // Should be called whenever the ApkAssets are changed.
   void BuildDynamicRefTable();

   // Purge all resources that are cached and vary by the configuration axis denoted by the
   // bitmask `diff`.
   void InvalidateCaches(uint32_t diff);

   // The ordered list of ApkAssets to search. These are not owned by the AssetManager, and must
   // have a longer lifetime.
   std::vector<const ApkAssets*> apk_assets_;

   struct PackageGroup {
     std::vector<const LoadedPackage*> packages_;
     std::vector<ApkAssetsCookie> cookies_;
     DynamicRefTable dynamic_ref_table;
   };

   // DynamicRefTables for shared library package resolution.
   // These are ordered according to apk_assets_. The mappings may change depending on what is
   // in apk_assets_, therefore they must be stored in the AssetManager and not in the
   // immutable ApkAssets class.
   std::vector<PackageGroup> package_groups_;

   // An array mapping package ID to index into package_groups. This keeps the lookup fast
   // without taking too much memory.
   std::array<uint8_t, std::numeric_limits<uint8_t>::max() + 1> package_ids_;

   // The current configuration set for this AssetManager. When this changes, cached resources
   // may need to be purged.
   ResTable_config configuration_;

   // Cached set of bags. These are cached because they can inherit keys from parent bags,
   // which involves some calculation.
   std::unordered_map<uint32_t, util::unique_cptr<ResolvedBag>> cached_bags_;
 };

 class Theme {
   friend class AssetManager2;

  public:
   ~Theme();

   // Applies the style identified by `resid` to this theme. This can be called
   // multiple times with different styles. By default, any theme attributes that
   // are already defined before this call are not overridden. If `force` is set
   // to true, this behavior is changed and all theme attributes from the style at
   // `resid` are applied.
   // Returns false if the style failed to apply.
   bool ApplyStyle(uint32_t resid, bool force = false);

   // Sets this Theme to be a copy of `o` if `o` has the same AssetManager as this Theme.
   // Returns false if the AssetManagers of the Themes were not compatible.
   bool SetTo(const Theme& o);

   void Clear();

   inline const AssetManager2* GetAssetManager() const {
     return asset_manager_;
   }

   inline AssetManager2* GetAssetManager() {
     return asset_manager_;
   }

   // Returns a bit mask of configuration changes that will impact this
   // theme (and thus require completely reloading it).
   inline uint32_t GetChangingConfigurations() const {
     return type_spec_flags_;
   }

   // Retrieve a value in the theme. If the theme defines this value, returns an asset cookie
   // indicating which ApkAssets it came from and populates `out_value` with the value.
   // `out_flags` is populated with a bitmask of the configuration axis with which the resource
   // varies.
   //
   // If the attribute is not found, returns kInvalidCookie.
   //
   // NOTE: This function does not do reference traversal. If you want to follow references to other
   // resources to get the "real" value to use, you need to call ResolveReference() after this
   // function.
   ApkAssetsCookie GetAttribute(uint32_t resid, Res_value* out_value, uint32_t* out_flags) const;

   // This is like AssetManager2::ResolveReference(), but also takes
   // care of resolving attribute references to the theme.
   ApkAssetsCookie ResolveAttributeReference(ApkAssetsCookie cookie, Res_value* in_out_value,
                                             ResTable_config* in_out_selected_config = nullptr,
                                             uint32_t* in_out_type_spec_flags = nullptr,
                                             uint32_t* out_last_ref = nullptr);

  private:
   DISALLOW_COPY_AND_ASSIGN(Theme);

   // Called by AssetManager2.
   explicit Theme(AssetManager2* asset_manager);

   AssetManager2* asset_manager_;
   uint32_t type_spec_flags_ = 0u;

   // Defined in the cpp.
   struct Package;

   constexpr static size_t kPackageCount = std::numeric_limits<uint8_t>::max() + 1;
   std::array<std::unique_ptr<Package>, kPackageCount> packages_;
 };

 inline const ResolvedBag::Entry* begin(const ResolvedBag* bag) {
   return bag->entries;
 }

 inline const ResolvedBag::Entry* end(const ResolvedBag* bag) {
   return bag->entries + bag->entry_count;
 }

 }  // namespace android

 #endif /* ANDROIDFW_ASSETMANAGER2_H_ */
	/*
	* 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.
	*/

	#ifndef ANDROIDFW_ASSETMANAGER2_H_
	#define ANDROIDFW_ASSETMANAGER2_H_

	#include "android-base/macros.h"

	#include <array>
	#include <limits>
	#include <set>
	#include <unordered_map>

	#include "androidfw/ApkAssets.h"
	#include "androidfw/Asset.h"
	#include "androidfw/AssetManager.h"
	#include "androidfw/ResourceTypes.h"
	#include "androidfw/Util.h"

	namespace android {

	class Theme;

	using ApkAssetsCookie = int32_t;

	enum : ApkAssetsCookie {
	kInvalidCookie = -1,
	};

	// Holds a bag that has been merged with its parent, if one exists.
	struct ResolvedBag {
	// A single key-value entry in a bag.
	struct Entry {
	// The key, as described in ResTable_map::name.
	uint32_t key;

	Res_value value;

	// Which ApkAssets this entry came from.
	ApkAssetsCookie cookie;

	ResStringPool* key_pool;
	ResStringPool* type_pool;
	};

	// Denotes the configuration axis that this bag varies with.
	// If a configuration changes with respect to one of these axis,
	// the bag should be reloaded.
	uint32_t type_spec_flags;

	// The number of entries in this bag. Access them by indexing into `entries`.
	uint32_t entry_count;

	// The array of entries for this bag. An empty array is a neat trick to force alignment
	// of the Entry structs that follow this structure and avoids a bunch of casts.
	Entry entries[0];
	};

	// AssetManager2 is the main entry point for accessing assets and resources.
	// AssetManager2 provides caching of resources retrieved via the underlying ApkAssets.
	class AssetManager2 {
	public:
	struct ResourceName {
	const char* package = nullptr;
	size_t package_len = 0u;

	const char* type = nullptr;
	const char16_t* type16 = nullptr;
	size_t type_len = 0u;

	const char* entry = nullptr;
	const char16_t* entry16 = nullptr;
	size_t entry_len = 0u;
	};

	AssetManager2();

	// Sets/resets the underlying ApkAssets for this AssetManager. The ApkAssets
	// are not owned by the AssetManager, and must have a longer lifetime.
	//
	// Only pass invalidate_caches=false when it is known that the structure
	// change in ApkAssets is due to a safe addition of resources with completely
	// new resource IDs.
	bool SetApkAssets(const std::vector<const ApkAssets*>& apk_assets, bool invalidate_caches = true);

	inline const std::vector<const ApkAssets*> GetApkAssets() const {
	return apk_assets_;
	}

	// Returns the string pool for the given asset cookie.
	// Use the string pool returned here with a valid Res_value object of type Res_value::TYPE_STRING.
	const ResStringPool* GetStringPoolForCookie(ApkAssetsCookie cookie) const;

	// Returns the DynamicRefTable for the given package ID.
	// This may be nullptr if the APK represented by `cookie` has no resource table.
	const DynamicRefTable* GetDynamicRefTableForPackage(uint32_t package_id) const;

	// Returns the DynamicRefTable for the ApkAssets represented by the cookie.
	// This may be nullptr if the APK represented by `cookie` has no resource table.
	const DynamicRefTable* GetDynamicRefTableForCookie(ApkAssetsCookie cookie) const;

	// Sets/resets the configuration for this AssetManager. This will cause all
	// caches that are related to the configuration change to be invalidated.
	void SetConfiguration(const ResTable_config& configuration);

	inline const ResTable_config& GetConfiguration() const {
	return configuration_;
	}

	// Returns all configurations for which there are resources defined. This includes resource
	// configurations in all the ApkAssets set for this AssetManager.
	// If `exclude_system` is set to true, resource configurations from system APKs
	// ('android' package, other libraries) will be excluded from the list.
	// If `exclude_mipmap` is set to true, resource configurations defined for resource type 'mipmap'
	// will be excluded from the list.
	std::set<ResTable_config> GetResourceConfigurations(bool exclude_system = false,
	bool exclude_mipmap = false);

	// Returns all the locales for which there are resources defined. This includes resource
	// locales in all the ApkAssets set for this AssetManager.
	// If `exclude_system` is set to true, resource locales from system APKs
	// ('android' package, other libraries) will be excluded from the list.
	// If `merge_equivalent_languages` is set to true, resource locales will be canonicalized
	// and de-duped in the resulting list.
	std::set<std::string> GetResourceLocales(bool exclude_system = false,
	bool merge_equivalent_languages = false);

	// Searches the set of APKs loaded by this AssetManager and opens the first one found located
	// in the assets/ directory.
	// `mode` controls how the file is opened.
	//
	// NOTE: The loaded APKs are searched in reverse order.
	std::unique_ptr<Asset> Open(const std::string& filename, Asset::AccessMode mode);

	// Opens a file within the assets/ directory of the APK specified by `cookie`.
	// `mode` controls how the file is opened.
	std::unique_ptr<Asset> Open(const std::string& filename, ApkAssetsCookie cookie,
	Asset::AccessMode mode);

	// Opens the directory specified by `dirname`. The result is an AssetDir that is the combination
	// of all directories matching `dirname` under the assets/ directory of every ApkAssets loaded.
	// The entries are sorted by their ASCII name.
	std::unique_ptr<AssetDir> OpenDir(const std::string& dirname);

	// Searches the set of APKs loaded by this AssetManager and opens the first one found.
	// `mode` controls how the file is opened.
	// `out_cookie` is populated with the cookie of the APK this file was found in.
	//
	// NOTE: The loaded APKs are searched in reverse order.
	std::unique_ptr<Asset> OpenNonAsset(const std::string& filename, Asset::AccessMode mode,
	ApkAssetsCookie* out_cookie = nullptr);

	// Opens a file in the APK specified by `cookie`. `mode` controls how the file is opened.
	// This is typically used to open a specific AndroidManifest.xml, or a binary XML file
	// referenced by a resource lookup with GetResource().
	std::unique_ptr<Asset> OpenNonAsset(const std::string& filename, ApkAssetsCookie cookie,
	Asset::AccessMode mode);

	// Populates the `out_name` parameter with resource name information.
	// Utf8 strings are preferred, and only if they are unavailable are
	// the Utf16 variants populated.
	// Returns false if the resource was not found or the name was missing/corrupt.
	bool GetResourceName(uint32_t resid, ResourceName* out_name);

	// Populates `out_flags` with the bitmask of configuration axis that this resource varies with.
	// See ResTable_config for the list of configuration axis.
	// Returns false if the resource was not found.
	bool GetResourceFlags(uint32_t resid, uint32_t* out_flags);

	// Finds the resource ID assigned to `resource_name`.
	// `resource_name` must be of the form '[package:][type/]entry'.
	// If no package is specified in `resource_name`, then `fallback_package` is used as the package.
	// If no type is specified in `resource_name`, then `fallback_type` is used as the type.
	// Returns 0x0 if no resource by that name was found.
	uint32_t GetResourceId(const std::string& resource_name, const std::string& fallback_type = {},
	const std::string& fallback_package = {});

	// Retrieves the best matching resource with ID `resid`. The resource value is filled into
	// `out_value` and the configuration for the selected value is populated in `out_selected_config`.
	// `out_flags` holds the same flags as retrieved with GetResourceFlags().
	// If `density_override` is non-zero, the configuration to match against is overridden with that
	// density.
	//
	// Returns a valid cookie if the resource was found. If the resource was not found, or if the
	// resource was a map/bag type, then kInvalidCookie is returned. If `may_be_bag` is false,
	// this function logs if the resource was a map/bag type before returning kInvalidCookie.
	ApkAssetsCookie GetResource(uint32_t resid, bool may_be_bag, uint16_t density_override,
	Res_value* out_value, ResTable_config* out_selected_config,
	uint32_t* out_flags);

	// Resolves the resource reference in `in_out_value` if the data type is
	// Res_value::TYPE_REFERENCE.
	// `cookie` is the ApkAssetsCookie of the reference in `in_out_value`.
	// `in_out_value` is the reference to resolve. The result is placed back into this object.
	// `in_out_flags` is the type spec flags returned from calls to GetResource() or
	// GetResourceFlags(). Configuration flags of the values pointed to by the reference
	// are OR'd together with `in_out_flags`.
	// `in_out_config` is populated with the configuration for which the resolved value was defined.
	// `out_last_reference` is populated with the last reference ID before resolving to an actual
	// value. This is only initialized if the passed in `in_out_value` is a reference.
	// Returns the cookie of the APK the resolved resource was defined in, or kInvalidCookie if
	// it was not found.
	ApkAssetsCookie ResolveReference(ApkAssetsCookie cookie, Res_value* in_out_value,
	ResTable_config* in_out_selected_config, uint32_t* in_out_flags,
	uint32_t* out_last_reference);

	// Retrieves the best matching bag/map resource with ID `resid`.
	// This method will resolve all parent references for this bag and merge keys with the child.
	// To iterate over the keys, use the following idiom:
	//
	// const AssetManager2::ResolvedBag* bag = asset_manager->GetBag(id);
	// if (bag != nullptr) {
	// for (auto iter = begin(bag); iter != end(bag); ++iter) {
	// ...
	// }
	// }
	const ResolvedBag* GetBag(uint32_t resid);

	// Creates a new Theme from this AssetManager.
	std::unique_ptr<Theme> NewTheme();

	template <typename Func>
	void ForEachPackage(Func func) {
	for (const PackageGroup& package_group : package_groups_) {
	func(package_group.packages_.front()->GetPackageName(),
	package_group.dynamic_ref_table.mAssignedPackageId);
	}
	}

	void DumpToLog() const;

	private:
	DISALLOW_COPY_AND_ASSIGN(AssetManager2);

	// Finds the best entry for `resid` from the set of ApkAssets. The entry can be a simple
	// Res_value, or a complex map/bag type. If successful, it is available in `out_entry`.
	// Returns kInvalidCookie on failure. Otherwise, the return value is the cookie associated with
	// the ApkAssets in which the entry was found.
	//
	// `density_override` overrides the density of the current configuration when doing a search.
	//
	// When `stop_at_first_match` is true, the first match found is selected and the search
	// terminates. This is useful for methods that just look up the name of a resource and don't
	// care about the value. In this case, the value of `FindEntryResult::type_flags` is incomplete
	// and should not be used.
	//
	// NOTE: FindEntry takes care of ensuring that structs within FindEntryResult have been properly
	// bounds-checked. Callers of FindEntry are free to trust the data if this method succeeds.
	ApkAssetsCookie FindEntry(uint32_t resid, uint16_t density_override, bool stop_at_first_match,
	FindEntryResult* out_entry);

	// Assigns package IDs to all shared library ApkAssets.
	// Should be called whenever the ApkAssets are changed.
	void BuildDynamicRefTable();

	// Purge all resources that are cached and vary by the configuration axis denoted by the
	// bitmask `diff`.
	void InvalidateCaches(uint32_t diff);

	// The ordered list of ApkAssets to search. These are not owned by the AssetManager, and must
	// have a longer lifetime.
	std::vector<const ApkAssets*> apk_assets_;

	struct PackageGroup {
	std::vector<const LoadedPackage*> packages_;
	std::vector<ApkAssetsCookie> cookies_;
	DynamicRefTable dynamic_ref_table;
	};

	// DynamicRefTables for shared library package resolution.
	// These are ordered according to apk_assets_. The mappings may change depending on what is
	// in apk_assets_, therefore they must be stored in the AssetManager and not in the
	// immutable ApkAssets class.
	std::vector<PackageGroup> package_groups_;

	// An array mapping package ID to index into package_groups. This keeps the lookup fast
	// without taking too much memory.
	std::array<uint8_t, std::numeric_limits<uint8_t>::max() + 1> package_ids_;

	// The current configuration set for this AssetManager. When this changes, cached resources
	// may need to be purged.
	ResTable_config configuration_;

	// Cached set of bags. These are cached because they can inherit keys from parent bags,
	// which involves some calculation.
	std::unordered_map<uint32_t, util::unique_cptr<ResolvedBag>> cached_bags_;
	};

	class Theme {
	friend class AssetManager2;

	public:
	~Theme();

	// Applies the style identified by `resid` to this theme. This can be called
	// multiple times with different styles. By default, any theme attributes that
	// are already defined before this call are not overridden. If `force` is set
	// to true, this behavior is changed and all theme attributes from the style at
	// `resid` are applied.
	// Returns false if the style failed to apply.
	bool ApplyStyle(uint32_t resid, bool force = false);

	// Sets this Theme to be a copy of `o` if `o` has the same AssetManager as this Theme.
	// Returns false if the AssetManagers of the Themes were not compatible.
	bool SetTo(const Theme& o);

	void Clear();

	inline const AssetManager2* GetAssetManager() const {
	return asset_manager_;
	}

	inline AssetManager2* GetAssetManager() {
	return asset_manager_;
	}

	// Returns a bit mask of configuration changes that will impact this
	// theme (and thus require completely reloading it).
	inline uint32_t GetChangingConfigurations() const {
	return type_spec_flags_;
	}

	// Retrieve a value in the theme. If the theme defines this value, returns an asset cookie
	// indicating which ApkAssets it came from and populates `out_value` with the value.
	// `out_flags` is populated with a bitmask of the configuration axis with which the resource
	// varies.
	//
	// If the attribute is not found, returns kInvalidCookie.
	//
	// NOTE: This function does not do reference traversal. If you want to follow references to other
	// resources to get the "real" value to use, you need to call ResolveReference() after this
	// function.
	ApkAssetsCookie GetAttribute(uint32_t resid, Res_value* out_value, uint32_t* out_flags) const;

	// This is like AssetManager2::ResolveReference(), but also takes
	// care of resolving attribute references to the theme.
	ApkAssetsCookie ResolveAttributeReference(ApkAssetsCookie cookie, Res_value* in_out_value,
	ResTable_config* in_out_selected_config = nullptr,
	uint32_t* in_out_type_spec_flags = nullptr,
	uint32_t* out_last_ref = nullptr);

	private:
	DISALLOW_COPY_AND_ASSIGN(Theme);

	// Called by AssetManager2.
	explicit Theme(AssetManager2* asset_manager);

	AssetManager2* asset_manager_;
	uint32_t type_spec_flags_ = 0u;

	// Defined in the cpp.
	struct Package;

	constexpr static size_t kPackageCount = std::numeric_limits<uint8_t>::max() + 1;
	std::array<std::unique_ptr<Package>, kPackageCount> packages_;
	};

	inline const ResolvedBag::Entry* begin(const ResolvedBag* bag) {
	return bag->entries;
	}

	inline const ResolvedBag::Entry* end(const ResolvedBag* bag) {
	return bag->entries + bag->entry_count;
	}

	} // namespace android

	#endif /* ANDROIDFW_ASSETMANAGER2_H_ */