[native_assets_cli] asset id option 3

pkgs/native_assets_builder/test/build_runner/link_dry_run_test.dart

@@ -111,4 +111,4 @@ void main() async {
 }
 
 Iterable<String> _getNames(List<AssetImpl> assets) =>
-    assets.whereType<cli.DataAsset>().map((asset) => asset.name);
+    assets.whereType<cli.DataAsset>().map((asset) => asset.id.name);

pkgs/native_assets_builder/test/build_runner/link_test.dart

@@ -205,4 +205,4 @@ void main() async {
 }
 
 Iterable<String> _getNames(List<AssetImpl> assets) =>
-    assets.whereType<cli.DataAsset>().map((asset) => asset.name);
+    assets.whereType<cli.DataAsset>().map((asset) => asset.id.name);

pkgs/native_assets_builder/test/test_data/native_dynamic_linking_test.dart

@@ -83,7 +83,7 @@ void main() async {
           );
 
           final addLibraryPath = assets
-              .firstWhere((asset) => asset.id.endsWith('add.dart'))
+              .firstWhere((asset) => asset.id.string.endsWith('add.dart'))
               .file!
               .toFilePath();
           final addResult = await runProcess(

pkgs/native_assets_builder/test_data/add_asset_link/hook/link.dart

@@ -10,8 +10,7 @@ void main(List<String> arguments) async {
     output
       ..addAsset(
         NativeCodeAsset(
-          package: 'add_asset_link',
-          name: 'dylib_add_link',
+          id: AssetId('add_asset_link', 'dylib_add_link'),
           linkMode: builtDylib.linkMode,
           os: builtDylib.os,
           architecture: builtDylib.architecture,

pkgs/native_assets_builder/test_data/complex_link/hook/build.dart

@@ -26,8 +26,7 @@ void main(List<String> args) async {
 
       output.addAsset(
         DataAsset(
-          package: packageName,
-          name: name,
+          id: AssetId(packageName, name),
           file: dataAsset.uri,
         ),
         linkInPackage: config.linkingEnabled ? packageName : null,

pkgs/native_assets_builder/test_data/complex_link/hook/link.dart

@@ -11,5 +11,5 @@ void main(List<String> args) async {
   );
 }
 
-Iterable<Asset> treeshake(Iterable<Asset> assets) =>
-    assets.where((asset) => !asset.id.endsWith('assets/data_helper_2.json'));
+Iterable<Asset> treeshake(Iterable<Asset> assets) => assets
+    .where((asset) => !asset.id.string.endsWith('assets/data_helper_2.json'));

pkgs/native_assets_builder/test_data/complex_link_helper/hook/build.dart

@@ -27,8 +27,7 @@ void main(List<String> args) async {
       final forLinking = name.contains('2') || name.contains('3');
       output.addAsset(
         DataAsset(
-          package: packageName,
-          name: name,
+          id: AssetId(packageName, name),
           file: dataAsset.uri,
         ),
         linkInPackage:

pkgs/native_assets_builder/test_data/drop_dylib_link/hook/link.dart

@@ -9,7 +9,8 @@ void main(List<String> arguments) async {
     print('''
 Received ${config.assets.length} assets: ${config.assets.map((e) => e.id)}.
 ''');
-    output.addAssets(config.assets.where((asset) => asset.id.endsWith('add')));
+    output.addAssets(
+        config.assets.where((asset) => asset.id.string.endsWith('add')));
     print('''
 Keeping only ${output.assets.map((e) => e.id)}.
 ''');

pkgs/native_assets_builder/test_data/fail_on_os_sdk_version_link/hook/build.dart

@@ -8,9 +8,8 @@ void main(List<String> arguments) async {
   await build(arguments, (config, output) async {
     output.addAsset(
       DataAsset(
-        name: 'data',
+        id: AssetId(config.packageName, 'data'),
         file: config.packageRoot.resolve('assets/data.json'),
-        package: config.packageName,
       ),
       linkInPackage:
           config.linkingEnabled ? 'fail_on_os_sdk_version_linker' : null,

pkgs/native_assets_builder/test_data/simple_data_asset/hook/build.dart

@@ -26,8 +26,7 @@ void main(List<String> args) async {
 
         output.addAsset(
           DataAsset(
-            package: config.packageName,
-            name: name,
+            id: AssetId(config.packageName, name),
             file: dataAsset.uri,
           ),
         );

pkgs/native_assets_builder/test_data/simple_link/hook/build.dart

@@ -26,8 +26,7 @@ void main(List<String> args) async {
 
       output.addAsset(
         DataAsset(
-          package: packageName,
-          name: name,
+          id: AssetId(packageName, name),
           file: dataAsset.uri,
         ),
         linkInPackage: config.linkingEnabled ? packageName : null,

pkgs/native_assets_builder/test_data/treeshaking_native_libs/hook/link.dart

@@ -12,7 +12,7 @@ void main(List<String> arguments) async {
     (config, output) async {
       final linker = CLinker.library(
         name: config.packageName,
-        assetName: config.assets.single.id.split('/').skip(1).join('/'),
+        assetName: config.assets.single.id.name,
         linkerOptions: LinkerOptions.treeshake(symbols: ['add']),
         sources: [config.assets.single.file!.toFilePath()],
       );

pkgs/native_assets_builder/test_data/wrong_linker/hook/build.dart

@@ -18,8 +18,7 @@ void main(List<String> arguments) async {
 
     output.addAsset(
       NativeCodeAsset(
-        package: config.packageName,
-        name: 'foo',
+        id: AssetId(config.packageName, 'foo'),
         file: assetUri,
         linkMode: DynamicLoadingBundled(),
         os: OS.current,

pkgs/native_assets_builder/test_data/wrong_namespace_asset/hook/build.dart

@@ -18,8 +18,7 @@ void main(List<String> arguments) async {
 
     output.addAsset(
       NativeCodeAsset(
-        package: 'other_package',
-        name: 'foo',
+        id: AssetId('other_package', 'foo'),
         file: assetUri,
         linkMode: DynamicLoadingBundled(),
         os: OS.current,

pkgs/native_assets_cli/example/build/local_asset/hook/build.dart

@@ -33,8 +33,7 @@ Future<void> main(List<String> args) async {
     output.addAsset(
       // TODO: Change to DataAsset once the Dart/Flutter SDK can consume it.
       NativeCodeAsset(
-        package: packageName,
-        name: 'asset.txt',
+        id: AssetId(packageName, 'asset.txt'),
         file: assetPath,
         linkMode: DynamicLoadingBundled(),
         os: config.targetOS,

pkgs/native_assets_cli/example/link/package_with_assets/hook/build.dart

@@ -26,8 +26,7 @@ void main(List<String> args) async {
 
       output.addAsset(
         DataAsset(
-          package: packageName,
-          name: name,
+          id: AssetId(packageName, name),
           file: dataAsset.uri,
         ),
         linkInPackage: config.linkingEnabled ? packageName : null,

pkgs/native_assets_cli/lib/native_assets_cli.dart

@@ -10,6 +10,7 @@ export 'src/api/architecture.dart' show Architecture;
 export 'src/api/asset.dart'
     show
         Asset,
+        AssetId,
         DataAsset,
         DynamicLoadingBundled,
         DynamicLoadingSystem,

pkgs/native_assets_cli/lib/src/api/asset.dart

@@ -50,7 +50,7 @@ abstract final class Asset {
   /// @Native<Int Function(Int, Int)>(assetId: 'package:foo/src/foo.dart')
   /// external int add(int a, int b);
   /// ```
-  String get id;
+  AssetId get id;
 
   /// The file to be bundled with the Dart or Flutter application.
   ///
@@ -64,3 +64,40 @@ abstract final class Asset {
   /// or Flutter.
   Uri? get file;
 }
+
+/// The identifier for an [Asset].
+///
+/// An [Asset] has a string identifier called "asset id". Dart code that uses
+/// an asset references the asset using this asset id.
+///
+/// An asset identifier consists of two elements, the `package` and `name`,
+/// which together make a library uri `package:<package>/<name>`. The package
+/// being part of the identifer prevents name collisions between assets of
+/// different packages.
+///
+/// The default asset id for an asset reference from `lib/src/foo.dart` is
+/// `'package:foo/src/foo.dart'`. For example a [NativeCodeAsset] can be accessed
+/// via `@Native` with the `assetId` argument omitted:
+///
+/// ```dart
+/// // file package:foo/src/foo.dart
+/// @Native<Int Function(Int, Int)>()
+/// external int add(int a, int b);
+/// ```
+///
+/// This will be then automatically expanded to
+///
+/// ```dart
+/// // file package:foo/src/foo.dart
+/// @Native<Int Function(Int, Int)>(assetId: 'package:foo/src/foo.dart')
+/// external int add(int a, int b);
+/// ```
+extension type AssetId._(String string) {
+  AssetId.fromString(this.string);
+
+  AssetId(String package, String name) : string = 'package:$package/$name';
+
+  String get name => string.split('/').skip(1).join('/');
+
+  String get package => string.split('/').first.replaceFirst('package:', '');
+}

pkgs/native_assets_cli/lib/src/api/data_asset.dart

@@ -14,25 +14,15 @@ part of 'asset.dart';
 /// bundle this code in the final application.
 abstract final class DataAsset implements Asset {
   /// Constructs a data asset.
-  ///
-  /// The unique [id] of this asset is a uri `package:<package>/<name>` from
-  /// [package] and [name].
   factory DataAsset({
-    required String package,
-    required String name,
+    required AssetId id,
     required Uri file,
   }) =>
       DataAssetImpl(
-        name: name,
-        package: package,
+        name: id.name,
+        package: id.package,
         file: file,
       );
 
-  /// The package which contains this asset.
-  String get package;
-
-  /// The name of this asset, which must be unique for the package.
-  String get name;
-
   static const String type = 'data';
 }

pkgs/native_assets_cli/lib/src/api/native_code_asset.dart

@@ -76,19 +76,15 @@ abstract final class NativeCodeAsset implements Asset {
   Uri? get file;
 
   /// Constructs a native code asset.
-  ///
-  /// The [id] of this asset is a uri `package:<package>/<name>` from [package]
-  /// and [name].
   factory NativeCodeAsset({
-    required String package,
-    required String name,
+    required AssetId id,
     required LinkMode linkMode,
     required OS os,
     Uri? file,
     Architecture? architecture,
   }) =>
       NativeCodeAssetImpl(
-        id: 'package:$package/$name',
+        id: id,
         linkMode: linkMode as LinkModeImpl,
         os: os as OSImpl,
         architecture: architecture as ArchitectureImpl?,

pkgs/native_assets_cli/lib/src/model/data_asset.dart

@@ -8,14 +8,12 @@ final class DataAssetImpl implements DataAsset, AssetImpl {
   @override
   final Uri file;
 
-  @override
   final String name;
 
-  @override
   final String package;
 
   @override
-  String get id => 'package:$package/$name';
+  AssetId get id => AssetId(package, name);
 
   DataAssetImpl({
     required this.file,

pkgs/native_assets_cli/lib/src/model/native_code_asset.dart

@@ -221,7 +221,7 @@ final class NativeCodeAssetImpl implements NativeCodeAsset, AssetImpl {
   final LinkModeImpl linkMode;
 
   @override
-  final String id;
+  final AssetId id;
 
   @override
   final OSImpl os;
@@ -301,7 +301,7 @@ final class NativeCodeAssetImpl implements NativeCodeAsset, AssetImpl {
     }
 
     return NativeCodeAssetImpl(
-      id: get<String>(jsonMap, _idKey),
+      id: AssetId.fromString(get<String>(jsonMap, _idKey)),
       os: os,
       architecture: architecture,
       linkMode: linkMode,
@@ -311,7 +311,7 @@ final class NativeCodeAssetImpl implements NativeCodeAsset, AssetImpl {
 
   NativeCodeAssetImpl copyWith({
     LinkModeImpl? linkMode,
-    String? id,
+    AssetId? id,
     OSImpl? os,
     ArchitectureImpl? architecture,
     Uri? file,
@@ -349,15 +349,15 @@ final class NativeCodeAssetImpl implements NativeCodeAsset, AssetImpl {
   Map<String, Object> toJson(Version version) {
     if (version == Version(1, 0, 0)) {
       return {
-        _idKey: id,
+        _idKey: id.string,
         ...linkMode.toJsonV1_0_0(file),
         _targetKey: Target.fromArchitectureAndOS(architecture!, os).toString(),
       }..sortOnKey();
     }
     return {
       if (architecture != null) _architectureKey: architecture.toString(),
       if (file != null) _fileKey: file!.toFilePath(),
-      _idKey: id,
+      _idKey: id.string,
       _linkModeKey: linkMode.toJson(),
       _osKey: os.toString(),
       typeKey: NativeCodeAsset.type,

pkgs/native_assets_cli/lib/src/validator/validator.dart

@@ -180,7 +180,7 @@ List<String> validateAssetId(
   final errors = <String>[];
   final packageName = config.packageName;
   for (final asset in output.assets) {
-    if (!asset.id.startsWith('package:$packageName/')) {
+    if (!asset.id.string.startsWith('package:$packageName/')) {
       final error = 'Asset "${asset.id}" does not start with '
           '"package:$packageName/".';
       errors.add(error);
@@ -193,7 +193,7 @@ List<String> validateNoDuplicateAssetIds(
   BuildOutput output,
 ) {
   final errors = <String>[];
-  final assetIds = <String>{};
+  final assetIds = <AssetId>{};
   for (final asset in output.assets) {
     if (assetIds.contains(asset.id)) {
       final error = 'Duplicate asset id: "${asset.id}".';
@@ -209,7 +209,7 @@ List<String> validateNoDuplicateDylibs(
   Iterable<Asset> assets,
 ) {
   final errors = <String>[];
-  final fileNameToAssetId = <String, Set<String>>{};
+  final fileNameToAssetId = <String, Set<AssetId>>{};
   for (final asset in assets.whereType<NativeCodeAsset>()) {
     if (asset.linkMode is! DynamicLoadingBundled) {
       continue;