Support different set of assets depending on platform and flavor parameters

packages/flutter_tools/bin/xcode_backend.sh

@@ -41,6 +41,11 @@ BuildApp() {
     project_path="${FLUTTER_APPLICATION_PATH}"
   fi
 
+  local flavor=""
+  if [[ -n "$FLUTTER_FLAVOR" ]]; then
+    flavor="${FLUTTER_FLAVOR}"
+  fi
+
   local target_path="lib/main.dart"
   if [[ -n "$FLUTTER_TARGET" ]]; then
     target_path="${FLUTTER_TARGET}"
@@ -239,6 +244,7 @@ BuildApp() {
     ${verbose_flag}                                                         \
     build bundle                                                            \
     --target-platform=ios                                                   \
+    --flavor="${flavor}"                                                    \
     --target="${target_path}"                                               \
     --${build_mode}                                                         \
     --depfile="${build_dir}/snapshot_blob.bin.d"                            \

packages/flutter_tools/gradle/flutter.gradle

@@ -349,6 +349,10 @@ class FlutterPlugin implements Plugin<Project> {
         if (project.hasProperty('target-platform')) {
             targetPlatformValue = project.property('target-platform')
         }
+        String flavorValue = null
+        if (project.hasProperty('flavor')) {
+            flavorValue = project.property('flavor')
+        }
 
         def addFlutterDeps = { variant ->
             String flutterBuildMode = buildModeFor(variant.buildType)
@@ -380,6 +384,7 @@ class FlutterPlugin implements Plugin<Project> {
                 baselineDir baselineDirValue
                 buildSharedLibrary buildSharedLibraryValue
                 targetPlatform targetPlatformValue
+                flavor flavorValue
                 sourceDir project.file(project.flutter.source)
                 intermediateDir project.file("${project.buildDir}/${AndroidProject.FD_INTERMEDIATES}/flutter/${variant.name}")
                 extraFrontEndOptions extraFrontEndOptionsValue
@@ -447,6 +452,8 @@ abstract class BaseFlutterTask extends DefaultTask {
     Boolean buildSharedLibrary
     @Optional @Input
     String targetPlatform
+    @Optional @Input
+    String flavor
     File sourceDir
     File intermediateDir
     @Optional @Input
@@ -556,6 +563,9 @@ abstract class BaseFlutterTask extends DefaultTask {
             if (targetPlatform != null) {
                 args "--target-platform", "${targetPlatform}"
             }
+            if (flavor != null) {
+                args "--flavor", "${flavor}"
+            }
             if (buildMode == "release" || buildMode == "profile") {
                 args "--precompiled"
             } else {

packages/flutter_tools/lib/src/android/gradle.dart

@@ -403,6 +403,8 @@ Future<void> _buildGradleProjectV2(
   }
   if (buildInfo.targetPlatform != null)
     command.add('-Ptarget-platform=${getNameForTargetPlatform(buildInfo.targetPlatform)}');
+  if (buildInfo.flavor != null)
+    command.add('-Pflavor=${buildInfo.flavor}');
 
   command.add(assembleTask);
   final int exitCode = await runCommandAndStreamOutput(

packages/flutter_tools/lib/src/asset.dart

@@ -40,6 +40,8 @@ abstract class AssetBundle {
 
   /// Returns 0 for success; non-zero for failure.
   Future<int> build({
+    TargetPlatform platform,
+    String flavor,
     String manifestPath = _ManifestAssetBundle.defaultManifestPath,
     String assetDirPath,
     String packagesPath,
@@ -88,17 +90,21 @@ class _ManifestAssetBundle implements AssetBundle {
 
   @override
   Future<int> build({
+    TargetPlatform platform,
+    String flavor,
     String manifestPath = defaultManifestPath,
     String assetDirPath,
     String packagesPath,
     bool includeDefaultFonts = true,
     bool reportLicensedPackages = false
   }) async {
+    final String platformName = platform != null ? getNameForTargetPlatform(platform) : null;
     assetDirPath ??= getAssetBuildDirectory();
     packagesPath ??= fs.path.absolute(PackageMap.globalPackagesPath);
     FlutterManifest flutterManifest;
     try {
-      flutterManifest = await FlutterManifest.createFromPath(manifestPath);
+      flutterManifest = await FlutterManifest.createFromPath(manifestPath,
+          platform: platformName, flavor: flavor);
     } catch (e) {
       printStatus('Error detected in pubspec.yaml:', emphasis: true);
       printError('$e');
@@ -145,7 +151,7 @@ class _ManifestAssetBundle implements AssetBundle {
       final Uri package = packageMap.map[packageName];
       if (package != null && package.scheme == 'file') {
         final String packageManifestPath = fs.path.fromUri(package.resolve('../pubspec.yaml'));
-        final FlutterManifest packageFlutterManifest = await FlutterManifest.createFromPath(packageManifestPath);
+        final FlutterManifest packageFlutterManifest = await FlutterManifest.createFromPath(packageManifestPath, platform: platformName);
         if (packageFlutterManifest == null)
           continue;
         // Skip the app itself

packages/flutter_tools/lib/src/bundle.dart

@@ -49,6 +49,7 @@ const String _kIsolateSnapshotInstr = 'isolate_snapshot_instr';
 Future<void> build({
   TargetPlatform platform,
   BuildMode buildMode,
+  String flavor,
   String mainPath = defaultMainPath,
   String manifestPath = defaultManifestPath,
   String applicationKernelFilePath,
@@ -143,6 +144,8 @@ Future<void> build({
   }
 
   final AssetBundle assets = await buildAssets(
+    platform: platform,
+    flavor: flavor,
     manifestPath: manifestPath,
     assetDirPath: assetDirPath,
     packagesPath: packagesPath,
@@ -162,6 +165,8 @@ Future<void> build({
 }
 
 Future<AssetBundle> buildAssets({
+  TargetPlatform platform,
+  String flavor,
   String manifestPath,
   String assetDirPath,
   String packagesPath,
@@ -174,6 +179,8 @@ Future<AssetBundle> buildAssets({
   // Build the asset bundle.
   final AssetBundle assetBundle = AssetBundleFactory.instance.createBundle();
   final int result = await assetBundle.build(
+    platform: platform,
+    flavor: flavor,
     manifestPath: manifestPath,
     assetDirPath: assetDirPath,
     packagesPath: packagesPath,

packages/flutter_tools/lib/src/commands/build_bundle.dart

@@ -18,6 +18,7 @@ class BuildBundleCommand extends BuildSubCommand {
     usesFilesystemOptions(hide: !verboseHelp);
     usesBuildNumberOption();
     addBuildModeFlags(verboseHelp: verboseHelp);
+    usesFlavorOption();
     addDynamicModeFlags(verboseHelp: verboseHelp);
     addDynamicBaselineFlags(verboseHelp: verboseHelp);
     argParser
@@ -73,6 +74,7 @@ class BuildBundleCommand extends BuildSubCommand {
       throwToolExit('Unknown platform: $targetPlatform');
 
     final BuildMode buildMode = getBuildMode();
+    final String flavor = getFlavor();
 
     int buildNumber;
     try {
@@ -86,6 +88,7 @@ class BuildBundleCommand extends BuildSubCommand {
     await build(
       platform: platform,
       buildMode: buildMode,
+      flavor: flavor,
       mainPath: targetFile,
       manifestPath: argResults['manifest'],
       depfilePath: argResults['depfile'],

packages/flutter_tools/lib/src/flutter_manifest.dart

@@ -29,11 +29,11 @@ class FlutterManifest {
   }
 
   /// Returns null on invalid manifest. Returns empty manifest on missing file.
-  static Future<FlutterManifest> createFromPath(String path) async {
+  static Future<FlutterManifest> createFromPath(String path,
+      {String platform, String flavor}) async {
     if (path == null || !fs.isFileSync(path))
       return _createFromYaml(null);
-    final String manifest = await fs.file(path).readAsString();
-    return createFromString(manifest);
+    return _createFromPathWithAssets(path, platform, flavor);
   }
 
   /// Returns null on missing or invalid manifest
@@ -56,14 +56,53 @@ class FlutterManifest {
 
     final Map<dynamic, dynamic> flutterMap = pubspec._descriptor['flutter'];
     if (flutterMap != null) {
-      pubspec._flutterDescriptor = flutterMap.cast<String, dynamic>();
+      pubspec._flutterDescriptor = Map<String, dynamic>.from(flutterMap);
     } else {
       pubspec._flutterDescriptor = <String, dynamic>{};
     }
 
     return pubspec;
   }
 
+  static Future<FlutterManifest> _createFromPath(String path) async {
+    final String manifest = await fs.file(path).readAsString();
+    return createFromString(manifest);
+  }
+
+  static Future<FlutterManifest> _createFromPathWithAssets(
+      String path, String platform, String flavor) async {
+    final FlutterManifest flutterManifest = await _createFromPath(path);
+    if (flutterManifest == null)
+      return null;
+
+    for (String assetPath in buildAssetFilePaths(path, platform, flavor)) {
+      if (!fs.isFileSync(assetPath))
+        continue;
+
+      final FlutterManifest manifest = await _createFromPath(assetPath);
+      if (manifest == null)
+        return null;
+
+      if (manifest._flutterDescriptor['uses-material-design'] != null) {
+        flutterManifest._flutterDescriptor['uses-material-design'] =
+          manifest._flutterDescriptor['uses-material-design'];
+      }
+
+      if (manifest._flutterDescriptor['assets'] != null) {
+        flutterManifest._flutterDescriptor['assets'] =
+          manifest._flutterDescriptor['assets'];
+      }
+
+      if (manifest._flutterDescriptor['fonts'] != null) {
+        flutterManifest._fonts = null;
+        flutterManifest._flutterDescriptor['fonts'] =
+          manifest._flutterDescriptor['fonts'];
+      }
+    }
+
+    return flutterManifest;
+  }
+
   /// A map representation of the entire `pubspec.yaml` file.
   Map<String, dynamic> _descriptor;
 
@@ -290,3 +329,28 @@ Future<bool> _validate(dynamic manifest) async {
     return false;
   }
 }
+
+const String _assetsFilesPrefix = 'assets';
+const String _assetsFilesDelimiter = '-';
+
+String _buildAssetFilePath(String dirname, {String platform, String flavor}) {
+  final List<String> segments = <String>[_assetsFilesPrefix];
+  if (platform != null) {
+    segments.add(platform.split('-').first);
+  }
+  if (flavor != null) {
+    segments.add(flavor);
+  }
+  return fs.path.join(dirname, '${segments.join(_assetsFilesDelimiter)}.yaml');
+}
+
+@visibleForTesting
+List<String> buildAssetFilePaths(String path, String platform, String flavor) {
+  final String dirname = fs.path.dirname(path);
+  final Set<String> paths = Set<String>()
+    ..add(_buildAssetFilePath(dirname))
+    ..add(_buildAssetFilePath(dirname, platform: platform))
+    ..add(_buildAssetFilePath(dirname, flavor: flavor))
+    ..add(_buildAssetFilePath(dirname, platform: platform, flavor: flavor));
+  return paths.toList(growable: false);
+}

packages/flutter_tools/lib/src/ios/xcodeproj.dart

@@ -49,6 +49,9 @@ Future<void> updateGeneratedXcodeProperties({
   if (targetOverride != null)
     localsBuffer.writeln('FLUTTER_TARGET=$targetOverride');
 
+  if (buildInfo.flavor != null)
+    localsBuffer.writeln('FLUTTER_FLAVOR=${buildInfo.flavor}');
+
   // The build outputs directory, relative to FLUTTER_APPLICATION_PATH.
   localsBuffer.writeln('FLUTTER_BUILD_DIR=${getBuildDirectory()}');
 

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -337,6 +337,10 @@ abstract class FlutterCommand extends Command<void> {
     return _defaultBuildMode;
   }
 
+  String getFlavor() => argParser.options.containsKey('flavor') && argResults['flavor'] != ''
+        ? argResults['flavor']
+        : null;
+
   void usesFlavorOption() {
     argParser.addOption(
       'flavor',
@@ -377,10 +381,7 @@ abstract class FlutterCommand extends Command<void> {
           '--patch-number (${argResults['patch-number']}) must be an int.', null);
     }
 
-    return BuildInfo(getBuildMode(),
-      argParser.options.containsKey('flavor')
-        ? argResults['flavor']
-        : null,
+    return BuildInfo(getBuildMode(), getFlavor(),
       trackWidgetCreation: trackWidgetCreation,
       compilationTraceFilePath: argParser.options.containsKey('compilation-trace-file')
           ? argResults['compilation-trace-file']