Make resources nullable

Author: mosuem

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

@@ -11,21 +11,23 @@ const packageName = 'treeshaking_native_assets';
 void main(List<String> arguments) async {
   await link(arguments, (config, output) async {
     final usedSymbols =
-        config.resources.map((resource) => resource.metadata.toString());
+        config.resources?.map((resource) => resource.metadata.toString());
     final dynamicLibrary = config.assets.firstWhere((asset) =>
         asset.id == 'package:$packageName/src/${packageName}_bindings.dart');
     final staticLibrary = config.assets
         .firstWhere((asset) => asset.id == 'package:$packageName/staticlib');
 
-    final linkerScript = await _writeLinkerScript(usedSymbols);
-    await _treeshakeStaticLibrary(
-      usedSymbols,
-      linkerScript,
-      dynamicLibrary,
-      staticLibrary,
-    );
-    output.addAsset(dynamicLibrary);
-    output.addDependency(config.packageRoot.resolve('hook/link.dart'));
+    if (usedSymbols != null) {
+      final linkerScript = await _writeLinkerScript(usedSymbols);
+      await _treeshakeStaticLibrary(
+        usedSymbols,
+        linkerScript,
+        dynamicLibrary,
+        staticLibrary,
+      );
+      output.addAsset(dynamicLibrary);
+      output.addDependency(config.packageRoot.resolve('hook/link.dart'));
+    }
   });
 }
 

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

@@ -7,8 +7,10 @@ import 'package:native_assets_cli/native_assets_cli.dart';
 void main(List<String> args) async {
   await link(args, (config, output) async {
     final assetsWithResource = config.assets.whereType<DataAsset>().where(
-        (asset) => config.resources
-            .any((resource) => resource.metadata == asset.name));
+        (asset) =>
+            config.resources
+                ?.any((resource) => resource.metadata == asset.name) ??
+            true);
     output.addAssets(assetsWithResource);
   });
 }

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

@@ -17,7 +17,8 @@ import 'link_config.dart';
 ///
 /// As the linking runs after kernel compilation, you can use treeshaking
 /// information provided through [LinkConfig.resources] to decide which assets
-/// to include.
+/// to include. The resources are only collected in AOT mode, therefore the
+/// field is null in JIT mode.
 ///
 ///
 /// ```dart

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

@@ -35,7 +35,9 @@ abstract class LinkConfig implements HookConfig {
   /// A collection of methods annotated with `@ResourceIdentifier`, which are
   /// called in the tree-shaken Dart code. This information can be used to
   /// dispose unused [assets].
-  List<Resource> get resources;
+  ///
+  /// This is `null` in JIT mode, where no resources are collected.
+  List<Resource>? get resources;
 
   /// Generate the [LinkConfig] from the input arguments to the linking script.
   factory LinkConfig.fromArguments(List<String> arguments) =>

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

@@ -19,7 +19,7 @@ class LinkConfigImpl extends HookConfigImpl implements LinkConfig {
   final BuildConfigImpl _buildConfig;
 
   @override
-  final List<Resource> resources;
+  final List<Resource>? resources;
 
   final _LinkConfigArgs _args;
 
@@ -99,8 +99,8 @@ class LinkConfigImpl extends HookConfigImpl implements LinkConfig {
   static Version latestVersion = Version(1, 0, 0);
 }
 
-List<Resource> fromIdentifiers(ResourceIdentifiers? resourceIdentifiers) =>
-    (resourceIdentifiers?.identifiers ?? [])
+List<Resource>? fromIdentifiers(ResourceIdentifiers? resourceIdentifiers) =>
+    resourceIdentifiers?.identifiers
         .map((e) => Resource(name: e.name, metadata: e.id))
         .toList();