Tagging 'implements-federated-plugin:<name>' for packages that implement a plugin.

app/lib/frontend/templates/views/pkg/info_box.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:_pub_shared/format/encoding.dart';
+import 'package:_pub_shared/search/tags.dart';
 import 'package:pana/pana.dart';
 import 'package:pub_dev/service/download_counts/download_counts.dart';
 import 'package:pubspec_parse/pubspec_parse.dart' as pubspek;
@@ -105,7 +106,10 @@ d.Node packageInfoBoxNode({
       ),
     if (license != null) _block('License', license),
     if (dependencies != null) _block('Dependencies', dependencies),
-    _more(package.name!),
+    _more(
+      package.name!,
+      showImplementsLink: data.version.pubspec?.hasFlutterPlugin ?? false,
+    ),
   ]);
 }
 
@@ -160,14 +164,26 @@ d.Node _metadata({
   ]);
 }
 
-d.Node _more(String packageName) {
+d.Node _more(String packageName, {required bool showImplementsLink}) {
   return _block(
     'More',
-    d.a(
-      href: urls.searchUrl(q: 'dependency:$packageName'),
-      rel: 'nofollow',
-      text: 'Packages that depend on $packageName',
-    ),
+    d.fragment([
+      d.a(
+        href: urls.searchUrl(q: 'dependency:$packageName'),
+        rel: 'nofollow',
+        text: 'Packages that depend on $packageName',
+      ),
+      if (showImplementsLink) ...[
+        d.br(),
+        d.br(),
+        d.a(
+          href: urls.searchUrl(
+              q: PackageVersionTags.implementsFederatedPlugin(packageName)),
+          rel: 'nofollow',
+          text: 'Packages that implement $packageName',
+        ),
+      ],
+    ]),
   );
 }
 

app/lib/package/model_properties.dart

@@ -29,7 +29,6 @@ Map<String, dynamic> _loadYaml(String yamlString) {
 class Pubspec {
   final pubspek.Pubspec _inner;
   final String jsonString;
-  Map<String, dynamic>? _json;
   String? _canonicalVersion;
 
   Pubspec._(this._inner, this.jsonString);
@@ -44,10 +43,9 @@ class Pubspec {
   factory Pubspec.fromJson(Map<String, dynamic> map) =>
       Pubspec._(pubspek.Pubspec.fromJson(map, lenient: true), json.encode(map));
 
-  Map<String, dynamic> get asJson {
-    _load();
-    return _json!;
-  }
+  late final _json = _loadYaml(jsonString);
+
+  Map<String, dynamic> get asJson => _json;
 
   String get name => _inner.name;
 
@@ -84,8 +82,7 @@ class Pubspec {
       .toList();
 
   Map<String, dynamic>? get executables {
-    _load();
-    final map = _json!['executables'];
+    final map = _json['executables'];
     return map is Map<String, dynamic> ? map : null;
   }
 
@@ -97,7 +94,6 @@ class Pubspec {
   /// Returns null if the constraint is missing or does not follow the
   /// `>=<version>` pattern.
   MinSdkVersion? get minSdkVersion {
-    _load();
     return MinSdkVersion.tryParse(_inner.environment['sdk']);
   }
 
@@ -106,7 +102,6 @@ class Pubspec {
   /// Returns null if the constraint is missing or does not follow the
   /// `>=<version>` pattern.
   late final _minFlutterSdkVersion = () {
-    _load();
     return MinSdkVersion.tryParse(_inner.environment['flutter']);
   }();
 
@@ -162,27 +157,32 @@ class Pubspec {
               .intersect(VersionConstraint.parse('<2.12.0-0'))
               .isEmpty;
 
-  /// Whether the pubspec file contains a flutter.plugin entry.
-  bool get hasFlutterPlugin {
-    _load();
-    final flutter = _json!['flutter'];
-    if (flutter == null || flutter is! Map) return false;
+  late final _flutterPluginMap = () {
+    final flutter = _json['flutter'];
+    if (flutter == null || flutter is! Map) {
+      return null;
+    }
     final plugin = flutter['plugin'];
-    return plugin != null && plugin is Map;
-  }
+    if (plugin != null && plugin is Map<String, dynamic>) {
+      return plugin;
+    } else {
+      return null;
+    }
+  }();
+
+  /// Whether the pubspec file contains a flutter.plugin entry.
+  bool get hasFlutterPlugin => _flutterPluginMap != null;
 
   /// Whether the package has a dependency on flutter.
   bool get dependsOnFlutter {
-    _load();
-    final dependencies = _json!['dependencies'];
+    final dependencies = _json['dependencies'];
     if (dependencies == null || dependencies is! Map) return false;
     return dependencies.containsKey('flutter');
   }
 
   /// Whether the package has a dependency on flutter and it refers to the SDK.
   bool get dependsOnFlutterSdk {
-    _load();
-    final dependencies = _json!['dependencies'];
+    final dependencies = _json['dependencies'];
     if (dependencies == null || dependencies is! Map) return false;
     final flutter = dependencies['flutter'];
     if (flutter == null || flutter is! Map) return false;
@@ -195,14 +195,24 @@ class Pubspec {
   bool get hasOptedIntoNullSafety =>
       _sdkConstraintStatus.hasOptedIntoNullSafety;
 
-  void _load() {
-    _json ??= _loadYaml(jsonString);
-  }
-
   late final List<Uri> funding = _inner.funding ?? const <Uri>[];
 
   /// Whether the pubspec has any topic entry.
   bool get hasTopic => canonicalizedTopics.isNotEmpty;
+
+  /// If package is implementing a federated Flutter plugin, this will be name
+  /// of the plugin package, `null` otherwise.
+  late final implementsFederatedPluginName = () {
+    if (_flutterPluginMap == null) {
+      return null;
+    }
+    final implements = _flutterPluginMap['implements'];
+    if (implements != null && implements is String) {
+      return implements;
+    } else {
+      return null;
+    }
+  }();
 }
 
 class MinSdkVersion {

app/lib/package/models.dart

@@ -658,13 +658,18 @@ class PackageVersion extends db.ExpandoModel<String> {
 
   /// List of tags from the properties on the current [PackageVersion] entity.
   Iterable<String> getTags() {
+    final pluginForName = pubspec!.implementsFederatedPluginName;
     return <String>{
       if (pubspec!.supportsOnlyLegacySdk) ...[
         PackageVersionTags.isLegacy,
         PackageTags.isUnlisted,
       ],
       if (pubspec!.funding.isNotEmpty) PackageVersionTags.hasFundingLink,
       if (pubspec!.hasTopic) PackageVersionTags.hasTopic,
+      if (pluginForName != null) ...[
+        PackageVersionTags.hasImplementsFederatedPlugin,
+        PackageVersionTags.implementsFederatedPlugin(pluginForName),
+      ],
     };
   }
 

pkg/_pub_shared/lib/search/search_form.dart

@@ -17,7 +17,7 @@ final RegExp _allDependencyRegExp =
 final _sortRegExp = RegExp('sort:([a-z]+)');
 final _updatedRegExp = RegExp('updated:([0-9][0-9a-z]*)');
 final _tagRegExp =
-    RegExp(r'([\+|\-]?[a-z0-9]+:[a-z0-9\-_\.]+)', caseSensitive: false);
+    RegExp(r'([\+|\-]?[a-z0-9\-]+:[a-z0-9\-_\.]+)', caseSensitive: false);
 
 /// The tag prefixes that we can detect in the user-provided search query.
 final _detectedTagPrefixes = <String>{

pkg/_pub_shared/lib/search/tags.dart

@@ -16,7 +16,8 @@ const allowedTagPrefixes = [
   'sdk:',
   'show:',
   'has:',
-  'topic:'
+  'topic:',
+  'implements-federated-plugin:',
 ];
 
 /// Collection of package-related tags.
@@ -87,6 +88,14 @@ abstract class PackageVersionTags {
   /// Package version may be used in WASM compilation.
   static const String isWasmReady = 'is:wasm-ready';
 
+  /// Package version has an entry indicating it implements a federated plugin.
+  static const String hasImplementsFederatedPlugin =
+      'has:implements-federated-plugin';
+
+  /// The `implements-federated-plugin:<name>` tag.
+  static String implementsFederatedPlugin(String name) =>
+      'implements-federated-plugin:$name';
+
   /// Version tags that provide a positive, forward-looking property
   /// of a prerelease or preview version.
   ///
@@ -167,5 +176,7 @@ const _futureVersionTags = <String>{
 /// Returns whether a [tag] is relevant to the package search,
 /// if it is a value from a preview or prerelease version.
 bool isFutureVersionTag(String tag) {
-  return _futureVersionTags.contains(tag) || tag.startsWith('runtime:');
+  return _futureVersionTags.contains(tag) ||
+      tag.startsWith('runtime:') ||
+      tag.startsWith('plugin-for:');
 }

pkg/_pub_shared/test/search/search_form_test.dart

@@ -180,6 +180,14 @@ void main() {
           query.parsedQuery.tagsPredicate.toQueryParameters(), ['is:legacy']);
     });
 
+    test('complex tag', () {
+      final query =
+          SearchForm(query: 'implements-federated-plugin:url_launcher');
+      expect(query.parsedQuery.text, isNull);
+      expect(query.parsedQuery.tagsPredicate.toQueryParameters(),
+          ['implements-federated-plugin:url_launcher']);
+    });
+
     test('forbidden known tag', () {
       final query = SearchForm(query: '-is:legacy');
       expect(query.parsedQuery.text, isNull);