packages/flutter_tools/lib/src/plugins.dart - mirrors/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'package:pub_semver/pub_semver.dart';
 import 'package:yaml/yaml.dart';

 import 'base/common.dart';
 import 'base/file_system.dart';
 import 'platform_plugins.dart';

 class Plugin {
   Plugin({
     required this.name,
     required this.path,
     required this.platforms,
     required this.defaultPackagePlatforms,
     required this.pluginDartClassPlatforms,
     this.flutterConstraint,
     required this.dependencies,
     required this.isDirectDependency,
     this.implementsPackage,
   });

   /// Parses [Plugin] specification from the provided pluginYaml.
   ///
   /// This currently supports two formats. Legacy and Multi-platform.
   ///
   /// Example of the deprecated Legacy format.
   ///
   ///     flutter:
   ///      plugin:
   ///        androidPackage: io.flutter.plugins.sample
   ///        iosPrefix: FLT
   ///        pluginClass: SamplePlugin
   ///
   /// Example Multi-platform format.
   ///
   ///     flutter:
   ///      plugin:
   ///        platforms:
   ///          android:
   ///            package: io.flutter.plugins.sample
   ///            pluginClass: SamplePlugin
   ///          ios:
   ///            # A plugin implemented through method channels.
   ///            pluginClass: SamplePlugin
   ///          linux:
   ///            # A plugin implemented purely in Dart code.
   ///            dartPluginClass: SamplePlugin
   ///          macos:
   ///            # A plugin implemented with `dart:ffi`.
   ///            ffiPlugin: true
   ///          windows:
   ///            # A plugin using platform-specific Dart and method channels.
   ///            dartPluginClass: SamplePlugin
   ///            pluginClass: SamplePlugin
   factory Plugin.fromYaml(
     String name,
     String path,
     YamlMap? pluginYaml,
     VersionConstraint? flutterConstraint,
     List<String> dependencies, {
     required FileSystem fileSystem,
     Set<String>? appDependencies,
   }) {
     final List<String> errors = validatePluginYaml(pluginYaml);
     if (errors.isNotEmpty) {
       throwToolExit('Invalid plugin specification $name.\n${errors.join('\n')}');
     }
     if (pluginYaml != null && pluginYaml['platforms'] != null) {
       return Plugin._fromMultiPlatformYaml(
         name,
         path,
         pluginYaml,
         flutterConstraint,
         dependencies,
         fileSystem,
         appDependencies != null && appDependencies.contains(name),
       );
     }
     return Plugin._fromLegacyYaml(
       name,
       path,
       pluginYaml,
       flutterConstraint,
       dependencies,
       fileSystem,
       appDependencies != null && appDependencies.contains(name),
     );
   }

   factory Plugin._fromMultiPlatformYaml(
     String name,
     String path,
     YamlMap pluginYaml,
     VersionConstraint? flutterConstraint,
     List<String> dependencies,
     FileSystem fileSystem,
     bool isDirectDependency,
   ) {
     assert (pluginYaml['platforms'] != null, 'Invalid multi-platform plugin specification $name.');
     final YamlMap platformsYaml = pluginYaml['platforms'] as YamlMap;

     assert (_validateMultiPlatformYaml(platformsYaml).isEmpty,
             'Invalid multi-platform plugin specification $name.');

     final Map<String, PluginPlatform> platforms = <String, PluginPlatform>{};

     if (_providesImplementationForPlatform(platformsYaml, AndroidPlugin.kConfigKey)) {
       platforms[AndroidPlugin.kConfigKey] = AndroidPlugin.fromYaml(
         name,
         platformsYaml[AndroidPlugin.kConfigKey] as YamlMap,
         path,
         fileSystem,
       );
     }

     if (_providesImplementationForPlatform(platformsYaml, IOSPlugin.kConfigKey)) {
       platforms[IOSPlugin.kConfigKey] =
           IOSPlugin.fromYaml(name, platformsYaml[IOSPlugin.kConfigKey] as YamlMap);
     }

     if (_providesImplementationForPlatform(platformsYaml, LinuxPlugin.kConfigKey)) {
       platforms[LinuxPlugin.kConfigKey] =
           LinuxPlugin.fromYaml(name, platformsYaml[LinuxPlugin.kConfigKey] as YamlMap);
     }

     if (_providesImplementationForPlatform(platformsYaml, MacOSPlugin.kConfigKey)) {
       platforms[MacOSPlugin.kConfigKey] =
           MacOSPlugin.fromYaml(name, platformsYaml[MacOSPlugin.kConfigKey] as YamlMap);
     }

     if (_providesImplementationForPlatform(platformsYaml, WebPlugin.kConfigKey)) {
       platforms[WebPlugin.kConfigKey] =
           WebPlugin.fromYaml(name, platformsYaml[WebPlugin.kConfigKey] as YamlMap);
     }

     if (_providesImplementationForPlatform(platformsYaml, WindowsPlugin.kConfigKey)) {
       platforms[WindowsPlugin.kConfigKey] =
           WindowsPlugin.fromYaml(name, platformsYaml[WindowsPlugin.kConfigKey] as YamlMap);
     }

     // TODO(stuartmorgan): Consider merging web into this common handling; the
     // fact that its implementation of Dart-only plugins and default packages
     // are separate is legacy.
     final List<String> sharedHandlingPlatforms = <String>[
       AndroidPlugin.kConfigKey,
       IOSPlugin.kConfigKey,
       LinuxPlugin.kConfigKey,
       MacOSPlugin.kConfigKey,
       WindowsPlugin.kConfigKey,
     ];
     final Map<String, String> defaultPackages = <String, String>{};
     final Map<String, String> dartPluginClasses = <String, String>{};
     for (final String platform in sharedHandlingPlatforms) {
         final String? defaultPackage = _getDefaultPackageForPlatform(platformsYaml, platform);
         if (defaultPackage != null) {
           defaultPackages[platform] = defaultPackage;
         }
         final String? dartClass = _getPluginDartClassForPlatform(platformsYaml, platform);
         if (dartClass != null) {
           dartPluginClasses[platform] = dartClass;
         }
     }

     return Plugin(
       name: name,
       path: path,
       platforms: platforms,
       defaultPackagePlatforms: defaultPackages,
       pluginDartClassPlatforms: dartPluginClasses,
       flutterConstraint: flutterConstraint,
       dependencies: dependencies,
       isDirectDependency: isDirectDependency,
       implementsPackage: pluginYaml['implements'] != null ? pluginYaml['implements'] as String : '',
     );
   }

   factory Plugin._fromLegacyYaml(
     String name,
     String path,
     dynamic pluginYaml,
     VersionConstraint? flutterConstraint,
     List<String> dependencies,
     FileSystem fileSystem,
     bool isDirectDependency,
   ) {
     final Map<String, PluginPlatform> platforms = <String, PluginPlatform>{};
     final String? pluginClass = (pluginYaml as Map<dynamic, dynamic>)['pluginClass'] as String?;
     if (pluginClass != null) {
       final String? androidPackage = pluginYaml['androidPackage'] as String?;
       if (androidPackage != null) {
         platforms[AndroidPlugin.kConfigKey] = AndroidPlugin(
           name: name,
           package: androidPackage,
           pluginClass: pluginClass,
           pluginPath: path,
           fileSystem: fileSystem,
         );
       }

       final String iosPrefix = pluginYaml['iosPrefix'] as String? ?? '';
       platforms[IOSPlugin.kConfigKey] =
           IOSPlugin(
             name: name,
             classPrefix: iosPrefix,
             pluginClass: pluginClass,
           );
     }
     return Plugin(
       name: name,
       path: path,
       platforms: platforms,
       defaultPackagePlatforms: <String, String>{},
       pluginDartClassPlatforms: <String, String>{},
       flutterConstraint: flutterConstraint,
       dependencies: dependencies,
       isDirectDependency: isDirectDependency,
     );
   }

   /// Create a YamlMap that represents the supported platforms.
   ///
   /// For example, if the `platforms` contains 'ios' and 'android', the return map looks like:
   ///
   ///     android:
   ///       package: io.flutter.plugins.sample
   ///       pluginClass: SamplePlugin
   ///     ios:
   ///       pluginClass: SamplePlugin
   static YamlMap createPlatformsYamlMap(List<String> platforms, String pluginClass, String androidPackage) {
     final Map<String, dynamic> map = <String, dynamic>{};
     for (final String platform in platforms) {
       map[platform] = <String, String>{
         'pluginClass': pluginClass,
         ...platform == 'android' ? <String, String>{'package': androidPackage} : <String, String>{},
       };
     }
     return YamlMap.wrap(map);
   }

   static List<String> validatePluginYaml(YamlMap? yaml) {
     if (yaml == null) {
       return <String>['Invalid "plugin" specification.'];
     }

     final bool usesOldPluginFormat = const <String>{
       'androidPackage',
       'iosPrefix',
       'pluginClass',
     }.any(yaml.containsKey);

     final bool usesNewPluginFormat = yaml.containsKey('platforms');

     if (usesOldPluginFormat && usesNewPluginFormat) {
       const String errorMessage =
           'The flutter.plugin.platforms key cannot be used in combination with the old '
           'flutter.plugin.{androidPackage,iosPrefix,pluginClass} keys. '
           'See: https://flutter.dev/docs/development/packages-and-plugins/developing-packages#plugin';
       return <String>[errorMessage];
     }

     if (!usesOldPluginFormat && !usesNewPluginFormat) {
       const String errorMessage =
           'Cannot find the `flutter.plugin.platforms` key in the `pubspec.yaml` file. '
           'An instruction to format the `pubspec.yaml` can be found here: '
           'https://flutter.dev/docs/development/packages-and-plugins/developing-packages#plugin-platforms';
       return <String>[errorMessage];
     }

     if (usesNewPluginFormat) {
       if (yaml['platforms'] != null && yaml['platforms'] is! YamlMap) {
         const String errorMessage = 'flutter.plugin.platforms should be a map with the platform name as the key';
         return <String>[errorMessage];
       }
       return _validateMultiPlatformYaml(yaml['platforms'] as YamlMap?);
     } else {
       return _validateLegacyYaml(yaml);
     }
   }

   static List<String> _validateMultiPlatformYaml(YamlMap? yaml) {
     bool isInvalid(String key, bool Function(YamlMap) validate) {
       if (!yaml!.containsKey(key)) {
         return false;
       }
       final dynamic yamlValue = yaml[key];
       if (yamlValue is! YamlMap) {
         return true;
       }
       if (yamlValue.containsKey('default_package')) {
         return false;
       }
       return !validate(yamlValue);
     }

     if (yaml == null) {
       return <String>['Invalid "platforms" specification.'];
     }
     final List<String> errors = <String>[];
     if (isInvalid(AndroidPlugin.kConfigKey, AndroidPlugin.validate)) {
       errors.add('Invalid "android" plugin specification.');
     }
     if (isInvalid(IOSPlugin.kConfigKey, IOSPlugin.validate)) {
       errors.add('Invalid "ios" plugin specification.');
     }
     if (isInvalid(LinuxPlugin.kConfigKey, LinuxPlugin.validate)) {
       errors.add('Invalid "linux" plugin specification.');
     }
     if (isInvalid(MacOSPlugin.kConfigKey, MacOSPlugin.validate)) {
       errors.add('Invalid "macos" plugin specification.');
     }
     if (isInvalid(WindowsPlugin.kConfigKey, WindowsPlugin.validate)) {
       errors.add('Invalid "windows" plugin specification.');
     }
     return errors;
   }

   static List<String> _validateLegacyYaml(YamlMap yaml) {
     final List<String> errors = <String>[];

     if (yaml['androidPackage'] != null && yaml['androidPackage'] is! String) {
       errors.add('The "androidPackage" must either be null or a string.');
     }
     if (yaml['iosPrefix'] != null && yaml['iosPrefix'] is! String) {
       errors.add('The "iosPrefix" must either be null or a string.');
     }
     if (yaml['pluginClass'] != null && yaml['pluginClass'] is! String) {
       errors.add('The "pluginClass" must either be null or a string..');
     }
     return errors;
   }

   static bool _supportsPlatform(YamlMap platformsYaml, String platformKey) {
     if (!platformsYaml.containsKey(platformKey)) {
       return false;
     }
     if (platformsYaml[platformKey] is YamlMap) {
       return true;
     }
     return false;
   }

   static String? _getDefaultPackageForPlatform(YamlMap platformsYaml, String platformKey) {
     if (!_supportsPlatform(platformsYaml, platformKey)) {
       return null;
     }
     if ((platformsYaml[platformKey] as YamlMap).containsKey(kDefaultPackage)) {
       return (platformsYaml[platformKey] as YamlMap)[kDefaultPackage] as String;
     }
     return null;
   }

   static String? _getPluginDartClassForPlatform(YamlMap platformsYaml, String platformKey) {
     if (!_supportsPlatform(platformsYaml, platformKey)) {
       return null;
     }
     if ((platformsYaml[platformKey] as YamlMap).containsKey(kDartPluginClass)) {
       return (platformsYaml[platformKey] as YamlMap)[kDartPluginClass] as String;
     }
     return null;
   }

   static bool _providesImplementationForPlatform(YamlMap platformsYaml, String platformKey) {
     if (!_supportsPlatform(platformsYaml, platformKey)) {
       return false;
     }
     if ((platformsYaml[platformKey] as YamlMap).containsKey(kDefaultPackage)) {
       return false;
     }
     return true;
   }

   final String name;
   final String path;

   /// The name of the interface package that this plugin implements.
   /// If [null], this plugin doesn't implement an interface.
   final String? implementsPackage;

   /// The required version of Flutter, if specified.
   final VersionConstraint? flutterConstraint;

   /// The name of the packages this plugin depends on.
   final List<String> dependencies;

   /// This is a mapping from platform config key to the plugin platform spec.
   final Map<String, PluginPlatform> platforms;

   /// This is a mapping from platform config key to the default package implementation.
   final Map<String, String> defaultPackagePlatforms;

   /// This is a mapping from platform config key to the plugin class for the given platform.
   final Map<String, String> pluginDartClassPlatforms;

   /// Whether this plugin is a direct dependency of the app.
   /// If [false], the plugin is a dependency of another plugin.
   final bool isDirectDependency;

   /// Expected path to the plugin's Package.swift. Returns null if the plugin
   /// does not support the [platform] or the [platform] is not iOS or macOS.
   String? pluginSwiftPackageManifestPath(
     FileSystem fileSystem,
     String platform,
   ) {
     final String? platformDirectoryName = _darwinPluginDirectoryName(platform);
     if (platformDirectoryName == null) {
       return null;
     }
     return fileSystem.path.join(
       path,
       platformDirectoryName,
       name,
       'Package.swift',
     );
   }

   /// Expected path to the plugin's podspec. Returns null if the plugin does
   /// not support the [platform] or the [platform] is not iOS or macOS.
   String? pluginPodspecPath(FileSystem fileSystem, String platform) {
     final String? platformDirectoryName = _darwinPluginDirectoryName(platform);
     if (platformDirectoryName == null) {
       return null;
     }
     return fileSystem.path.join(path, platformDirectoryName, '$name.podspec');
   }

   String? _darwinPluginDirectoryName(String platform) {
     final PluginPlatform? platformPlugin = platforms[platform];
     if (platformPlugin == null ||
         (platform != IOSPlugin.kConfigKey &&
             platform != MacOSPlugin.kConfigKey)) {
       return null;
     }

     // iOS and macOS code can be shared in "darwin" directory, otherwise
     // respectively in "ios" or "macos" directories.
     if (platformPlugin is DarwinPlugin &&
         (platformPlugin as DarwinPlugin).sharedDarwinSource) {
       return 'darwin';
     }
     return platform;
   }
 }

 /// Metadata associated with the resolution of a platform interface of a plugin.
 class PluginInterfaceResolution {
   PluginInterfaceResolution({
     required this.plugin,
     required this.platform,
   });

   /// The plugin.
   final Plugin plugin;
   // The name of the platform that this plugin implements.
   final String platform;

   Map<String, String> toMap() {
     return <String, String> {
       'pluginName': plugin.name,
       'platform': platform,
       'dartClass': plugin.pluginDartClassPlatforms[platform] ?? '',
     };
   }

   @override
   String toString() {
     return '<PluginInterfaceResolution ${plugin.name} for $platform>';
   }
 }
	// Copyright 2014 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'package:pub_semver/pub_semver.dart';
	import 'package:yaml/yaml.dart';

	import 'base/common.dart';
	import 'base/file_system.dart';
	import 'platform_plugins.dart';

	class Plugin {
	Plugin({
	required this.name,
	required this.path,
	required this.platforms,
	required this.defaultPackagePlatforms,
	required this.pluginDartClassPlatforms,
	this.flutterConstraint,
	required this.dependencies,
	required this.isDirectDependency,
	this.implementsPackage,
	});

	/// Parses [Plugin] specification from the provided pluginYaml.
	///
	/// This currently supports two formats. Legacy and Multi-platform.
	///
	/// Example of the deprecated Legacy format.
	///
	/// flutter:
	/// plugin:
	/// androidPackage: io.flutter.plugins.sample
	/// iosPrefix: FLT
	/// pluginClass: SamplePlugin
	///
	/// Example Multi-platform format.
	///
	/// flutter:
	/// plugin:
	/// platforms:
	/// android:
	/// package: io.flutter.plugins.sample
	/// pluginClass: SamplePlugin
	/// ios:
	/// # A plugin implemented through method channels.
	/// pluginClass: SamplePlugin
	/// linux:
	/// # A plugin implemented purely in Dart code.
	/// dartPluginClass: SamplePlugin
	/// macos:
	/// # A plugin implemented with `dart:ffi`.
	/// ffiPlugin: true
	/// windows:
	/// # A plugin using platform-specific Dart and method channels.
	/// dartPluginClass: SamplePlugin
	/// pluginClass: SamplePlugin
	factory Plugin.fromYaml(
	String name,
	String path,
	YamlMap? pluginYaml,
	VersionConstraint? flutterConstraint,
	List<String> dependencies, {
	required FileSystem fileSystem,
	Set<String>? appDependencies,
	}) {
	final List<String> errors = validatePluginYaml(pluginYaml);
	if (errors.isNotEmpty) {
	throwToolExit('Invalid plugin specification $name.\n${errors.join('\n')}');
	}
	if (pluginYaml != null && pluginYaml['platforms'] != null) {
	return Plugin._fromMultiPlatformYaml(
	name,
	path,
	pluginYaml,
	flutterConstraint,
	dependencies,
	fileSystem,
	appDependencies != null && appDependencies.contains(name),
	);
	}
	return Plugin._fromLegacyYaml(
	name,
	path,
	pluginYaml,
	flutterConstraint,
	dependencies,
	fileSystem,
	appDependencies != null && appDependencies.contains(name),
	);
	}

	factory Plugin._fromMultiPlatformYaml(
	String name,
	String path,
	YamlMap pluginYaml,
	VersionConstraint? flutterConstraint,
	List<String> dependencies,
	FileSystem fileSystem,
	bool isDirectDependency,
	) {
	assert (pluginYaml['platforms'] != null, 'Invalid multi-platform plugin specification $name.');
	final YamlMap platformsYaml = pluginYaml['platforms'] as YamlMap;

	assert (_validateMultiPlatformYaml(platformsYaml).isEmpty,
	'Invalid multi-platform plugin specification $name.');

	final Map<String, PluginPlatform> platforms = <String, PluginPlatform>{};

	if (_providesImplementationForPlatform(platformsYaml, AndroidPlugin.kConfigKey)) {
	platforms[AndroidPlugin.kConfigKey] = AndroidPlugin.fromYaml(
	name,
	platformsYaml[AndroidPlugin.kConfigKey] as YamlMap,
	path,
	fileSystem,
	);
	}

	if (_providesImplementationForPlatform(platformsYaml, IOSPlugin.kConfigKey)) {
	platforms[IOSPlugin.kConfigKey] =
	IOSPlugin.fromYaml(name, platformsYaml[IOSPlugin.kConfigKey] as YamlMap);
	}

	if (_providesImplementationForPlatform(platformsYaml, LinuxPlugin.kConfigKey)) {
	platforms[LinuxPlugin.kConfigKey] =
	LinuxPlugin.fromYaml(name, platformsYaml[LinuxPlugin.kConfigKey] as YamlMap);
	}

	if (_providesImplementationForPlatform(platformsYaml, MacOSPlugin.kConfigKey)) {
	platforms[MacOSPlugin.kConfigKey] =
	MacOSPlugin.fromYaml(name, platformsYaml[MacOSPlugin.kConfigKey] as YamlMap);
	}

	if (_providesImplementationForPlatform(platformsYaml, WebPlugin.kConfigKey)) {
	platforms[WebPlugin.kConfigKey] =
	WebPlugin.fromYaml(name, platformsYaml[WebPlugin.kConfigKey] as YamlMap);
	}

	if (_providesImplementationForPlatform(platformsYaml, WindowsPlugin.kConfigKey)) {
	platforms[WindowsPlugin.kConfigKey] =
	WindowsPlugin.fromYaml(name, platformsYaml[WindowsPlugin.kConfigKey] as YamlMap);
	}

	// TODO(stuartmorgan): Consider merging web into this common handling; the
	// fact that its implementation of Dart-only plugins and default packages
	// are separate is legacy.
	final List<String> sharedHandlingPlatforms = <String>[
	AndroidPlugin.kConfigKey,
	IOSPlugin.kConfigKey,
	LinuxPlugin.kConfigKey,
	MacOSPlugin.kConfigKey,
	WindowsPlugin.kConfigKey,
	];
	final Map<String, String> defaultPackages = <String, String>{};
	final Map<String, String> dartPluginClasses = <String, String>{};
	for (final String platform in sharedHandlingPlatforms) {
	final String? defaultPackage = _getDefaultPackageForPlatform(platformsYaml, platform);
	if (defaultPackage != null) {
	defaultPackages[platform] = defaultPackage;
	}
	final String? dartClass = _getPluginDartClassForPlatform(platformsYaml, platform);
	if (dartClass != null) {
	dartPluginClasses[platform] = dartClass;
	}
	}

	return Plugin(
	name: name,
	path: path,
	platforms: platforms,
	defaultPackagePlatforms: defaultPackages,
	pluginDartClassPlatforms: dartPluginClasses,
	flutterConstraint: flutterConstraint,
	dependencies: dependencies,
	isDirectDependency: isDirectDependency,
	implementsPackage: pluginYaml['implements'] != null ? pluginYaml['implements'] as String : '',
	);
	}

	factory Plugin._fromLegacyYaml(
	String name,
	String path,
	dynamic pluginYaml,
	VersionConstraint? flutterConstraint,
	List<String> dependencies,
	FileSystem fileSystem,
	bool isDirectDependency,
	) {
	final Map<String, PluginPlatform> platforms = <String, PluginPlatform>{};
	final String? pluginClass = (pluginYaml as Map<dynamic, dynamic>)['pluginClass'] as String?;
	if (pluginClass != null) {
	final String? androidPackage = pluginYaml['androidPackage'] as String?;
	if (androidPackage != null) {
	platforms[AndroidPlugin.kConfigKey] = AndroidPlugin(
	name: name,
	package: androidPackage,
	pluginClass: pluginClass,
	pluginPath: path,
	fileSystem: fileSystem,
	);
	}

	final String iosPrefix = pluginYaml['iosPrefix'] as String? ?? '';
	platforms[IOSPlugin.kConfigKey] =
	IOSPlugin(
	name: name,
	classPrefix: iosPrefix,
	pluginClass: pluginClass,
	);
	}
	return Plugin(
	name: name,
	path: path,
	platforms: platforms,
	defaultPackagePlatforms: <String, String>{},
	pluginDartClassPlatforms: <String, String>{},
	flutterConstraint: flutterConstraint,
	dependencies: dependencies,
	isDirectDependency: isDirectDependency,
	);
	}

	/// Create a YamlMap that represents the supported platforms.
	///
	/// For example, if the `platforms` contains 'ios' and 'android', the return map looks like:
	///
	/// android:
	/// package: io.flutter.plugins.sample
	/// pluginClass: SamplePlugin
	/// ios:
	/// pluginClass: SamplePlugin
	static YamlMap createPlatformsYamlMap(List<String> platforms, String pluginClass, String androidPackage) {
	final Map<String, dynamic> map = <String, dynamic>{};
	for (final String platform in platforms) {
	map[platform] = <String, String>{
	'pluginClass': pluginClass,
	...platform == 'android' ? <String, String>{'package': androidPackage} : <String, String>{},
	};
	}
	return YamlMap.wrap(map);
	}

	static List<String> validatePluginYaml(YamlMap? yaml) {
	if (yaml == null) {
	return <String>['Invalid "plugin" specification.'];
	}

	final bool usesOldPluginFormat = const <String>{
	'androidPackage',
	'iosPrefix',
	'pluginClass',
	}.any(yaml.containsKey);

	final bool usesNewPluginFormat = yaml.containsKey('platforms');

	if (usesOldPluginFormat && usesNewPluginFormat) {
	const String errorMessage =
	'The flutter.plugin.platforms key cannot be used in combination with the old '
	'flutter.plugin.{androidPackage,iosPrefix,pluginClass} keys. '
	'See: https://flutter.dev/docs/development/packages-and-plugins/developing-packages#plugin';
	return <String>[errorMessage];
	}

	if (!usesOldPluginFormat && !usesNewPluginFormat) {
	const String errorMessage =
	'Cannot find the `flutter.plugin.platforms` key in the `pubspec.yaml` file. '
	'An instruction to format the `pubspec.yaml` can be found here: '
	'https://flutter.dev/docs/development/packages-and-plugins/developing-packages#plugin-platforms';
	return <String>[errorMessage];
	}

	if (usesNewPluginFormat) {
	if (yaml['platforms'] != null && yaml['platforms'] is! YamlMap) {
	const String errorMessage = 'flutter.plugin.platforms should be a map with the platform name as the key';
	return <String>[errorMessage];
	}
	return _validateMultiPlatformYaml(yaml['platforms'] as YamlMap?);
	} else {
	return _validateLegacyYaml(yaml);
	}
	}

	static List<String> _validateMultiPlatformYaml(YamlMap? yaml) {
	bool isInvalid(String key, bool Function(YamlMap) validate) {
	if (!yaml!.containsKey(key)) {
	return false;
	}
	final dynamic yamlValue = yaml[key];
	if (yamlValue is! YamlMap) {
	return true;
	}
	if (yamlValue.containsKey('default_package')) {
	return false;
	}
	return !validate(yamlValue);
	}

	if (yaml == null) {
	return <String>['Invalid "platforms" specification.'];
	}
	final List<String> errors = <String>[];
	if (isInvalid(AndroidPlugin.kConfigKey, AndroidPlugin.validate)) {
	errors.add('Invalid "android" plugin specification.');
	}
	if (isInvalid(IOSPlugin.kConfigKey, IOSPlugin.validate)) {
	errors.add('Invalid "ios" plugin specification.');
	}
	if (isInvalid(LinuxPlugin.kConfigKey, LinuxPlugin.validate)) {
	errors.add('Invalid "linux" plugin specification.');
	}
	if (isInvalid(MacOSPlugin.kConfigKey, MacOSPlugin.validate)) {
	errors.add('Invalid "macos" plugin specification.');
	}
	if (isInvalid(WindowsPlugin.kConfigKey, WindowsPlugin.validate)) {
	errors.add('Invalid "windows" plugin specification.');
	}
	return errors;
	}

	static List<String> _validateLegacyYaml(YamlMap yaml) {
	final List<String> errors = <String>[];

	if (yaml['androidPackage'] != null && yaml['androidPackage'] is! String) {
	errors.add('The "androidPackage" must either be null or a string.');
	}
	if (yaml['iosPrefix'] != null && yaml['iosPrefix'] is! String) {
	errors.add('The "iosPrefix" must either be null or a string.');
	}
	if (yaml['pluginClass'] != null && yaml['pluginClass'] is! String) {
	errors.add('The "pluginClass" must either be null or a string..');
	}
	return errors;
	}

	static bool _supportsPlatform(YamlMap platformsYaml, String platformKey) {
	if (!platformsYaml.containsKey(platformKey)) {
	return false;
	}
	if (platformsYaml[platformKey] is YamlMap) {
	return true;
	}
	return false;
	}

	static String? _getDefaultPackageForPlatform(YamlMap platformsYaml, String platformKey) {
	if (!_supportsPlatform(platformsYaml, platformKey)) {
	return null;
	}
	if ((platformsYaml[platformKey] as YamlMap).containsKey(kDefaultPackage)) {
	return (platformsYaml[platformKey] as YamlMap)[kDefaultPackage] as String;
	}
	return null;
	}

	static String? _getPluginDartClassForPlatform(YamlMap platformsYaml, String platformKey) {
	if (!_supportsPlatform(platformsYaml, platformKey)) {
	return null;
	}
	if ((platformsYaml[platformKey] as YamlMap).containsKey(kDartPluginClass)) {
	return (platformsYaml[platformKey] as YamlMap)[kDartPluginClass] as String;
	}
	return null;
	}

	static bool _providesImplementationForPlatform(YamlMap platformsYaml, String platformKey) {
	if (!_supportsPlatform(platformsYaml, platformKey)) {
	return false;
	}
	if ((platformsYaml[platformKey] as YamlMap).containsKey(kDefaultPackage)) {
	return false;
	}
	return true;
	}

	final String name;
	final String path;

	/// The name of the interface package that this plugin implements.
	/// If [null], this plugin doesn't implement an interface.
	final String? implementsPackage;

	/// The required version of Flutter, if specified.
	final VersionConstraint? flutterConstraint;

	/// The name of the packages this plugin depends on.
	final List<String> dependencies;

	/// This is a mapping from platform config key to the plugin platform spec.
	final Map<String, PluginPlatform> platforms;

	/// This is a mapping from platform config key to the default package implementation.
	final Map<String, String> defaultPackagePlatforms;

	/// This is a mapping from platform config key to the plugin class for the given platform.
	final Map<String, String> pluginDartClassPlatforms;

	/// Whether this plugin is a direct dependency of the app.
	/// If [false], the plugin is a dependency of another plugin.
	final bool isDirectDependency;

	/// Expected path to the plugin's Package.swift. Returns null if the plugin
	/// does not support the [platform] or the [platform] is not iOS or macOS.
	String? pluginSwiftPackageManifestPath(
	FileSystem fileSystem,
	String platform,
	) {
	final String? platformDirectoryName = _darwinPluginDirectoryName(platform);
	if (platformDirectoryName == null) {
	return null;
	}
	return fileSystem.path.join(
	path,
	platformDirectoryName,
	name,
	'Package.swift',
	);
	}

	/// Expected path to the plugin's podspec. Returns null if the plugin does
	/// not support the [platform] or the [platform] is not iOS or macOS.
	String? pluginPodspecPath(FileSystem fileSystem, String platform) {
	final String? platformDirectoryName = _darwinPluginDirectoryName(platform);
	if (platformDirectoryName == null) {
	return null;
	}
	return fileSystem.path.join(path, platformDirectoryName, '$name.podspec');
	}

	String? _darwinPluginDirectoryName(String platform) {
	final PluginPlatform? platformPlugin = platforms[platform];
	if (platformPlugin == null \|\|
	(platform != IOSPlugin.kConfigKey &&
	platform != MacOSPlugin.kConfigKey)) {
	return null;
	}

	// iOS and macOS code can be shared in "darwin" directory, otherwise
	// respectively in "ios" or "macos" directories.
	if (platformPlugin is DarwinPlugin &&
	(platformPlugin as DarwinPlugin).sharedDarwinSource) {
	return 'darwin';
	}
	return platform;
	}
	}

	/// Metadata associated with the resolution of a platform interface of a plugin.
	class PluginInterfaceResolution {
	PluginInterfaceResolution({
	required this.plugin,
	required this.platform,
	});

	/// The plugin.
	final Plugin plugin;
	// The name of the platform that this plugin implements.
	final String platform;

	Map<String, String> toMap() {
	return <String, String> {
	'pluginName': plugin.name,
	'platform': platform,
	'dartClass': plugin.pluginDartClassPlatforms[platform] ?? '',
	};
	}

	@override
	String toString() {
	return '<PluginInterfaceResolution ${plugin.name} for $platform>';
	}
	}