Migrate most of debugging/metadata and loaders directories to null safety (#1659)

* Removed dependecies on dwds.dart inside dwds code

* Migrate loaders and debugging/metadata directories to null safety

* Add format errors

* Removed unnecessary 'late' from metadata fields

* Format

* Fix failing test

* Addressed CR comments

* Relax some require API to allow nulls, fix test failures

Author: Anna Gringauze

dwds/lib/src/debugging/metadata/function.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.import 'dart:async';
 
-// @dart = 2.9
-
 import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart';
 
 import '../../loaders/strategy.dart';
@@ -43,8 +41,9 @@ class FunctionMetaData {
       response,
       evalContents: evalExpression,
     );
-    var name = response.result['result']['value'] as String;
-    if (name.isEmpty) name = 'Closure';
+    final name = response.result?['result']?['value'] as String?;
+    if (name == null) return FunctionMetaData('<unknown>');
+    if (name.isEmpty) return FunctionMetaData('Closure');
     return FunctionMetaData(name);
   }
 }

dwds/lib/src/debugging/metadata/module_metadata.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 /// Module metadata format version
 ///
 /// Module reader always creates the current version but is able to read
@@ -77,10 +75,9 @@ class LibraryMetadata {
   LibraryMetadata(this.name, this.importUri, this.partUris);
 
   LibraryMetadata.fromJson(Map<String, dynamic> json)
-      : name = json['name'] as String,
-        importUri = json['importUri'] as String,
-        partUris =
-            List.castFrom<dynamic, String>(json['partUris'] as List<dynamic>);
+      : name = _readRequiredField(json, 'name'),
+        importUri = _readRequiredField(json, 'importUri'),
+        partUris = _readOptionalList(json, 'partUris') ?? [];
 
   Map<String, dynamic> toJson() {
     return {
@@ -98,7 +95,7 @@ class LibraryMetadata {
 /// See: https://goto.google.com/dart-web-debugger-metadata
 class ModuleMetadata {
   /// Metadata format version
-  String version;
+  late final String version;
 
   /// Module name
   ///
@@ -125,8 +122,8 @@ class ModuleMetadata {
 
   ModuleMetadata(this.name, this.closureName, this.sourceMapUri, this.moduleUri,
       this.soundNullSafety,
-      {this.version}) {
-    version ??= ModuleMetadataVersion.current.version;
+      {String? ver}) {
+    version = ver ?? ModuleMetadataVersion.current.version;
   }
 
   /// Add [library] to metadata
@@ -145,12 +142,12 @@ class ModuleMetadata {
   }
 
   ModuleMetadata.fromJson(Map<String, dynamic> json)
-      : version = json['version'] as String,
-        name = json['name'] as String,
-        closureName = json['closureName'] as String,
-        sourceMapUri = json['sourceMapUri'] as String,
-        moduleUri = json['moduleUri'] as String,
-        soundNullSafety = (json['soundNullSafety'] as bool) ?? false {
+      : version = _readRequiredField(json, 'version'),
+        name = _readRequiredField(json, 'name'),
+        closureName = _readRequiredField(json, 'closureName'),
+        sourceMapUri = _readRequiredField(json, 'sourceMapUri'),
+        moduleUri = _readRequiredField(json, 'moduleUri'),
+        soundNullSafety = _readOptionalField(json, 'soundNullSafety') ?? false {
     if (!ModuleMetadataVersion.current.isCompatibleWith(version) &&
         !ModuleMetadataVersion.previous.isCompatibleWith(version)) {
       throw Exception('Unsupported metadata version $version. '
@@ -159,7 +156,7 @@ class ModuleMetadata {
           '\n    ${ModuleMetadataVersion.previous.version}');
     }
 
-    for (var l in json['libraries'] as List<dynamic>) {
+    for (var l in _readRequiredList(json, 'libraries')) {
       addLibrary(LibraryMetadata.fromJson(l as Map<String, dynamic>));
     }
   }
@@ -176,3 +173,23 @@ class ModuleMetadata {
     };
   }
 }
+
+T _readRequiredField<T>(Map<String, dynamic> json, String field) {
+  if (!json.containsKey(field)) {
+    throw FormatException('Required field $field is not set in $json');
+  }
+  return json[field]! as T;
+}
+
+T? _readOptionalField<T>(Map<String, dynamic> json, String field) =>
+    json[field] as T?;
+
+List<T> _readRequiredList<T>(Map<String, dynamic> json, String field) {
+  final list = _readRequiredField<List<dynamic>>(json, field);
+  return List.castFrom<dynamic, T>(list);
+}
+
+List<T>? _readOptionalList<T>(Map<String, dynamic> json, String field) {
+  final list = _readOptionalField<List<dynamic>>(json, field);
+  return list == null ? null : List.castFrom<dynamic, T>(list);
+}

dwds/lib/src/debugging/metadata/provider.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.import 'dart:async';
 
-// @dart = 2.9
-
 import 'dart:async';
 import 'dart:convert';
 
@@ -194,8 +192,7 @@ class MetadataProvider {
           _addSdkMetadata();
           for (var contents in merged.split('\n')) {
             try {
-              if (contents == null ||
-                  contents.isEmpty ||
+              if (contents.isEmpty ||
                   contents.startsWith('// intentionally empty:')) continue;
               final moduleJson = json.decode(contents);
               final metadata =
@@ -237,7 +234,7 @@ class MetadataProvider {
       for (var path in library.partUris) {
         // Parts in metadata are relative to the library Uri directory.
         final partPath = p.url.join(p.dirname(library.importUri), path);
-        _scripts[library.importUri].add(partPath);
+        _scripts[library.importUri]!.add(partPath);
         _scriptToModule[partPath] = metadata.name;
       }
     }

dwds/lib/src/handlers/injector.dart

@@ -123,7 +123,10 @@ class DwdsInjector {
             return response.change(body: body, headers: newHeaders);
           } else {
             final loadResponse = await _loadStrategy.handler(request);
-            if (loadResponse != null) return loadResponse;
+            if (loadResponse != null &&
+                loadResponse.statusCode != HttpStatus.notFound) {
+              return loadResponse;
+            }
             return innerHandler(request);
           }
         };

dwds/lib/src/loaders/build_runner_require.dart

@@ -2,11 +2,10 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:convert';
 import 'dart:io';
 
+import 'package:logging/logging.dart';
 import 'package:path/path.dart' as p;
 import 'package:shelf/shelf.dart';
 
@@ -18,26 +17,28 @@ import 'require.dart';
 
 /// Provides a [RequireStrategy] suitable for use with `package:build_runner`.
 class BuildRunnerRequireStrategyProvider {
+  final _logger = Logger('BuildRunnerRequireStrategyProvider');
+
   final Handler _assetHandler;
   final ReloadConfiguration _configuration;
   final AssetReader _assetReader;
 
-  RequireStrategy _requireStrategy;
+  late final RequireStrategy _requireStrategy = RequireStrategy(
+    _configuration,
+    _moduleProvider,
+    _digestsProvider,
+    _moduleForServerPath,
+    _serverPathForModule,
+    _sourceMapPathForModule,
+    _serverPathForAppUri,
+    _moduleInfoForProvider,
+    _assetReader,
+  );
 
   BuildRunnerRequireStrategyProvider(
       this._assetHandler, this._configuration, this._assetReader);
 
-  RequireStrategy get strategy => _requireStrategy ??= RequireStrategy(
-        _configuration,
-        _moduleProvider,
-        _digestsProvider,
-        _moduleForServerPath,
-        _serverPathForModule,
-        _sourceMapPathForModule,
-        _serverPathForAppUri,
-        _moduleInfoForProvider,
-        _assetReader,
-      );
+  RequireStrategy get strategy => _requireStrategy;
 
   Future<Map<String, String>> _digestsProvider(
       MetadataProvider metadataProvider) async {
@@ -51,9 +52,18 @@ class BuildRunnerRequireStrategyProvider {
       throw StateError('Could not read digests at path: $digestsPath');
     }
     final body = await response.readAsString();
+    final digests = json.decode(body) as Map<String, dynamic>;
+
+    for (final key in digests.keys) {
+      if (!modules.containsKey(key)) {
+        _logger.warning('Digest key $key is not a module name.');
+      }
+    }
+
     return {
-      for (var entry in (json.decode(body) as Map<String, dynamic>).entries)
-        modules[entry.key]: entry.value as String,
+      for (var entry in digests.entries)
+        if (modules.containsKey(entry.key))
+          modules[entry.key]!: entry.value as String,
     };
   }
 
@@ -62,10 +72,17 @@ class BuildRunnerRequireStrategyProvider {
       (await metadataProvider.moduleToModulePath).map((key, value) =>
           MapEntry(key, stripTopLevelDirectory(removeJsExtension(value))));
 
-  Future<String> _moduleForServerPath(
-          MetadataProvider metadataProvider, String serverPath) async =>
-      (await metadataProvider.modulePathToModule).map((key, value) => MapEntry(
-          stripTopLevelDirectory(key), value))[relativizePath(serverPath)];
+  Future<String?> _moduleForServerPath(
+      MetadataProvider metadataProvider, String serverPath) async {
+    final modulePathToModule = await metadataProvider.modulePathToModule;
+    final relativePath = relativizePath(serverPath);
+    for (var e in modulePathToModule.entries) {
+      if (stripTopLevelDirectory(e.key) == relativePath) {
+        return e.value;
+      }
+    }
+    return null;
+  }
 
   Future<String> _serverPathForModule(
       MetadataProvider metadataProvider, String module) async {
@@ -80,7 +97,7 @@ class BuildRunnerRequireStrategyProvider {
     return stripTopLevelDirectory(path);
   }
 
-  String _serverPathForAppUri(String appUri) {
+  String? _serverPathForAppUri(String appUri) {
     if (appUri.startsWith('org-dartlang-app:')) {
       // We skip the root from which we are serving.
       return Uri.parse(appUri).pathSegments.skip(1).join('/');

dwds/lib/src/loaders/frontend_server_require.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:path/path.dart' as p;
 
 import '../debugging/metadata/provider.dart';
@@ -19,22 +17,22 @@ class FrontendServerRequireStrategyProvider {
   final Future<Map<String, String>> Function() _digestsProvider;
   final String _basePath;
 
-  RequireStrategy _requireStrategy;
+  late final RequireStrategy _requireStrategy = RequireStrategy(
+    _configuration,
+    _moduleProvider,
+    (_) => _digestsProvider(),
+    _moduleForServerPath,
+    _serverPathForModule,
+    _sourceMapPathForModule,
+    _serverPathForAppUri,
+    _moduleInfoForProvider,
+    _assetReader,
+  );
 
   FrontendServerRequireStrategyProvider(this._configuration, this._assetReader,
       this._digestsProvider, this._basePath);
 
-  RequireStrategy get strategy => _requireStrategy ??= RequireStrategy(
-        _configuration,
-        _moduleProvider,
-        (_) => _digestsProvider(),
-        _moduleForServerPath,
-        _serverPathForModule,
-        _sourceMapPathForModule,
-        _serverPathForAppUri,
-        _moduleInfoForProvider,
-        _assetReader,
-      );
+  RequireStrategy get strategy => _requireStrategy;
 
   String _removeBasePath(String path) {
     if (_basePath.isEmpty) return path;
@@ -43,20 +41,20 @@ class FrontendServerRequireStrategyProvider {
     return path.startsWith(base) ? path.substring(base.length) : path;
   }
 
-  String _addBasePath(String serverPath) =>
-      _basePath == null || _basePath.isEmpty
-          ? relativizePath(serverPath)
-          : '$_basePath/${relativizePath(serverPath)}';
+  String _addBasePath(String serverPath) => _basePath.isEmpty
+      ? relativizePath(serverPath)
+      : '$_basePath/${relativizePath(serverPath)}';
 
   Future<Map<String, String>> _moduleProvider(
           MetadataProvider metadataProvider) async =>
       (await metadataProvider.moduleToModulePath).map((key, value) =>
           MapEntry(key, relativizePath(removeJsExtension(value))));
 
-  Future<String> _moduleForServerPath(
+  Future<String?> _moduleForServerPath(
       MetadataProvider metadataProvider, String serverPath) async {
     final modulePathToModule = await metadataProvider.modulePathToModule;
-    return modulePathToModule[_removeBasePath(serverPath)];
+    final relativeServerPath = _removeBasePath(serverPath);
+    return modulePathToModule[relativeServerPath];
   }
 
   Future<String> _serverPathForModule(
@@ -67,7 +65,7 @@ class FrontendServerRequireStrategyProvider {
           MetadataProvider metadataProvider, String module) async =>
       _addBasePath((await metadataProvider.moduleToSourceMap)[module] ?? '');
 
-  String _serverPathForAppUri(String appUri) {
+  String? _serverPathForAppUri(String appUri) {
     if (appUri.startsWith('org-dartlang-app:')) {
       return _addBasePath(Uri.parse(appUri).path);
     }
@@ -79,7 +77,7 @@ class FrontendServerRequireStrategyProvider {
     final modules = await metadataProvider.moduleToModulePath;
     final result = <String, ModuleInfo>{};
     for (var module in modules.keys) {
-      final modulePath = modules[module];
+      final modulePath = modules[module]!;
       result[module] = ModuleInfo(
           // TODO: Save locations of full kernel files in ddc metadata.
           // Issue: https://github.com/dart-lang/sdk/issues/43684

dwds/lib/src/loaders/legacy.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:shelf/shelf.dart';
 
 import '../debugging/metadata/provider.dart';
@@ -61,7 +59,7 @@ class LegacyStrategy extends LoadStrategy {
   ///
   /// Will return `null` if the provided uri is not
   /// an app URI.
-  final String Function(String appUri) _serverPathForAppUri;
+  final String? Function(String appUri) _serverPathForAppUri;
 
   LegacyStrategy(
     this.reloadConfiguration,
@@ -74,7 +72,7 @@ class LegacyStrategy extends LoadStrategy {
   ) : super(assetReader);
 
   @override
-  Handler get handler => (request) => null;
+  Handler get handler => (request) => Response.notFound(request.url);
 
   @override
   String get id => 'legacy';
@@ -121,5 +119,5 @@ class LegacyStrategy extends LoadStrategy {
       _sourceMapPathForModule(metadataProviderFor(entrypoint), module);
 
   @override
-  String serverPathForAppUri(String appUri) => _serverPathForAppUri(appUri);
+  String? serverPathForAppUri(String appUri) => _serverPathForAppUri(appUri);
 }