Add minimal AnalysisDriverModel implementation (#3814)

* Make `resolver_test.dart` test `AnalysisDriverModel` exactly like it
tests `BuildAssetUriResolver`.

Add minimal implementation to `AnalysisDriverModel` to make the tests pass.

Add TODOs where there is functionality not covered by tests that is
therefore not added.

* Address review comments.

* Address review comments.

build_resolvers/CHANGELOG.md

@@ -1,7 +1,8 @@
 ## 2.4.4-wip
 
 - Refactor `BuildAssetUriResolver` into `AnalysisDriverModel` and
-  `AnalysisDriverModelUriResolver`.
+  `AnalysisDriverModelUriResolver`. Add new implementation of
+  `AnalysisDriverModel`.
 
 ## 2.4.3
 

build_resolvers/lib/src/analysis_driver_model.dart

@@ -3,11 +3,17 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:collection';
 
+import 'package:analyzer/dart/analysis/utilities.dart';
+import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 // ignore: implementation_imports
 import 'package:analyzer/src/clients/build_resolvers/build_resolvers.dart';
 import 'package:build/build.dart';
+import 'package:path/path.dart' as p;
+
+import 'analysis_driver_model_uri_resolver.dart';
 
 /// Manages analysis driver and related build state.
 ///
@@ -19,36 +25,145 @@ import 'package:build/build.dart';
 /// - Maintains an in-memory filesystem that is the analyzer's view of the
 ///   build.
 /// - Notifies the analyzer of changes to that in-memory filesystem.
-abstract class AnalysisDriverModel {
+///
+/// TODO(davidmorgan): the implementation here is unfinished and not used
+/// anywhere; finish it. See `build_asset_uri_resolver.dart` for the current
+/// implementation.
+class AnalysisDriverModel {
   /// In-memory filesystem for the analyzer.
-  abstract final MemoryResourceProvider resourceProvider;
+  final MemoryResourceProvider resourceProvider =
+      MemoryResourceProvider(context: p.posix);
 
   /// Notifies that [step] has completed.
   ///
   /// All build steps must complete before [reset] is called.
-  void notifyComplete(BuildStep step);
+  void notifyComplete(BuildStep step) {
+    // TODO(davidmorgan): add test coverage, fix implementation.
+  }
 
   /// Clear cached information specific to an individual build.
-  void reset();
+  void reset() {
+    // TODO(davidmorgan): add test coverage, fix implementation.
+  }
 
   /// Attempts to parse [uri] into an [AssetId] and returns it if it is cached.
   ///
   /// Handles 'package:' or 'asset:' URIs, as well as 'file:' URIs of the form
   /// `/$packageName/$assetPath`.
   ///
-  /// Returns null if the Uri cannot be parsed or is not cached.
-  AssetId? lookupCachedAsset(Uri uri);
+  /// Returns null if the `Uri` cannot be parsed or is not cached.
+  AssetId? lookupCachedAsset(Uri uri) {
+    final assetId = AnalysisDriverModelUriResolver.parseAsset(uri);
+    // TODO(davidmorgan): not clear if this is the right "exists" check.
+    if (assetId == null || !resourceProvider.getFile(assetId.asPath).exists) {
+      return null;
+    }
+
+    return assetId;
+  }
 
   /// Updates [resourceProvider] and the analysis driver given by
   /// `withDriverResource`  with updated versions of [entryPoints].
   ///
   /// If [transitive], then all the transitive imports from [entryPoints] are
   /// also updated.
+  ///
+  /// Notifies [buildStep] of all inputs that result from analysis. If
+  /// [transitive], this includes all transitive dependencies.
+  ///
+  /// If while finding transitive deps a `.transitive_deps` file is
+  /// encountered next to a source file then this cuts off the reporting
+  /// of deps to the [buildStep], but does not affect the reporting of
+  /// files to the analysis driver.
   Future<void> performResolve(
       BuildStep buildStep,
       List<AssetId> entryPoints,
       Future<void> Function(
               FutureOr<void> Function(AnalysisDriverForPackageBuild))
           withDriverResource,
-      {required bool transitive});
+      {required bool transitive}) async {
+    /// TODO(davidmorgan): add test coverage for whether transitive
+    /// sources are read when [transitive] is false, fix the implementation
+    /// here.
+    /// TODO(davidmorgan): add test coverage for whether
+    /// `.transitive_deps` files cut off the reporting of deps to the
+    /// [buildStep], fix the implementation here.
+
+    // Find transitive deps, this also informs [buildStep] of all inputs).
+    final ids = await _expandToTransitive(buildStep, entryPoints);
+
+    // Apply changes to in-memory filesystem.
+    for (final id in ids) {
+      if (await buildStep.canRead(id)) {
+        final content = await buildStep.readAsString(id);
+
+        /// TODO(davidmorgan): add test coverage for when a file is
+        /// modified rather than added, fix the implementation here.
+        resourceProvider.newFile(id.asPath, content);
+      } else {
+        if (resourceProvider.getFile(id.asPath).exists) {
+          resourceProvider.deleteFile(id.asPath);
+        }
+      }
+    }
+
+    // Notify the analyzer of changes.
+    await withDriverResource((driver) async {
+      for (final id in ids) {
+        // TODO(davidmorgan): add test coverage for over-notification of
+        // changes, fix the implementaion here.
+        driver.changeFile(id.asPath);
+      }
+      await driver.applyPendingFileChanges();
+    });
+  }
+
+  /// Walks the import graph from [ids], returns full transitive deps.
+  Future<Set<AssetId>> _expandToTransitive(
+      AssetReader reader, Iterable<AssetId> ids) async {
+    final result = ids.toSet();
+    final nextIds = Queue.of(ids);
+    while (nextIds.isNotEmpty) {
+      final nextId = nextIds.removeFirst();
+
+      // Skip if not readable. Note that calling `canRead` still makes it a
+      // dependency of the `BuildStep`.
+      if (!await reader.canRead(nextId)) continue;
+
+      final content = await reader.readAsString(nextId);
+      final deps = _parseDependencies(content, nextId);
+
+      // For each dep, if it's not in `result` yet, it's newly-discovered:
+      // add it to `nextIds`.
+      for (final dep in deps) {
+        if (result.add(dep)) {
+          nextIds.add(dep);
+        }
+      }
+    }
+    return result;
+  }
+}
+
+const _ignoredSchemes = ['dart', 'dart-ext'];
+
+/// Parses Dart source in [content], returns all depedencies: all assets
+/// mentioned in directives, excluding `dart:` and `dart-ext` schemes.
+List<AssetId> _parseDependencies(String content, AssetId from) =>
+    parseString(content: content, throwIfDiagnostics: false)
+        .unit
+        .directives
+        .whereType<UriBasedDirective>()
+        .map((directive) => directive.uri.stringValue)
+        // Uri.stringValue can be null for strings that use interpolation.
+        .nonNulls
+        .where(
+          (uriContent) => !_ignoredSchemes.any(Uri.parse(uriContent).isScheme),
+        )
+        .map((content) => AssetId.resolve(Uri.parse(content), from: from))
+        .toList();
+
+extension _AssetIdExtensions on AssetId {
+  /// Asset path for the in-memory filesystem.
+  String get asPath => AnalysisDriverModelUriResolver.assetPath(this);
 }

build_resolvers/lib/src/analysis_driver_model_uri_resolver.dart

@@ -67,6 +67,7 @@ class AnalysisDriverModelUriResolver implements UriResolver {
     return null;
   }
 
+  /// Path of [assetId] for the in-memory filesystem.
   static String assetPath(AssetId assetId) =>
       p.posix.join('/${assetId.package}', assetId.path);
 }

build_resolvers/lib/src/resolver.dart

@@ -412,16 +412,15 @@ class AnalyzerResolvers implements Resolvers {
     AnalysisOptions? analysisOptions,
     Future<String> Function()? sdkSummaryGenerator,
     PackageConfig? packageConfig,
-  }) {
-    final buildAssetUriResolver = BuildAssetUriResolver();
-    return AnalyzerResolvers._(
-        analysisOptions: analysisOptions,
-        sdkSummaryGenerator: sdkSummaryGenerator,
-        packageConfig: packageConfig,
-        // Custom resolvers get their own asset uri resolver, as there should
-        // always be a 1:1 relationship between them.
-        analysisDriverModel: buildAssetUriResolver);
-  }
+    AnalysisDriverModel? analysisDriverModel,
+  }) =>
+      AnalyzerResolvers._(
+          analysisOptions: analysisOptions,
+          sdkSummaryGenerator: sdkSummaryGenerator,
+          packageConfig: packageConfig,
+          // Custom resolvers get their own asset uri resolver by default as
+          // there should always be a 1:1 relationship between them.
+          analysisDriverModel: analysisDriverModel ?? BuildAssetUriResolver());
 
   /// See [AnalyzerResolvers.custom] for docs.
   @Deprecated('Use either the AnalyzerResolvers.custom constructor or the '