Set ContentCache for created AnalysisContext(s) to control its view of the world.

pkg/analyzer/lib/src/dart/analysis/driver.dart

Index: pkg/analyzer/lib/src/dart/analysis/driver.dart
diff --git a/pkg/analyzer/lib/src/dart/analysis/driver.dart b/pkg/analyzer/lib/src/dart/analysis/driver.dart
index ab34b86e42aa6b0181a4706a3fe2a1ad3f677a3a..5982439b2532e93fe7bd33e681f66af328332ff8 100644
--- a/pkg/analyzer/lib/src/dart/analysis/driver.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/driver.dart
@@ -20,7 +20,7 @@ import 'package:analyzer/src/dart/analysis/search.dart';
 import 'package:analyzer/src/dart/analysis/status.dart';
 import 'package:analyzer/src/dart/analysis/top_level_declaration.dart';
 import 'package:analyzer/src/generated/engine.dart'
-    show AnalysisContext, AnalysisEngine, AnalysisOptions, ChangeSet;
+    show AnalysisContext, AnalysisEngine, AnalysisOptions;
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/services/lint.dart';
 import 'package:analyzer/src/summary/api_signature.dart';
@@ -683,17 +683,6 @@ class AnalysisDriver {
       _LibraryContext libraryContext = _createLibraryContext(libraryFile);
       AnalysisContext analysisContext = _createAnalysisContext(libraryContext);
       try {
-        analysisContext.setContents(file.source, file.content);
-
-        // TODO(scheglov) Remove this.
-        // https://github.com/dart-lang/sdk/issues/28110
-        analysisContext.setContents(libraryFile.source, libraryFile.content);
-        for (FileState part in libraryFile.partedFiles) {
-          if (part.exists) {
-            analysisContext.setContents(part.source, part.content);
-          }
-        }
-
         CompilationUnit resolvedUnit = analysisContext.resolveCompilationUnit2(
             file.source, libraryFile.source);
         List<AnalysisError> errors = analysisContext.computeErrors(file.source);
@@ -761,12 +750,10 @@ class AnalysisDriver {
     AnalysisContextImpl analysisContext =
         AnalysisEngine.instance.createAnalysisContext();
     analysisContext.analysisOptions = _analysisOptions;
-
     analysisContext.sourceFactory = _sourceFactory.clone();
+    analysisContext.contentCache = new _ContentCacheWrapper(_fsState);
     analysisContext.resultProvider =
         new InputPackagesResultProvider(analysisContext, libraryContext.store);
-    analysisContext
-        .applyChanges(new ChangeSet()..addedSource(libraryContext.file.source));
     return analysisContext;
   }
 
@@ -1531,6 +1518,45 @@ class PerformanceLogSection {
 }
 
 /**
+ * [ContentCache] wrapper around [FileContentOverlay].
+ */
+class _ContentCacheWrapper implements ContentCache {
+  final FileSystemState fsState;
+
+  _ContentCacheWrapper(this.fsState);
+
+  @override
+  void accept(ContentCacheVisitor visitor) {
+    throw new UnimplementedError();
+  }
+
+  @override
+  String getContents(Source source) {
+    return _getFileForSource(source).content;
+  }
+
+  @override
+  bool getExists(Source source) {
+    return _getFileForSource(source).exists;
+  }
+
+  @override
+  int getModificationStamp(Source source) {
+    return getExists(source) ? 0 : -1;

[Paul Berry, 2017/01/04 20:50:50]

Since the contract for `getExists` says it might return `null`, it's not obvious
why this is safe.  Consider adding a quick comment here explaining that this is
safe because our override of `getExists` never returns `null`.

+  }
+
+  @override
+  String setContents(Source source, String contents) {
+    throw new UnimplementedError();
+  }
+
+  FileState _getFileForSource(Source source) {
+    String path = source.fullName;
+    return fsState.getFileForPath(path);
+  }
+}
+
+/**
  * Task that computes the list of files that were added to the driver and
  * have at least one reference to an identifier [name] defined outside of the
  * file.