CQ. Scan from strings and drop scanner reader shim.

Remove the analyzer-only `scanner/reader.dart` re-export and refactor
`Scanner` to accept source text directly.

* Delete `pkg/analyzer/src/dart/scanner/reader.dart`, which only re-exported
  `_fe_analyzer_shared` reader types.
* Replace the `Scanner(CharacterReader, ...)` factory with
  `Scanner(String contents, ...)`, aligning the API with the underlying
  `scanString` implementation.
* Update analyzer, analysis_server, analyzer_cli, analyzer_plugin, and scrape
  call sites to pass the source string directly instead of constructing
  `CharSequenceReader`.

This removes an unnecessary abstraction layer, reduces
imports/indirection, and makes scanner usage simpler and more uniform
across the repo.

Change-Id: I380b365676c8a62971a3700deadb695d1519d653
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/477600
Reviewed-by: Paul Berry <paulberry@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analysis_server/lib/src/g3/utilities.dart

@@ -13,7 +13,6 @@ import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/source/line_info.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
 import 'package:analyzer/src/dart/analysis/results.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/generated/parser.dart' as p;
 import 'package:analyzer/src/string_source.dart';
@@ -54,13 +53,12 @@ ParseStringResult sortDirectives(String contents, {String? fileName}) {
 }) {
   var source = StringSource(contents, fullName);
   var diagnosticListener = RecordingDiagnosticListener();
-  var reader = CharSequenceReader(contents);
   var featureSet = FeatureSet.fromEnableFlags2(
     sdkLanguageVersion: ExperimentStatus.currentVersion,
     flags: [],
   );
   var diagnosticReporter = DiagnosticReporter(diagnosticListener, source);
-  var scanner = Scanner(reader, diagnosticReporter)
+  var scanner = Scanner(contents, diagnosticReporter)
     ..configureFeatures(
       featureSetForOverriding: FeatureSet.latestLanguageVersion(),
       featureSet: featureSet,

pkg/analysis_server/lib/src/lsp/source_edits.dart

@@ -15,7 +15,6 @@ import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/source/line_info.dart';
 import 'package:analyzer/source/source.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart' as plugin;
 import 'package:dart_style/dart_style.dart' hide TrailingCommas;
@@ -701,7 +700,7 @@ class _MinimalEditComputer {
     try {
       var scanner =
           Scanner(
-            CharSequenceReader(s),
+            s,
             DiagnosticReporter(
               DiagnosticListener.nullListener,
               _SourceMock.instance,

pkg/analysis_server/lib/src/services/correction/statement_analyzer.dart

@@ -14,7 +14,6 @@ import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/source/source.dart';
 import 'package:analyzer/source/source_range.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer_plugin/utilities/range_factory.dart';
 
@@ -25,7 +24,7 @@ List<Token> _getTokens(String text, FeatureSet featureSet) {
     var tokens = <Token>[];
     var scanner =
         Scanner(
-          CharSequenceReader(text),
+          text,
           DiagnosticReporter(
             DiagnosticListener.nullListener,
             _SourceMock.instance,

pkg/analysis_server/test/stress/replay/replay.dart

@@ -14,7 +14,6 @@ import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/error/listener.dart' as error;
 import 'package:analyzer/source/line_info.dart';
 import 'package:analyzer/source/source.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/util/file_paths.dart' as file_paths;
 import 'package:analyzer/src/util/glob.dart';
@@ -226,7 +225,7 @@ class Driver {
     var featureSet = FeatureSet.latestLanguageVersion();
     var scanner =
         Scanner(
-          CharSequenceReader(text),
+          text,
           error.DiagnosticReporter(
             error.DiagnosticListener.nullListener,
             _TestSource(),

pkg/analysis_server_plugin/lib/edit/correction_utils.dart

@@ -13,7 +13,6 @@ import 'package:analyzer/source/source.dart';
 import 'package:analyzer/source/source_range.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
 import 'package:analyzer/src/dart/ast/extensions.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/utilities/extensions/string.dart';
 import 'package:analyzer_plugin/src/utilities/string_utilities.dart';
@@ -459,7 +458,7 @@ class TokenUtils {
       var tokens = <Token>[];
       var scanner =
           Scanner(
-            CharSequenceReader(s),
+            s,
             DiagnosticReporter(DiagnosticListener.nullListener, _SourceMock()),
           )..configureFeatures(
             featureSetForOverriding: featureSet,

pkg/analyzer/lib/dart/analysis/utilities.dart

@@ -16,7 +16,6 @@ import 'package:analyzer/file_system/physical_file_system.dart';
 import 'package:analyzer/source/line_info.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
 import 'package:analyzer/src/dart/analysis/results.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/generated/parser.dart';
 import 'package:analyzer/src/string_source.dart';
@@ -82,10 +81,9 @@ ParseStringResult parseString({
 }) {
   featureSet ??= FeatureSet.latestLanguageVersion();
   var source = StringSource(content, path ?? '');
-  var reader = CharSequenceReader(content);
   var diagnosticCollector = RecordingDiagnosticListener();
   var diagnosticReporter = DiagnosticReporter(diagnosticCollector, source);
-  var scanner = Scanner(reader, diagnosticReporter)
+  var scanner = Scanner(content, diagnosticReporter)
     ..configureFeatures(
       featureSetForOverriding: featureSet,
       featureSet: featureSet,

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

@@ -30,7 +30,6 @@ import 'package:analyzer/src/dart/analysis/unlinked_api_signature.dart';
 import 'package:analyzer/src/dart/analysis/unlinked_data.dart';
 import 'package:analyzer/src/dart/analysis/unlinked_unit_store.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/dartdoc/dartdoc_directive_info.dart';
 import 'package:analyzer/src/exception/exception.dart';
@@ -581,9 +580,8 @@ class FileState {
     return performance.run('parseCode', (performance) {
       performance.getDataInt('length').add(code.length);
 
-      CharSequenceReader reader = CharSequenceReader(code);
       var diagnosticReporter = DiagnosticReporter(diagnosticListener, source);
-      Scanner scanner = Scanner(reader, diagnosticReporter)
+      Scanner scanner = Scanner(code, diagnosticReporter)
         ..configureFeatures(
           featureSetForOverriding: featureSet,
           featureSet: featureSet.restrictToVersion(packageLanguageVersion),

pkg/analyzer/lib/src/dart/scanner/reader.dart

@@ -1,8 +0,0 @@
-// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
-// 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.
-
-export 'package:_fe_analyzer_shared/src/scanner/reader.dart'
-    show CharacterReader, CharSequenceReader, SubSequenceReader;
-
-/// This file is intentionally left blank except for exports.

pkg/analyzer/lib/src/dart/scanner/scanner.dart

@@ -11,7 +11,6 @@ import 'package:_fe_analyzer_shared/src/scanner/token.dart'
 import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/source/source.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/translate_error_token.dart'
     show translateErrorToken;
 import 'package:analyzer/src/diagnostic/diagnostic.dart' as diag;
@@ -62,18 +61,11 @@ class Scanner {
 
   late FeatureSet _featureSet;
 
-  /// Initialize a newly created scanner to scan characters from the given
-  /// [source]. The given character [reader] will be used to read the characters
-  /// in the source. The given [diagnosticReporter] will be informed of any
-  /// errors that are found.
-  factory Scanner(
-    CharacterReader reader,
-    DiagnosticReporter diagnosticReporter,
-  ) => Scanner.fasta(
-    diagnosticReporter,
-    contents: reader.getContents(),
-    offset: reader.offset,
-  );
+  /// Initializes a scanner to scan the given [contents].
+  ///
+  /// The [diagnosticReporter] will be informed of any errors that are found.
+  factory Scanner(String contents, DiagnosticReporter diagnosticReporter) =>
+      Scanner.fasta(diagnosticReporter, contents: contents);
 
   factory Scanner.fasta(
     DiagnosticReporter diagnosticReporter, {

pkg/analyzer/test/generated/scanner_test.dart

@@ -7,7 +7,6 @@ import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/source/line_info.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/string_source.dart';
 import 'package:analyzer_testing/resource_provider_mixin.dart';
@@ -76,13 +75,11 @@ class LineInfoTest {
     String source = "var\r\ni\n=\n1;\n";
     GatheringDiagnosticListener listener = GatheringDiagnosticListener();
     Scanner scanner =
-        Scanner(
-          CharSequenceReader(source),
-          DiagnosticReporter(listener, TestSource()),
-        )..configureFeatures(
-          featureSetForOverriding: featureSet,
-          featureSet: featureSet,
-        );
+        Scanner(source, DiagnosticReporter(listener, TestSource()))
+          ..configureFeatures(
+            featureSetForOverriding: featureSet,
+            featureSet: featureSet,
+          );
     var token = scanner.tokenize();
     expect(token.lexeme, 'var');
     var lineStarts = scanner.lineStarts;
@@ -96,13 +93,11 @@ class LineInfoTest {
     String source = '<!-- @Component(';
     GatheringDiagnosticListener listener = GatheringDiagnosticListener();
     Scanner scanner =
-        Scanner(
-          CharSequenceReader(source),
-          DiagnosticReporter(listener, TestSource()),
-        )..configureFeatures(
-          featureSetForOverriding: featureSet,
-          featureSet: featureSet,
-        );
+        Scanner(source, DiagnosticReporter(listener, TestSource()))
+          ..configureFeatures(
+            featureSetForOverriding: featureSet,
+            featureSet: featureSet,
+          );
     Token token = scanner.tokenize(reportScannerErrors: false);
     expect(token, TypeMatcher<UnmatchedToken>());
     token = token.next!;
@@ -139,13 +134,11 @@ class LineInfoTest {
 
   Token _scanWithListener(String source, GatheringDiagnosticListener listener) {
     Scanner scanner =
-        Scanner(
-          CharSequenceReader(source),
-          DiagnosticReporter(listener, TestSource()),
-        )..configureFeatures(
-          featureSetForOverriding: featureSet,
-          featureSet: featureSet,
-        );
+        Scanner(source, DiagnosticReporter(listener, TestSource()))
+          ..configureFeatures(
+            featureSetForOverriding: featureSet,
+            featureSet: featureSet,
+          );
     Token result = scanner.tokenize();
     LineInfo lineInfo = LineInfo(scanner.lineStarts);
     listener.setLineInfo(TestSource(), lineInfo);
@@ -201,9 +194,8 @@ class ScannerTest with ResourceProviderMixin {
   Scanner _createScanner(String content) {
     var path = convertPath('/test/lib/a.dart');
     var source = StringSource(content, path);
-    var reader = CharSequenceReader(content);
     var diagnosticCollector = RecordingDiagnosticListener();
-    return Scanner(reader, DiagnosticReporter(diagnosticCollector, source));
+    return Scanner(content, DiagnosticReporter(diagnosticCollector, source));
   }
 }
 

pkg/analyzer/test/src/dart/ast/parse_base.dart

@@ -9,7 +9,6 @@ import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/source/file_source.dart';
 import 'package:analyzer/source/line_info.dart';
 import 'package:analyzer/src/clients/build_resolvers/build_resolvers.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/generated/parser.dart';
 import 'package:analyzer_testing/resource_provider_mixin.dart';
@@ -27,9 +26,8 @@ class ParseBase with ResourceProviderMixin {
 
     var diagnosticListener = RecordingDiagnosticListener();
 
-    var reader = CharSequenceReader(content);
     var diagnosticReporter = DiagnosticReporter(diagnosticListener, source);
-    var scanner = Scanner(reader, diagnosticReporter)
+    var scanner = Scanner(content, diagnosticReporter)
       ..configureFeatures(
         featureSetForOverriding: featureSet,
         featureSet: featureSet,

pkg/analyzer_cli/tool/perf.dart

@@ -19,7 +19,6 @@ import 'package:analyzer/source/line_info.dart';
 import 'package:analyzer/source/source.dart';
 import 'package:analyzer/src/context/packages.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/dart/sdk/sdk.dart' show FolderBasedDartSdk;
 import 'package:analyzer/src/file_system/file_system.dart';
@@ -234,7 +233,7 @@ ScannerResult tokenize(Source source) {
   // first converting to String?
   var scanner =
       Scanner(
-          CharSequenceReader(contents),
+          contents,
           DiagnosticReporter(DiagnosticListener.nullListener, source),
         )
         ..configureFeatures(

pkg/scrape/lib/scrape.dart

@@ -13,7 +13,6 @@ import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/source/line_info.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
-import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/generated/parser.dart';
 import 'package:analyzer/src/string_source.dart';
@@ -275,11 +274,10 @@ class Scrape {
     var featureSet = FeatureSet.latestLanguageVersion();
 
     // Tokenize the source.
-    var reader = CharSequenceReader(source);
     var stringSource = StringSource(source, file.path);
     var diagnosticReporter =
         DiagnosticReporter(diagnosticListener, stringSource);
-    var scanner = Scanner(reader, diagnosticReporter);
+    var scanner = Scanner(source, diagnosticReporter);
     scanner.configureFeatures(
         featureSet: featureSet, featureSetForOverriding: featureSet);
     var startToken = scanner.tokenize();