[analyzer/cfe] Parse final class modifier.

Change-Id: Ia554c4f8f9617cc883a472eeb819aab2fd849077
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/278090
Reviewed-by: Johnni Winther <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Kallen Tu <[email protected]>

Author: kallentu

pkg/_fe_analyzer_shared/lib/src/parser/forwarding_listener.dart

@@ -75,6 +75,7 @@ class ForwardingListener implements Listener {
       Token? sealedToken,
       Token? baseToken,
       Token? interfaceToken,
+      Token? finalToken,
       Token? augmentToken,
       Token? mixinToken,
       Token name) {
@@ -86,6 +87,7 @@ class ForwardingListener implements Listener {
         sealedToken,
         baseToken,
         interfaceToken,
+        finalToken,
         augmentToken,
         mixinToken,
         name);
@@ -397,10 +399,16 @@ class ForwardingListener implements Listener {
   }
 
   @override
-  void beginMixinDeclaration(Token? augmentToken, Token? sealedToken,
-      Token? baseToken, Token? interfaceToken, Token mixinKeyword, Token name) {
+  void beginMixinDeclaration(
+      Token? augmentToken,
+      Token? sealedToken,
+      Token? baseToken,
+      Token? interfaceToken,
+      Token? finalToken,
+      Token mixinKeyword,
+      Token name) {
     listener?.beginMixinDeclaration(augmentToken, sealedToken, baseToken,
-        interfaceToken, mixinKeyword, name);
+        interfaceToken, finalToken, mixinKeyword, name);
   }
 
   @override
@@ -417,6 +425,7 @@ class ForwardingListener implements Listener {
       Token? sealedToken,
       Token? baseToken,
       Token? interfaceToken,
+      Token? finalToken,
       Token? augmentToken,
       Token? mixinToken,
       Token name) {
@@ -428,6 +437,7 @@ class ForwardingListener implements Listener {
         sealedToken,
         baseToken,
         interfaceToken,
+        finalToken,
         augmentToken,
         mixinToken,
         name);

pkg/_fe_analyzer_shared/lib/src/parser/listener.dart

@@ -141,6 +141,7 @@ class Listener implements UnescapeErrorListener {
       Token? sealedToken,
       Token? baseToken,
       Token? interfaceToken,
+      Token? finalToken,
       Token? augmentToken,
       Token? mixinToken,
       Token name) {}
@@ -207,6 +208,7 @@ class Listener implements UnescapeErrorListener {
       Token? sealedToken,
       Token? baseToken,
       Token? interfaceToken,
+      Token? finalToken,
       Token mixinKeyword,
       Token name) {}
 
@@ -794,6 +796,7 @@ class Listener implements UnescapeErrorListener {
       Token? sealedToken,
       Token? baseToken,
       Token? interfaceToken,
+      Token? finalToken,
       Token? augmentToken,
       Token? mixinToken,
       Token name) {}

pkg/_fe_analyzer_shared/lib/src/parser/modifier_context.dart

@@ -128,7 +128,6 @@ class ModifierContext {
       reportTopLevelModifierError(externalToken!, keyword);
     }
     reportExtraneousModifier(covariantToken);
-    reportExtraneousModifier(finalToken);
     reportExtraneousModifier(lateToken);
     reportExtraneousModifier(requiredToken);
     reportExtraneousModifier(staticToken);
@@ -160,7 +159,6 @@ class ModifierContext {
     reportTopLevelModifierError(externalToken, keyword);
     reportExtraneousModifier(abstractToken);
     reportExtraneousModifier(covariantToken);
-    reportExtraneousModifier(finalToken);
     reportExtraneousModifier(lateToken);
     reportExtraneousModifier(requiredToken);
     reportExtraneousModifier(staticToken);

pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart

@@ -528,19 +528,25 @@ class Parser {
           /* sealedToken = */ null,
           /* baseToken = */ null,
           /* interfaceToken = */ null,
+          /* finalToken = */ null,
           directiveState);
     }
     Token start = token;
+    Token? finalToken;
     // Skip modifiers to find a top level keyword or identifier
     if (next.isModifier) {
       if (optional('var', next) ||
           optional('late', next) ||
-          ((optional('const', next) || optional('final', next)) &&
-              // Ignore `const class` and `final class` so that it is reported
-              // below as an invalid modifier on a class.
+          (optional('const', next) &&
+              // Ignore `const class` so that it is reported below as an invalid
+              // modifier on a class.
               !optional('class', next.next!))) {
         directiveState?.checkDeclaration();
         return parseTopLevelMemberImpl(token);
+      } else if (optional('final', next) &&
+          (optional('class', next.next!) || optional('mixin', next.next!))) {
+        // Take note of the final class modifier while parsing modifiers.
+        finalToken = next;
       }
       while (token.next!.isModifier) {
         token = token.next!;
@@ -594,6 +600,7 @@ class Parser {
           /* sealedToken = */ sealedToken,
           /* baseToken = */ baseToken,
           /* interfaceToken = */ interfaceToken,
+          /* finalToken = */ finalToken,
           directiveState);
     } else if (next.isKeywordOrIdentifier) {
       // TODO(danrubel): improve parseTopLevelMember
@@ -634,6 +641,7 @@ class Parser {
       Token? sealedToken,
       Token? baseToken,
       Token? interfaceToken,
+      Token? finalToken,
       DirectiveContext? directiveState) {
     assert(keyword.isTopLevelKeyword);
     final String? value = keyword.stringValue;
@@ -646,6 +654,7 @@ class Parser {
           sealedToken,
           baseToken,
           interfaceToken,
+          finalToken,
           null,
           directiveState);
     } else if (identical(value, 'enum')) {
@@ -716,13 +725,14 @@ class Parser {
                 sealedToken,
                 baseToken,
                 null,
+                null,
                 keyword,
                 directiveState);
           }
           context.parseMixinModifiers(start, keyword);
           directiveState?.checkDeclaration();
           return parseMixin(context.augmentToken, sealedToken, baseToken,
-              interfaceToken, keyword);
+              interfaceToken, finalToken, keyword);
         } else if (identical(value, 'extension')) {
           context.parseTopLevelKeywordModifiers(start, keyword);
           directiveState?.checkDeclaration();
@@ -755,6 +765,7 @@ class Parser {
       Token? sealedToken,
       Token? baseToken,
       Token? interfaceToken,
+      Token? finalToken,
       Token? mixinToken,
       DirectiveContext? directiveState) {
     directiveState?.checkDeclaration();
@@ -773,6 +784,7 @@ class Parser {
         sealedToken,
         baseToken,
         interfaceToken,
+        finalToken,
         augmentToken,
         mixinToken,
         classKeyword);
@@ -2534,6 +2546,7 @@ class Parser {
       Token? sealedToken,
       Token? baseToken,
       Token? interfaceToken,
+      Token? finalToken,
       Token? augmentToken,
       Token? mixinToken,
       Token classKeyword) {
@@ -2557,6 +2570,7 @@ class Parser {
           sealedToken,
           baseToken,
           interfaceToken,
+          finalToken,
           augmentToken,
           mixinToken,
           name);
@@ -2570,6 +2584,7 @@ class Parser {
           sealedToken,
           baseToken,
           interfaceToken,
+          finalToken,
           augmentToken,
           mixinToken,
           name);
@@ -2791,10 +2806,10 @@ class Parser {
   ///        '{' [ClassMember]* '}'
   /// ;
   ///
-  /// mixinModifiers: 'sealed' | 'base' | 'interface'
+  /// mixinModifiers: 'sealed' | 'base' | 'interface' | 'final'
   /// ```
   Token parseMixin(Token? augmentToken, Token? sealedToken, Token? baseToken,
-      Token? interfaceToken, Token mixinKeyword) {
+      Token? interfaceToken, Token? finalToken, Token mixinKeyword) {
     assert(optional('mixin', mixinKeyword));
     listener.beginClassOrMixinOrNamedMixinApplicationPrelude(mixinKeyword);
     Token name = ensureIdentifier(
@@ -2803,7 +2818,7 @@ class Parser {
             name, /* inDeclaration = */ true, /* allowsVariance = */ true)
         .parseVariables(name, this);
     listener.beginMixinDeclaration(augmentToken, sealedToken, baseToken,
-        interfaceToken, mixinKeyword, name);
+        interfaceToken, finalToken, mixinKeyword, name);
     Token token = parseMixinHeaderOpt(headerStart, mixinKeyword);
     if (!optional('{', token.next!)) {
       // Recovery

pkg/analyzer/lib/src/dart/ast/ast.dart

@@ -1823,7 +1823,7 @@ class ChildEntity {
 ///        '{' [ClassMember]* '}'
 ///
 ///    classModifiers ::= 'sealed'
-///      | 'abstract' ('base' | 'interface')?
+///      | 'abstract' ('base' | 'interface' | 'final')?
 ///      | 'abstract'? 'base'? 'mixin'
 ///
 class ClassDeclarationImpl extends NamedCompilationUnitMemberImpl
@@ -1848,6 +1848,9 @@ class ClassDeclarationImpl extends NamedCompilationUnitMemberImpl
   /// The 'interface' keyword, or `null` if the keyword was absent.
   final Token? interfaceKeyword;
 
+  /// The 'final' keyword, or `null` if the keyword was absent.
+  final Token? finalKeyword;
+
   /// The 'augment' keyword, or `null` if the keyword was absent.
   final Token? augmentKeyword;
 
@@ -1909,6 +1912,7 @@ class ClassDeclarationImpl extends NamedCompilationUnitMemberImpl
     required this.sealedKeyword,
     required this.baseKeyword,
     required this.interfaceKeyword,
+    required this.finalKeyword,
     required this.augmentKeyword,
     required this.mixinKeyword,
     required this.classKeyword,
@@ -1956,6 +1960,7 @@ class ClassDeclarationImpl extends NamedCompilationUnitMemberImpl
         sealedKeyword ??
         baseKeyword ??
         interfaceKeyword ??
+        finalKeyword ??
         augmentKeyword ??
         mixinKeyword ??
         classKeyword;
@@ -2000,6 +2005,7 @@ class ClassDeclarationImpl extends NamedCompilationUnitMemberImpl
     ..addToken('sealedKeyword', sealedKeyword)
     ..addToken('baseKeyword', baseKeyword)
     ..addToken('interfaceKeyword', interfaceKeyword)
+    ..addToken('finalKeyword', finalKeyword)
     ..addToken('augmentKeyword', augmentKeyword)
     ..addToken('mixinKeyword', mixinKeyword)
     ..addToken('classKeyword', classKeyword)
@@ -2046,7 +2052,7 @@ abstract class ClassMemberImpl extends DeclarationImpl implements ClassMember {
 ///        mixinApplication
 ///
 ///    classModifiers ::= 'sealed'
-///      | 'abstract' ('base' | 'interface')?
+///      | 'abstract' ('base' | 'interface' | 'final')?
 ///      | 'abstract'? 'base'? 'mixin'
 ///
 ///    mixinApplication ::=
@@ -2086,6 +2092,10 @@ class ClassTypeAliasImpl extends TypeAliasImpl implements ClassTypeAlias {
   /// an interface class.
   final Token? interfaceKeyword;
 
+  /// The token for the 'final' keyword, or `null` if this is not defining a
+  /// final class.
+  final Token? finalKeyword;
+
   /// The token for the 'augment' keyword, or `null` if this is not defining an
   /// augmentation class.
   final Token? augmentKeyword;
@@ -2126,6 +2136,7 @@ class ClassTypeAliasImpl extends TypeAliasImpl implements ClassTypeAlias {
     required this.sealedKeyword,
     required this.baseKeyword,
     required this.interfaceKeyword,
+    required this.finalKeyword,
     required this.augmentKeyword,
     required this.mixinKeyword,
     required NamedTypeImpl superclass,
@@ -2154,6 +2165,7 @@ class ClassTypeAliasImpl extends TypeAliasImpl implements ClassTypeAlias {
         sealedKeyword ??
         baseKeyword ??
         interfaceKeyword ??
+        finalKeyword ??
         augmentKeyword ??
         mixinKeyword ??
         typedefKeyword;
@@ -2199,6 +2211,7 @@ class ClassTypeAliasImpl extends TypeAliasImpl implements ClassTypeAlias {
     ..addToken('sealedKeyword', sealedKeyword)
     ..addToken('baseKeyword', baseKeyword)
     ..addToken('interfaceKeyword', interfaceKeyword)
+    ..addToken('finalKeyword', finalKeyword)
     ..addToken('augmentKeyword', augmentKeyword)
     ..addToken('mixinKeyword', mixinKeyword)
     ..addNode('superclass', superclass)
@@ -9023,7 +9036,7 @@ class MethodInvocationImpl extends InvocationExpressionImpl
 ///        [TypeParameterList]? [RequiresClause]? [ImplementsClause]?
 ///        '{' [ClassMember]* '}'
 ///
-///    mixinModifiers ::= 'sealed' | 'base' | 'interface'
+///    mixinModifiers ::= 'sealed' | 'base' | 'interface' | 'final'
 class MixinDeclarationImpl extends NamedCompilationUnitMemberImpl
     implements MixinDeclaration {
   /// Return the 'augment' keyword, or `null` if the keyword was absent.
@@ -9039,6 +9052,9 @@ class MixinDeclarationImpl extends NamedCompilationUnitMemberImpl
   /// Return the 'interface' keyword, or `null` if the keyword was absent.
   final Token? interfaceKeyword;
 
+  /// Return the 'final' keyword, or `null` if the keyword was absent.
+  final Token? finalKeyword;
+
   @override
   final Token mixinKeyword;
 
@@ -9082,6 +9098,7 @@ class MixinDeclarationImpl extends NamedCompilationUnitMemberImpl
     required this.sealedKeyword,
     required this.baseKeyword,
     required this.interfaceKeyword,
+    required this.finalKeyword,
     required this.mixinKeyword,
     required super.name,
     required TypeParameterListImpl? typeParameters,
@@ -9108,7 +9125,11 @@ class MixinDeclarationImpl extends NamedCompilationUnitMemberImpl
 
   @override
   Token get firstTokenAfterCommentAndMetadata {
-    return sealedKeyword ?? baseKeyword ?? interfaceKeyword ?? mixinKeyword;
+    return sealedKeyword ??
+        baseKeyword ??
+        interfaceKeyword ??
+        finalKeyword ??
+        mixinKeyword;
   }
 
   @override
@@ -9140,6 +9161,7 @@ class MixinDeclarationImpl extends NamedCompilationUnitMemberImpl
     ..addToken('sealedKeyword', sealedKeyword)
     ..addToken('baseKeyword', baseKeyword)
     ..addToken('interfaceKeyword', interfaceKeyword)
+    ..addToken('finalKeyword', finalKeyword)
     ..addToken('mixinKeyword', mixinKeyword)
     ..addToken('name', name)
     ..addNode('typeParameters', typeParameters)