support class native clause

pkg/front_end/lib/src/fasta/parser/parser.dart

 // Copyright (c) 2012, 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.
 
 library fasta.parser.parser;
 
 import '../fasta_codes.dart' show Code, Message, Template;
 
 import '../fasta_codes.dart' as fasta;
 
@@ skipping 839 matching lines @@
     }
     Token implementsKeyword;
     int interfacesCount = 0;
     if (optional('implements', token)) {
       implementsKeyword = token;
       do {
         token = parseType(token.next);
         ++interfacesCount;
       } while (optional(',', token));
     }
+    Token nativeToken;
+    if (optional('native', token)) {
+      nativeToken = token;
+      token = parseNativeClause(token.next);
+      reportRecoverableError(
+          nativeToken, fasta.messageNativeClauseShouldBeAnnotation);
+    }
     token = parseClassBody(token);
     listener.endClassDeclaration(interfacesCount, begin, classKeyword,
-        extendsKeyword, implementsKeyword, token);
+        extendsKeyword, implementsKeyword, nativeToken, token);
     return token.next;
   }
 
   Token parseStringPart(Token token) {
     if (token.kind != STRING_TOKEN) {
       token =
           reportUnrecoverableErrorWithToken(token, fasta.templateExpectedString)
               .next;
     }
     listener.handleStringPart(token);
@@ skipping 1225 matching lines @@
 
     typeContinuation ??=
         (isVarAllowed || memberKind == MemberKind.GeneralizedFunctionType)
             ? TypeContinuation.Required
             : TypeContinuation.Optional;
 
     token = parseType(token, typeContinuation, null, memberKind);
     return token;
   }
 
+  Token parseNativeClause(Token token) {
+    if (!identical(token.kind, STRING_TOKEN)) return token;

[ahe, 2017/08/21 12:04:10]

We don't need to use identical on token.kind.

[danrubel, 2017/08/22 01:35:28]

Good point. Fixed.

+    return parseSingleLiteralString(token);

[ahe, 2017/08/21 12:04:10]

We should generate an event here. I'm thinking something like this:

Token parseNativeClause(Token token) {
  listener.beginNativeClause(token);
  bool hasName = false;
  if (STRING_TOKEN == token.kind) {
    hasName = true;
    token = parseLiteralString(token);
  }
  listener.endNativeClause(token, hasName);
  return token;
}

[danrubel, 2017/08/22 01:35:28]

Good point. Per discussion I've added a handleNativeClause(token, hasName)
instead. That makes the listeners a bit cleaner and clearer than my current
implementation and should make adding support for native clauses on methods and
functions a bit easier.

+  }
+
   Token skipClassBody(Token token) {
     if (!optional('{', token)) {
       return reportUnrecoverableErrorWithToken(
               token, fasta.templateExpectedClassBodyToSkip)
           .next;
     }
     Token closeBrace = closeBraceTokenFor(token);
     if (closeBrace == null ||
         !identical(closeBrace.kind, $CLOSE_CURLY_BRACKET)) {
       return reportUnmatchedToken(token).next;
@@ skipping 1947 matching lines @@
   }
 
   Token reportUnexpectedToken(Token token) {
     return reportUnrecoverableErrorWithToken(
         token, fasta.templateUnexpectedToken);
   }
 }
 
 // TODO(ahe): Remove when analyzer supports generalized function syntax.
 typedef _MessageWithArgument<T> = Message Function(T);