support class native clause

pkg/analyzer/lib/src/fasta/ast_builder.dart

Index: pkg/analyzer/lib/src/fasta/ast_builder.dart
diff --git a/pkg/analyzer/lib/src/fasta/ast_builder.dart b/pkg/analyzer/lib/src/fasta/ast_builder.dart
index 7580511ad0e7d1d44dadacb5129acc57205adbaa..359712b9e4f4b056a4bfa63dbc33e9cd08088375 100644
--- a/pkg/analyzer/lib/src/fasta/ast_builder.dart
+++ b/pkg/analyzer/lib/src/fasta/ast_builder.dart
@@ -31,6 +31,10 @@ import 'package:front_end/src/fasta/source/scope_listener.dart'
 import 'package:analyzer/src/dart/error/syntactic_errors.dart';
 
 class AstBuilder extends ScopeListener {
+  /// The native clause in class, method, and function declarations
+  /// is being replaced by the @native(...) annotation.
+  static bool isNativeClauseAllowed = true;

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

I think this should only be true if:

* The current library is a platform library.

* The current library has an import that uses the scheme "dart-ext".

Those two properties could be left as a todo.

More importantly, this shouldn't be a static field and I've added a suggestion
for how to avoid that in parser_fasta_test.dart.

[danrubel, 2017/08/22 01:35:27]

Good point. Cleaned up and added TODO per discussion.

+
   final AstFactory ast = standard.astFactory;
 
   final ErrorReporter errorReporter;
@@ -1284,9 +1288,14 @@ class AstBuilder extends ScopeListener {
       Token classKeyword,
       Token extendsKeyword,
       Token implementsKeyword,
+      Token nativeToken,
       Token endToken) {
     debugEvent("ClassDeclaration");
     _ClassBody body = pop();
+    NativeClause nativeClause;
+    if (nativeToken?.next?.type == TokenType.STRING) {

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

This feels like implementing parser logic in the listener.

What I would expect is this:

if (nativeToken != null) {
  nativeClause = pop();
}

[danrubel, 2017/08/22 01:35:27]

I was trying for the simplest thing given that this functionality will be
replaced by @native(...) in future. That said, I like your suggestion of adding
a new nativeClause event. With that new event, this expression reverts back to
the simple null check that I previously had.

+      nativeClause = ast.nativeClause(nativeToken, pop());
+    }
     ImplementsClause implementsClause;
     if (implementsKeyword != null) {
       List<TypeName> interfaces = popList(interfacesCount);
@@ -1314,7 +1323,7 @@ class AstBuilder extends ScopeListener {
     Token abstractKeyword = modifiers?.abstractKeyword;
     List<Annotation> metadata = pop();
     Comment comment = pop();
-    declarations.add(ast.classDeclaration(
+    ClassDeclaration classDeclaration = ast.classDeclaration(
         comment,
         metadata,
         abstractKeyword,
@@ -1326,7 +1335,9 @@ class AstBuilder extends ScopeListener {
         implementsClause,
         body.beginToken,
         body.members,
-        body.endToken));
+        body.endToken);
+    classDeclaration.nativeClause = nativeClause;
+    declarations.add(classDeclaration);
   }
 
   @override
@@ -1891,6 +1902,14 @@ class AstBuilder extends ScopeListener {
         errorReporter?.reportErrorForOffset(
             ParserErrorCode.EXPECTED_TYPE_NAME, charOffset, 1);
         return;
+      case "NATIVE_CLAUSE_SHOULD_BE_ANNOTATION":
+        if (!isNativeClauseAllowed) {
+          errorReporter?.reportErrorForOffset(
+              ParserErrorCode.NATIVE_CLAUSE_SHOULD_BE_ANNOTATION,
+              charOffset,
+              1);
+        }
+        return;
       case "EXPECTED_STRING_LITERAL":
         errorReporter?.reportErrorForOffset(
             ParserErrorCode.EXPECTED_STRING_LITERAL, charOffset, 1);