Library prefix should be an identifier

vm/parser.cc

 // Copyright (c) 2011, 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.
 
 #include "vm/parser.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/compiler_stats.h"
@@ skipping 3144 matching lines @@
       if ((CurrentToken() != Token::kIDENT) ||
           !kPrefix.Equals(*CurrentLiteral())) {
         ErrorMsg("prefix: expected");
       }
       ConsumeToken();
       ExpectToken(Token::kCOLON);
       if (CurrentToken() != Token::kSTRING) {
         ErrorMsg("prefix expected");
       }
       prefix = CurrentLiteral()->raw();
+      // Canonicalize the prefix string, this also simplifies the string.
+      prefix = String::NewSymbol(prefix);

[hausner, 2011/11/21 21:58:10]

The scanner already makes a symbol out of a string literal. In other words,

#import("/foo.dart", prefix: "foo");

"foo" is already a symbol, no need to call NewSymbol again.

[siva, 2011/11/21 22:14:28]

Done.

+      // TODO(asiva): Need to also check that prefix is not a reserved keyword.
+      if (!Scanner::IsIdent(prefix)) {
+        ErrorMsg("prefix should be an identifier");
+      }
       ConsumeToken();
     }
     ExpectToken(Token::kRPAREN);
     ExpectToken(Token::kSEMICOLON);
     Dart_Handle handle = CallLibraryTagHandler(kCanonicalizeUrl,
                                                import_pos,
                                                url);
     const String& canon_url = String::CheckedHandle(Api::UnwrapHandle(handle));
     // Lookup the library URL.
     Library& library = Library::Handle(Library::LookupLibrary(canon_url));
     if (library.IsNull()) {
       // Create a new library object and call the library tag handler.
       library = Library::New(canon_url);
       library.Register();
       // The tag handler expects the importing library as a parameter.
       CallLibraryTagHandler(kImportTag, import_pos, canon_url);
     }
     // Add the import to the library.
     if (prefix.IsNull() || (prefix.Length() == 0)) {
       library_.AddImport(library);
     } else {
       if (library_.LookupLocalObject(prefix) != Object::null()) {
         ErrorMsg(token_index_, "'%s' is already defined", prefix.ToCString());
       }
-      prefix = String::NewSymbol(prefix);
       const LibraryPrefix& library_prefix =
           LibraryPrefix::Handle(LibraryPrefix::New(prefix, library));
       library_.AddObject(library_prefix, prefix);
     }
   }
 }
 
 
 void Parser::ParseLibraryInclude() {
   while (CurrentToken() == Token::kSOURCE) {
@@ skipping 4229 matching lines @@
 }
 
 
 void Parser::SkipNestedExpr() {
   const bool saved_mode = SetAllowFunctionLiterals(true);
   SkipExpr();
   SetAllowFunctionLiterals(saved_mode);
 }
 
 }  // namespace dart