Prefix string literal must be identifier

compiler/java/com/google/dart/compiler/parser/DartParser.java

 // 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.
 
 package com.google.dart.compiler.parser;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.io.CharStreams;
 import com.google.dart.compiler.DartCompilationError;
 import com.google.dart.compiler.DartCompilerListener;
@@ skipping 344 matching lines @@
     expect(Token.LIBRARY);
     expect(Token.LPAREN);
     beginLiteral();
     expect(Token.STRING);
     DartStringLiteral libname = done(DartStringLiteral.get(ctx.getTokenString()));
     expectCloseParen();
     expect(Token.SEMICOLON);
     return new DartLibraryDirective(libname);
   }
 
+  private boolean VerifyStringIdentifier(String id) {

[mmendez, 2011/11/02 13:45:58]

Nit: VerifyString... -> verifyString...

Please add comment about why '$' is special here.

[codefu, 2011/11/02 14:32:57]

Done.

+    boolean pass = false;
+    if(id.charAt(0) == '$') {
+      pass = id.matches("[_$a-zA-Z]([_$A-Za-z0-9]*)");
+    } else {
+      pass = id.matches("[_a-zA-Z]([_A-Za-z0-9]*)");
+    }
+    return pass;
+  }
+
   private DartImportDirective parseImportDirective() {
     expect(Token.IMPORT);
     expect(Token.LPAREN);
     beginLiteral();
     expect(Token.STRING);
     DartStringLiteral libUri = done(DartStringLiteral.get(ctx.getTokenString()));
     DartStringLiteral prefix = null;
     if (optional(Token.COMMA)) {
       if (!optionalPseudoKeyword(PREFIX_KEYWORD)) {
         reportError(position(), ParserErrorCode.EXPECTED_PREFIX_KEYWORD);
       }
       expect(Token.COLON);
       beginLiteral();
       expect(Token.STRING);
+      if (!VerifyStringIdentifier(ctx.getTokenString())){
+        reportError(position(), ParserErrorCode.EXPECTED_PREFIX_IDENTIFIER);
+      }
       prefix = done(DartStringLiteral.get(ctx.getTokenString()));
     }
     expectCloseParen();
     expect(Token.SEMICOLON);
     return new DartImportDirective(libUri, prefix);
   }
 
   private DartSourceDirective parseSourceDirective() {
     expect(Token.SOURCE);
     expect(Token.LPAREN);
@@ skipping 3083 matching lines @@
     } else {
       ctx.error(dartError);
       errorHistory.add(dartError.hashCode());
     }
   }
 
   private void reportError(DartNode node, ErrorCode errorCode, Object... arguments) {
     reportError(new DartCompilationError(node, errorCode, arguments));
   }
 }