Add validation of private symbols to the dart2js mirrors.

sdk/lib/internal/symbol.dart

 // Copyright (c) 2013, 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.
 
 part of dart._internal;
 
 /**
  * Implementation of [core.Symbol].  This class uses the same name as
  * a core class so a user can't tell the difference.
  *
  * The purpose of this class is to hide [_name] from user code, but
  * make it accessible to Dart platform code via the static method
  * [getName].
  */
 class Symbol implements core.Symbol {
   final String _name;
 
   // Reserved words are not allowed as identifiers.

[ahe, 2014/02/24 10:43:23]

How about turning these comments into proper documentation comments?

[Lasse Reichstein Nielsen, 2014/03/03 12:58:44]

Done.

   static const String reservedWordRE =
       r'(?:assert|break|c(?:a(?:se|tch)|lass|on(?:st|tinue))|d(?:efault|o)|'
       r'e(?:lse|num|xtends)|f(?:alse|inal(?:ly)?|or)|i[fns]|n(?:ew|ull)|'
       r'ret(?:hrow|urn)|s(?:uper|witch)|t(?:h(?:is|row)|r(?:ue|y))|'
       r'v(?:ar|oid)|w(?:hile|ith))';
-  // Mathces a public identifier (identifier not starting with '_').
+  // Matches a public identifier (identifier not starting with '_').
   static const String publicIdentifierRE =
       r'(?!' '$reservedWordRE' r'\b(?!\$))[a-zA-Z$][\w$]*';
+  // Matches a public or private identifier.

[ahe, 2014/02/24 10:43:23]

I suggest:

/// Matches an identifier (public or private).

[Lasse Reichstein Nielsen, 2014/03/03 12:58:44]

rewritten.

+  static const String identifierRE =
+      r'(?!' '$reservedWordRE' r'\b(?!\$))[a-zA-Z$_][\w$]*';
   // Matches the names of declarable operators.
   static const String operatorRE =
       r'(?:[\-+*/%&|^]|\[\]=?|==|~/?|<[<=]?|>[>=]?|unary-)';
 
   // Grammar:
   //    symbol ::= qualifiedName | <empty>
   //    qualifiedName ::= publicIdentifier '.' qualifiedName | name
   //    name ::= publicIdentifier
   //           | publicIdentifier '='
   //           | operator
@@ skipping 10 matching lines @@
   //       \                     /
   //        \------[operator]---/
   //            \              /
   //             \------------/
   //
 
   // Validates non-empty symbol (empty symbol is handled before using this).
   static final RegExp validationPattern = new RegExp(
       '^(?:$operatorRE\$|$publicIdentifierRE(?:=?\$|[.](?!\$)))+?\$');
 
+  static final RegExp privateValidationPattern = new RegExp(

[ahe, 2014/02/24 10:43:23]

This name is slightly confusing: this doesn't validate that something is
private.

How about this rename:

validationPattern -> nonPrivateValidationPattern.
privateValidationPattern -> validationPattern.

[Lasse Reichstein Nielsen, 2014/03/03 12:58:44]

Changed to publicSymbolPattern and symbolPattern.

+      '^(?:$operatorRE\$|$identifierRE(?:=?\$|[.](?!\$)))+?\$');
+
   external const Symbol(String name);
 
   /**
    * Platform-private method used by the mirror system to create
    * otherwise invalid names.
    */
   const Symbol.unvalidated(this._name);
 
   // This is called by dart2js.
   Symbol.validated(String name)
@@ skipping 15 matching lines @@
     if (name.isEmpty || validationPattern.hasMatch(name)) return name;
     if (name.startsWith('_')) {
       // There may be other private parts in a qualified name than the first
       // one, but this is a common case that deserves a specific error
       // message.
       throw new ArgumentError('"$name" is a private identifier');
     }
     throw new ArgumentError(
         '"$name" is not a valid (qualified) symbol name');
   }
+
+  static String validatePrivate(String name) {
+    if (name.isEmpty || privateValidationPattern.hasMatch(name)) return name;
+    if (name.startsWith('_')) {
+      // There may be other private parts in a qualified name than the first
+      // one, but this is a common case that deserves a specific error
+      // message.
+      throw new ArgumentError('"$name" is a private identifier');
+    }
+    throw new ArgumentError(
+        '"$name" is not a valid (qualified) symbol name');
+  }
 }