Add validation of private symbols to the dart2js mirrors.

sdk/lib/internal/symbol.dart

Index: sdk/lib/internal/symbol.dart
diff --git a/sdk/lib/internal/symbol.dart b/sdk/lib/internal/symbol.dart
index 338b06b0b7e5930cc7f2f756134afbb6f2d11b8b..08fb6b302fa7916b7445ef0297fd101282f58b8c 100644
--- a/sdk/lib/internal/symbol.dart
+++ b/sdk/lib/internal/symbol.dart
@@ -21,9 +21,12 @@ class Symbol implements core.Symbol {
       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-)';
@@ -54,6 +57,9 @@ class Symbol implements core.Symbol {
   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);
 
   /**
@@ -89,4 +95,16 @@ class Symbol implements core.Symbol {
     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');
+  }
 }