Add validation of private symbols to the dart2js mirrors.

sdk/lib/_internal/lib/mirrors_patch.dart

Index: sdk/lib/_internal/lib/mirrors_patch.dart
diff --git a/sdk/lib/_internal/lib/mirrors_patch.dart b/sdk/lib/_internal/lib/mirrors_patch.dart
index 71c1e68c7b55a3538910eddf6f628846c16b738d..518277ad7a8689372749b7aab9635070cc2dba18 100644
--- a/sdk/lib/_internal/lib/mirrors_patch.dart
+++ b/sdk/lib/_internal/lib/mirrors_patch.dart
@@ -5,12 +5,37 @@
 // Patch library for dart:mirrors.
 
 import 'dart:_js_mirrors' as js;
+import 'dart:_internal' as internal show Symbol;
 
 patch class MirrorSystem {
   patch static String getName(Symbol symbol) => js.getName(symbol);
 
   patch static Symbol getSymbol(String name, [LibraryMirror library]) {

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

Could you move this code to a top-level in _js_mirrors? Generally, I think that
the less code you have in patch files, the easier it is to understand what is
going on. Also, you reduce the number of imports of dart:_internal.

I failed to point this out when reflectClass and reflectType were changed.

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

Done.

-    throw new UnimplementedError("MirrorSystem.getSymbol not implemented");
+    if (_isPublicSymbol(name)) {
+      return new internal.Symbol.validated(name);
+    }
+    if (library == null) {
+      throw new ArgumentError(
+          "Library required for private symbol name: $name");
+    }
+    if (!internal.Symbol.validatePrivate(name)) {
+      throw new ArgumentError("Not a valid symbol name: $name");
+    }
+    throw new UnimplementedError(
+        "MirrorSystem.getSymbol not implemented for private names");
+  }
+
+  static bool _isPublicSymbol(String name) {
+    // A symbol is public if it doesn't start with '_' and it doesn't
+    // have a part (following a '.') that starts with '_'.
+    const int UNDERSCORE = 0x5f;
+    if (name.isEmpty) return true;
+    int index = -1;
+    do {
+      if (name.codeUnitAt(index + 1) == UNDERSCORE) return false;
+      index = name.indexOf('.', index + 1);
+    } while (index >= 0 && index + 1 < name.length);
+    return true;
   }
 }