[dart2js] new-rti: Implement general As/Check methods

rakudrama · commit-bot@chromium.org · commit 18ff5ce893e2 · 2019-07-02T00:49:20.000Z
TBR=fishythefish@google.com Change-Id: Ib2ac75dd3787401129a8b7420c60d59013d80f21 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107824 Reviewed-by: Stephen Adams <sra@google.com> Commit-Queue: Stephen Adams <sra@google.com>
diff --git a/sdk/lib/_internal/js_runtime/lib/rti.dart b/sdk/lib/_internal/js_runtime/lib/rti.dart
@@ -335,21 +335,30 @@ bool _generalIsTestImplementation(object) {
 
 /// Called from generated code.
 _generalAsCheckImplementation(object) {
+  if (object == null) return object;
   // This static method is installed on an Rti object as a JavaScript instance
   // method. The Rti object is 'this'.
   Rti testRti = _castToRti(JS('', 'this'));
-  throw UnimplementedError(
-      '${Error.safeToString(object)} as ${_rtiToString(testRti, null)}');
+  Rti objectRti = instanceType(object);
+  if (isSubtype(_theUniverse(), objectRti, testRti)) return object;
+  var message = "${Error.safeToString(object)}:"
+      " type '${_rtiToString(objectRti, null)}'"
+      " is not a subtype of type '${_rtiToString(testRti, null)}'";
+  throw new _CastError.fromMessage('CastError: $message');
 }
 
 /// Called from generated code.
 _generalTypeCheckImplementation(object) {
+  if (object == null) return object;
   // This static method is installed on an Rti object as a JavaScript instance
   // method. The Rti object is 'this'.
   Rti testRti = _castToRti(JS('', 'this'));
-  throw UnimplementedError(
-      '${Error.safeToString(object)} as ${_rtiToString(testRti, null)}'
-      ' (TypeError)');
+  Rti objectRti = instanceType(object);
+  if (isSubtype(_theUniverse(), objectRti, testRti)) return object;
+  var message = "${Error.safeToString(object)}:"
+      " type '${_rtiToString(objectRti, null)}'"
+      " is not a subtype of type '${_rtiToString(testRti, null)}'";
+  throw new _TypeError.fromMessage('TypeError: $message');
 }
 
 /// Called from generated code.
@@ -361,6 +370,14 @@ checkTypeBound(Rti type, Rti bound, variable) {
   throw _TypeError.fromMessage('TypeError: $message');
 }
 
+class _CastError extends Error implements CastError {
+  final String message;
+  _CastError.fromMessage(this.message);
+
+  @override
+  String toString() => message;
+}
+
 class _TypeError extends Error implements TypeError {
   final String message;
   _TypeError.fromMessage(this.message);
