Evaluate expression in context of an object

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
===================================================================
--- runtime/vm/compiler.cc	(revision 26007)
+++ runtime/vm/compiler.cc	(working copy)
@@ -854,7 +854,57 @@
   return error.raw();
 }
 
+static RawPatchClass* MakeTempPatchClass(const Class& cls,
+                                         const String& expr) {
+  String& src = String::Handle(String::New("() => "));
+  src = String::Concat(src, expr);
+  src = String::Concat(src, Symbols::Semicolon());
+  Script& script = Script::Handle();
+  script = Script::New(Symbols::Empty(), src, RawScript::kSourceTag);
+  // In order to tokenize the source, we need to get the key to mangle
+  // private names from the library from which the object's class
+  // originates.
+  const Library& lib = Library::Handle(cls.library());
+  ASSERT(!lib.IsNull());
+  const String& lib_key = String::Handle(lib.private_key());
+  script.Tokenize(lib_key);
 
+  const String& src_class_name = String::Handle(Symbols::New(":internal"));
+  const Class& src_class = Class::Handle(
+      Class::New(src_class_name, script, Scanner::kDummyTokenIndex));
+  src_class.set_is_finalized();
+  src_class.set_library(lib);
+  return PatchClass::New(cls, src_class);
+}
+
+
+RawObject* Compiler::Evaluate(const Instance& obj, const String& expr) {

[hausner, 2013/08/14 23:54:09]

Should this functionality be here in class Compiler or should it move somewhere
else?

[Ivan Posva, 2013/08/19 21:32:18]

Could you add Evaluate on the Instance C++ class? Once we start supporting
evaluation in the context of a class or library then we could add Evaluate there
as well.

[hausner, 2013/08/19 22:47:38]

Done.

+  const Class& obj_cls = Class::Handle(obj.clazz());
+  const PatchClass& temp_class =
+      PatchClass::Handle(MakeTempPatchClass(obj_cls, expr));
+  const String& eval_func_name = String::Handle(Symbols::New(":eval"));
+  const Function& eval_func =
+      Function::Handle(Function::New(eval_func_name,
+                                     RawFunction::kRegularFunction,
+                                     false,  // Not static.
+                                     false,  // Not const.
+                                     false,  // Not abstract.
+                                     false,  // Not external.
+                                     temp_class,
+                                     0));
+  eval_func.set_result_type(Type::Handle(Type::DynamicType()));
+  eval_func.set_num_fixed_parameters(1);
+  eval_func.SetNumOptionalParameters(0, true);
+  eval_func.set_is_optimizable(false);
+
+  const Array& args = Array::Handle(Array::New(1));
+  args.SetAt(0, obj);
+  const Object& result =
+      Object::Handle(DartEntry::InvokeFunction(eval_func, args));
+  return result.raw();
+}
+
+
 RawObject* Compiler::ExecuteOnce(SequenceNode* fragment) {
   Isolate* isolate = Isolate::Current();
   LongJump* base = isolate->long_jump_base();