Evaluate expression in context of an object

runtime/vm/compiler.cc

 // Copyright (c) 2012, 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.
 
 #include "vm/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/code_generator.h"
@@ skipping 836 matching lines @@
         !func.IsRedirectingFactory()) {
       error = CompileFunction(func);
       if (!error.IsNull()) {
         return error.raw();
       }
     }
   }
   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();
   LongJump jump;
   isolate->set_long_jump_base(&jump);
   if (setjmp(*jump.Set()) == 0) {
     if (FLAG_trace_compiler) {
       OS::Print("compiling expression: ");
       AstPrinter::PrintNode(fragment);
@@ skipping 41 matching lines @@
       Object::Handle(isolate->object_store()->sticky_error());
     isolate->object_store()->clear_sticky_error();
     isolate->set_long_jump_base(base);
     return result.raw();
   }
   UNREACHABLE();
   return Object::null();
 }
 
 }  // namespace dart