- Add functionality to morph a string into an external string

vm/dart_api_impl.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 "include/dart_api.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart.h"
@@ skipping 1689 matching lines @@
   intptr_t str_len = str_obj.Length();
   intptr_t copy_len = (str_len > *length) ? *length : str_len;
   for (intptr_t i = 0; i < copy_len; i++) {
     utf16_array[i] = static_cast<uint16_t>(str_obj.CharAt(i));
   }
   *length = copy_len;
   return Api::Success(isolate);
 }
 
 
+DART_EXPORT Dart_Handle Dart_MakeExternalString(Dart_Handle str,
+                                                void* array,
+                                                intptr_t length,
+                                                void* peer,
+                                                Dart_PeerFinalizer cback) {
+  Isolate* isolate = Isolate::Current();
+  DARTSCOPE(isolate);
+  const String& str_obj = Api::UnwrapStringHandle(isolate, str);
+  if (str_obj.IsNull() || str_obj.IsExternal()) {
+    RETURN_TYPE_ERROR(isolate, str, String);

[Tom Ball, 2012/11/07 00:38:43]

Is passing in an external string necessarily an error?  The original handle
could instead be returned.

[siva, 2012/11/07 21:43:27]

Yes we could.

Does that make sense however, it seems like a lot of code
to return back the same handle. I am wondering if the
embedder code would prefer knowing when this happens.

On 2012/11/07 00:38:43, Tom Ball wrote:

+  }
+  if (array == NULL) {
+    RETURN_NULL_ERROR(array);
+  }
+  intptr_t str_length = (str_obj.Length() * str_obj.CharSize());
+  if ((length < str_length) || (length > String::kMaxElements)) {
+    return Api::NewError("Dart_MakeExternalString "
+                         "expects argument length to be in the range"
+                         "[%"Pd"..%"Pd"].",
+                         str_length, String::kMaxElements);
+  }
+  return Api::NewHandle(isolate,
+                        str_obj.MakeExternal(array, length, peer, cback));
+}
+
+
 // --- Lists ---
 
 
 static RawInstance* GetListInstance(Isolate* isolate, const Object& obj) {
   if (obj.IsInstance()) {
     const Instance& instance = Instance::Cast(obj);
     const Type& type =
         Type::Handle(isolate, isolate->object_store()->list_interface());
     Error& malformed_type_error = Error::Handle(isolate);
     if (instance.IsInstanceOf(type,
@@ skipping 2724 matching lines @@
   }
   {
     NoGCScope no_gc;
     RawObject* raw_obj = obj.raw();
     isolate->heap()->SetPeer(raw_obj, peer);
   }
   return Api::Success(isolate);
 }
 
 }  // namespace dart