Implement external strings.

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index 3c2932efc6c7995b21660180e8142758adb1fb3e..1e2c3417ed67875965eb14896b66dd6ff3b8fc9d 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -723,17 +723,55 @@ DART_EXPORT Dart_Handle Dart_NewString32(const uint32_t* codepoints,
                                          intptr_t length) {
   Zone zone;  // Setup a VM zone as we are creating some handles.
   HandleScope scope;  // Setup a VM handle scope.
-  UNIMPLEMENTED();
   const String& obj = String::Handle(String::New(codepoints, length));
   return Api::NewLocalHandle(obj);
 }
 
 
+DART_EXPORT Dart_Handle Dart_NewExternalString8(
+    uint8_t* codepoints,
+    intptr_t length,
+    Dart_ExternalString8Finalizer finalizer) {
+  Zone zone;  // Setup a VM zone as we are creating some handles.
+  HandleScope scope;  // Setup a VM handle scope.
+  const String& obj =
+      String::Handle(
+          ExternalOneByteString::New(codepoints, length, finalizer));
+  return Api::NewLocalHandle(obj);
+}
+
+
+DART_EXPORT Dart_Handle Dart_NewExternalString16(
+    uint16_t* codepoints,
+    intptr_t length,
+    Dart_ExternalString16Finalizer finalizer) {
+  Zone zone;  // Setup a VM zone as we are creating some handles.
+  HandleScope scope;  // Setup a VM handle scope.
+  const String& obj =
+        String::Handle(
+          ExternalTwoByteString::New(codepoints, length, finalizer));
+  return Api::NewLocalHandle(obj);
+}
+
+
+DART_EXPORT Dart_Handle Dart_NewExternalString32(
+    uint32_t* codepoints,
+    intptr_t length,
+    Dart_ExternalString32Finalizer finalizer) {
+  Zone zone;  // Setup a VM zone as we are creating some handles.
+  HandleScope scope;  // Setup a VM handle scope.
+  const String& obj =
+      String::Handle(
+          ExternalFourByteString::New(codepoints, length, finalizer));
+  return Api::NewLocalHandle(obj);
+}
+
+
 DART_EXPORT bool Dart_IsString8(Dart_Handle object) {
   Zone zone;  // Setup a VM zone as we are creating some handles.
   HandleScope scope;  // Setup a VM handle scope.
   const Object& obj = Object::Handle(Api::UnwrapHandle(object));
-  return obj.IsOneByteString();
+  return obj.IsOneByteString() || obj.IsExternalOneByteString();
 }
 
 
@@ -741,7 +779,8 @@ DART_EXPORT bool Dart_IsString16(Dart_Handle object) {
   Zone zone;  // Setup a VM zone as we are creating some handles.
   HandleScope scope;  // Setup a VM handle scope.
   const Object& obj = Object::Handle(Api::UnwrapHandle(object));
-  return obj.IsOneByteString() || obj.IsTwoByteString();
+  return (obj.IsOneByteString() || obj.IsExternalOneByteString() ||
+          obj.IsTwoByteString() || obj.IsExternalOneByteString());
 }