Add native extensions for the Dart shell to mac and windows

runtime/bin/extensions_win.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 <stdio.h>
+
 #include "bin/extensions.h"
+#include "bin/dartutils.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 
 Dart_Handle Extensions::LoadExtension(const char* extension_url,
                                       Dart_Handle parent_library) {
-  UNIMPLEMENTED();
-  return NULL;
+  ASSERT(DartUtils::IsDartExtensionSchemeURL(extension_url));
+  fprintf(stderr, "Reached 1\n");

[Bill Hesse, 2012/03/06 15:04:07]

Remove this fprintf.

+  const char* extension_name =
+      extension_url + strlen(DartUtils::kDartExtensionScheme);
+  const int buffer_length = strlen(extension_name) + strlen(".dll") + 1;
+  char* library_path = new char[buffer_length];
+  snprintf(library_path, buffer_length, "%s.dll", extension_name);

[Mads Ager (google), 2012/03/06 15:32:50]

On the other platforms the dll has to be called libextension_name.extension. We
should make it consistent and either require the 'lib' prefix here as well or
remove the requirement from linux and mac.

+  printf("%s\n", library_path);

[Bill Hesse, 2012/03/06 15:04:07]

Remove this printf.

+  HMODULE extension_dll = LoadLibrary(library_path);
+  assert(extension_dll != NULL);
+
+  // Reuse library_path buffer for intialization function name.
+  char* library_init_function = library_path;
+  snprintf(library_init_function, buffer_length, "%s_Init", extension_name);
+  typedef Dart_Handle (*InitPtrType)(Dart_Handle);
+  static InitPtrType initPtr =
+        (InitPtrType)GetProcAddress(extension_dll, library_init_function);

[Mads Ager (google), 2012/03/06 15:32:50]

Please use reinterpret_cast

+  delete[] library_path;
+  assert(initPtr != NULL);
+
+  return (*initPtr)(parent_library);

[Søren Gjesse, 2012/03/07 06:58:31]

reinterpret_cast here as well.

 }