New thunk system for Pepper proxy and implementation

ppapi/thunk/enter.h

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PPAPI_THUNK_ENTER_H_
+#define PPAPI_THUNK_ENTER_H_
+
+#include "base/basictypes.h"
+#include "ppapi/c/pp_resource.h"
+#include "ppapi/proxy/interface_id.h"
+#include "ppapi/shared_impl/function_group_base.h"
+#include "ppapi/shared_impl/resource_object_base.h"
+#include "ppapi/shared_impl/tracker_base.h"
+
+namespace ppapi {
+namespace thunk {
+
+// EnterHost* helper objects: These objects wrap a call from the C PPAPI into
+// the internal implementation. They make sure the lock is acquired and will
+// automatically set up some stuff for you.
+//
+// You should always check whether the enter succeeded before using the object.
+// If this fails, then the instance or resource ID supplied was invalid.
+//
+// The |report_error| arguments to the constructor should indicate if errors
+// should be logged to the console. If the calling function expects that the
+// input values are correct (the normal case), this should be set to true. In
+// some case like |IsFoo(PP_Resource)| the caller is quersioning whether their
+// handle is this type, and we don't want to report an error if it's not.
+//
+// Standalone functions: EnterHostFunction
+//   Automatically gets the implementation for the function API for the
+//   supplied PP_Instance.
+//
+// Resource member functions: EnterHostResource
+//   Automatically interprets the given PP_Resource as a resource ID and sets
+//   up the resource object for you.
+
+template<typename FunctionsT>
+class EnterFunction {
+ public:
+  EnterFunction(PP_Instance instance, bool report_error)
+      : functions_(NULL) {
+    shared_impl::FunctionGroupBase* base =
+        shared_impl::TrackerBase::Get()->GetFunctionAPI(
+            instance, FunctionsT::interface_id);
+    if (base)
+      functions_ = base->GetAs<FunctionsT>();
+    // TODO(brettw) check error and if report_error is set, do something.
+  }
+  ~EnterFunction() {}
+
+  bool succeeded() const { return !!functions_; }
+  bool failed() const { return !functions_; }
+
+  FunctionsT* functions() { return functions_; }
+
+ private:
+  FunctionsT* functions_;
+
+  DISALLOW_COPY_AND_ASSIGN(EnterFunction);
+};
+
+template<typename ResourceT>
+class EnterResource {
+ public:
+  EnterResource(PP_Resource resource, bool report_error)
+      : object_(NULL) {
+    shared_impl::ResourceObjectBase* base =
+        shared_impl::TrackerBase::Get()->GetResourceAPI(resource);
+    if (base)
+      object_ = base->GetAs<ResourceT>();
+    // TODO(brettw) check error and if report_error is set, do something.
+  }
+  ~EnterResource() {}
+
+  bool succeeded() const { return !!object_; }
+  bool failed() const { return !object_; }
+
+  ResourceT* object() { return object_; }
+
+ private:
+  ResourceT* object_;
+
+  DISALLOW_COPY_AND_ASSIGN(EnterResource);
+};
+
+}  // namespace thunk
+}  // namespace ppapi
+
+#endif  // PPAPI_THUNK_ENTER_H_