Callback: De-inline CallbackBase, and move to callback_helpers -> callback_internal.h

base/callback_internal.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.
 
 // This file contains utility functions and classes that help the
 // implementation, and management of the Callback objects.
 
-#ifndef BASE_CALLBACK_HELPERS_H_
-#define BASE_CALLBACK_HELPERS_H_
+#ifndef BASE_CALLBACK_INTERNAL_H_
+#define BASE_CALLBACK_INTERNAL_H_
 #pragma once
 
 #include "base/ref_counted.h"
 
 namespace base {
 namespace internal {
 
 // InvokerStorageBase is used to provide an opaque handle that the Callback
 // class can use to represent a function object with bound arguments.  It
 // behaves as an existential type that is used by a corresponding
@@ skipping 22 matching lines @@
   }
 
   mutable scoped_refptr<InvokerStorageBase> invoker_storage_;
 };
 
 template <typename T>
 InvokerStorageHolder<T> MakeInvokerStorageHolder(T* o) {
   return InvokerStorageHolder<T>(o);
 }
 
+// Holds the Callback methods that don't require specialization to reduce
+// template bloat.
+class CallbackBase {
+ public:
+  // Returns true if Callback is null (doesn't refer to anything).
+  bool is_null() const;
+
+  // Returns the Callback into an uninitalized state.
+  void Reset();
+
+  bool Equals(const CallbackBase& other) const;
+
+ protected:
+  // In C++, it is safe to cast function pointers to function pointers of
+  // another type. It is not okay to use void*. We create a InvokeFuncStorage
+  // that that can store our function pointer, and then cast it back to
+  // the original type on usage.
+  typedef void(*InvokeFuncStorage)(void);
+
+  CallbackBase(InvokeFuncStorage polymorphic_invoke,
+               scoped_refptr<InvokerStorageBase>* invoker_storage);

[Elliot Glaysher, 2011/02/18 20:39:11]

Drive by: add a destructor. The autogenerated one would probably be larger than
the declared ctor through scoped_refptr<> since it'll have to do deallocation.

[awong, 2011/02/18 21:27:24]

Done. Added comment summarizing our IM discussion too.

+
+  scoped_refptr<InvokerStorageBase> invoker_storage_;
+  InvokeFuncStorage polymorphic_invoke_;
+};
+
 }  // namespace internal
 }  // namespace base
 
-#endif  // BASE_CALLBACK_HELPERS_H_
+#endif  // BASE_CALLBACK_INTERNAL_H_