Specialize base::IsWeakReceiver for Blink weak pointers to support base::Bind (1/5)

third_party/WebKit/Source/wtf/Functional.h

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 25 matching lines @@
 #include "wtf/ThreadSafeRefCounted.h"
 #include "wtf/TypeTraits.h"
 #include "wtf/WeakPtr.h"
 #include <tuple>
 #include <utility>
 
 namespace blink {
 template<typename T> class CrossThreadPersistent;
 }
 
+namespace base {
+
+template <typename T>
+struct IsWeakReceiver<WTF::WeakPtr<T>> : std::true_type {};
+
+}
+
 namespace WTF {
 
 // Functional.h provides a very simple way to bind a function pointer and arguments together into a function object
 // that can be stored, copied and invoked, similar to how boost::bind and std::bind in C++11.
 
 // Thread Safety:
 //
 // WTF::bind() and SameThreadClosure should be used for same-thread closures
 // only, i.e. the closures must be created, executed and destructed on
 // the same thread.
@@ skipping 127 matching lines @@
 public:
     typedef R ResultType;
     // + 1 is for |this| as an argument.
     static const size_t numberOfArguments = sizeof...(Parameters) + 1;
 
     explicit FunctionWrapper(R(C::*function)(Parameters...))
         : m_function(function)
     {
     }
 
-    template <typename... IncomingParameters>
-    R operator()(C* c, IncomingParameters&&... parameters)
+    template <typename Receiver, typename... IncomingParameters>
+    R operator()(Receiver&& receiver, IncomingParameters&&... parameters)
     {
-        return (c->*m_function)(std::forward<IncomingParameters>(parameters)...);
-    }
+        if (base::IsWeakReceiver<typename std::decay<Receiver>::type>::value && !receiver) {
+            return R();
+        }
 
-    template <typename... IncomingParameters>
-    R operator()(const std::unique_ptr<C>& c, IncomingParameters&&... parameters)
-    {
-        return (c.get()->*m_function)(std::forward<IncomingParameters>(parameters)...);
-    }
-
-    template <typename... IncomingParameters>
-    R operator()(const WeakPtr<C>& c, IncomingParameters&&... parameters)
-    {
-        C* obj = c.get();
-        if (!obj)
-            return R();
-        return (obj->*m_function)(std::forward<IncomingParameters>(parameters)...);
+        C& c = *receiver;
+        return (c.*m_function)(std::forward<IncomingParameters>(parameters)...);
     }
 
 private:
     R(C::*m_function)(Parameters...);
 };
 
 template <typename T>
 struct ParamStorageTraits {
     typedef T StorageType;
 
@@ skipping 187 matching lines @@
 
 using WTF::passed;
 using WTF::unretained;
 using WTF::crossThreadUnretained;
 
 using WTF::Function;
 using WTF::SameThreadClosure;
 using WTF::CrossThreadClosure;
 
 #endif // WTF_Functional_h