Support binding WeakPtr<> to methods with void return types.

base/bind_internal.h

 // This file was GENERATED by command:
 //     pump.py bind_internal.h.pump
 // DO NOT EDIT BY HAND!!!
 
 
 
 // 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 BASE_BIND_INTERNAL_H_
 #define BASE_BIND_INTERNAL_H_
 #pragma once
 
 #include "base/bind_helpers.h"
 #include "base/callback_internal.h"
 #include "base/template_util.h"
 #include "build/build_config.h"
+#include "base/memory/weak_ptr.h"

[willchan no longer on Chromium, 2011/05/14 01:25:10]

Again, sort alphabetically :)

[awong, 2011/05/16 20:01:27]

Done.

 
 #if defined(OS_WIN)
 #include "base/bind_internal_win.h"
 #endif
 
 namespace base {
 namespace internal {
 
 // The method by which a function is invoked is determined by 3 different
 // dimensions:
 //
 //   1) The type of function (normal or method).
 //   2) The arity of the function.
 //   3) The number of bound parameters.
 //
 // The templates below handle the determination of each of these dimensions.
 // In brief:
 //
 //   FunctionTraits<> -- Provides a normalied signature, and other traits.
 //   InvokerN<> -- Provides a DoInvoke() function that actually executes
 //                 a calback.
 //   InvokerStorageN<> -- Provides storage for the bound parameters, and
 //                        typedefs to the above.
+//   IsWeakMethod<> -- Determines if we are binding a method to a WeakPtr<>.
 //
 // More details about the design of each class is included in a comment closer
 // to their defition.
 
+
+// IsWeakMethod determines if we are binding a method to a WeakPtr<> for an
+// object.  It is used to select an InvokerN that will no-op itself in the
+// event the WeakPtr<> for the target object is invalidated.
+template <bool IsMethod, typename T>
+struct IsWeakMethod : public false_type {};
+
+template <typename T>
+struct IsWeakMethod<true, WeakPtr<T> > : public true_type {};
+
 // FunctionTraits<>
 //
 // The FunctionTraits<> template determines the type of function, and also
 // creates a NormalizedType used to select the InvokerN classes.  It turns out
 // that syntactically, you only really have 2 variations when invoking a
 // funciton pointer: normal, and method.  One is invoked func_ptr(arg1). The
 // other is invoked (*obj_->method_ptr(arg1)).
 //
 // However, in the type system, there are many more distinctions. In standard
 // C++, there's all variations of const, and volatile on the function pointer.
@@ skipping 12 matching lines @@
 
 template <typename Sig>
 struct FunctionTraits;
 
 // Function: Arity 0.
 template <typename R>
 struct FunctionTraits<R(*)()> {
   typedef R (*NormalizedSig)();
   typedef false_type IsMethod;
 
+  typedef R Return;
+
 };
 
 // Method: Arity 0.
 template <typename R, typename T>
 struct FunctionTraits<R(T::*)()> {
   typedef R (T::*NormalizedSig)();
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
 
 };
 
 // Const Method: Arity 0.
 template <typename R, typename T>
 struct FunctionTraits<R(T::*)() const> {
   typedef R (T::*NormalizedSig)();
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
 
 };
 
 // Function: Arity 1.
 template <typename R, typename X1>
 struct FunctionTraits<R(*)(X1)> {
   typedef R (*NormalizedSig)(X1);
   typedef false_type IsMethod;
+
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef X1 B1;
 
 };
 
 // Method: Arity 1.
 template <typename R, typename T, typename X1>
 struct FunctionTraits<R(T::*)(X1)> {
   typedef R (T::*NormalizedSig)(X1);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
 
 };
 
 // Const Method: Arity 1.
 template <typename R, typename T, typename X1>
 struct FunctionTraits<R(T::*)(X1) const> {
   typedef R (T::*NormalizedSig)(X1);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
 
 };
 
 // Function: Arity 2.
 template <typename R, typename X1, typename X2>
 struct FunctionTraits<R(*)(X1, X2)> {
   typedef R (*NormalizedSig)(X1, X2);
   typedef false_type IsMethod;
+
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef X1 B1;
   typedef X2 B2;
 
 };
 
 // Method: Arity 2.
 template <typename R, typename T, typename X1, typename X2>
 struct FunctionTraits<R(T::*)(X1, X2)> {
   typedef R (T::*NormalizedSig)(X1, X2);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
   typedef X2 B3;
 
 };
 
 // Const Method: Arity 2.
 template <typename R, typename T, typename X1, typename X2>
 struct FunctionTraits<R(T::*)(X1, X2) const> {
   typedef R (T::*NormalizedSig)(X1, X2);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
   typedef X2 B3;
 
 };
 
 // Function: Arity 3.
 template <typename R, typename X1, typename X2, typename X3>
 struct FunctionTraits<R(*)(X1, X2, X3)> {
   typedef R (*NormalizedSig)(X1, X2, X3);
   typedef false_type IsMethod;
+
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef X1 B1;
   typedef X2 B2;
   typedef X3 B3;
 
 };
 
 // Method: Arity 3.
 template <typename R, typename T, typename X1, typename X2, typename X3>
 struct FunctionTraits<R(T::*)(X1, X2, X3)> {
   typedef R (T::*NormalizedSig)(X1, X2, X3);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
   typedef X2 B3;
   typedef X3 B4;
 
 };
 
 // Const Method: Arity 3.
 template <typename R, typename T, typename X1, typename X2, typename X3>
 struct FunctionTraits<R(T::*)(X1, X2, X3) const> {
   typedef R (T::*NormalizedSig)(X1, X2, X3);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
   typedef X2 B3;
   typedef X3 B4;
 
 };
 
 // Function: Arity 4.
 template <typename R, typename X1, typename X2, typename X3, typename X4>
 struct FunctionTraits<R(*)(X1, X2, X3, X4)> {
   typedef R (*NormalizedSig)(X1, X2, X3, X4);
   typedef false_type IsMethod;
+
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef X1 B1;
   typedef X2 B2;
   typedef X3 B3;
   typedef X4 B4;
 
 };
 
 // Method: Arity 4.
 template <typename R, typename T, typename X1, typename X2, typename X3,
     typename X4>
 struct FunctionTraits<R(T::*)(X1, X2, X3, X4)> {
   typedef R (T::*NormalizedSig)(X1, X2, X3, X4);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
   typedef X2 B3;
   typedef X3 B4;
   typedef X4 B5;
 
 };
 
 // Const Method: Arity 4.
 template <typename R, typename T, typename X1, typename X2, typename X3,
     typename X4>
 struct FunctionTraits<R(T::*)(X1, X2, X3, X4) const> {
   typedef R (T::*NormalizedSig)(X1, X2, X3, X4);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
   typedef X2 B3;
   typedef X3 B4;
   typedef X4 B5;
 
 };
 
 // Function: Arity 5.
 template <typename R, typename X1, typename X2, typename X3, typename X4,
     typename X5>
 struct FunctionTraits<R(*)(X1, X2, X3, X4, X5)> {
   typedef R (*NormalizedSig)(X1, X2, X3, X4, X5);
   typedef false_type IsMethod;
+
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef X1 B1;
   typedef X2 B2;
   typedef X3 B3;
   typedef X4 B4;
   typedef X5 B5;
 
 };
 
 // Method: Arity 5.
 template <typename R, typename T, typename X1, typename X2, typename X3,
     typename X4, typename X5>
 struct FunctionTraits<R(T::*)(X1, X2, X3, X4, X5)> {
   typedef R (T::*NormalizedSig)(X1, X2, X3, X4, X5);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
   typedef X2 B3;
   typedef X3 B4;
   typedef X4 B5;
   typedef X5 B6;
 
 };
 
 // Const Method: Arity 5.
 template <typename R, typename T, typename X1, typename X2, typename X3,
     typename X4, typename X5>
 struct FunctionTraits<R(T::*)(X1, X2, X3, X4, X5) const> {
   typedef R (T::*NormalizedSig)(X1, X2, X3, X4, X5);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
   typedef X2 B3;
   typedef X3 B4;
   typedef X4 B5;
   typedef X5 B6;
 
 };
 
 // Function: Arity 6.
 template <typename R, typename X1, typename X2, typename X3, typename X4,
     typename X5, typename X6>
 struct FunctionTraits<R(*)(X1, X2, X3, X4, X5, X6)> {
   typedef R (*NormalizedSig)(X1, X2, X3, X4, X5, X6);
   typedef false_type IsMethod;
+
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef X1 B1;
   typedef X2 B2;
   typedef X3 B3;
   typedef X4 B4;
   typedef X5 B5;
   typedef X6 B6;
 
 };
 
 // Method: Arity 6.
 template <typename R, typename T, typename X1, typename X2, typename X3,
     typename X4, typename X5, typename X6>
 struct FunctionTraits<R(T::*)(X1, X2, X3, X4, X5, X6)> {
   typedef R (T::*NormalizedSig)(X1, X2, X3, X4, X5, X6);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
   typedef X2 B3;
   typedef X3 B4;
   typedef X4 B5;
   typedef X5 B6;
   typedef X6 B7;
 
 };
 
 // Const Method: Arity 6.
 template <typename R, typename T, typename X1, typename X2, typename X3,
     typename X4, typename X5, typename X6>
 struct FunctionTraits<R(T::*)(X1, X2, X3, X4, X5, X6) const> {
   typedef R (T::*NormalizedSig)(X1, X2, X3, X4, X5, X6);
   typedef true_type IsMethod;
 
+  typedef R Return;
+
   // Target type for each bound parameter.
   typedef T B1;
   typedef X1 B2;
   typedef X2 B3;
   typedef X3 B4;
   typedef X4 B5;
   typedef X5 B6;
   typedef X6 B7;
 
 };
@@ skipping 11 matching lines @@
 //
 // As long as we ensure that DoInvoke() is only used with pointers there were
 // upcasted from the correct StorageType, we can be sure that execution is
 // safe.
 //
 // The InvokerN templates are the only point that knows the number of bound
 // and unbound arguments.  This is intentional because it allows the other
 // templates classes in the system to only have as many specializations as
 // the max arity of function we wish to support.
 
-template <typename StorageType, typename NormalizedSig>
+template <bool IsWeak, typename StorageType, typename NormalizedSig>
 struct Invoker0;
 
 // Function: Arity 0 -> 0.
 template <typename StorageType, typename R>
-struct Invoker0<StorageType, R(*)()> {
+struct Invoker0<false, StorageType, R(*)()> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_();
   }
 };
 
 // Function: Arity 1 -> 1.
 template <typename StorageType, typename R,typename X1>
-struct Invoker0<StorageType, R(*)(X1)> {
+struct Invoker0<false, StorageType, R(*)(X1)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X1>::ForwardType x1) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(x1);
   }
 };
 
 // Function: Arity 2 -> 2.
 template <typename StorageType, typename R,typename X1, typename X2>
-struct Invoker0<StorageType, R(*)(X1, X2)> {
+struct Invoker0<false, StorageType, R(*)(X1, X2)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X1>::ForwardType x1,
       typename internal::ParamTraits<X2>::ForwardType x2) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(x1, x2);
   }
 };
 
 // Function: Arity 3 -> 3.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3>
-struct Invoker0<StorageType, R(*)(X1, X2, X3)> {
+struct Invoker0<false, StorageType, R(*)(X1, X2, X3)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X1>::ForwardType x1,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(x1, x2, x3);
   }
 };
 
 // Function: Arity 4 -> 4.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4>
-struct Invoker0<StorageType, R(*)(X1, X2, X3, X4)> {
+struct Invoker0<false, StorageType, R(*)(X1, X2, X3, X4)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X1>::ForwardType x1,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(x1, x2, x3, x4);
   }
 };
 
 // Function: Arity 5 -> 5.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5>
-struct Invoker0<StorageType, R(*)(X1, X2, X3, X4, X5)> {
+struct Invoker0<false, StorageType, R(*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X1>::ForwardType x1,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(x1, x2, x3, x4, x5);
   }
 };
 
 // Function: Arity 6 -> 6.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5, typename X6>
-struct Invoker0<StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
+struct Invoker0<false, StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X1>::ForwardType x1,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5,
       typename internal::ParamTraits<X6>::ForwardType x6) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(x1, x2, x3, x4, x5, x6);
   }
 };
 
-template <typename StorageType, typename NormalizedSig>
+template <bool IsWeak, typename StorageType, typename NormalizedSig>
 struct Invoker1;
 
 // Function: Arity 1 -> 0.
 template <typename StorageType, typename R,typename X1>
-struct Invoker1<StorageType, R(*)(X1)> {
+struct Invoker1<false, StorageType, R(*)(X1)> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_));
   }
 };
 
 // Method: Arity 0 -> 0.
 template <typename StorageType, typename R, typename T>
-struct Invoker1<StorageType, R(T::*)()> {
+struct Invoker1<false, StorageType, R(T::*)()> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)();
   }
 };
 
+// WeakPtr Method: Arity 0 -> 0.
+template <typename StorageType, typename T>
+struct Invoker1<true, StorageType, void(T::*)()> {
+  static void DoInvoke(InvokerStorageBase* base) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {

[willchan no longer on Chromium, 2011/05/14 01:25:10]

It's non-obvious from reading the code that this is a WeakPtr. 'true' for IsWeak
isn't obvious if you're just reading this specific point. For clarity's sake, I
suggest you break this down.

const WeakPtr& ptr = invoker->p1_;
...

[awong, 2011/05/16 20:01:27]

Made a stab at it.  I need to take another pass through and rename some
variables plug break apart expressions.  In particular, this
StorageType::P1Traits::StorageType is confusing to read. :-/

But would like to do that in a different CL.

[willchan no longer on Chromium, 2011/05/16 22:01:26]

OK.

+      return;
+    }
+    (invoker->p1_->*invoker->f_)();
+  }
+};
+
 // Function: Arity 2 -> 1.
 template <typename StorageType, typename R,typename X1, typename X2>
-struct Invoker1<StorageType, R(*)(X1, X2)> {
+struct Invoker1<false, StorageType, R(*)(X1, X2)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X2>::ForwardType x2) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), x2);
   }
 };
 
 // Method: Arity 1 -> 1.
 template <typename StorageType, typename R, typename T, typename X1>
-struct Invoker1<StorageType, R(T::*)(X1)> {
+struct Invoker1<false, StorageType, R(T::*)(X1)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X1>::ForwardType x1) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(x1);
   }
 };
 
+// WeakPtr Method: Arity 1 -> 1.
+template <typename StorageType, typename T, typename X1>
+struct Invoker1<true, StorageType, void(T::*)(X1)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X1>::ForwardType x1) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(x1);
+  }
+};
+
 // Function: Arity 3 -> 2.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3>
-struct Invoker1<StorageType, R(*)(X1, X2, X3)> {
+struct Invoker1<false, StorageType, R(*)(X1, X2, X3)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), x2, x3);
   }
 };
 
 // Method: Arity 2 -> 2.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2>
-struct Invoker1<StorageType, R(T::*)(X1, X2)> {
+struct Invoker1<false, StorageType, R(T::*)(X1, X2)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X1>::ForwardType x1,
       typename internal::ParamTraits<X2>::ForwardType x2) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(x1, x2);
   }
 };
 
+// WeakPtr Method: Arity 2 -> 2.
+template <typename StorageType, typename T, typename X1, typename X2>
+struct Invoker1<true, StorageType, void(T::*)(X1, X2)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X1>::ForwardType x1,
+      typename internal::ParamTraits<X2>::ForwardType x2) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(x1, x2);
+  }
+};
+
 // Function: Arity 4 -> 3.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4>
-struct Invoker1<StorageType, R(*)(X1, X2, X3, X4)> {
+struct Invoker1<false, StorageType, R(*)(X1, X2, X3, X4)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), x2, x3, x4);
   }
 };
 
 // Method: Arity 3 -> 3.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3>
-struct Invoker1<StorageType, R(T::*)(X1, X2, X3)> {
+struct Invoker1<false, StorageType, R(T::*)(X1, X2, X3)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X1>::ForwardType x1,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(x1, x2, x3);
   }
 };
 
+// WeakPtr Method: Arity 3 -> 3.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3>
+struct Invoker1<true, StorageType, void(T::*)(X1, X2, X3)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X1>::ForwardType x1,
+      typename internal::ParamTraits<X2>::ForwardType x2,
+      typename internal::ParamTraits<X3>::ForwardType x3) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(x1, x2, x3);
+  }
+};
+
 // Function: Arity 5 -> 4.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5>
-struct Invoker1<StorageType, R(*)(X1, X2, X3, X4, X5)> {
+struct Invoker1<false, StorageType, R(*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), x2, x3, x4, x5);
   }
 };
 
 // Method: Arity 4 -> 4.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3, typename X4>
-struct Invoker1<StorageType, R(T::*)(X1, X2, X3, X4)> {
+struct Invoker1<false, StorageType, R(T::*)(X1, X2, X3, X4)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X1>::ForwardType x1,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(x1, x2, x3, x4);
   }
 };
 
+// WeakPtr Method: Arity 4 -> 4.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3, typename X4>
+struct Invoker1<true, StorageType, void(T::*)(X1, X2, X3, X4)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X1>::ForwardType x1,
+      typename internal::ParamTraits<X2>::ForwardType x2,
+      typename internal::ParamTraits<X3>::ForwardType x3,
+      typename internal::ParamTraits<X4>::ForwardType x4) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(x1, x2, x3, x4);
+  }
+};
+
 // Function: Arity 6 -> 5.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5, typename X6>
-struct Invoker1<StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
+struct Invoker1<false, StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5,
       typename internal::ParamTraits<X6>::ForwardType x6) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), x2, x3, x4, x5, x6);
   }
 };
 
 // Method: Arity 5 -> 5.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3, typename X4, typename X5>
-struct Invoker1<StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
+struct Invoker1<false, StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X1>::ForwardType x1,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(x1, x2, x3, x4, x5);
   }
 };
 
-template <typename StorageType, typename NormalizedSig>
+// WeakPtr Method: Arity 5 -> 5.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3, typename X4, typename X5>
+struct Invoker1<true, StorageType, void(T::*)(X1, X2, X3, X4, X5)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X1>::ForwardType x1,
+      typename internal::ParamTraits<X2>::ForwardType x2,
+      typename internal::ParamTraits<X3>::ForwardType x3,
+      typename internal::ParamTraits<X4>::ForwardType x4,
+      typename internal::ParamTraits<X5>::ForwardType x5) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(x1, x2, x3, x4, x5);
+  }
+};
+
+template <bool IsWeak, typename StorageType, typename NormalizedSig>
 struct Invoker2;
 
 // Function: Arity 2 -> 0.
 template <typename StorageType, typename R,typename X1, typename X2>
-struct Invoker2<StorageType, R(*)(X1, X2)> {
+struct Invoker2<false, StorageType, R(*)(X1, X2)> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_));
   }
 };
 
 // Method: Arity 1 -> 0.
 template <typename StorageType, typename R, typename T, typename X1>
-struct Invoker2<StorageType, R(T::*)(X1)> {
+struct Invoker2<false, StorageType, R(T::*)(X1)> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_));
   }
 };
 
+// WeakPtr Method: Arity 1 -> 0.
+template <typename StorageType, typename T, typename X1>
+struct Invoker2<true, StorageType, void(T::*)(X1)> {
+  static void DoInvoke(InvokerStorageBase* base) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_));
+  }
+};
+
 // Function: Arity 3 -> 1.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3>
-struct Invoker2<StorageType, R(*)(X1, X2, X3)> {
+struct Invoker2<false, StorageType, R(*)(X1, X2, X3)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X3>::ForwardType x3) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_), x3);
   }
 };
 
 // Method: Arity 2 -> 1.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2>
-struct Invoker2<StorageType, R(T::*)(X1, X2)> {
+struct Invoker2<false, StorageType, R(T::*)(X1, X2)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X2>::ForwardType x2) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_), x2);
   }
 };
 
+// WeakPtr Method: Arity 2 -> 1.
+template <typename StorageType, typename T, typename X1, typename X2>
+struct Invoker2<true, StorageType, void(T::*)(X1, X2)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X2>::ForwardType x2) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), x2);
+  }
+};
+
 // Function: Arity 4 -> 2.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4>
-struct Invoker2<StorageType, R(*)(X1, X2, X3, X4)> {
+struct Invoker2<false, StorageType, R(*)(X1, X2, X3, X4)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_), x3, x4);
   }
 };
 
 // Method: Arity 3 -> 2.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3>
-struct Invoker2<StorageType, R(T::*)(X1, X2, X3)> {
+struct Invoker2<false, StorageType, R(T::*)(X1, X2, X3)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_), x2, x3);
   }
 };
 
+// WeakPtr Method: Arity 3 -> 2.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3>
+struct Invoker2<true, StorageType, void(T::*)(X1, X2, X3)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X2>::ForwardType x2,
+      typename internal::ParamTraits<X3>::ForwardType x3) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), x2, x3);
+  }
+};
+
 // Function: Arity 5 -> 3.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5>
-struct Invoker2<StorageType, R(*)(X1, X2, X3, X4, X5)> {
+struct Invoker2<false, StorageType, R(*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_), x3, x4, x5);
   }
 };
 
 // Method: Arity 4 -> 3.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3, typename X4>
-struct Invoker2<StorageType, R(T::*)(X1, X2, X3, X4)> {
+struct Invoker2<false, StorageType, R(T::*)(X1, X2, X3, X4)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_), x2, x3,
         x4);
   }
 };
 
+// WeakPtr Method: Arity 4 -> 3.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3, typename X4>
+struct Invoker2<true, StorageType, void(T::*)(X1, X2, X3, X4)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X2>::ForwardType x2,
+      typename internal::ParamTraits<X3>::ForwardType x3,
+      typename internal::ParamTraits<X4>::ForwardType x4) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), x2, x3, x4);
+  }
+};
+
 // Function: Arity 6 -> 4.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5, typename X6>
-struct Invoker2<StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
+struct Invoker2<false, StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5,
       typename internal::ParamTraits<X6>::ForwardType x6) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_), x3, x4, x5,
         x6);
   }
 };
 
 // Method: Arity 5 -> 4.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3, typename X4, typename X5>
-struct Invoker2<StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
+struct Invoker2<false, StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X2>::ForwardType x2,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_), x2, x3,
         x4, x5);
   }
 };
 
-template <typename StorageType, typename NormalizedSig>
+// WeakPtr Method: Arity 5 -> 4.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3, typename X4, typename X5>
+struct Invoker2<true, StorageType, void(T::*)(X1, X2, X3, X4, X5)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X2>::ForwardType x2,
+      typename internal::ParamTraits<X3>::ForwardType x3,
+      typename internal::ParamTraits<X4>::ForwardType x4,
+      typename internal::ParamTraits<X5>::ForwardType x5) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), x2, x3, x4, x5);
+  }
+};
+
+template <bool IsWeak, typename StorageType, typename NormalizedSig>
 struct Invoker3;
 
 // Function: Arity 3 -> 0.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3>
-struct Invoker3<StorageType, R(*)(X1, X2, X3)> {
+struct Invoker3<false, StorageType, R(*)(X1, X2, X3)> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_),
         Unwrap(invoker->p3_));
   }
 };
 
 // Method: Arity 2 -> 0.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2>
-struct Invoker3<StorageType, R(T::*)(X1, X2)> {
+struct Invoker3<false, StorageType, R(T::*)(X1, X2)> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_),
         Unwrap(invoker->p3_));
   }
 };
 
+// WeakPtr Method: Arity 2 -> 0.
+template <typename StorageType, typename T, typename X1, typename X2>
+struct Invoker3<true, StorageType, void(T::*)(X1, X2)> {
+  static void DoInvoke(InvokerStorageBase* base) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), Unwrap(invoker->p3_));
+  }
+};
+
 // Function: Arity 4 -> 1.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4>
-struct Invoker3<StorageType, R(*)(X1, X2, X3, X4)> {
+struct Invoker3<false, StorageType, R(*)(X1, X2, X3, X4)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X4>::ForwardType x4) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), x4);
   }
 };
 
 // Method: Arity 3 -> 1.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3>
-struct Invoker3<StorageType, R(T::*)(X1, X2, X3)> {
+struct Invoker3<false, StorageType, R(T::*)(X1, X2, X3)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X3>::ForwardType x3) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), x3);
   }
 };
 
+// WeakPtr Method: Arity 3 -> 1.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3>
+struct Invoker3<true, StorageType, void(T::*)(X1, X2, X3)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X3>::ForwardType x3) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), Unwrap(invoker->p3_),
+        x3);
+  }
+};
+
 // Function: Arity 5 -> 2.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5>
-struct Invoker3<StorageType, R(*)(X1, X2, X3, X4, X5)> {
+struct Invoker3<false, StorageType, R(*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), x4, x5);
   }
 };
 
 // Method: Arity 4 -> 2.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3, typename X4>
-struct Invoker3<StorageType, R(T::*)(X1, X2, X3, X4)> {
+struct Invoker3<false, StorageType, R(T::*)(X1, X2, X3, X4)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), x3, x4);
   }
 };
 
+// WeakPtr Method: Arity 4 -> 2.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3, typename X4>
+struct Invoker3<true, StorageType, void(T::*)(X1, X2, X3, X4)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X3>::ForwardType x3,
+      typename internal::ParamTraits<X4>::ForwardType x4) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), Unwrap(invoker->p3_),
+        x3, x4);
+  }
+};
+
 // Function: Arity 6 -> 3.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5, typename X6>
-struct Invoker3<StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
+struct Invoker3<false, StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5,
       typename internal::ParamTraits<X6>::ForwardType x6) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), x4, x5, x6);
   }
 };
 
 // Method: Arity 5 -> 3.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3, typename X4, typename X5>
-struct Invoker3<StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
+struct Invoker3<false, StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X3>::ForwardType x3,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), x3, x4, x5);
   }
 };
 
-template <typename StorageType, typename NormalizedSig>
+// WeakPtr Method: Arity 5 -> 3.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3, typename X4, typename X5>
+struct Invoker3<true, StorageType, void(T::*)(X1, X2, X3, X4, X5)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X3>::ForwardType x3,
+      typename internal::ParamTraits<X4>::ForwardType x4,
+      typename internal::ParamTraits<X5>::ForwardType x5) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), Unwrap(invoker->p3_),
+        x3, x4, x5);
+  }
+};
+
+template <bool IsWeak, typename StorageType, typename NormalizedSig>
 struct Invoker4;
 
 // Function: Arity 4 -> 0.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4>
-struct Invoker4<StorageType, R(*)(X1, X2, X3, X4)> {
+struct Invoker4<false, StorageType, R(*)(X1, X2, X3, X4)> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_));
   }
 };
 
 // Method: Arity 3 -> 0.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3>
-struct Invoker4<StorageType, R(T::*)(X1, X2, X3)> {
+struct Invoker4<false, StorageType, R(T::*)(X1, X2, X3)> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_));
   }
 };
 
+// WeakPtr Method: Arity 3 -> 0.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3>
+struct Invoker4<true, StorageType, void(T::*)(X1, X2, X3)> {
+  static void DoInvoke(InvokerStorageBase* base) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), Unwrap(invoker->p3_),
+        Unwrap(invoker->p4_));
+  }
+};
+
 // Function: Arity 5 -> 1.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5>
-struct Invoker4<StorageType, R(*)(X1, X2, X3, X4, X5)> {
+struct Invoker4<false, StorageType, R(*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X5>::ForwardType x5) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_), x5);
   }
 };
 
 // Method: Arity 4 -> 1.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3, typename X4>
-struct Invoker4<StorageType, R(T::*)(X1, X2, X3, X4)> {
+struct Invoker4<false, StorageType, R(T::*)(X1, X2, X3, X4)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X4>::ForwardType x4) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_), x4);
   }
 };
 
+// WeakPtr Method: Arity 4 -> 1.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3, typename X4>
+struct Invoker4<true, StorageType, void(T::*)(X1, X2, X3, X4)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X4>::ForwardType x4) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), Unwrap(invoker->p3_),
+        Unwrap(invoker->p4_), x4);
+  }
+};
+
 // Function: Arity 6 -> 2.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5, typename X6>
-struct Invoker4<StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
+struct Invoker4<false, StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X5>::ForwardType x5,
       typename internal::ParamTraits<X6>::ForwardType x6) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_), x5, x6);
   }
 };
 
 // Method: Arity 5 -> 2.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3, typename X4, typename X5>
-struct Invoker4<StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
+struct Invoker4<false, StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X4>::ForwardType x4,
       typename internal::ParamTraits<X5>::ForwardType x5) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_), x4, x5);
   }
 };
 
-template <typename StorageType, typename NormalizedSig>
+// WeakPtr Method: Arity 5 -> 2.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3, typename X4, typename X5>
+struct Invoker4<true, StorageType, void(T::*)(X1, X2, X3, X4, X5)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X4>::ForwardType x4,
+      typename internal::ParamTraits<X5>::ForwardType x5) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), Unwrap(invoker->p3_),
+        Unwrap(invoker->p4_), x4, x5);
+  }
+};
+
+template <bool IsWeak, typename StorageType, typename NormalizedSig>
 struct Invoker5;
 
 // Function: Arity 5 -> 0.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5>
-struct Invoker5<StorageType, R(*)(X1, X2, X3, X4, X5)> {
+struct Invoker5<false, StorageType, R(*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_), Unwrap(invoker->p5_));
   }
 };
 
 // Method: Arity 4 -> 0.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3, typename X4>
-struct Invoker5<StorageType, R(T::*)(X1, X2, X3, X4)> {
+struct Invoker5<false, StorageType, R(T::*)(X1, X2, X3, X4)> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_), Unwrap(invoker->p5_));
   }
 };
 
+// WeakPtr Method: Arity 4 -> 0.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3, typename X4>
+struct Invoker5<true, StorageType, void(T::*)(X1, X2, X3, X4)> {
+  static void DoInvoke(InvokerStorageBase* base) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), Unwrap(invoker->p3_),
+        Unwrap(invoker->p4_), Unwrap(invoker->p5_));
+  }
+};
+
 // Function: Arity 6 -> 1.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5, typename X6>
-struct Invoker5<StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
+struct Invoker5<false, StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X6>::ForwardType x6) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_), Unwrap(invoker->p5_), x6);
   }
 };
 
 // Method: Arity 5 -> 1.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3, typename X4, typename X5>
-struct Invoker5<StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
+struct Invoker5<false, StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base,
       typename internal::ParamTraits<X5>::ForwardType x5) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_), Unwrap(invoker->p5_), x5);
   }
 };
 
-template <typename StorageType, typename NormalizedSig>
+// WeakPtr Method: Arity 5 -> 1.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3, typename X4, typename X5>
+struct Invoker5<true, StorageType, void(T::*)(X1, X2, X3, X4, X5)> {
+  static void DoInvoke(InvokerStorageBase* base,
+      typename internal::ParamTraits<X5>::ForwardType x5) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), Unwrap(invoker->p3_),
+        Unwrap(invoker->p4_), Unwrap(invoker->p5_), x5);
+  }
+};
+
+template <bool IsWeak, typename StorageType, typename NormalizedSig>
 struct Invoker6;
 
 // Function: Arity 6 -> 0.
 template <typename StorageType, typename R,typename X1, typename X2,
     typename X3, typename X4, typename X5, typename X6>
-struct Invoker6<StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
+struct Invoker6<false, StorageType, R(*)(X1, X2, X3, X4, X5, X6)> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return invoker->f_(Unwrap(invoker->p1_), Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_), Unwrap(invoker->p5_),
         Unwrap(invoker->p6_));
   }
 };
 
 // Method: Arity 5 -> 0.
 template <typename StorageType, typename R, typename T, typename X1,
     typename X2, typename X3, typename X4, typename X5>
-struct Invoker6<StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
+struct Invoker6<false, StorageType, R(T::*)(X1, X2, X3, X4, X5)> {
   static R DoInvoke(InvokerStorageBase* base) {
     StorageType* invoker = static_cast<StorageType*>(base);
     return (Unwrap(invoker->p1_)->*invoker->f_)(Unwrap(invoker->p2_),
         Unwrap(invoker->p3_), Unwrap(invoker->p4_), Unwrap(invoker->p5_),
         Unwrap(invoker->p6_));
   }
 };
 
+// WeakPtr Method: Arity 5 -> 0.
+template <typename StorageType, typename T, typename X1, typename X2,
+    typename X3, typename X4, typename X5>
+struct Invoker6<true, StorageType, void(T::*)(X1, X2, X3, X4, X5)> {
+  static void DoInvoke(InvokerStorageBase* base) {
+    StorageType* invoker = static_cast<StorageType*>(base);
+    if (!invoker->p1_.get()) {
+      return;
+    }
+    (invoker->p1_->*invoker->f_)(Unwrap(invoker->p2_), Unwrap(invoker->p3_),
+        Unwrap(invoker->p4_), Unwrap(invoker->p5_), Unwrap(invoker->p6_));
+  }
+};
 
 // InvokerStorageN<>
 //
 // These are the actual storage classes for the Invokers.
 //
 // Though these types are "classes", they are being used as structs with
 // all member variable public.  We cannot make it a struct because it inherits
 // from a class which causes a compiler warning.  We cannot add a "Run()" method
 // that forwards the unbound arguments because that would require we unwrap the
 // Sig type like in InvokerN above to know the return type, and the arity
 // of Run().
 //
 // An alternate solution would be to merge InvokerN and InvokerStorageN,
 // but the generated code seemed harder to read.
 
 template <typename Sig>
 class InvokerStorage0 : public InvokerStorageBase {
  public:
   typedef InvokerStorage0 StorageType;
   typedef FunctionTraits<Sig> TargetTraits;
-  typedef Invoker0<StorageType, typename TargetTraits::NormalizedSig> Invoker;
   typedef typename TargetTraits::IsMethod IsMethod;
+  typedef Invoker0<false, StorageType,
+                   typename TargetTraits::NormalizedSig> Invoker;
 
 
 
   InvokerStorage0(Sig f)
       : f_(f) {
   }
 
   virtual ~InvokerStorage0() {  }
 
   Sig f_;
 };
 
 template <typename Sig, typename P1>
 class InvokerStorage1 : public InvokerStorageBase {
  public:
   typedef InvokerStorage1 StorageType;
   typedef FunctionTraits<Sig> TargetTraits;
-  typedef Invoker1<StorageType, typename TargetTraits::NormalizedSig> Invoker;
   typedef typename TargetTraits::IsMethod IsMethod;
+  typedef Invoker1<IsWeakMethod<IsMethod::value, P1>::value, StorageType,
+                   typename TargetTraits::NormalizedSig> Invoker;
+  COMPILE_ASSERT(!(IsWeakMethod<IsMethod::value, P1>::value) ||
+                 is_void<typename TargetTraits::Return>::value,
+                 weak_ptrs_can_only_bind_to_methods_without_return_values);
 
   // For methods, we need to be careful for parameter 1.  We skip the
   // scoped_refptr check because the binder itself takes care of this. We also
   // disallow binding of an array as the method's target object.
   COMPILE_ASSERT(IsMethod::value ||
                  !internal::UnsafeBindtoRefCountedArg<P1>::value,
                  p1_is_refcounted_type_and_needs_scoped_refptr);
   COMPILE_ASSERT(!IsMethod::value || !is_array<P1>::value,
                  first_bound_argument_to_method_cannot_be_array);
 
@@ skipping 18 matching lines @@
 
   Sig f_;
   typename ParamTraits<P1>::StorageType p1_;
 };
 
 template <typename Sig, typename P1, typename P2>
 class InvokerStorage2 : public InvokerStorageBase {
  public:
   typedef InvokerStorage2 StorageType;
   typedef FunctionTraits<Sig> TargetTraits;
-  typedef Invoker2<StorageType, typename TargetTraits::NormalizedSig> Invoker;
   typedef typename TargetTraits::IsMethod IsMethod;
+  typedef Invoker2<IsWeakMethod<IsMethod::value, P1>::value, StorageType,
+                   typename TargetTraits::NormalizedSig> Invoker;
+  COMPILE_ASSERT(!(IsWeakMethod<IsMethod::value, P1>::value) ||
+                 is_void<typename TargetTraits::Return>::value,
+                 weak_ptrs_can_only_bind_to_methods_without_return_values);
 
   // For methods, we need to be careful for parameter 1.  We skip the
   // scoped_refptr check because the binder itself takes care of this. We also
   // disallow binding of an array as the method's target object.
   COMPILE_ASSERT(IsMethod::value ||
                  !internal::UnsafeBindtoRefCountedArg<P1>::value,
                  p1_is_refcounted_type_and_needs_scoped_refptr);
   COMPILE_ASSERT(!IsMethod::value || !is_array<P1>::value,
                  first_bound_argument_to_method_cannot_be_array);
   COMPILE_ASSERT(!internal::UnsafeBindtoRefCountedArg<P2>::value,
@@ skipping 23 matching lines @@
   Sig f_;
   typename ParamTraits<P1>::StorageType p1_;
   typename ParamTraits<P2>::StorageType p2_;
 };
 
 template <typename Sig, typename P1, typename P2, typename P3>
 class InvokerStorage3 : public InvokerStorageBase {
  public:
   typedef InvokerStorage3 StorageType;
   typedef FunctionTraits<Sig> TargetTraits;
-  typedef Invoker3<StorageType, typename TargetTraits::NormalizedSig> Invoker;
   typedef typename TargetTraits::IsMethod IsMethod;
+  typedef Invoker3<IsWeakMethod<IsMethod::value, P1>::value, StorageType,
+                   typename TargetTraits::NormalizedSig> Invoker;
+  COMPILE_ASSERT(!(IsWeakMethod<IsMethod::value, P1>::value) ||
+                 is_void<typename TargetTraits::Return>::value,
+                 weak_ptrs_can_only_bind_to_methods_without_return_values);
 
   // For methods, we need to be careful for parameter 1.  We skip the
   // scoped_refptr check because the binder itself takes care of this. We also
   // disallow binding of an array as the method's target object.
   COMPILE_ASSERT(IsMethod::value ||
                  !internal::UnsafeBindtoRefCountedArg<P1>::value,
                  p1_is_refcounted_type_and_needs_scoped_refptr);
   COMPILE_ASSERT(!IsMethod::value || !is_array<P1>::value,
                  first_bound_argument_to_method_cannot_be_array);
   COMPILE_ASSERT(!internal::UnsafeBindtoRefCountedArg<P2>::value,
@@ skipping 28 matching lines @@
   typename ParamTraits<P1>::StorageType p1_;
   typename ParamTraits<P2>::StorageType p2_;
   typename ParamTraits<P3>::StorageType p3_;
 };
 
 template <typename Sig, typename P1, typename P2, typename P3, typename P4>
 class InvokerStorage4 : public InvokerStorageBase {
  public:
   typedef InvokerStorage4 StorageType;
   typedef FunctionTraits<Sig> TargetTraits;
-  typedef Invoker4<StorageType, typename TargetTraits::NormalizedSig> Invoker;
   typedef typename TargetTraits::IsMethod IsMethod;
+  typedef Invoker4<IsWeakMethod<IsMethod::value, P1>::value, StorageType,
+                   typename TargetTraits::NormalizedSig> Invoker;
+  COMPILE_ASSERT(!(IsWeakMethod<IsMethod::value, P1>::value) ||
+                 is_void<typename TargetTraits::Return>::value,
+                 weak_ptrs_can_only_bind_to_methods_without_return_values);
 
   // For methods, we need to be careful for parameter 1.  We skip the
   // scoped_refptr check because the binder itself takes care of this. We also
   // disallow binding of an array as the method's target object.
   COMPILE_ASSERT(IsMethod::value ||
                  !internal::UnsafeBindtoRefCountedArg<P1>::value,
                  p1_is_refcounted_type_and_needs_scoped_refptr);
   COMPILE_ASSERT(!IsMethod::value || !is_array<P1>::value,
                  first_bound_argument_to_method_cannot_be_array);
   COMPILE_ASSERT(!internal::UnsafeBindtoRefCountedArg<P2>::value,
@@ skipping 34 matching lines @@
   typename ParamTraits<P3>::StorageType p3_;
   typename ParamTraits<P4>::StorageType p4_;
 };
 
 template <typename Sig, typename P1, typename P2, typename P3, typename P4,
     typename P5>
 class InvokerStorage5 : public InvokerStorageBase {
  public:
   typedef InvokerStorage5 StorageType;
   typedef FunctionTraits<Sig> TargetTraits;
-  typedef Invoker5<StorageType, typename TargetTraits::NormalizedSig> Invoker;
   typedef typename TargetTraits::IsMethod IsMethod;
+  typedef Invoker5<IsWeakMethod<IsMethod::value, P1>::value, StorageType,
+                   typename TargetTraits::NormalizedSig> Invoker;
+  COMPILE_ASSERT(!(IsWeakMethod<IsMethod::value, P1>::value) ||
+                 is_void<typename TargetTraits::Return>::value,
+                 weak_ptrs_can_only_bind_to_methods_without_return_values);
 
   // For methods, we need to be careful for parameter 1.  We skip the
   // scoped_refptr check because the binder itself takes care of this. We also
   // disallow binding of an array as the method's target object.
   COMPILE_ASSERT(IsMethod::value ||
                  !internal::UnsafeBindtoRefCountedArg<P1>::value,
                  p1_is_refcounted_type_and_needs_scoped_refptr);
   COMPILE_ASSERT(!IsMethod::value || !is_array<P1>::value,
                  first_bound_argument_to_method_cannot_be_array);
   COMPILE_ASSERT(!internal::UnsafeBindtoRefCountedArg<P2>::value,
@@ skipping 40 matching lines @@
   typename ParamTraits<P4>::StorageType p4_;
   typename ParamTraits<P5>::StorageType p5_;
 };
 
 template <typename Sig, typename P1, typename P2, typename P3, typename P4,
     typename P5, typename P6>
 class InvokerStorage6 : public InvokerStorageBase {
  public:
   typedef InvokerStorage6 StorageType;
   typedef FunctionTraits<Sig> TargetTraits;
-  typedef Invoker6<StorageType, typename TargetTraits::NormalizedSig> Invoker;
   typedef typename TargetTraits::IsMethod IsMethod;
+  typedef Invoker6<IsWeakMethod<IsMethod::value, P1>::value, StorageType,
+                   typename TargetTraits::NormalizedSig> Invoker;
+  COMPILE_ASSERT(!(IsWeakMethod<IsMethod::value, P1>::value) ||
+                 is_void<typename TargetTraits::Return>::value,
+                 weak_ptrs_can_only_bind_to_methods_without_return_values);
 
   // For methods, we need to be careful for parameter 1.  We skip the
   // scoped_refptr check because the binder itself takes care of this. We also
   // disallow binding of an array as the method's target object.
   COMPILE_ASSERT(IsMethod::value ||
                  !internal::UnsafeBindtoRefCountedArg<P1>::value,
                  p1_is_refcounted_type_and_needs_scoped_refptr);
   COMPILE_ASSERT(!IsMethod::value || !is_array<P1>::value,
                  first_bound_argument_to_method_cannot_be_array);
   COMPILE_ASSERT(!internal::UnsafeBindtoRefCountedArg<P2>::value,
@@ skipping 43 matching lines @@
   typename ParamTraits<P3>::StorageType p3_;
   typename ParamTraits<P4>::StorageType p4_;
   typename ParamTraits<P5>::StorageType p5_;
   typename ParamTraits<P6>::StorageType p6_;
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_BIND_INTERNAL_H_