Bind: Use VariadicTemplates in bind_internal.h

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_
 
 #include "base/bind_helpers.h"
 #include "base/callback_internal.h"
 #include "base/memory/raw_scoped_refptr_mismatch_checker.h"
 #include "base/memory/weak_ptr.h"
 #include "base/template_util.h"
+#include "base/tuple.h"
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 #include "base/bind_internal_win.h"
 #endif
 
 namespace base {
 namespace internal {
 
 // See base/callback.h for user documentation.
@@ skipping 16 matching lines @@
 //  (Bound)ArgsType -- A function type that is being (ab)used to store the
 //                     types of set of arguments.  The "return" type is always
 //                     void here.  We use this hack so that we do not need
 //                     a new type name for each arity of type. (eg.,
 //                     BindState1, BindState2).  This makes forward
 //                     declarations and friending much much easier.
 //
 // Types:
 //  RunnableAdapter<> -- Wraps the various "function" pointer types into an
 //                       object that adheres to the Runnable interface.
-//  FunctionTraits<> -- Type traits that unwrap a function signature into a
-//                      a set of easier to use typedefs.  Used mainly for
-//                      compile time asserts.
-//                      There are |ARITY| FunctionTraits types.
 //  ForceVoidReturn<> -- Helper class for translating function signatures to
 //                       equivalent forms with a "void" return type.
 //  FunctorTraits<> -- Type traits used determine the correct RunType and
 //                     RunnableType for a Functor.  This is where function
 //                     signature adapters are applied.
 //  MakeRunnable<> -- Takes a Functor and returns an object in the Runnable
 //                    type class that represents the underlying Functor.
 //                    There are |O(1)| MakeRunnable types.
 //  InvokeHelper<> -- Take a Runnable + arguments and actully invokes it.
-// Handle the differing syntaxes needed for WeakPtr<> support,
-//                    and for ignoring return values.  This is separate from
-//                    Invoker to avoid creating multiple version of Invoker<>
-//                    which grows at O(n^2) with the arity.
+//                    Handle the differing syntaxes needed for WeakPtr<>
+//                    support, and for ignoring return values.  This is separate
+//                    from Invoker to avoid creating multiple version of
+//                    Invoker<>.
 //  Invoker<> -- Unwraps the curried parameters and executes the Runnable.
-//               There are |(ARITY^2 + ARITY)/2| Invoketypes.
 //  BindState<> -- Stores the curried parameters, and is the main entry point
 //                 into the Bind() system, doing most of the type resolution.
 //                 There are ARITY BindState types.
 
 // HasNonConstReferenceParam selects true_type when any of the parameters in
 // |Sig| is a non-const reference.
 // Implementation note: This non-specialized case handles zero-arity case only.
 // Non-zero-arity cases should be handled by the specialization below.
 template <typename Sig>
 struct HasNonConstReferenceParam : false_type {};
@@ skipping 119 matching lines @@
 
   R Run(const T* object,
         typename CallbackParamTraits<Args>::ForwardType... args) {
     return (object->*method_)(CallbackForward(args)...);
   }
 
  private:
   R (T::*method_)(Args...) const;
 };
 
-// TODO(tzik): Remove FunctionTraits after we finish removing bind.pump.
-// FunctionTraits<>
-//
-// Breaks a function signature apart into typedefs for easier introspection.
-template <typename Sig>
-struct FunctionTraits;
-
-template <typename R>
-struct FunctionTraits<R()> {
-  typedef R ReturnType;
-};
-
-template <typename R, typename A1>
-struct FunctionTraits<R(A1)> {
-  typedef R ReturnType;
-  typedef A1 A1Type;
-};
-
-template <typename R, typename A1, typename A2>
-struct FunctionTraits<R(A1, A2)> {
-  typedef R ReturnType;
-  typedef A1 A1Type;
-  typedef A2 A2Type;
-};
-
-template <typename R, typename A1, typename A2, typename A3>
-struct FunctionTraits<R(A1, A2, A3)> {
-  typedef R ReturnType;
-  typedef A1 A1Type;
-  typedef A2 A2Type;
-  typedef A3 A3Type;
-};
-
-template <typename R, typename A1, typename A2, typename A3, typename A4>
-struct FunctionTraits<R(A1, A2, A3, A4)> {
-  typedef R ReturnType;
-  typedef A1 A1Type;
-  typedef A2 A2Type;
-  typedef A3 A3Type;
-  typedef A4 A4Type;
-};
-
-template <typename R, typename A1, typename A2, typename A3, typename A4,
-    typename A5>
-struct FunctionTraits<R(A1, A2, A3, A4, A5)> {
-  typedef R ReturnType;
-  typedef A1 A1Type;
-  typedef A2 A2Type;
-  typedef A3 A3Type;
-  typedef A4 A4Type;
-  typedef A5 A5Type;
-};
-
-template <typename R, typename A1, typename A2, typename A3, typename A4,
-    typename A5, typename A6>
-struct FunctionTraits<R(A1, A2, A3, A4, A5, A6)> {
-  typedef R ReturnType;
-  typedef A1 A1Type;
-  typedef A2 A2Type;
-  typedef A3 A3Type;
-  typedef A4 A4Type;
-  typedef A5 A5Type;
-  typedef A6 A6Type;
-};
-
-template <typename R, typename A1, typename A2, typename A3, typename A4,
-    typename A5, typename A6, typename A7>
-struct FunctionTraits<R(A1, A2, A3, A4, A5, A6, A7)> {
-  typedef R ReturnType;
-  typedef A1 A1Type;
-  typedef A2 A2Type;
-  typedef A3 A3Type;
-  typedef A4 A4Type;
-  typedef A5 A5Type;
-  typedef A6 A6Type;
-  typedef A7 A7Type;
-};
-
 
 // ForceVoidReturn<>
 //
 // Set of templates that support forcing the function return type to void.
 template <typename Sig>
 struct ForceVoidReturn;
 
 template <typename R, typename... Args>
 struct ForceVoidReturn<R(Args...)> {
   typedef void(RunType)(Args...);
 };
 
 
 // FunctorTraits<>
 //
 // See description at top of file.
 template <typename T>
 struct FunctorTraits {
   typedef RunnableAdapter<T> RunnableType;
   typedef typename RunnableType::RunType RunType;
 };
 
 template <typename T>
-struct FunctorTraits<IgnoreResultHelper<T> > {
+struct FunctorTraits<IgnoreResultHelper<T>> {
   typedef typename FunctorTraits<T>::RunnableType RunnableType;
   typedef typename ForceVoidReturn<
       typename RunnableType::RunType>::RunType RunType;
 };
 
 template <typename T>
-struct FunctorTraits<Callback<T> > {
+struct FunctorTraits<Callback<T>> {
   typedef Callback<T> RunnableType;
   typedef typename Callback<T>::RunType RunType;
 };
 
 
 // MakeRunnable<>
 //
 // Converts a passed in functor to a RunnableType using type inference.
 
 template <typename T>
 typename FunctorTraits<T>::RunnableType MakeRunnable(const T& t) {
   return RunnableAdapter<T>(t);
 }
 
 template <typename T>
 typename FunctorTraits<T>::RunnableType
 MakeRunnable(const IgnoreResultHelper<T>& t) {
   return MakeRunnable(t.functor_);
 }
 
 template <typename T>
-const typename FunctorTraits<Callback<T> >::RunnableType&
+const typename FunctorTraits<Callback<T>>::RunnableType&
 MakeRunnable(const Callback<T>& t) {
   DCHECK(!t.is_null());
   return t;
 }
 
 
 // InvokeHelper<>
 //
 // There are 3 logical InvokeHelper<> specializations: normal, void-return,
 // WeakCalls.
 //
 // The normal type just calls the underlying runnable.
 //
 // We need a InvokeHelper to handle void return types in order to support
 // IgnoreResult().  Normally, if the Runnable's RunType had a void return,
 // the template system would just accept "return functor.Run()" ignoring
 // the fact that a void function is being used with return. This piece of
 // sugar breaks though when the Runnable's RunType is not void.  Thus, we
 // need a partial specialization to change the syntax to drop the "return"
 // from the invocation call.
 //
 // WeakCalls similarly need special syntax that is applied to the first
 // argument to check if they should no-op themselves.
 template <bool IsWeakCall, typename ReturnType, typename Runnable,
           typename ArgsType>
 struct InvokeHelper;
 
 template <typename ReturnType, typename Runnable, typename... Args>
-struct InvokeHelper<false, ReturnType, Runnable,
-    void(Args...)>  {
+struct InvokeHelper<false, ReturnType, Runnable, TypeList<Args...>> {
   static ReturnType MakeItSo(Runnable runnable, Args... args) {
     return runnable.Run(CallbackForward(args)...);
   }
 };
 
 template <typename Runnable, typename... Args>
-struct InvokeHelper<false, void, Runnable, void(Args...)>  {
+struct InvokeHelper<false, void, Runnable, TypeList<Args...>> {
   static void MakeItSo(Runnable runnable, Args... args) {
     runnable.Run(CallbackForward(args)...);
   }
 };
 
 template <typename Runnable, typename BoundWeakPtr, typename... Args>
-struct InvokeHelper<true, void, Runnable, void(BoundWeakPtr, Args...)>  {
+struct InvokeHelper<true, void, Runnable, TypeList<BoundWeakPtr, Args...>> {
   static void MakeItSo(Runnable runnable, BoundWeakPtr weak_ptr, Args... args) {
     if (!weak_ptr.get()) {
       return;
     }
     runnable.Run(weak_ptr.get(), CallbackForward(args)...);
   }
 };
 
 #if !defined(_MSC_VER)
 
 template <typename ReturnType, typename Runnable, typename ArgsType>
 struct InvokeHelper<true, ReturnType, Runnable, ArgsType> {
   // WeakCalls are only supported for functions with a void return type.
   // Otherwise, the function result would be undefined if the the WeakPtr<>
   // is invalidated.
   COMPILE_ASSERT(is_void<ReturnType>::value,
                  weak_ptrs_can_only_bind_to_methods_without_return_values);
 };
 
 #endif
 
 // Invoker<>
 //
 // See description at the top of the file.
-template <int NumBound, typename Storage, typename RunType>
+template <typename BoundIndices,
+          typename StorageType, typename Unwrappers,
+          typename InvokeHelperType, typename UnboundForwardRunType>
 struct Invoker;
 
-// Arity 0 -> 0.
-template <typename StorageType, typename R>
-struct Invoker<0, StorageType, R()> {
-  typedef R(RunType)(BindStateBase*);
-
-  typedef R(UnboundRunType)();
-
-  static R Run(BindStateBase* base) {
+template <size_t... bound_indices,
+          typename StorageType,
+          typename... Unwrappers,
+          typename InvokeHelperType,
+          typename R,
+          typename... UnboundForwardArgs>
+struct Invoker<IndexSequence<bound_indices...>,
+               StorageType, TypeList<Unwrappers...>,
+               InvokeHelperType, R(UnboundForwardArgs...)> {
+  static R Run(BindStateBase* base,
+               UnboundForwardArgs... unbound_args) {
     StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void()>
-               ::MakeItSo(storage->runnable_);
+    return InvokeHelperType::MakeItSo(
+        storage->runnable_,
+        Unwrappers::Unwrap(get<bound_indices>(storage->bound_args_))...,
+        CallbackForward(unbound_args)...);
   }
 };
 
-// Arity 1 -> 1.
-template <typename StorageType, typename R,typename X1>
-struct Invoker<0, StorageType, R(X1)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X1>::ForwardType);
-
-  typedef R(UnboundRunType)(X1);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X1>::ForwardType x1) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename CallbackParamTraits<X1>::ForwardType x1)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1));
-  }
-};
-
-// Arity 1 -> 0.
-template <typename StorageType, typename R,typename X1>
-struct Invoker<1, StorageType, R(X1)> {
-  typedef R(RunType)(BindStateBase*);
-
-  typedef R(UnboundRunType)();
-
-  static R Run(BindStateBase* base) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1));
-  }
-};
-
-// Arity 2 -> 2.
-template <typename StorageType, typename R,typename X1, typename X2>
-struct Invoker<0, StorageType, R(X1, X2)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X1>::ForwardType,
-      typename CallbackParamTraits<X2>::ForwardType);
-
-  typedef R(UnboundRunType)(X1, X2);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X1>::ForwardType x1,
-      typename CallbackParamTraits<X2>::ForwardType x2) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename CallbackParamTraits<X1>::ForwardType x1,
-               typename CallbackParamTraits<X2>::ForwardType x2)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2));
-  }
-};
-
-// Arity 2 -> 1.
-template <typename StorageType, typename R,typename X1, typename X2>
-struct Invoker<1, StorageType, R(X1, X2)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X2>::ForwardType);
-
-  typedef R(UnboundRunType)(X2);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X2>::ForwardType x2) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X2>::ForwardType x2)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2));
-  }
-};
-
-// Arity 2 -> 0.
-template <typename StorageType, typename R,typename X1, typename X2>
-struct Invoker<2, StorageType, R(X1, X2)> {
-  typedef R(RunType)(BindStateBase*);
-
-  typedef R(UnboundRunType)();
-
-  static R Run(BindStateBase* base) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2));
-  }
-};
-
-// Arity 3 -> 3.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3>
-struct Invoker<0, StorageType, R(X1, X2, X3)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X1>::ForwardType,
-      typename CallbackParamTraits<X2>::ForwardType,
-      typename CallbackParamTraits<X3>::ForwardType);
-
-  typedef R(UnboundRunType)(X1, X2, X3);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X1>::ForwardType x1,
-      typename CallbackParamTraits<X2>::ForwardType x2,
-      typename CallbackParamTraits<X3>::ForwardType x3) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename CallbackParamTraits<X1>::ForwardType x1,
-               typename CallbackParamTraits<X2>::ForwardType x2,
-               typename CallbackParamTraits<X3>::ForwardType x3)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3));
-  }
-};
-
-// Arity 3 -> 2.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3>
-struct Invoker<1, StorageType, R(X1, X2, X3)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X2>::ForwardType,
-      typename CallbackParamTraits<X3>::ForwardType);
-
-  typedef R(UnboundRunType)(X2, X3);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X2>::ForwardType x2,
-      typename CallbackParamTraits<X3>::ForwardType x3) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X2>::ForwardType x2,
-               typename CallbackParamTraits<X3>::ForwardType x3)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3));
-  }
-};
-
-// Arity 3 -> 1.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3>
-struct Invoker<2, StorageType, R(X1, X2, X3)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X3>::ForwardType);
-
-  typedef R(UnboundRunType)(X3);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X3>::ForwardType x3) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X3>::ForwardType x3)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3));
-  }
-};
-
-// Arity 3 -> 0.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3>
-struct Invoker<3, StorageType, R(X1, X2, X3)> {
-  typedef R(RunType)(BindStateBase*);
-
-  typedef R(UnboundRunType)();
-
-  static R Run(BindStateBase* base) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3));
-  }
-};
-
-// Arity 4 -> 4.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4>
-struct Invoker<0, StorageType, R(X1, X2, X3, X4)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X1>::ForwardType,
-      typename CallbackParamTraits<X2>::ForwardType,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType);
-
-  typedef R(UnboundRunType)(X1, X2, X3, X4);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X1>::ForwardType x1,
-      typename CallbackParamTraits<X2>::ForwardType x2,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename CallbackParamTraits<X1>::ForwardType x1,
-               typename CallbackParamTraits<X2>::ForwardType x2,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4));
-  }
-};
-
-// Arity 4 -> 3.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4>
-struct Invoker<1, StorageType, R(X1, X2, X3, X4)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X2>::ForwardType,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType);
-
-  typedef R(UnboundRunType)(X2, X3, X4);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X2>::ForwardType x2,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X2>::ForwardType x2,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4));
-  }
-};
-
-// Arity 4 -> 2.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4>
-struct Invoker<2, StorageType, R(X1, X2, X3, X4)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType);
-
-  typedef R(UnboundRunType)(X3, X4);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4));
-  }
-};
-
-// Arity 4 -> 1.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4>
-struct Invoker<3, StorageType, R(X1, X2, X3, X4)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X4>::ForwardType);
-
-  typedef R(UnboundRunType)(X4);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X4>::ForwardType x4) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X4>::ForwardType x4)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4));
-  }
-};
-
-// Arity 4 -> 0.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4>
-struct Invoker<4, StorageType, R(X1, X2, X3, X4)> {
-  typedef R(RunType)(BindStateBase*);
-
-  typedef R(UnboundRunType)();
-
-  static R Run(BindStateBase* base) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-    typedef typename StorageType::Bound4UnwrapTraits Bound4UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    typename Bound4UnwrapTraits::ForwardType x4 =
-        Bound4UnwrapTraits::Unwrap(storage->p4_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename Bound4UnwrapTraits::ForwardType)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4));
-  }
-};
-
-// Arity 5 -> 5.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5>
-struct Invoker<0, StorageType, R(X1, X2, X3, X4, X5)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X1>::ForwardType,
-      typename CallbackParamTraits<X2>::ForwardType,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType);
-
-  typedef R(UnboundRunType)(X1, X2, X3, X4, X5);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X1>::ForwardType x1,
-      typename CallbackParamTraits<X2>::ForwardType x2,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename CallbackParamTraits<X1>::ForwardType x1,
-               typename CallbackParamTraits<X2>::ForwardType x2,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5));
-  }
-};
-
-// Arity 5 -> 4.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5>
-struct Invoker<1, StorageType, R(X1, X2, X3, X4, X5)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X2>::ForwardType,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType);
-
-  typedef R(UnboundRunType)(X2, X3, X4, X5);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X2>::ForwardType x2,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X2>::ForwardType x2,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5));
-  }
-};
-
-// Arity 5 -> 3.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5>
-struct Invoker<2, StorageType, R(X1, X2, X3, X4, X5)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType);
-
-  typedef R(UnboundRunType)(X3, X4, X5);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5));
-  }
-};
-
-// Arity 5 -> 2.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5>
-struct Invoker<3, StorageType, R(X1, X2, X3, X4, X5)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType);
-
-  typedef R(UnboundRunType)(X4, X5);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5));
-  }
-};
-
-// Arity 5 -> 1.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5>
-struct Invoker<4, StorageType, R(X1, X2, X3, X4, X5)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X5>::ForwardType);
-
-  typedef R(UnboundRunType)(X5);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X5>::ForwardType x5) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-    typedef typename StorageType::Bound4UnwrapTraits Bound4UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    typename Bound4UnwrapTraits::ForwardType x4 =
-        Bound4UnwrapTraits::Unwrap(storage->p4_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename Bound4UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X5>::ForwardType x5)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5));
-  }
-};
-
-// Arity 5 -> 0.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5>
-struct Invoker<5, StorageType, R(X1, X2, X3, X4, X5)> {
-  typedef R(RunType)(BindStateBase*);
-
-  typedef R(UnboundRunType)();
-
-  static R Run(BindStateBase* base) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-    typedef typename StorageType::Bound4UnwrapTraits Bound4UnwrapTraits;
-    typedef typename StorageType::Bound5UnwrapTraits Bound5UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    typename Bound4UnwrapTraits::ForwardType x4 =
-        Bound4UnwrapTraits::Unwrap(storage->p4_);
-    typename Bound5UnwrapTraits::ForwardType x5 =
-        Bound5UnwrapTraits::Unwrap(storage->p5_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename Bound4UnwrapTraits::ForwardType,
-               typename Bound5UnwrapTraits::ForwardType)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5));
-  }
-};
-
-// Arity 6 -> 6.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6>
-struct Invoker<0, StorageType, R(X1, X2, X3, X4, X5, X6)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X1>::ForwardType,
-      typename CallbackParamTraits<X2>::ForwardType,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType,
-      typename CallbackParamTraits<X6>::ForwardType);
-
-  typedef R(UnboundRunType)(X1, X2, X3, X4, X5, X6);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X1>::ForwardType x1,
-      typename CallbackParamTraits<X2>::ForwardType x2,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5,
-      typename CallbackParamTraits<X6>::ForwardType x6) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename CallbackParamTraits<X1>::ForwardType x1,
-               typename CallbackParamTraits<X2>::ForwardType x2,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5,
-               typename CallbackParamTraits<X6>::ForwardType x6)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6));
-  }
-};
-
-// Arity 6 -> 5.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6>
-struct Invoker<1, StorageType, R(X1, X2, X3, X4, X5, X6)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X2>::ForwardType,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType,
-      typename CallbackParamTraits<X6>::ForwardType);
-
-  typedef R(UnboundRunType)(X2, X3, X4, X5, X6);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X2>::ForwardType x2,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5,
-      typename CallbackParamTraits<X6>::ForwardType x6) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X2>::ForwardType x2,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5,
-               typename CallbackParamTraits<X6>::ForwardType x6)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6));
-  }
-};
-
-// Arity 6 -> 4.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6>
-struct Invoker<2, StorageType, R(X1, X2, X3, X4, X5, X6)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType,
-      typename CallbackParamTraits<X6>::ForwardType);
-
-  typedef R(UnboundRunType)(X3, X4, X5, X6);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5,
-      typename CallbackParamTraits<X6>::ForwardType x6) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5,
-               typename CallbackParamTraits<X6>::ForwardType x6)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6));
-  }
-};
-
-// Arity 6 -> 3.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6>
-struct Invoker<3, StorageType, R(X1, X2, X3, X4, X5, X6)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType,
-      typename CallbackParamTraits<X6>::ForwardType);
-
-  typedef R(UnboundRunType)(X4, X5, X6);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5,
-      typename CallbackParamTraits<X6>::ForwardType x6) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5,
-               typename CallbackParamTraits<X6>::ForwardType x6)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6));
-  }
-};
-
-// Arity 6 -> 2.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6>
-struct Invoker<4, StorageType, R(X1, X2, X3, X4, X5, X6)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X5>::ForwardType,
-      typename CallbackParamTraits<X6>::ForwardType);
-
-  typedef R(UnboundRunType)(X5, X6);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X5>::ForwardType x5,
-      typename CallbackParamTraits<X6>::ForwardType x6) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-    typedef typename StorageType::Bound4UnwrapTraits Bound4UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    typename Bound4UnwrapTraits::ForwardType x4 =
-        Bound4UnwrapTraits::Unwrap(storage->p4_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename Bound4UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X5>::ForwardType x5,
-               typename CallbackParamTraits<X6>::ForwardType x6)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6));
-  }
-};
-
-// Arity 6 -> 1.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6>
-struct Invoker<5, StorageType, R(X1, X2, X3, X4, X5, X6)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X6>::ForwardType);
-
-  typedef R(UnboundRunType)(X6);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X6>::ForwardType x6) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-    typedef typename StorageType::Bound4UnwrapTraits Bound4UnwrapTraits;
-    typedef typename StorageType::Bound5UnwrapTraits Bound5UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    typename Bound4UnwrapTraits::ForwardType x4 =
-        Bound4UnwrapTraits::Unwrap(storage->p4_);
-    typename Bound5UnwrapTraits::ForwardType x5 =
-        Bound5UnwrapTraits::Unwrap(storage->p5_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename Bound4UnwrapTraits::ForwardType,
-               typename Bound5UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X6>::ForwardType x6)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6));
-  }
-};
-
-// Arity 6 -> 0.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6>
-struct Invoker<6, StorageType, R(X1, X2, X3, X4, X5, X6)> {
-  typedef R(RunType)(BindStateBase*);
-
-  typedef R(UnboundRunType)();
-
-  static R Run(BindStateBase* base) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-    typedef typename StorageType::Bound4UnwrapTraits Bound4UnwrapTraits;
-    typedef typename StorageType::Bound5UnwrapTraits Bound5UnwrapTraits;
-    typedef typename StorageType::Bound6UnwrapTraits Bound6UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    typename Bound4UnwrapTraits::ForwardType x4 =
-        Bound4UnwrapTraits::Unwrap(storage->p4_);
-    typename Bound5UnwrapTraits::ForwardType x5 =
-        Bound5UnwrapTraits::Unwrap(storage->p5_);
-    typename Bound6UnwrapTraits::ForwardType x6 =
-        Bound6UnwrapTraits::Unwrap(storage->p6_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename Bound4UnwrapTraits::ForwardType,
-               typename Bound5UnwrapTraits::ForwardType,
-               typename Bound6UnwrapTraits::ForwardType)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6));
-  }
-};
-
-// Arity 7 -> 7.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6, typename X7>
-struct Invoker<0, StorageType, R(X1, X2, X3, X4, X5, X6, X7)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X1>::ForwardType,
-      typename CallbackParamTraits<X2>::ForwardType,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType,
-      typename CallbackParamTraits<X6>::ForwardType,
-      typename CallbackParamTraits<X7>::ForwardType);
-
-  typedef R(UnboundRunType)(X1, X2, X3, X4, X5, X6, X7);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X1>::ForwardType x1,
-      typename CallbackParamTraits<X2>::ForwardType x2,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5,
-      typename CallbackParamTraits<X6>::ForwardType x6,
-      typename CallbackParamTraits<X7>::ForwardType x7) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename CallbackParamTraits<X1>::ForwardType x1,
-               typename CallbackParamTraits<X2>::ForwardType x2,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5,
-               typename CallbackParamTraits<X6>::ForwardType x6,
-               typename CallbackParamTraits<X7>::ForwardType x7)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6), CallbackForward(x7));
-  }
-};
-
-// Arity 7 -> 6.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6, typename X7>
-struct Invoker<1, StorageType, R(X1, X2, X3, X4, X5, X6, X7)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X2>::ForwardType,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType,
-      typename CallbackParamTraits<X6>::ForwardType,
-      typename CallbackParamTraits<X7>::ForwardType);
-
-  typedef R(UnboundRunType)(X2, X3, X4, X5, X6, X7);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X2>::ForwardType x2,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5,
-      typename CallbackParamTraits<X6>::ForwardType x6,
-      typename CallbackParamTraits<X7>::ForwardType x7) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X2>::ForwardType x2,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5,
-               typename CallbackParamTraits<X6>::ForwardType x6,
-               typename CallbackParamTraits<X7>::ForwardType x7)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6), CallbackForward(x7));
-  }
-};
-
-// Arity 7 -> 5.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6, typename X7>
-struct Invoker<2, StorageType, R(X1, X2, X3, X4, X5, X6, X7)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X3>::ForwardType,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType,
-      typename CallbackParamTraits<X6>::ForwardType,
-      typename CallbackParamTraits<X7>::ForwardType);
-
-  typedef R(UnboundRunType)(X3, X4, X5, X6, X7);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X3>::ForwardType x3,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5,
-      typename CallbackParamTraits<X6>::ForwardType x6,
-      typename CallbackParamTraits<X7>::ForwardType x7) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X3>::ForwardType x3,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5,
-               typename CallbackParamTraits<X6>::ForwardType x6,
-               typename CallbackParamTraits<X7>::ForwardType x7)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6), CallbackForward(x7));
-  }
-};
-
-// Arity 7 -> 4.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6, typename X7>
-struct Invoker<3, StorageType, R(X1, X2, X3, X4, X5, X6, X7)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X4>::ForwardType,
-      typename CallbackParamTraits<X5>::ForwardType,
-      typename CallbackParamTraits<X6>::ForwardType,
-      typename CallbackParamTraits<X7>::ForwardType);
-
-  typedef R(UnboundRunType)(X4, X5, X6, X7);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X4>::ForwardType x4,
-      typename CallbackParamTraits<X5>::ForwardType x5,
-      typename CallbackParamTraits<X6>::ForwardType x6,
-      typename CallbackParamTraits<X7>::ForwardType x7) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X4>::ForwardType x4,
-               typename CallbackParamTraits<X5>::ForwardType x5,
-               typename CallbackParamTraits<X6>::ForwardType x6,
-               typename CallbackParamTraits<X7>::ForwardType x7)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6), CallbackForward(x7));
-  }
-};
-
-// Arity 7 -> 3.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6, typename X7>
-struct Invoker<4, StorageType, R(X1, X2, X3, X4, X5, X6, X7)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X5>::ForwardType,
-      typename CallbackParamTraits<X6>::ForwardType,
-      typename CallbackParamTraits<X7>::ForwardType);
-
-  typedef R(UnboundRunType)(X5, X6, X7);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X5>::ForwardType x5,
-      typename CallbackParamTraits<X6>::ForwardType x6,
-      typename CallbackParamTraits<X7>::ForwardType x7) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-    typedef typename StorageType::Bound4UnwrapTraits Bound4UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    typename Bound4UnwrapTraits::ForwardType x4 =
-        Bound4UnwrapTraits::Unwrap(storage->p4_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename Bound4UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X5>::ForwardType x5,
-               typename CallbackParamTraits<X6>::ForwardType x6,
-               typename CallbackParamTraits<X7>::ForwardType x7)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6), CallbackForward(x7));
-  }
-};
-
-// Arity 7 -> 2.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6, typename X7>
-struct Invoker<5, StorageType, R(X1, X2, X3, X4, X5, X6, X7)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X6>::ForwardType,
-      typename CallbackParamTraits<X7>::ForwardType);
-
-  typedef R(UnboundRunType)(X6, X7);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X6>::ForwardType x6,
-      typename CallbackParamTraits<X7>::ForwardType x7) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-    typedef typename StorageType::Bound4UnwrapTraits Bound4UnwrapTraits;
-    typedef typename StorageType::Bound5UnwrapTraits Bound5UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    typename Bound4UnwrapTraits::ForwardType x4 =
-        Bound4UnwrapTraits::Unwrap(storage->p4_);
-    typename Bound5UnwrapTraits::ForwardType x5 =
-        Bound5UnwrapTraits::Unwrap(storage->p5_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename Bound4UnwrapTraits::ForwardType,
-               typename Bound5UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X6>::ForwardType x6,
-               typename CallbackParamTraits<X7>::ForwardType x7)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6), CallbackForward(x7));
-  }
-};
-
-// Arity 7 -> 1.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6, typename X7>
-struct Invoker<6, StorageType, R(X1, X2, X3, X4, X5, X6, X7)> {
-  typedef R(RunType)(BindStateBase*,
-      typename CallbackParamTraits<X7>::ForwardType);
-
-  typedef R(UnboundRunType)(X7);
-
-  static R Run(BindStateBase* base,
-      typename CallbackParamTraits<X7>::ForwardType x7) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-    typedef typename StorageType::Bound4UnwrapTraits Bound4UnwrapTraits;
-    typedef typename StorageType::Bound5UnwrapTraits Bound5UnwrapTraits;
-    typedef typename StorageType::Bound6UnwrapTraits Bound6UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    typename Bound4UnwrapTraits::ForwardType x4 =
-        Bound4UnwrapTraits::Unwrap(storage->p4_);
-    typename Bound5UnwrapTraits::ForwardType x5 =
-        Bound5UnwrapTraits::Unwrap(storage->p5_);
-    typename Bound6UnwrapTraits::ForwardType x6 =
-        Bound6UnwrapTraits::Unwrap(storage->p6_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename Bound4UnwrapTraits::ForwardType,
-               typename Bound5UnwrapTraits::ForwardType,
-               typename Bound6UnwrapTraits::ForwardType,
-               typename CallbackParamTraits<X7>::ForwardType x7)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6), CallbackForward(x7));
-  }
-};
-
-// Arity 7 -> 0.
-template <typename StorageType, typename R,typename X1, typename X2,
-    typename X3, typename X4, typename X5, typename X6, typename X7>
-struct Invoker<7, StorageType, R(X1, X2, X3, X4, X5, X6, X7)> {
-  typedef R(RunType)(BindStateBase*);
-
-  typedef R(UnboundRunType)();
-
-  static R Run(BindStateBase* base) {
-    StorageType* storage = static_cast<StorageType*>(base);
-
-    // Local references to make debugger stepping easier. If in a debugger,
-    // you really want to warp ahead and step through the
-    // InvokeHelper<>::MakeItSo() call below.
-    typedef typename StorageType::Bound1UnwrapTraits Bound1UnwrapTraits;
-    typedef typename StorageType::Bound2UnwrapTraits Bound2UnwrapTraits;
-    typedef typename StorageType::Bound3UnwrapTraits Bound3UnwrapTraits;
-    typedef typename StorageType::Bound4UnwrapTraits Bound4UnwrapTraits;
-    typedef typename StorageType::Bound5UnwrapTraits Bound5UnwrapTraits;
-    typedef typename StorageType::Bound6UnwrapTraits Bound6UnwrapTraits;
-    typedef typename StorageType::Bound7UnwrapTraits Bound7UnwrapTraits;
-
-    typename Bound1UnwrapTraits::ForwardType x1 =
-        Bound1UnwrapTraits::Unwrap(storage->p1_);
-    typename Bound2UnwrapTraits::ForwardType x2 =
-        Bound2UnwrapTraits::Unwrap(storage->p2_);
-    typename Bound3UnwrapTraits::ForwardType x3 =
-        Bound3UnwrapTraits::Unwrap(storage->p3_);
-    typename Bound4UnwrapTraits::ForwardType x4 =
-        Bound4UnwrapTraits::Unwrap(storage->p4_);
-    typename Bound5UnwrapTraits::ForwardType x5 =
-        Bound5UnwrapTraits::Unwrap(storage->p5_);
-    typename Bound6UnwrapTraits::ForwardType x6 =
-        Bound6UnwrapTraits::Unwrap(storage->p6_);
-    typename Bound7UnwrapTraits::ForwardType x7 =
-        Bound7UnwrapTraits::Unwrap(storage->p7_);
-    return InvokeHelper<StorageType::IsWeakCall::value, R,
-           typename StorageType::RunnableType,
-           void(typename Bound1UnwrapTraits::ForwardType,
-               typename Bound2UnwrapTraits::ForwardType,
-               typename Bound3UnwrapTraits::ForwardType,
-               typename Bound4UnwrapTraits::ForwardType,
-               typename Bound5UnwrapTraits::ForwardType,
-               typename Bound6UnwrapTraits::ForwardType,
-               typename Bound7UnwrapTraits::ForwardType)>
-               ::MakeItSo(storage->runnable_, CallbackForward(x1),
-                   CallbackForward(x2), CallbackForward(x3),
-                   CallbackForward(x4), CallbackForward(x5),
-                   CallbackForward(x6), CallbackForward(x7));
-  }
-};
-
 
 // BindState<>
 //
 // This stores all the state passed into Bind() and is also where most
 // of the template resolution magic occurs.
 //
 // Runnable is the functor we are binding arguments to.
 // RunType is type of the Run() function that the Invoker<> should use.
 // Normally, this is the same as the RunType of the Runnable, but it can
 // be different if an adapter like IgnoreResult() has been used.
 //
 // BoundArgsType contains the storage type for all the bound arguments by
 // (ab)using a function type.
-template <typename Runnable, typename RunType, typename BoundArgsType>
+template <typename Runnable, typename RunType, typename BoundArgList>
 struct BindState;
 
-template <typename Runnable, typename RunType>
-struct BindState<Runnable, RunType, void()> : public BindStateBase {
-  typedef Runnable RunnableType;
-  typedef false_type IsWeakCall;
-  typedef Invoker<0, BindState, RunType> InvokerType;
-  typedef typename InvokerType::UnboundRunType UnboundRunType;
-  explicit BindState(const Runnable& runnable)
-      : runnable_(runnable) {
-  }
+template <typename Runnable,
+          typename R, typename... Args,
+          typename... BoundArgs>
+struct BindState<Runnable, R(Args...), TypeList<BoundArgs...>>
+    : public BindStateBase {
+  using StorageType = BindState<Runnable, R(Args...), TypeList<BoundArgs...>>;
+  using RunnableType = Runnable;
+
+  // true_type if Runnable is a method invocation and the first bound argument
+  // is a WeakPtr.
+  using IsWeakCall =
+      IsWeakMethod<HasIsMethodTag<Runnable>::value, BoundArgs...>;
+
+  using BoundIndices = MakeIndexSequence<sizeof...(BoundArgs)>;
+  using Unwrappers = TypeList<UnwrapTraits<BoundArgs>...>;
+  using UnboundForwardArgs = DropTypeListItem<
+      sizeof...(BoundArgs),
+      TypeList<typename CallbackParamTraits<Args>::ForwardType...>>;
+  using UnboundForwardRunType = MakeFunctionType<R, UnboundForwardArgs>;
+
+  using InvokeHelperArgs = ConcatTypeLists<
+      TypeList<typename UnwrapTraits<BoundArgs>::ForwardType...>,
+      UnboundForwardArgs>;
+  using InvokeHelperType =
+      InvokeHelper<IsWeakCall::value, R, Runnable, InvokeHelperArgs>;
+
+  using InvokerType = Invoker<BoundIndices, StorageType, Unwrappers,
+                              InvokeHelperType, UnboundForwardRunType>;
+
+  using UnboundArgs = DropTypeListItem<sizeof...(BoundArgs), TypeList<Args...>>;
+  using UnboundRunType = MakeFunctionType<R, UnboundArgs>;
+
+  BindState(const Runnable& runnable, const BoundArgs&... bound_args)
+      : runnable_(runnable), ref_(bound_args...), bound_args_(bound_args...) {}
 
   RunnableType runnable_;
+  MaybeScopedRefPtr<HasIsMethodTag<Runnable>::value, BoundArgs...> ref_;
+  Tuple<BoundArgs...> bound_args_;
 
  private:
-  ~BindState() override {  }
-
-};
-
-template <typename Runnable, typename RunType, typename P1>
-struct BindState<Runnable, RunType, void(P1)> : public BindStateBase {
-  typedef Runnable RunnableType;
-  typedef IsWeakMethod<HasIsMethodTag<Runnable>::value, P1> IsWeakCall;
-  typedef Invoker<1, BindState, RunType> InvokerType;
-  typedef typename InvokerType::UnboundRunType UnboundRunType;
-
-  // Convenience typedefs for bound argument types.
-  typedef UnwrapTraits<P1> Bound1UnwrapTraits;
-
-  BindState(const Runnable& runnable, const P1& p1)
-      : runnable_(runnable),
-        p1_(p1) {
-    MaybeRefcount<HasIsMethodTag<Runnable>::value, P1>::AddRef(p1_);
-  }
-
-  RunnableType runnable_;
-  P1 p1_;
-
- private:
-  ~BindState() override {    MaybeRefcount<HasIsMethodTag<Runnable>::value,
-      P1>::Release(p1_);  }
-
-};
-
-template <typename Runnable, typename RunType, typename P1, typename P2>
-struct BindState<Runnable, RunType, void(P1, P2)> : public BindStateBase {
-  typedef Runnable RunnableType;
-  typedef IsWeakMethod<HasIsMethodTag<Runnable>::value, P1> IsWeakCall;
-  typedef Invoker<2, BindState, RunType> InvokerType;
-  typedef typename InvokerType::UnboundRunType UnboundRunType;
-
-  // Convenience typedefs for bound argument types.
-  typedef UnwrapTraits<P1> Bound1UnwrapTraits;
-  typedef UnwrapTraits<P2> Bound2UnwrapTraits;
-
-  BindState(const Runnable& runnable, const P1& p1, const P2& p2)
-      : runnable_(runnable),
-        p1_(p1),
-        p2_(p2) {
-    MaybeRefcount<HasIsMethodTag<Runnable>::value, P1>::AddRef(p1_);
-  }
-
-  RunnableType runnable_;
-  P1 p1_;
-  P2 p2_;
-
- private:
-  ~BindState() override {    MaybeRefcount<HasIsMethodTag<Runnable>::value,
-      P1>::Release(p1_);  }
-
-};
-
-template <typename Runnable, typename RunType, typename P1, typename P2,
-    typename P3>
-struct BindState<Runnable, RunType, void(P1, P2, P3)> : public BindStateBase {
-  typedef Runnable RunnableType;
-  typedef IsWeakMethod<HasIsMethodTag<Runnable>::value, P1> IsWeakCall;
-  typedef Invoker<3, BindState, RunType> InvokerType;
-  typedef typename InvokerType::UnboundRunType UnboundRunType;
-
-  // Convenience typedefs for bound argument types.
-  typedef UnwrapTraits<P1> Bound1UnwrapTraits;
-  typedef UnwrapTraits<P2> Bound2UnwrapTraits;
-  typedef UnwrapTraits<P3> Bound3UnwrapTraits;
-
-  BindState(const Runnable& runnable, const P1& p1, const P2& p2, const P3& p3)
-      : runnable_(runnable),
-        p1_(p1),
-        p2_(p2),
-        p3_(p3) {
-    MaybeRefcount<HasIsMethodTag<Runnable>::value, P1>::AddRef(p1_);
-  }
-
-  RunnableType runnable_;
-  P1 p1_;
-  P2 p2_;
-  P3 p3_;
-
- private:
-  ~BindState() override {    MaybeRefcount<HasIsMethodTag<Runnable>::value,
-      P1>::Release(p1_);  }
-
-};
-
-template <typename Runnable, typename RunType, typename P1, typename P2,
-    typename P3, typename P4>
-struct BindState<Runnable, RunType, void(P1, P2, P3,
-    P4)> : public BindStateBase {
-  typedef Runnable RunnableType;
-  typedef IsWeakMethod<HasIsMethodTag<Runnable>::value, P1> IsWeakCall;
-  typedef Invoker<4, BindState, RunType> InvokerType;
-  typedef typename InvokerType::UnboundRunType UnboundRunType;
-
-  // Convenience typedefs for bound argument types.
-  typedef UnwrapTraits<P1> Bound1UnwrapTraits;
-  typedef UnwrapTraits<P2> Bound2UnwrapTraits;
-  typedef UnwrapTraits<P3> Bound3UnwrapTraits;
-  typedef UnwrapTraits<P4> Bound4UnwrapTraits;
-
-  BindState(const Runnable& runnable, const P1& p1, const P2& p2, const P3& p3,
-      const P4& p4)
-      : runnable_(runnable),
-        p1_(p1),
-        p2_(p2),
-        p3_(p3),
-        p4_(p4) {
-    MaybeRefcount<HasIsMethodTag<Runnable>::value, P1>::AddRef(p1_);
-  }
-
-  RunnableType runnable_;
-  P1 p1_;
-  P2 p2_;
-  P3 p3_;
-  P4 p4_;
-
- private:
-  ~BindState() override {    MaybeRefcount<HasIsMethodTag<Runnable>::value,
-      P1>::Release(p1_);  }
-
-};
-
-template <typename Runnable, typename RunType, typename P1, typename P2,
-    typename P3, typename P4, typename P5>
-struct BindState<Runnable, RunType, void(P1, P2, P3, P4,
-    P5)> : public BindStateBase {
-  typedef Runnable RunnableType;
-  typedef IsWeakMethod<HasIsMethodTag<Runnable>::value, P1> IsWeakCall;
-  typedef Invoker<5, BindState, RunType> InvokerType;
-  typedef typename InvokerType::UnboundRunType UnboundRunType;
-
-  // Convenience typedefs for bound argument types.
-  typedef UnwrapTraits<P1> Bound1UnwrapTraits;
-  typedef UnwrapTraits<P2> Bound2UnwrapTraits;
-  typedef UnwrapTraits<P3> Bound3UnwrapTraits;
-  typedef UnwrapTraits<P4> Bound4UnwrapTraits;
-  typedef UnwrapTraits<P5> Bound5UnwrapTraits;
-
-  BindState(const Runnable& runnable, const P1& p1, const P2& p2, const P3& p3,
-      const P4& p4, const P5& p5)
-      : runnable_(runnable),
-        p1_(p1),
-        p2_(p2),
-        p3_(p3),
-        p4_(p4),
-        p5_(p5) {
-    MaybeRefcount<HasIsMethodTag<Runnable>::value, P1>::AddRef(p1_);
-  }
-
-  RunnableType runnable_;
-  P1 p1_;
-  P2 p2_;
-  P3 p3_;
-  P4 p4_;
-  P5 p5_;
-
- private:
-  ~BindState() override {    MaybeRefcount<HasIsMethodTag<Runnable>::value,
-      P1>::Release(p1_);  }
-
-};
-
-template <typename Runnable, typename RunType, typename P1, typename P2,
-    typename P3, typename P4, typename P5, typename P6>
-struct BindState<Runnable, RunType, void(P1, P2, P3, P4, P5,
-    P6)> : public BindStateBase {
-  typedef Runnable RunnableType;
-  typedef IsWeakMethod<HasIsMethodTag<Runnable>::value, P1> IsWeakCall;
-  typedef Invoker<6, BindState, RunType> InvokerType;
-  typedef typename InvokerType::UnboundRunType UnboundRunType;
-
-  // Convenience typedefs for bound argument types.
-  typedef UnwrapTraits<P1> Bound1UnwrapTraits;
-  typedef UnwrapTraits<P2> Bound2UnwrapTraits;
-  typedef UnwrapTraits<P3> Bound3UnwrapTraits;
-  typedef UnwrapTraits<P4> Bound4UnwrapTraits;
-  typedef UnwrapTraits<P5> Bound5UnwrapTraits;
-  typedef UnwrapTraits<P6> Bound6UnwrapTraits;
-
-  BindState(const Runnable& runnable, const P1& p1, const P2& p2, const P3& p3,
-      const P4& p4, const P5& p5, const P6& p6)
-      : runnable_(runnable),
-        p1_(p1),
-        p2_(p2),
-        p3_(p3),
-        p4_(p4),
-        p5_(p5),
-        p6_(p6) {
-    MaybeRefcount<HasIsMethodTag<Runnable>::value, P1>::AddRef(p1_);
-  }
-
-  RunnableType runnable_;
-  P1 p1_;
-  P2 p2_;
-  P3 p3_;
-  P4 p4_;
-  P5 p5_;
-  P6 p6_;
-
- private:
-  ~BindState() override {    MaybeRefcount<HasIsMethodTag<Runnable>::value,
-      P1>::Release(p1_);  }
-
-};
-
-template <typename Runnable, typename RunType, typename P1, typename P2,
-    typename P3, typename P4, typename P5, typename P6, typename P7>
-struct BindState<Runnable, RunType, void(P1, P2, P3, P4, P5, P6,
-    P7)> : public BindStateBase {
-  typedef Runnable RunnableType;
-  typedef IsWeakMethod<HasIsMethodTag<Runnable>::value, P1> IsWeakCall;
-  typedef Invoker<7, BindState, RunType> InvokerType;
-  typedef typename InvokerType::UnboundRunType UnboundRunType;
-
-  // Convenience typedefs for bound argument types.
-  typedef UnwrapTraits<P1> Bound1UnwrapTraits;
-  typedef UnwrapTraits<P2> Bound2UnwrapTraits;
-  typedef UnwrapTraits<P3> Bound3UnwrapTraits;
-  typedef UnwrapTraits<P4> Bound4UnwrapTraits;
-  typedef UnwrapTraits<P5> Bound5UnwrapTraits;
-  typedef UnwrapTraits<P6> Bound6UnwrapTraits;
-  typedef UnwrapTraits<P7> Bound7UnwrapTraits;
-
-  BindState(const Runnable& runnable, const P1& p1, const P2& p2, const P3& p3,
-      const P4& p4, const P5& p5, const P6& p6, const P7& p7)
-      : runnable_(runnable),
-        p1_(p1),
-        p2_(p2),
-        p3_(p3),
-        p4_(p4),
-        p5_(p5),
-        p6_(p6),
-        p7_(p7) {
-    MaybeRefcount<HasIsMethodTag<Runnable>::value, P1>::AddRef(p1_);
-  }
-
-  RunnableType runnable_;
-  P1 p1_;
-  P2 p2_;
-  P3 p3_;
-  P4 p4_;
-  P5 p5_;
-  P6 p6_;
-  P7 p7_;
-
- private:
-  ~BindState() override {    MaybeRefcount<HasIsMethodTag<Runnable>::value,
-      P1>::Release(p1_);  }
-
+  ~BindState() override {}
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_BIND_INTERNAL_H_