Add Callback::IsCancelled

base/bind_internal.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_BIND_INTERNAL_H_
 #define BASE_BIND_INTERNAL_H_
 
 #include <stddef.h>
 
 #include <tuple>
@@ skipping 355 matching lines @@
 IsNull(const Functor& functor) {
   return !functor;
 }
 
 template <typename Functor>
 typename std::enable_if<!FunctorTraits<Functor>::is_nullable, bool>::type
 IsNull(const Functor&) {
   return false;
 }
 
+template <typename Functor, typename... BoundArgs>
+struct BindState;
+
+template <typename BindStateType, typename SFINAE = void>
+struct CancellationChecker {
+  static bool Run(const BindStateBase*) {
+    return false;
+  }
+};
+
+template <typename Functor, typename... BoundArgs>
+struct CancellationChecker<
+    BindState<Functor, BoundArgs...>,
+    typename std::enable_if<IsWeakMethod<FunctorTraits<Functor>::is_method,
+                                         BoundArgs...>::value>::type> {
+  static bool Run(const BindStateBase* base) {
+    using BindStateType = BindState<Functor, BoundArgs...>;
+    const BindStateType* bind_state = static_cast<const BindStateType*>(base);
+    return !base::get<0>(bind_state->bound_args_);
+  }
+};
+
+template <typename Signature, typename... BoundArgs>
+struct CancellationChecker<BindState<Callback<Signature>, BoundArgs...>> {
+  static bool Run(const BindStateBase* base) {
+    using Functor = Callback<Signature>;
+    using BindStateType = BindState<Functor, BoundArgs...>;
+    const BindStateType* bind_state = static_cast<const BindStateType*>(base);
+    return bind_state->functor_.IsCancelled();
+  }
+};
+
 // BindState<>
 //
 // This stores all the state passed into Bind().
 template <typename Functor, typename... BoundArgs>
 struct BindState final : BindStateBase {
   template <typename ForwardFunctor, typename... ForwardBoundArgs>
   explicit BindState(BindStateBase::InvokeFuncStorage invoke_func,
                      ForwardFunctor&& functor,
                      ForwardBoundArgs&&... bound_args)
-      : BindStateBase(invoke_func, &Destroy),
+      : BindStateBase(invoke_func, &Destroy,
+                      &CancellationChecker<BindState>::Run),
         functor_(std::forward<ForwardFunctor>(functor)),
         bound_args_(std::forward<ForwardBoundArgs>(bound_args)...) {
     DCHECK(!IsNull(functor_));
   }
 
   Functor functor_;
   std::tuple<BoundArgs...> bound_args_;
 
  private:
   ~BindState() {}
@@ skipping 51 matching lines @@
 
 // Returns a RunType of bound functor.
 // E.g. MakeUnboundRunType<R(A, B, C), A, B> is evaluated to R(C).
 template <typename Functor, typename... BoundArgs>
 using MakeUnboundRunType =
     typename internal::MakeUnboundRunTypeImpl<Functor, BoundArgs...>::Type;
 
 }  // namespace base
 
 #endif  // BASE_BIND_INTERNAL_H_