mojo/public/cpp/bindings/callback.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MOJO_PUBLIC_CPP_BINDINGS_CALLBACK_H_
   6 #define MOJO_PUBLIC_CPP_BINDINGS_CALLBACK_H_
   7
   8 #include "mojo/public/cpp/bindings/lib/callback_internal.h"
   9 #include "mojo/public/cpp/bindings/lib/shared_ptr.h"
  10 #include "mojo/public/cpp/bindings/lib/template_util.h"
  11
  12 namespace mojo {
  13
  14 template <typename Sig>
  15 class Callback;
  16
  17 template <typename... Args>
  18 class Callback<void(Args...)> {
  19  public:
  20   struct Runnable {
  21     virtual ~Runnable() {}
  22     virtual void Run(
  23         typename internal::Callback_ParamTraits<Args>::ForwardType...)
  24         const = 0;
  25   };
  26
  27   Callback() {}
  28
  29   // The Callback assumes ownership of |runnable|.
  30   explicit Callback(Runnable* runnable) : sink_(runnable) {}
  31
  32   // Any class that is copy-constructable and has a compatible Run method may
  33   // be adapted to a Callback using this constructor.
  34   template <typename Sink>
  35   Callback(const Sink& sink)
  36       : sink_(new Adapter<Sink>(sink)) {}
  37
  38   void Run(typename internal::Callback_ParamTraits<Args>::ForwardType... args)
  39       const {
  40     if (sink_.get())
  41       sink_->Run(internal::Forward(args)...);
  42   }
  43
  44   bool is_null() const { return !sink_.get(); }
  45
  46   void reset() { sink_.reset(); }
  47
  48  private:
  49   template <typename Sink>
  50   struct Adapter : public Runnable {
  51     explicit Adapter(const Sink& sink) : sink(sink) {}
  52     virtual void Run(
  53         typename internal::Callback_ParamTraits<Args>::ForwardType... args)
  54         const override {
  55       sink.Run(internal::Forward(args)...);
  56     }
  57     Sink sink;
  58   };
  59
  60   internal::SharedPtr<Runnable> sink_;
  61 };
  62
  63 typedef Callback<void()> Closure;
  64
  65 }  // namespace mojo
  66
  67 #endif  // MOJO_PUBLIC_CPP_BINDINGS_CALLBACK_H_