mojo/public/cpp/bindings/interface_request.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_INTERFACE_REQUEST_H_
   6 #define MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_REQUEST_H_
   7
   8 #include "mojo/public/cpp/bindings/interface_ptr.h"
   9
  10 namespace mojo {
  11
  12 // Used in methods that return instances of remote objects.
  13 template <typename Interface>
  14 class InterfaceRequest {
  15   MOJO_MOVE_ONLY_TYPE_FOR_CPP_03(InterfaceRequest, RValue)
  16  public:
  17   InterfaceRequest() {}
  18
  19   InterfaceRequest(RValue other) {
  20     handle_ = other.object->handle_.Pass();
  21   }
  22   InterfaceRequest& operator=(RValue other) {
  23     handle_ = other.object->handle_.Pass();
  24     return *this;
  25   }
  26
  27   // Returns true if the request has yet to be completed.
  28   bool is_pending() const { return handle_.is_valid(); }
  29
  30   void Bind(ScopedMessagePipeHandle handle) {
  31     handle_ = handle.Pass();
  32   }
  33
  34   ScopedMessagePipeHandle PassMessagePipe() {
  35     return handle_.Pass();
  36   }
  37
  38  private:
  39   ScopedMessagePipeHandle handle_;
  40 };
  41
  42 template <typename Interface>
  43 InterfaceRequest<Interface> MakeRequest(ScopedMessagePipeHandle handle) {
  44   InterfaceRequest<Interface> request;
  45   request.Bind(handle.Pass());
  46   return request.Pass();
  47 }
  48
  49 // Used to construct a request that synchronously binds an InterfacePtr<..>,
  50 // making it immediately usable upon return. The resulting request object may
  51 // then be later bound to an InterfaceImpl<..> via BindToRequest.
  52 //
  53 // Given the following interface:
  54 //
  55 //   interface Foo {
  56 //     CreateBar(Bar& bar);
  57 //   }
  58 //
  59 // The caller of CreateBar would have code similar to the following:
  60 //
  61 //   InterfacePtr<Foo> foo = ...;
  62 //   InterfacePtr<Bar> bar;
  63 //   foo->CreateBar(Get(&bar));
  64 //
  65 // Upon return from CreateBar, |bar| is ready to have methods called on it.
  66 //
  67 template <typename Interface>
  68 InterfaceRequest<Interface> Get(InterfacePtr<Interface>* ptr) {
  69   MessagePipe pipe;
  70   ptr->Bind(pipe.handle0.Pass());
  71   return MakeRequest<Interface>(pipe.handle1.Pass());
  72 }
  73
  74 }  // namespace mojo
  75
  76 #endif  // MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_REQUEST_H_