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