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      1 // Copyright 2015 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_ASSOCIATED_INTERFACE_REQUEST_H_
      6 #define MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_INTERFACE_REQUEST_H_
      7 
      8 #include <utility>
      9 
     10 #include "base/macros.h"
     11 #include "mojo/public/cpp/bindings/scoped_interface_endpoint_handle.h"
     12 
     13 namespace mojo {
     14 
     15 // AssociatedInterfaceRequest represents an associated interface request. It is
     16 // similar to InterfaceRequest except that it doesn't own a message pipe handle.
     17 template <typename Interface>
     18 class AssociatedInterfaceRequest {
     19  public:
     20   // Constructs an empty AssociatedInterfaceRequest, representing that the
     21   // client is not requesting an implementation of Interface.
     22   AssociatedInterfaceRequest() {}
     23   AssociatedInterfaceRequest(decltype(nullptr)) {}
     24 
     25   // Takes the interface endpoint handle from another
     26   // AssociatedInterfaceRequest.
     27   AssociatedInterfaceRequest(AssociatedInterfaceRequest&& other) {
     28     handle_ = std::move(other.handle_);
     29   }
     30   AssociatedInterfaceRequest& operator=(AssociatedInterfaceRequest&& other) {
     31     if (this != &other)
     32       handle_ = std::move(other.handle_);
     33     return *this;
     34   }
     35 
     36   // Assigning to nullptr resets the AssociatedInterfaceRequest to an empty
     37   // state, closing the interface endpoint handle currently bound to it (if
     38   // any).
     39   AssociatedInterfaceRequest& operator=(decltype(nullptr)) {
     40     handle_.reset();
     41     return *this;
     42   }
     43 
     44   // Indicates whether the request currently contains a valid interface endpoint
     45   // handle.
     46   bool is_pending() const { return handle_.is_valid(); }
     47 
     48   void Bind(ScopedInterfaceEndpointHandle handle) {
     49     handle_ = std::move(handle);
     50   }
     51 
     52   ScopedInterfaceEndpointHandle PassHandle() {
     53     return std::move(handle_);
     54   }
     55 
     56   const ScopedInterfaceEndpointHandle& handle() const { return handle_; }
     57 
     58   bool Equals(const AssociatedInterfaceRequest& other) const {
     59     if (this == &other)
     60       return true;
     61 
     62     // Now that the two refer to different objects, they are equivalent if
     63     // and only if they are both invalid.
     64     return !is_pending() && !other.is_pending();
     65   }
     66 
     67  private:
     68   ScopedInterfaceEndpointHandle handle_;
     69 
     70   DISALLOW_COPY_AND_ASSIGN(AssociatedInterfaceRequest);
     71 };
     72 
     73 // Makes an AssociatedInterfaceRequest bound to the specified associated
     74 // endpoint.
     75 template <typename Interface>
     76 AssociatedInterfaceRequest<Interface> MakeAssociatedRequest(
     77     ScopedInterfaceEndpointHandle handle) {
     78   AssociatedInterfaceRequest<Interface> request;
     79   request.Bind(std::move(handle));
     80   return request;
     81 }
     82 
     83 }  // namespace mojo
     84 
     85 #endif  // MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_INTERFACE_REQUEST_H_
     86