mojo/public/cpp/application/service_provider_impl.h

// Copyright 2014 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 MOJO_PUBLIC_APPLICATION_SERVICE_PROVIDER_IMPL_H_
#define MOJO_PUBLIC_APPLICATION_SERVICE_PROVIDER_IMPL_H_

#include <functional>
#include <string>

#include "mojo/public/cpp/application/application_connection.h"
#include "mojo/public/cpp/application/connection_context.h"
#include "mojo/public/cpp/application/lib/interface_factory_connector.h"
#include "mojo/public/cpp/application/lib/service_connector_registry.h"
#include "mojo/public/cpp/application/service_connector.h"
#include "mojo/public/cpp/bindings/binding.h"
#include "mojo/public/interfaces/application/service_provider.mojom.h"

namespace mojo {

// An implementation of |ServiceProvider|, which can be customized appropriately
// (to select what services it provides).
class ServiceProviderImpl : public ServiceProvider {
 public:
  // A |InterfaceRequestHandler<Interface>| is simply a function that handles an
  // interface request for |Interface|. If it determines (e.g., based on the
  // given |ConnectionContext|) that the request should be "accepted", then it
  // should "connect" ("take ownership of") request. Otherwise, it can simply
  // drop |interface_request| (as implied  by the interface).
  template <typename Interface>
  using InterfaceRequestHandler =
      std::function<void(const ConnectionContext& connection_context,
                         InterfaceRequest<Interface> interface_request)>;

  // Constructs this service provider implementation in an unbound state.
  ServiceProviderImpl();

  // Constructs this service provider implementation, binding it to the given
  // interface request.
  // TODO(vtl): This should take a |ConnectionContext|, to provide
  // |InterfaceRequestHandler<I>|s.
  explicit ServiceProviderImpl(
      InterfaceRequest<ServiceProvider> service_provider_request);

  ~ServiceProviderImpl() override;

  // Binds this service provider implementation to the given interface request.
  // This may only be called if this object is unbound.
  // TODO(vtl): This should take a |ConnectionContext|, to provide
  // |InterfaceRequestHandler<I>|s.
  void Bind(InterfaceRequest<ServiceProvider> service_provider_request);

  // Disconnect this service provider implementation and put it in a state where
  // it can be rebound to a new request (i.e., restores this object to an
  // unbound state). This may be called even if this object is already unbound.
  void Close();

  // TODO(vtl): Remove this.
  template <typename Interface>
  void AddService(InterfaceFactory<Interface>* factory,
                  const std::string& interface_name = Interface::Name_) {
    service_connector_registry_.SetServiceConnectorForName(
        std::unique_ptr<ServiceConnector>(
            new internal::InterfaceFactoryConnector<Interface>(factory)),
        interface_name);
  }

  // Adds a supported service with the given |name|, using the given
  // |interface_request_handler| (see above for information about
  // |InterfaceRequestHandler<Interface>|). |interface_request_handler| should
  // remain valid for the lifetime of this object.
  //
  // A typical usage may be:
  //
  //   service_provider_impl_->AddServiceNew<Foobar>(
  //       [](const ConnectionContext& connection_context,
  //          InterfaceRequest<FooBar> foobar_request) {
  //         // |FoobarImpl| owns itself.
  //         new FoobarImpl(std::move(foobar_request));
  //       });
  // TODO(vtl): Remove the AddService() above and rename this to AddService().
  template <typename Interface>
  void AddServiceNew(
      InterfaceRequestHandler<Interface> interface_request_handler,
      const std::string& name = Interface::Name_) {
    service_connector_registry_.SetServiceConnectorForName(
        std::unique_ptr<ServiceConnector>(new ServiceConnectorImpl<Interface>(
            std::move(interface_request_handler))),
        name);
  }

  // This uses the provided |fallback_service_provider| for connection requests
  // for services that are not known (haven't been added). (Set it to null to
  // not have any fallback.) A fallback must outlive this object (or until it is
  // "cleared" or replaced by a different fallback.
  void set_fallback_service_provider(
      ServiceProvider* fallback_service_provider) {
    fallback_service_provider_ = fallback_service_provider;
  }

 private:
  // Objects of this class are used to adapt a generic (untyped) connection
  // request (i.e., |ServiceConnector::ConnectToService()|) to the type-safe
  // |InterfaceRequestHandler<Interface>|.
  template <typename Interface>
  class ServiceConnectorImpl : public ServiceConnector {
   public:
    explicit ServiceConnectorImpl(
        InterfaceRequestHandler<Interface> interface_request_handler)
        : interface_request_handler_(std::move(interface_request_handler)) {}
    ~ServiceConnectorImpl() override {}

    void ConnectToService(ApplicationConnection* application_connection,
                          const std::string& interface_name,
                          ScopedMessagePipeHandle client_handle) override {
      // TODO(vtl): This should be given a |const ConnectionContext&|, instead
      // of an |ApplicationConnection*| -- which may be null!
      interface_request_handler_(
          application_connection
              ? application_connection->GetConnectionContext()
              : ConnectionContext(),
          InterfaceRequest<Interface>(client_handle.Pass()));
    }

   private:
    const InterfaceRequestHandler<Interface> interface_request_handler_;

    MOJO_DISALLOW_COPY_AND_ASSIGN(ServiceConnectorImpl);
  };

  // Overridden from |ServiceProvider|:
  void ConnectToService(const String& service_name,
                        ScopedMessagePipeHandle client_handle) override;

  Binding<ServiceProvider> binding_;

  internal::ServiceConnectorRegistry service_connector_registry_;
  ServiceProvider* fallback_service_provider_;

  MOJO_DISALLOW_COPY_AND_ASSIGN(ServiceProviderImpl);
};

}  // namespace mojo

#endif  // MOJO_PUBLIC_APPLICATION_SERVICE_PROVIDER_IMPL_H_