remoting/base/dispatch_win.h - chromium/src - Git at Google

 // This file was GENERATED by command:
 //     pump.py dispatch_win.h.pump
 // DO NOT EDIT BY HAND!!!

 // Copyright (c) 2012 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 REMOTING_BASE_IDISPATCH_DRIVER_WIN_H_
 #define REMOTING_BASE_IDISPATCH_DRIVER_WIN_H_

 #include <oaidl.h>

 #include "base/macros.h"
 #include "base/template_util.h"
 #include "base/win/scoped_variant.h"

 namespace remoting {

 namespace dispatch {

 namespace internal {

 // A helper wrapper for |VARIANTARG| that is used to pass parameters to and from
 // IDispatch::Invoke(). The latter accepts parameters as an array of
 // |VARIANTARG| structures. The calling convention of IDispatch::Invoke() is:
 //   - [in] parameters are initialized and freed if needed by the caller.
 //   - [out] parameters are initialized by IDispatch::Invoke(). It is up to
 //         the caller to free leakable variants (such as VT_DISPATCH).
 //   - [in] [out] parameters are combination of both: the caller initializes
 //         them before the call and the callee assigns new values correctly
 //         freeing leakable variants.
 //
 // Using |ScopedVariantArg| instead of naked |VARIANTARG| ensures that
 // the resources allocated during the call will be properly freed. It also
 // provides wrapping methods that convert between C++ types and VARIANTs.
 // At the moment the only supported parameter type is |VARIANT| (or
 // |VARIANTARG|).
 //
 // It must be possible to cast a pointer to an array of |ScopedVariantArg| to
 // a pointer to an array of |VARIANTARG| structures.
 class ScopedVariantArg : public VARIANTARG {
  public:
   ScopedVariantArg() {
     vt = VT_EMPTY;
   }

   ~ScopedVariantArg() {
     VariantClear(this);
   }

   // Wrap() routines pack the input parameters into VARIANTARG structures so
   // that they can be passed to IDispatch::Invoke.

   HRESULT Wrap(const VARIANT& param) {
     DCHECK(vt == VT_EMPTY);
     return VariantCopy(this, &param);
   }

   HRESULT Wrap(VARIANT* const & param) {
     DCHECK(vt == VT_EMPTY);

     // Make the input value of an [in] [out] parameter visible to
     // IDispatch::Invoke().
     //
     // N.B. We treat both [out] and [in] [out] parameters as [in] [out]. In
     // other words the caller is always responsible for initializing and freeing
     // [out] and [in] [out] parameters.
     Swap(param);
     return S_OK;
   }

   // Unwrap() routines unpack the output parameters from VARIANTARG structures
   // to the locations specified by the caller.

   void Unwrap(const VARIANT& param_out) {
     // Do nothing for an [in] parameter.
   }

   void Unwrap(VARIANT* const & param_out) {
     // Return the output value of an [in] [out] parameter to the caller.
     Swap(param_out);
   }

  private:
   // Exchanges the value (and ownership) of the passed VARIANT with the one
   // wrapped by |ScopedVariantArg|.
   void Swap(VARIANT* other) {
     VARIANT temp = *other;
     *other = *this;
     *static_cast<VARIANTARG*>(this) = temp;
   }

   DISALLOW_COPY_AND_ASSIGN(ScopedVariantArg);
 };

 // Make sure the layouts of |VARIANTARG| and |ScopedVariantArg| are identical.
 static_assert(sizeof(ScopedVariantArg) == sizeof(VARIANTARG),
               "scoped variant arg should not add data members");

 }  // namespace internal

 // Invoke() is a convenience wrapper for IDispatch::Invoke. It takes care of
 // calling the desired method by its ID and implements logic for passing
 // a variable number of in/out parameters to the called method.
 //
 // The calling convention is:
 //   - [in] parameters are passsed as a constant reference or by value.
 //   - [out] and [in] [out] parameters are passed by pointer. The pointed value
 //         is overwritten when the function returns. The pointed-to value must
 //         be initialized before the call, and will be replaced when it returns.
 //         [out] parameters may be initialized to VT_EMPTY.
 //
 // Current limitations:
 //   - more than 7 parameters are not supported.
 //   - the method ID cannot be cached and reused.
 //   - VARIANT is the only supported parameter type at the moment.

 HRESULT Invoke(IDispatch* object,
                LPCOLESTR const_name,
                WORD flags,
                VARIANT* const & result_out) {
   // Retrieve the ID of the method to be called.
   DISPID disp_id;
   LPOLESTR name = const_cast<LPOLESTR>(const_name);
   HRESULT hr = object->GetIDsOfNames(
       IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
   if (FAILED(hr))
     return hr;

   // Request the return value if asked by the caller.
   internal::ScopedVariantArg result;
   VARIANT* disp_result = NULL;
   if (result_out != NULL)
     disp_result = &result;


   // Invoke the method passing the parameters via the DISPPARAMS structure.
   // DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
   // the property setter to be named, so |cNamedArgs| and |rgdispidNamedArgs|
   // structure members should be initialized.
   DISPPARAMS disp_params = { NULL, NULL, 0, 0 };
   DISPID dispid_named = DISPID_PROPERTYPUT;
   if (flags == DISPATCH_PROPERTYPUT || flags == DISPATCH_PROPERTYPUTREF) {
     disp_params.cNamedArgs = 1;
     disp_params.rgdispidNamedArgs = &dispid_named;
   }

   hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
                       &disp_params, disp_result, NULL, NULL);
   if (FAILED(hr))
     return hr;


   // Unwrap the return value.
   if (result_out != NULL) {
     result.Unwrap(result_out);
   }

   return S_OK;
 }

 template <typename P1>
 HRESULT Invoke(IDispatch* object,
                LPCOLESTR const_name,
                WORD flags,
                const P1& p1,
                VARIANT* const & result_out) {
   // Retrieve the ID of the method to be called.
   DISPID disp_id;
   LPOLESTR name = const_cast<LPOLESTR>(const_name);
   HRESULT hr = object->GetIDsOfNames(
       IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
   if (FAILED(hr))
     return hr;

   // Request the return value if asked by the caller.
   internal::ScopedVariantArg result;
   VARIANT* disp_result = NULL;
   if (result_out != NULL)
     disp_result = &result;

   // Wrap the parameters into an array of VARIANT structures.
   internal::ScopedVariantArg disp_args[1];
   hr = disp_args[1 - 1].Wrap(p1);
   if (FAILED(hr))
     return hr;

   // Invoke the method passing the parameters via the DISPPARAMS structure.
   // DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
   // the property setter to be named, so |cNamedArgs| and |rgdispidNamedArgs|
   // structure members should be initialized.
   DISPPARAMS disp_params = { disp_args, NULL, 1, 0 };
   DISPID dispid_named = DISPID_PROPERTYPUT;
   if (flags == DISPATCH_PROPERTYPUT || flags == DISPATCH_PROPERTYPUTREF) {
     disp_params.cNamedArgs = 1;
     disp_params.rgdispidNamedArgs = &dispid_named;
   }

   hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
                       &disp_params, disp_result, NULL, NULL);
   if (FAILED(hr))
     return hr;

   // Unwrap the parameters.
   disp_args[1 - 1].Unwrap(p1);

   // Unwrap the return value.
   if (result_out != NULL) {
     result.Unwrap(result_out);
   }

   return S_OK;
 }

 template <typename P1, typename P2>
 HRESULT Invoke(IDispatch* object,
                LPCOLESTR const_name,
                WORD flags,
                const P1& p1,
                const P2& p2,
                VARIANT* const & result_out) {
   // Retrieve the ID of the method to be called.
   DISPID disp_id;
   LPOLESTR name = const_cast<LPOLESTR>(const_name);
   HRESULT hr = object->GetIDsOfNames(
       IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
   if (FAILED(hr))
     return hr;

   // Request the return value if asked by the caller.
   internal::ScopedVariantArg result;
   VARIANT* disp_result = NULL;
   if (result_out != NULL)
     disp_result = &result;

   // Wrap the parameters into an array of VARIANT structures.
   internal::ScopedVariantArg disp_args[2];
   hr = disp_args[2 - 1].Wrap(p1);
   if (FAILED(hr))
     return hr;
   hr = disp_args[2 - 2].Wrap(p2);
   if (FAILED(hr))
     return hr;

   // Invoke the method passing the parameters via the DISPPARAMS structure.
   // DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
   // the property setter to be named, so |cNamedArgs| and |rgdispidNamedArgs|
   // structure members should be initialized.
   DISPPARAMS disp_params = { disp_args, NULL, 2, 0 };
   DISPID dispid_named = DISPID_PROPERTYPUT;
   if (flags == DISPATCH_PROPERTYPUT || flags == DISPATCH_PROPERTYPUTREF) {
     disp_params.cNamedArgs = 1;
     disp_params.rgdispidNamedArgs = &dispid_named;
   }

   hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
                       &disp_params, disp_result, NULL, NULL);
   if (FAILED(hr))
     return hr;

   // Unwrap the parameters.
   disp_args[2 - 1].Unwrap(p1);
   disp_args[2 - 2].Unwrap(p2);

   // Unwrap the return value.
   if (result_out != NULL) {
     result.Unwrap(result_out);
   }

   return S_OK;
 }

 template <typename P1, typename P2, typename P3>
 HRESULT Invoke(IDispatch* object,
                LPCOLESTR const_name,
                WORD flags,
                const P1& p1,
                const P2& p2,
                const P3& p3,
                VARIANT* const & result_out) {
   // Retrieve the ID of the method to be called.
   DISPID disp_id;
   LPOLESTR name = const_cast<LPOLESTR>(const_name);
   HRESULT hr = object->GetIDsOfNames(
       IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
   if (FAILED(hr))
     return hr;

   // Request the return value if asked by the caller.
   internal::ScopedVariantArg result;
   VARIANT* disp_result = NULL;
   if (result_out != NULL)
     disp_result = &result;

   // Wrap the parameters into an array of VARIANT structures.
   internal::ScopedVariantArg disp_args[3];
   hr = disp_args[3 - 1].Wrap(p1);
   if (FAILED(hr))
     return hr;
   hr = disp_args[3 - 2].Wrap(p2);
   if (FAILED(hr))
     return hr;
   hr = disp_args[3 - 3].Wrap(p3);
   if (FAILED(hr))
     return hr;

   // Invoke the method passing the parameters via the DISPPARAMS structure.
   // DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
   // the property setter to be named, so |cNamedArgs| and |rgdispidNamedArgs|
   // structure members should be initialized.
   DISPPARAMS disp_params = { disp_args, NULL, 3, 0 };
   DISPID dispid_named = DISPID_PROPERTYPUT;
   if (flags == DISPATCH_PROPERTYPUT || flags == DISPATCH_PROPERTYPUTREF) {
     disp_params.cNamedArgs = 1;
     disp_params.rgdispidNamedArgs = &dispid_named;
   }

   hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
                       &disp_params, disp_result, NULL, NULL);
   if (FAILED(hr))
     return hr;

   // Unwrap the parameters.
   disp_args[3 - 1].Unwrap(p1);
   disp_args[3 - 2].Unwrap(p2);
   disp_args[3 - 3].Unwrap(p3);

   // Unwrap the return value.
   if (result_out != NULL) {
     result.Unwrap(result_out);
   }

   return S_OK;
 }

 template <typename P1, typename P2, typename P3, typename P4>
 HRESULT Invoke(IDispatch* object,
                LPCOLESTR const_name,
                WORD flags,
                const P1& p1,
                const P2& p2,
                const P3& p3,
                const P4& p4,
                VARIANT* const & result_out) {
   // Retrieve the ID of the method to be called.
   DISPID disp_id;
   LPOLESTR name = const_cast<LPOLESTR>(const_name);
   HRESULT hr = object->GetIDsOfNames(
       IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
   if (FAILED(hr))
     return hr;

   // Request the return value if asked by the caller.
   internal::ScopedVariantArg result;
   VARIANT* disp_result = NULL;
   if (result_out != NULL)
     disp_result = &result;

   // Wrap the parameters into an array of VARIANT structures.
   internal::ScopedVariantArg disp_args[4];
   hr = disp_args[4 - 1].Wrap(p1);
   if (FAILED(hr))
     return hr;
   hr = disp_args[4 - 2].Wrap(p2);
   if (FAILED(hr))
     return hr;
   hr = disp_args[4 - 3].Wrap(p3);
   if (FAILED(hr))
     return hr;
   hr = disp_args[4 - 4].Wrap(p4);
   if (FAILED(hr))
     return hr;

   // Invoke the method passing the parameters via the DISPPARAMS structure.
   // DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
   // the property setter to be named, so |cNamedArgs| and |rgdispidNamedArgs|
   // structure members should be initialized.
   DISPPARAMS disp_params = { disp_args, NULL, 4, 0 };
   DISPID dispid_named = DISPID_PROPERTYPUT;
   if (flags == DISPATCH_PROPERTYPUT || flags == DISPATCH_PROPERTYPUTREF) {
     disp_params.cNamedArgs = 1;
     disp_params.rgdispidNamedArgs = &dispid_named;
   }

   hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
                       &disp_params, disp_result, NULL, NULL);
   if (FAILED(hr))
     return hr;

   // Unwrap the parameters.
   disp_args[4 - 1].Unwrap(p1);
   disp_args[4 - 2].Unwrap(p2);
   disp_args[4 - 3].Unwrap(p3);
   disp_args[4 - 4].Unwrap(p4);

   // Unwrap the return value.
   if (result_out != NULL) {
     result.Unwrap(result_out);
   }

   return S_OK;
 }

 template <typename P1, typename P2, typename P3, typename P4, typename P5>
 HRESULT Invoke(IDispatch* object,
                LPCOLESTR const_name,
                WORD flags,
                const P1& p1,
                const P2& p2,
                const P3& p3,
                const P4& p4,
                const P5& p5,
                VARIANT* const & result_out) {
   // Retrieve the ID of the method to be called.
   DISPID disp_id;
   LPOLESTR name = const_cast<LPOLESTR>(const_name);
   HRESULT hr = object->GetIDsOfNames(
       IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
   if (FAILED(hr))
     return hr;

   // Request the return value if asked by the caller.
   internal::ScopedVariantArg result;
   VARIANT* disp_result = NULL;
   if (result_out != NULL)
     disp_result = &result;

   // Wrap the parameters into an array of VARIANT structures.
   internal::ScopedVariantArg disp_args[5];
   hr = disp_args[5 - 1].Wrap(p1);
   if (FAILED(hr))
     return hr;
   hr = disp_args[5 - 2].Wrap(p2);
   if (FAILED(hr))
     return hr;
   hr = disp_args[5 - 3].Wrap(p3);
   if (FAILED(hr))
     return hr;
   hr = disp_args[5 - 4].Wrap(p4);
   if (FAILED(hr))
     return hr;
   hr = disp_args[5 - 5].Wrap(p5);
   if (FAILED(hr))
     return hr;

   // Invoke the method passing the parameters via the DISPPARAMS structure.
   // DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
   // the property setter to be named, so |cNamedArgs| and |rgdispidNamedArgs|
   // structure members should be initialized.
   DISPPARAMS disp_params = { disp_args, NULL, 5, 0 };
   DISPID dispid_named = DISPID_PROPERTYPUT;
   if (flags == DISPATCH_PROPERTYPUT || flags == DISPATCH_PROPERTYPUTREF) {
     disp_params.cNamedArgs = 1;
     disp_params.rgdispidNamedArgs = &dispid_named;
   }

   hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
                       &disp_params, disp_result, NULL, NULL);
   if (FAILED(hr))
     return hr;

   // Unwrap the parameters.
   disp_args[5 - 1].Unwrap(p1);
   disp_args[5 - 2].Unwrap(p2);
   disp_args[5 - 3].Unwrap(p3);
   disp_args[5 - 4].Unwrap(p4);
   disp_args[5 - 5].Unwrap(p5);

   // Unwrap the return value.
   if (result_out != NULL) {
     result.Unwrap(result_out);
   }

   return S_OK;
 }

 template <typename P1, typename P2, typename P3, typename P4, typename P5,
     typename P6>
 HRESULT Invoke(IDispatch* object,
                LPCOLESTR const_name,
                WORD flags,
                const P1& p1,
                const P2& p2,
                const P3& p3,
                const P4& p4,
                const P5& p5,
                const P6& p6,
                VARIANT* const & result_out) {
   // Retrieve the ID of the method to be called.
   DISPID disp_id;
   LPOLESTR name = const_cast<LPOLESTR>(const_name);
   HRESULT hr = object->GetIDsOfNames(
       IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
   if (FAILED(hr))
     return hr;

   // Request the return value if asked by the caller.
   internal::ScopedVariantArg result;
   VARIANT* disp_result = NULL;
   if (result_out != NULL)
     disp_result = &result;

   // Wrap the parameters into an array of VARIANT structures.
   internal::ScopedVariantArg disp_args[6];
   hr = disp_args[6 - 1].Wrap(p1);
   if (FAILED(hr))
     return hr;
   hr = disp_args[6 - 2].Wrap(p2);
   if (FAILED(hr))
     return hr;
   hr = disp_args[6 - 3].Wrap(p3);
   if (FAILED(hr))
     return hr;
   hr = disp_args[6 - 4].Wrap(p4);
   if (FAILED(hr))
     return hr;
   hr = disp_args[6 - 5].Wrap(p5);
   if (FAILED(hr))
     return hr;
   hr = disp_args[6 - 6].Wrap(p6);
   if (FAILED(hr))
     return hr;

   // Invoke the method passing the parameters via the DISPPARAMS structure.
   // DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
   // the property setter to be named, so |cNamedArgs| and |rgdispidNamedArgs|
   // structure members should be initialized.
   DISPPARAMS disp_params = { disp_args, NULL, 6, 0 };
   DISPID dispid_named = DISPID_PROPERTYPUT;
   if (flags == DISPATCH_PROPERTYPUT || flags == DISPATCH_PROPERTYPUTREF) {
     disp_params.cNamedArgs = 1;
     disp_params.rgdispidNamedArgs = &dispid_named;
   }

   hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
                       &disp_params, disp_result, NULL, NULL);
   if (FAILED(hr))
     return hr;

   // Unwrap the parameters.
   disp_args[6 - 1].Unwrap(p1);
   disp_args[6 - 2].Unwrap(p2);
   disp_args[6 - 3].Unwrap(p3);
   disp_args[6 - 4].Unwrap(p4);
   disp_args[6 - 5].Unwrap(p5);
   disp_args[6 - 6].Unwrap(p6);

   // Unwrap the return value.
   if (result_out != NULL) {
     result.Unwrap(result_out);
   }

   return S_OK;
 }

 template <typename P1, typename P2, typename P3, typename P4, typename P5,
     typename P6, typename P7>
 HRESULT Invoke(IDispatch* object,
                LPCOLESTR const_name,
                WORD flags,
                const P1& p1,
                const P2& p2,
                const P3& p3,
                const P4& p4,
                const P5& p5,
                const P6& p6,
                const P7& p7,
                VARIANT* const & result_out) {
   // Retrieve the ID of the method to be called.
   DISPID disp_id;
   LPOLESTR name = const_cast<LPOLESTR>(const_name);
   HRESULT hr = object->GetIDsOfNames(
       IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
   if (FAILED(hr))
     return hr;

   // Request the return value if asked by the caller.
   internal::ScopedVariantArg result;
   VARIANT* disp_result = NULL;
   if (result_out != NULL)
     disp_result = &result;

   // Wrap the parameters into an array of VARIANT structures.
   internal::ScopedVariantArg disp_args[7];
   hr = disp_args[7 - 1].Wrap(p1);
   if (FAILED(hr))
     return hr;
   hr = disp_args[7 - 2].Wrap(p2);
   if (FAILED(hr))
     return hr;
   hr = disp_args[7 - 3].Wrap(p3);
   if (FAILED(hr))
     return hr;
   hr = disp_args[7 - 4].Wrap(p4);
   if (FAILED(hr))
     return hr;
   hr = disp_args[7 - 5].Wrap(p5);
   if (FAILED(hr))
     return hr;
   hr = disp_args[7 - 6].Wrap(p6);
   if (FAILED(hr))
     return hr;
   hr = disp_args[7 - 7].Wrap(p7);
   if (FAILED(hr))
     return hr;

   // Invoke the method passing the parameters via the DISPPARAMS structure.
   // DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
   // the property setter to be named, so |cNamedArgs| and |rgdispidNamedArgs|
   // structure members should be initialized.
   DISPPARAMS disp_params = { disp_args, NULL, 7, 0 };
   DISPID dispid_named = DISPID_PROPERTYPUT;
   if (flags == DISPATCH_PROPERTYPUT || flags == DISPATCH_PROPERTYPUTREF) {
     disp_params.cNamedArgs = 1;
     disp_params.rgdispidNamedArgs = &dispid_named;
   }

   hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
                       &disp_params, disp_result, NULL, NULL);
   if (FAILED(hr))
     return hr;

   // Unwrap the parameters.
   disp_args[7 - 1].Unwrap(p1);
   disp_args[7 - 2].Unwrap(p2);
   disp_args[7 - 3].Unwrap(p3);
   disp_args[7 - 4].Unwrap(p4);
   disp_args[7 - 5].Unwrap(p5);
   disp_args[7 - 6].Unwrap(p6);
   disp_args[7 - 7].Unwrap(p7);

   // Unwrap the return value.
   if (result_out != NULL) {
     result.Unwrap(result_out);
   }

   return S_OK;
 }

 } // namespace dispatch

 } // namespace remoting

 #endif // REMOTING_BASE_IDISPATCH_DRIVER_WIN_H_
	// This file was GENERATED by command:
	// pump.py dispatch_win.h.pump
	// DO NOT EDIT BY HAND!!!

	// Copyright (c) 2012 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 REMOTING_BASE_IDISPATCH_DRIVER_WIN_H_
	#define REMOTING_BASE_IDISPATCH_DRIVER_WIN_H_

	#include <oaidl.h>

	#include "base/macros.h"
	#include "base/template_util.h"
	#include "base/win/scoped_variant.h"

	namespace remoting {

	namespace dispatch {

	namespace internal {

	// A helper wrapper for \|VARIANTARG\| that is used to pass parameters to and from
	// IDispatch::Invoke(). The latter accepts parameters as an array of
	// \|VARIANTARG\| structures. The calling convention of IDispatch::Invoke() is:
	// - [in] parameters are initialized and freed if needed by the caller.
	// - [out] parameters are initialized by IDispatch::Invoke(). It is up to
	// the caller to free leakable variants (such as VT_DISPATCH).
	// - [in] [out] parameters are combination of both: the caller initializes
	// them before the call and the callee assigns new values correctly
	// freeing leakable variants.
	//
	// Using \|ScopedVariantArg\| instead of naked \|VARIANTARG\| ensures that
	// the resources allocated during the call will be properly freed. It also
	// provides wrapping methods that convert between C++ types and VARIANTs.
	// At the moment the only supported parameter type is \|VARIANT\| (or
	// \|VARIANTARG\|).
	//
	// It must be possible to cast a pointer to an array of \|ScopedVariantArg\| to
	// a pointer to an array of \|VARIANTARG\| structures.
	class ScopedVariantArg : public VARIANTARG {
	public:
	ScopedVariantArg() {
	vt = VT_EMPTY;
	}

	~ScopedVariantArg() {
	VariantClear(this);
	}

	// Wrap() routines pack the input parameters into VARIANTARG structures so
	// that they can be passed to IDispatch::Invoke.

	HRESULT Wrap(const VARIANT& param) {
	DCHECK(vt == VT_EMPTY);
	return VariantCopy(this, &param);
	}

	HRESULT Wrap(VARIANT* const & param) {
	DCHECK(vt == VT_EMPTY);

	// Make the input value of an [in] [out] parameter visible to
	// IDispatch::Invoke().
	//
	// N.B. We treat both [out] and [in] [out] parameters as [in] [out]. In
	// other words the caller is always responsible for initializing and freeing
	// [out] and [in] [out] parameters.
	Swap(param);
	return S_OK;
	}

	// Unwrap() routines unpack the output parameters from VARIANTARG structures
	// to the locations specified by the caller.

	void Unwrap(const VARIANT& param_out) {
	// Do nothing for an [in] parameter.
	}

	void Unwrap(VARIANT* const & param_out) {
	// Return the output value of an [in] [out] parameter to the caller.
	Swap(param_out);
	}

	private:
	// Exchanges the value (and ownership) of the passed VARIANT with the one
	// wrapped by \|ScopedVariantArg\|.
	void Swap(VARIANT* other) {
	VARIANT temp = *other;
	other = this;
	static_cast<VARIANTARG>(this) = temp;
	}

	DISALLOW_COPY_AND_ASSIGN(ScopedVariantArg);
	};

	// Make sure the layouts of \|VARIANTARG\| and \|ScopedVariantArg\| are identical.
	static_assert(sizeof(ScopedVariantArg) == sizeof(VARIANTARG),
	"scoped variant arg should not add data members");

	} // namespace internal

	// Invoke() is a convenience wrapper for IDispatch::Invoke. It takes care of
	// calling the desired method by its ID and implements logic for passing
	// a variable number of in/out parameters to the called method.
	//
	// The calling convention is:
	// - [in] parameters are passsed as a constant reference or by value.
	// - [out] and [in] [out] parameters are passed by pointer. The pointed value
	// is overwritten when the function returns. The pointed-to value must
	// be initialized before the call, and will be replaced when it returns.
	// [out] parameters may be initialized to VT_EMPTY.
	//
	// Current limitations:
	// - more than 7 parameters are not supported.
	// - the method ID cannot be cached and reused.
	// - VARIANT is the only supported parameter type at the moment.

	HRESULT Invoke(IDispatch* object,
	LPCOLESTR const_name,
	WORD flags,
	VARIANT* const & result_out) {
	// Retrieve the ID of the method to be called.
	DISPID disp_id;
	LPOLESTR name = const_cast<LPOLESTR>(const_name);
	HRESULT hr = object->GetIDsOfNames(
	IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
	if (FAILED(hr))
	return hr;

	// Request the return value if asked by the caller.
	internal::ScopedVariantArg result;
	VARIANT* disp_result = NULL;
	if (result_out != NULL)
	disp_result = &result;


	// Invoke the method passing the parameters via the DISPPARAMS structure.
	// DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
	// the property setter to be named, so \|cNamedArgs\| and \|rgdispidNamedArgs\|
	// structure members should be initialized.
	DISPPARAMS disp_params = { NULL, NULL, 0, 0 };
	DISPID dispid_named = DISPID_PROPERTYPUT;
	if (flags == DISPATCH_PROPERTYPUT \|\| flags == DISPATCH_PROPERTYPUTREF) {
	disp_params.cNamedArgs = 1;
	disp_params.rgdispidNamedArgs = &dispid_named;
	}

	hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
	&disp_params, disp_result, NULL, NULL);
	if (FAILED(hr))
	return hr;


	// Unwrap the return value.
	if (result_out != NULL) {
	result.Unwrap(result_out);
	}

	return S_OK;
	}

	template <typename P1>
	HRESULT Invoke(IDispatch* object,
	LPCOLESTR const_name,
	WORD flags,
	const P1& p1,
	VARIANT* const & result_out) {
	// Retrieve the ID of the method to be called.
	DISPID disp_id;
	LPOLESTR name = const_cast<LPOLESTR>(const_name);
	HRESULT hr = object->GetIDsOfNames(
	IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
	if (FAILED(hr))
	return hr;

	// Request the return value if asked by the caller.
	internal::ScopedVariantArg result;
	VARIANT* disp_result = NULL;
	if (result_out != NULL)
	disp_result = &result;

	// Wrap the parameters into an array of VARIANT structures.
	internal::ScopedVariantArg disp_args[1];
	hr = disp_args[1 - 1].Wrap(p1);
	if (FAILED(hr))
	return hr;

	// Invoke the method passing the parameters via the DISPPARAMS structure.
	// DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
	// the property setter to be named, so \|cNamedArgs\| and \|rgdispidNamedArgs\|
	// structure members should be initialized.
	DISPPARAMS disp_params = { disp_args, NULL, 1, 0 };
	DISPID dispid_named = DISPID_PROPERTYPUT;
	if (flags == DISPATCH_PROPERTYPUT \|\| flags == DISPATCH_PROPERTYPUTREF) {
	disp_params.cNamedArgs = 1;
	disp_params.rgdispidNamedArgs = &dispid_named;
	}

	hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
	&disp_params, disp_result, NULL, NULL);
	if (FAILED(hr))
	return hr;

	// Unwrap the parameters.
	disp_args[1 - 1].Unwrap(p1);

	// Unwrap the return value.
	if (result_out != NULL) {
	result.Unwrap(result_out);
	}

	return S_OK;
	}

	template <typename P1, typename P2>
	HRESULT Invoke(IDispatch* object,
	LPCOLESTR const_name,
	WORD flags,
	const P1& p1,
	const P2& p2,
	VARIANT* const & result_out) {
	// Retrieve the ID of the method to be called.
	DISPID disp_id;
	LPOLESTR name = const_cast<LPOLESTR>(const_name);
	HRESULT hr = object->GetIDsOfNames(
	IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
	if (FAILED(hr))
	return hr;

	// Request the return value if asked by the caller.
	internal::ScopedVariantArg result;
	VARIANT* disp_result = NULL;
	if (result_out != NULL)
	disp_result = &result;

	// Wrap the parameters into an array of VARIANT structures.
	internal::ScopedVariantArg disp_args[2];
	hr = disp_args[2 - 1].Wrap(p1);
	if (FAILED(hr))
	return hr;
	hr = disp_args[2 - 2].Wrap(p2);
	if (FAILED(hr))
	return hr;

	// Invoke the method passing the parameters via the DISPPARAMS structure.
	// DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
	// the property setter to be named, so \|cNamedArgs\| and \|rgdispidNamedArgs\|
	// structure members should be initialized.
	DISPPARAMS disp_params = { disp_args, NULL, 2, 0 };
	DISPID dispid_named = DISPID_PROPERTYPUT;
	if (flags == DISPATCH_PROPERTYPUT \|\| flags == DISPATCH_PROPERTYPUTREF) {
	disp_params.cNamedArgs = 1;
	disp_params.rgdispidNamedArgs = &dispid_named;
	}

	hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
	&disp_params, disp_result, NULL, NULL);
	if (FAILED(hr))
	return hr;

	// Unwrap the parameters.
	disp_args[2 - 1].Unwrap(p1);
	disp_args[2 - 2].Unwrap(p2);

	// Unwrap the return value.
	if (result_out != NULL) {
	result.Unwrap(result_out);
	}

	return S_OK;
	}

	template <typename P1, typename P2, typename P3>
	HRESULT Invoke(IDispatch* object,
	LPCOLESTR const_name,
	WORD flags,
	const P1& p1,
	const P2& p2,
	const P3& p3,
	VARIANT* const & result_out) {
	// Retrieve the ID of the method to be called.
	DISPID disp_id;
	LPOLESTR name = const_cast<LPOLESTR>(const_name);
	HRESULT hr = object->GetIDsOfNames(
	IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
	if (FAILED(hr))
	return hr;

	// Request the return value if asked by the caller.
	internal::ScopedVariantArg result;
	VARIANT* disp_result = NULL;
	if (result_out != NULL)
	disp_result = &result;

	// Wrap the parameters into an array of VARIANT structures.
	internal::ScopedVariantArg disp_args[3];
	hr = disp_args[3 - 1].Wrap(p1);
	if (FAILED(hr))
	return hr;
	hr = disp_args[3 - 2].Wrap(p2);
	if (FAILED(hr))
	return hr;
	hr = disp_args[3 - 3].Wrap(p3);
	if (FAILED(hr))
	return hr;

	// Invoke the method passing the parameters via the DISPPARAMS structure.
	// DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
	// the property setter to be named, so \|cNamedArgs\| and \|rgdispidNamedArgs\|
	// structure members should be initialized.
	DISPPARAMS disp_params = { disp_args, NULL, 3, 0 };
	DISPID dispid_named = DISPID_PROPERTYPUT;
	if (flags == DISPATCH_PROPERTYPUT \|\| flags == DISPATCH_PROPERTYPUTREF) {
	disp_params.cNamedArgs = 1;
	disp_params.rgdispidNamedArgs = &dispid_named;
	}

	hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
	&disp_params, disp_result, NULL, NULL);
	if (FAILED(hr))
	return hr;

	// Unwrap the parameters.
	disp_args[3 - 1].Unwrap(p1);
	disp_args[3 - 2].Unwrap(p2);
	disp_args[3 - 3].Unwrap(p3);

	// Unwrap the return value.
	if (result_out != NULL) {
	result.Unwrap(result_out);
	}

	return S_OK;
	}

	template <typename P1, typename P2, typename P3, typename P4>
	HRESULT Invoke(IDispatch* object,
	LPCOLESTR const_name,
	WORD flags,
	const P1& p1,
	const P2& p2,
	const P3& p3,
	const P4& p4,
	VARIANT* const & result_out) {
	// Retrieve the ID of the method to be called.
	DISPID disp_id;
	LPOLESTR name = const_cast<LPOLESTR>(const_name);
	HRESULT hr = object->GetIDsOfNames(
	IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
	if (FAILED(hr))
	return hr;

	// Request the return value if asked by the caller.
	internal::ScopedVariantArg result;
	VARIANT* disp_result = NULL;
	if (result_out != NULL)
	disp_result = &result;

	// Wrap the parameters into an array of VARIANT structures.
	internal::ScopedVariantArg disp_args[4];
	hr = disp_args[4 - 1].Wrap(p1);
	if (FAILED(hr))
	return hr;
	hr = disp_args[4 - 2].Wrap(p2);
	if (FAILED(hr))
	return hr;
	hr = disp_args[4 - 3].Wrap(p3);
	if (FAILED(hr))
	return hr;
	hr = disp_args[4 - 4].Wrap(p4);
	if (FAILED(hr))
	return hr;

	// Invoke the method passing the parameters via the DISPPARAMS structure.
	// DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
	// the property setter to be named, so \|cNamedArgs\| and \|rgdispidNamedArgs\|
	// structure members should be initialized.
	DISPPARAMS disp_params = { disp_args, NULL, 4, 0 };
	DISPID dispid_named = DISPID_PROPERTYPUT;
	if (flags == DISPATCH_PROPERTYPUT \|\| flags == DISPATCH_PROPERTYPUTREF) {
	disp_params.cNamedArgs = 1;
	disp_params.rgdispidNamedArgs = &dispid_named;
	}

	hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
	&disp_params, disp_result, NULL, NULL);
	if (FAILED(hr))
	return hr;

	// Unwrap the parameters.
	disp_args[4 - 1].Unwrap(p1);
	disp_args[4 - 2].Unwrap(p2);
	disp_args[4 - 3].Unwrap(p3);
	disp_args[4 - 4].Unwrap(p4);

	// Unwrap the return value.
	if (result_out != NULL) {
	result.Unwrap(result_out);
	}

	return S_OK;
	}

	template <typename P1, typename P2, typename P3, typename P4, typename P5>
	HRESULT Invoke(IDispatch* object,
	LPCOLESTR const_name,
	WORD flags,
	const P1& p1,
	const P2& p2,
	const P3& p3,
	const P4& p4,
	const P5& p5,
	VARIANT* const & result_out) {
	// Retrieve the ID of the method to be called.
	DISPID disp_id;
	LPOLESTR name = const_cast<LPOLESTR>(const_name);
	HRESULT hr = object->GetIDsOfNames(
	IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
	if (FAILED(hr))
	return hr;

	// Request the return value if asked by the caller.
	internal::ScopedVariantArg result;
	VARIANT* disp_result = NULL;
	if (result_out != NULL)
	disp_result = &result;

	// Wrap the parameters into an array of VARIANT structures.
	internal::ScopedVariantArg disp_args[5];
	hr = disp_args[5 - 1].Wrap(p1);
	if (FAILED(hr))
	return hr;
	hr = disp_args[5 - 2].Wrap(p2);
	if (FAILED(hr))
	return hr;
	hr = disp_args[5 - 3].Wrap(p3);
	if (FAILED(hr))
	return hr;
	hr = disp_args[5 - 4].Wrap(p4);
	if (FAILED(hr))
	return hr;
	hr = disp_args[5 - 5].Wrap(p5);
	if (FAILED(hr))
	return hr;

	// Invoke the method passing the parameters via the DISPPARAMS structure.
	// DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
	// the property setter to be named, so \|cNamedArgs\| and \|rgdispidNamedArgs\|
	// structure members should be initialized.
	DISPPARAMS disp_params = { disp_args, NULL, 5, 0 };
	DISPID dispid_named = DISPID_PROPERTYPUT;
	if (flags == DISPATCH_PROPERTYPUT \|\| flags == DISPATCH_PROPERTYPUTREF) {
	disp_params.cNamedArgs = 1;
	disp_params.rgdispidNamedArgs = &dispid_named;
	}

	hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
	&disp_params, disp_result, NULL, NULL);
	if (FAILED(hr))
	return hr;

	// Unwrap the parameters.
	disp_args[5 - 1].Unwrap(p1);
	disp_args[5 - 2].Unwrap(p2);
	disp_args[5 - 3].Unwrap(p3);
	disp_args[5 - 4].Unwrap(p4);
	disp_args[5 - 5].Unwrap(p5);

	// Unwrap the return value.
	if (result_out != NULL) {
	result.Unwrap(result_out);
	}

	return S_OK;
	}

	template <typename P1, typename P2, typename P3, typename P4, typename P5,
	typename P6>
	HRESULT Invoke(IDispatch* object,
	LPCOLESTR const_name,
	WORD flags,
	const P1& p1,
	const P2& p2,
	const P3& p3,
	const P4& p4,
	const P5& p5,
	const P6& p6,
	VARIANT* const & result_out) {
	// Retrieve the ID of the method to be called.
	DISPID disp_id;
	LPOLESTR name = const_cast<LPOLESTR>(const_name);
	HRESULT hr = object->GetIDsOfNames(
	IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
	if (FAILED(hr))
	return hr;

	// Request the return value if asked by the caller.
	internal::ScopedVariantArg result;
	VARIANT* disp_result = NULL;
	if (result_out != NULL)
	disp_result = &result;

	// Wrap the parameters into an array of VARIANT structures.
	internal::ScopedVariantArg disp_args[6];
	hr = disp_args[6 - 1].Wrap(p1);
	if (FAILED(hr))
	return hr;
	hr = disp_args[6 - 2].Wrap(p2);
	if (FAILED(hr))
	return hr;
	hr = disp_args[6 - 3].Wrap(p3);
	if (FAILED(hr))
	return hr;
	hr = disp_args[6 - 4].Wrap(p4);
	if (FAILED(hr))
	return hr;
	hr = disp_args[6 - 5].Wrap(p5);
	if (FAILED(hr))
	return hr;
	hr = disp_args[6 - 6].Wrap(p6);
	if (FAILED(hr))
	return hr;

	// Invoke the method passing the parameters via the DISPPARAMS structure.
	// DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
	// the property setter to be named, so \|cNamedArgs\| and \|rgdispidNamedArgs\|
	// structure members should be initialized.
	DISPPARAMS disp_params = { disp_args, NULL, 6, 0 };
	DISPID dispid_named = DISPID_PROPERTYPUT;
	if (flags == DISPATCH_PROPERTYPUT \|\| flags == DISPATCH_PROPERTYPUTREF) {
	disp_params.cNamedArgs = 1;
	disp_params.rgdispidNamedArgs = &dispid_named;
	}

	hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
	&disp_params, disp_result, NULL, NULL);
	if (FAILED(hr))
	return hr;

	// Unwrap the parameters.
	disp_args[6 - 1].Unwrap(p1);
	disp_args[6 - 2].Unwrap(p2);
	disp_args[6 - 3].Unwrap(p3);
	disp_args[6 - 4].Unwrap(p4);
	disp_args[6 - 5].Unwrap(p5);
	disp_args[6 - 6].Unwrap(p6);

	// Unwrap the return value.
	if (result_out != NULL) {
	result.Unwrap(result_out);
	}

	return S_OK;
	}

	template <typename P1, typename P2, typename P3, typename P4, typename P5,
	typename P6, typename P7>
	HRESULT Invoke(IDispatch* object,
	LPCOLESTR const_name,
	WORD flags,
	const P1& p1,
	const P2& p2,
	const P3& p3,
	const P4& p4,
	const P5& p5,
	const P6& p6,
	const P7& p7,
	VARIANT* const & result_out) {
	// Retrieve the ID of the method to be called.
	DISPID disp_id;
	LPOLESTR name = const_cast<LPOLESTR>(const_name);
	HRESULT hr = object->GetIDsOfNames(
	IID_NULL, &name, 1, LOCALE_USER_DEFAULT, &disp_id);
	if (FAILED(hr))
	return hr;

	// Request the return value if asked by the caller.
	internal::ScopedVariantArg result;
	VARIANT* disp_result = NULL;
	if (result_out != NULL)
	disp_result = &result;

	// Wrap the parameters into an array of VARIANT structures.
	internal::ScopedVariantArg disp_args[7];
	hr = disp_args[7 - 1].Wrap(p1);
	if (FAILED(hr))
	return hr;
	hr = disp_args[7 - 2].Wrap(p2);
	if (FAILED(hr))
	return hr;
	hr = disp_args[7 - 3].Wrap(p3);
	if (FAILED(hr))
	return hr;
	hr = disp_args[7 - 4].Wrap(p4);
	if (FAILED(hr))
	return hr;
	hr = disp_args[7 - 5].Wrap(p5);
	if (FAILED(hr))
	return hr;
	hr = disp_args[7 - 6].Wrap(p6);
	if (FAILED(hr))
	return hr;
	hr = disp_args[7 - 7].Wrap(p7);
	if (FAILED(hr))
	return hr;

	// Invoke the method passing the parameters via the DISPPARAMS structure.
	// DISPATCH_PROPERTYPUT and DISPATCH_PROPERTYPUTREF require the parameter of
	// the property setter to be named, so \|cNamedArgs\| and \|rgdispidNamedArgs\|
	// structure members should be initialized.
	DISPPARAMS disp_params = { disp_args, NULL, 7, 0 };
	DISPID dispid_named = DISPID_PROPERTYPUT;
	if (flags == DISPATCH_PROPERTYPUT \|\| flags == DISPATCH_PROPERTYPUTREF) {
	disp_params.cNamedArgs = 1;
	disp_params.rgdispidNamedArgs = &dispid_named;
	}

	hr = object->Invoke(disp_id, IID_NULL, LOCALE_USER_DEFAULT, flags,
	&disp_params, disp_result, NULL, NULL);
	if (FAILED(hr))
	return hr;

	// Unwrap the parameters.
	disp_args[7 - 1].Unwrap(p1);
	disp_args[7 - 2].Unwrap(p2);
	disp_args[7 - 3].Unwrap(p3);
	disp_args[7 - 4].Unwrap(p4);
	disp_args[7 - 5].Unwrap(p5);
	disp_args[7 - 6].Unwrap(p6);
	disp_args[7 - 7].Unwrap(p7);

	// Unwrap the return value.
	if (result_out != NULL) {
	result.Unwrap(result_out);
	}

	return S_OK;
	}

	} // namespace dispatch

	} // namespace remoting

	#endif // REMOTING_BASE_IDISPATCH_DRIVER_WIN_H_