/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef nsISupportsBase_h__
#define nsISupportsBase_h__

#ifndef nscore_h___
#include "nscore.h"
#endif

#ifndef nsID_h__
#include "nsID.h"
#endif


/*@{*/
/**
 * IID for the nsISupports interface
 * {00000000-0000-0000-c000-000000000046}
 *
 * To maintain binary compatibility with COM's IUnknown, we define the IID
 * of nsISupports to be the same as that of COM's IUnknown.
 */
#define NS_ISUPPORTS_IID                                                      \
  { 0x00000000, 0x0000, 0x0000,                                               \
    {0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46} }

/**
 * Basic component object model interface. Objects which implement
 * this interface support runtime interface discovery (QueryInterface)
 * and a reference counted memory model (AddRef/Release). This is
 * modelled after the win32 IUnknown API.
 */
class NS_NO_VTABLE nsISupports {
public:

  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISUPPORTS_IID)

  /**
   * @name Methods
   */

  //@{
  /**
   * A run time mechanism for interface discovery.
   * @param aIID [in] A requested interface IID
   * @param aInstancePtr [out] A pointer to an interface pointer to
   * receive the result.
   * @return <b>NS_OK</b> if the interface is supported by the associated
   * instance, <b>NS_NOINTERFACE</b> if it is not.
   *
   * aInstancePtr must not be null.
   */
  NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) = 0;
  /**
   * Increases the reference count for this interface.
   * The associated instance will not be deleted unless
   * the reference count is returned to zero.
   *
   * @return The resulting reference count.
   */
  NS_IMETHOD_(nsrefcnt) AddRef(void) = 0;

  /**
   * Decreases the reference count for this interface.
   * Generally, if the reference count returns to zero,
   * the associated instance is deleted.
   *
   * @return The resulting reference count.
   */
  NS_IMETHOD_(nsrefcnt) Release(void) = 0;

  //@}
};

NS_DEFINE_STATIC_IID_ACCESSOR(nsISupports, NS_ISUPPORTS_IID)

/*@}*/

#endif
