windows-nt/Source/XPSP1/NT/enduser/windows.com/wuv3/cdminc/ar.h

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2020-09-26 03:20:57 -05:00
//=======================================================================
//
// Copyright (c) 1998-1999 Microsoft Corporation. All Rights Reserved.
//
// File: ar.h
//
// Owner: YanL
//
// Description:
//
// auto_resource and dirived definitions
//
//
//=======================================================================
#pragma once
//----------------------------------------------------------------------
//
// class auto_resource
// This class eliminates need for cleanup when working with pointers and
// handles of the different kind
//
// class _Rh - resource "handle"
//
// class _Rh_Traits - required traits for this recource "handle"
// Should be define as:
// struct _Rh_Traits {
// static _Rh invalid() {}
// static void release(_Rh rh) {}
// };
//
//----------------------------------------------------------------------
template< class _Rh, class _Rh_Traits >
class auto_resource {
public:
auto_resource(_Rh rh = _Rh_Traits::invalid()) : _r(rh)
{
}
~auto_resource()
{
release();
}
void release()
{
if (valid())
{
_Rh_Traits::release(_r);
_r = _Rh_Traits::invalid();
}
}
const auto_resource& operator=(_Rh rh)
{
release();
_r = rh;
return *this;
}
operator _Rh() const
{
return _r;
}
_Rh* operator&()
{
release();
return &_r;
}
bool valid() const
{
return (_Rh_Traits::invalid() != _r);
}
_Rh detach()
{
_Rh rh = _r;
_r = _Rh_Traits::invalid();
return rh;
}
protected:
_Rh _r;
private:
// should not use copy constructor etc.
auto_resource(const auto_resource&) {}
const auto_resource& operator=(const auto_resource&) {}
operator bool() const {}
bool operator !() const {}
};
// handle to file has -1 as invalid
struct auto_hfile_traits {
static HANDLE invalid() { return INVALID_HANDLE_VALUE; }
static void release(HANDLE h) { CloseHandle(h); }
};
typedef auto_resource< HANDLE, auto_hfile_traits > auto_hfile;
// handle to all other kernel objects
struct auto_handle_traits {
static HANDLE invalid() { return 0; }
static void release(HANDLE h) { CloseHandle(h); }
};
typedef auto_resource< HANDLE, auto_handle_traits > auto_handle;
// handle to registry key (RegOpenKey, etc.)
struct auto_hkey_traits {
static HKEY invalid() { return (HKEY)0; }
static void release(HKEY hkey) { RegCloseKey(hkey); }
};
typedef auto_resource<HKEY, auto_hkey_traits> auto_hkey;
// handle to SetupDiXxxx registry key - invalid is INVALID_HANDLE_VALUE, not 0
struct auto_hkeySetupDi_traits {
static HKEY invalid() { return (HKEY) INVALID_HANDLE_VALUE; }
static void release(HKEY hkey) { RegCloseKey(hkey); }
};
typedef auto_resource<HKEY, auto_hkeySetupDi_traits> auto_hkeySetupDi;
// handle to load lib key
struct auto_hlib_traits {
static HINSTANCE invalid() { return 0; }
static void release(HINSTANCE hlib) { FreeLibrary(hlib); }
};
typedef auto_resource< HINSTANCE, auto_hlib_traits > auto_hlib;
// auto handle to HANDLE FindFirstFile
struct auto_hfindfile_traits {
static HANDLE invalid() { return INVALID_HANDLE_VALUE; }
static void release(HANDLE hFindFile) { FindClose(hFindFile); }
};
typedef auto_resource< HANDLE, auto_hfindfile_traits > auto_hfindfile;
// Pointer
template< class _Ty >
struct auto_pointer_traits {
static _Ty* invalid() { return 0; }
static void release(_Ty* p) { delete p; }
};
template< class _Ty >
class auto_pointer : public auto_resource< _Ty*, auto_pointer_traits< _Ty > > {
public:
auto_pointer(_Ty* p = 0)
: auto_resource<_Ty*, auto_pointer_traits< _Ty > >(p)
{
}
const auto_pointer& operator=(_Ty* p)
{
auto_resource<_Ty*, auto_pointer_traits< _Ty > >::operator=(p);
return *this;
}
_Ty* operator->() const
{
return _r;
}
};