handle_guard.h

/*****************************************************/
/* lean Smart                   (c) Tobias Zirr 2011 */
/*****************************************************/

#ifndef LEAN_SMART_HANDLE_GUARD
#define LEAN_SMART_HANDLE_GUARD

#include "../lean.h"
#include "../tags/noncopyable.h"

namespace lean
{
namespace smart
{

template <class Handle>
struct close_handle_policy
{
    static LEAN_INLINE Handle invalid()
    {
        return INVALID_HANDLE_VALUE;
    }
    static LEAN_INLINE void release(Handle handle)
    {
        if (handle != NULL && handle != INVALID_HANDLE_VALUE)
            ::CloseHandle(handle);
    }
};

template <class Handle>
struct destroy_window_policy
{
    static LEAN_INLINE Handle invalid()
    {
        return NULL;
    }
    static LEAN_INLINE void release(Handle handle)
    {
        if (handle != NULL)
            ::DestroyWindow(handle);
    }
};

template <class Handle>
struct free_library_policy
{
    static LEAN_INLINE Handle invalid()
    {
        return NULL;
    }
    static LEAN_INLINE void release(Handle handle)
    {
        if (handle != NULL)
            ::FreeLibrary(handle);
    }
};

template < class Handle, class ReleasePolicy = close_handle_policy<Handle> >
class handle_guard : public noncopyable
{
private:
    Handle m_handle;

public:
    LEAN_INLINE explicit handle_guard(Handle handle)
        : m_handle(handle) { }
    LEAN_INLINE ~handle_guard()
    {
        ReleasePolicy::release(m_handle);
    }

    LEAN_INLINE Handle detatch()
    {
        Handle handle = m_handle;
        m_handle = ReleasePolicy::invalid();
        return handle;
    }

    LEAN_INLINE Handle get() const { return m_handle; }
    LEAN_INLINE operator Handle() const { return get(); }
};

} // namespace

using smart::handle_guard;

} // namespace

#endif