shellclasses.h

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/*
 * Copyright 2003, 2004, 2005 Martin Fuchs
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */


 //
 // Explorer clone
 //
 // shellclasses.h
 //
 // C++ wrapper classes for COM interfaces and shell objects
 //
 // Martin Fuchs, 20.07.2003
 //


 // windows shell headers
#include <shellapi.h>
#include <shlobj.h>

/*@@
#if _MSC_VER>=1300  // VS.Net
#include <comdefsp.h>
using namespace _com_util;
#endif
*/

#ifndef _INC_COMUTIL    // is comutil.h of MS headers not available?
#ifndef _NO_COMUTIL
#define _NO_COMUTIL
#endif
#endif

 // work around GCC's wide string constant bug when compiling inline functions
#ifdef __GNUC__
extern const LPCTSTR sCFSTR_SHELLIDLIST;
#undef CFSTR_SHELLIDLIST
#define CFSTR_SHELLIDLIST sCFSTR_SHELLIDLIST
#endif

#ifdef _MSC_VER
#define NOVTABLE __declspec(novtable)
#else
#define NOVTABLE
#endif
#define ANSUNC


 // Exception Handling

#ifndef _NO_COMUTIL

#define COMExceptionBase _com_error

#else

struct COMExceptionBase
{
    COMExceptionBase(HRESULT hr)
     :  _hr(hr)
    {
    }

    HRESULT Error() const
    {
        return _hr;
    }

    LPCTSTR ErrorMessage() const
    {
        if (_msg.empty()) {
            LPTSTR pBuf;

            if (FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM,
                0, _hr, MAKELANGID(LANG_NEUTRAL,SUBLANG_DEFAULT), (LPTSTR)&pBuf, 0, NULL)) {
                _msg = pBuf;
                LocalFree(pBuf);
             } else {
                TCHAR buffer[128];
                _sntprintf(buffer, COUNTOF(buffer), TEXT("unknown Exception: 0x%08lX"), _hr);
                _msg = buffer;
             }
        }

        return _msg;
    }

protected:
    HRESULT _hr;
    mutable String _msg;
};

#endif



struct COMException : public COMExceptionBase
{
    typedef COMExceptionBase super;

    COMException(HRESULT hr)
     :  super(hr),
        _context(CURRENT_CONTEXT),
        _file(NULL), _line(0)
    {
        LOG(toString());
        LOG(CURRENT_CONTEXT.getStackTrace());
    }

    COMException(HRESULT hr, const char* file, int line)
     :  super(hr),
        _context(CURRENT_CONTEXT),
        _file(file), _line(line)
    {
        LOG(toString());
        LOG(CURRENT_CONTEXT.getStackTrace());
    }

    COMException(HRESULT hr, const String& obj)
     :  super(hr),
        _context(CURRENT_CONTEXT),
        _file(NULL), _line(0)
    {
        LOG(toString());
        LOG(CURRENT_CONTEXT.getStackTrace());
    }

    COMException(HRESULT hr, const String& obj, const char* file, int line)
     :  super(hr),
        _context(CURRENT_CONTEXT),
        _file(file), _line(line)
    {
        LOG(toString());
        LOG(CURRENT_CONTEXT.getStackTrace());
    }

    String toString() const;

    Context _context;

    const char* _file;
    int _line;
};

#define THROW_EXCEPTION(hr) throw COMException(hr, __FILE__, __LINE__)
#define CHECKERROR(hr) ((void)(FAILED(hr)? THROW_EXCEPTION(hr): 0))


#ifdef _NO_COMUTIL

inline void CheckError(HRESULT hr)
{
    if (FAILED(hr))
        throw COMException(hr);
}

#endif



struct ComInit
{
    ComInit()
    {
        CHECKERROR(CoInitialize(0));
    }

#if (_WIN32_WINNT>=0x0400) || defined(_WIN32_DCOM)
    ComInit(DWORD flag)
    {
        CHECKERROR(CoInitializeEx(0, flag));
    }
#endif

    ~ComInit()
    {
        CoUninitialize();
    }
};



struct OleInit
{
    OleInit()
    {
        CHECKERROR(OleInitialize(0));
    }

    ~OleInit()
    {
        OleUninitialize();
    }
};



extern void HandleException(COMException& e, HWND hwnd);



struct CommonShellMalloc
{
    CommonShellMalloc()
    {
        _p = NULL;
    }

    void init()
    {
        if (!_p)
            CHECKERROR(SHGetMalloc(&_p));
    }

    ~CommonShellMalloc()
    {
        if (_p)
            _p->Release();
    }

    operator IMalloc*()
    {
        return _p;
    }

    IMalloc* _p;
};



struct ShellMalloc
{
    ShellMalloc()
    {
         // initialize s_cmn_shell_malloc
        s_cmn_shell_malloc.init();
    }

    IMalloc* operator->()
    {
        return s_cmn_shell_malloc;
    }

    static CommonShellMalloc s_cmn_shell_malloc;
};



template<typename T> struct SShellPtr
{
    ~SShellPtr()
    {
        _malloc->Free(_p);
    }

    T* operator->()
    {
        return _p;
    }

    T const* operator->() const
    {
        return _p;
    }

    operator T const *() const
    {
        return _p;
    }

    const T& operator*() const
    {
        return *_p;
    }

    T& operator*()
    {
        return *_p;
    }

protected:
    SShellPtr()
     :  _p(0)
    {
    }

    SShellPtr(T* p)
     :  _p(p)
    {
    }

    void Free()
    {
        _malloc->Free(_p);
        _p = NULL;
    }

    T* _p;
    mutable ShellMalloc _malloc;    // IMalloc memory management object

private:
     // disallow copying of SShellPtr objects
    SShellPtr(const SShellPtr&) {}
    void operator=(SShellPtr const&) {}
};



template<typename T> struct SIfacePtr
{
    SIfacePtr()
     :  _p(0)
    {
    }

    SIfacePtr(T* p)
     :  _p(p)
    {
        if (p)
            p->AddRef();
    }

    SIfacePtr(IUnknown* unknown, REFIID riid)
    {
        CHECKERROR(unknown->QueryInterface(riid, (LPVOID*)&_p));
    }

    ~SIfacePtr()
    {
        Free();
    }

    T* operator->()
    {
        return _p;
    }

    const T* operator->() const
    {
        return _p;
    }

/* not GCC compatible
    operator const T*() const
    {
        return _p;
    } */

    operator T*()
    {
        return _p;
    }

    T** operator&()
    {
        return &_p;
    }

    bool empty() const  //NOTE: GCC seems not to work correctly when defining operator bool() AND operator T*() at one time
    {
        return !_p;
    }

    SIfacePtr& operator=(T* p)
    {
        Free();

        if (p) {
            p->AddRef();
            _p = p;
        }

        return *this;
    }

    void operator=(SIfacePtr const& o)
    {
        T* h = _p;

        if (o._p)
            o._p->AddRef();

        _p = o._p;

        if (h)
            h->Release();
    }

    HRESULT CreateInstance(REFIID clsid, REFIID riid)
    {
        return CoCreateInstance(clsid, NULL, CLSCTX_INPROC_SERVER, riid, (LPVOID*)&_p);
    }

    template<typename I> HRESULT QueryInterface(REFIID riid, I* p)
    {
        return _p->QueryInterface(riid, (LPVOID*)p);
    }

    T* get()
    {
        return _p;
    }

    void Free()
    {
        T* h = _p;
        _p = NULL;

        if (h)
            h->Release();
    }

protected:
    SIfacePtr(const SIfacePtr& o)
     :  _p(o._p)
    {
        if (_p)
            _p->AddRef();
    }

    T* _p;
};


struct NOVTABLE ComSrvObject    // NOVTABLE erlaubt, da protected Destruktor
{
protected:
    ComSrvObject() : _ref(1) {}
    virtual ~ComSrvObject() {}

    ULONG   _ref;
};

struct SimpleComObject : public ComSrvObject
{
    ULONG IncRef() {return ++_ref;}
    ULONG DecRef() {ULONG ref=--_ref; if (!ref) {_ref++; delete this;} return ref;}
};


 // server object interfaces

template<typename BASE> struct IComSrvQI : public BASE
{
    IComSrvQI(REFIID uuid_base)
     :  _uuid_base(uuid_base)
    {
    }

    STDMETHODIMP QueryInterface(REFIID riid, LPVOID* ppv)
    {
        *ppv = NULL;

        if (IsEqualIID(riid, _uuid_base) || IsEqualIID(riid, IID_IUnknown))
            {*ppv=static_cast<BASE*>(this); this->AddRef(); return S_OK;}

        return E_NOINTERFACE;
    }

protected:
    IComSrvQI() {}
    virtual ~IComSrvQI() {}

    REFIID  _uuid_base;
};

template<> struct IComSrvQI<IUnknown> : public IUnknown
{
    STDMETHODIMP QueryInterface(REFIID riid, LPVOID* ppv)
    {
        *ppv = NULL;

        if (IsEqualIID(riid, IID_IUnknown))
            {*ppv=this; AddRef(); return S_OK;}

        return E_NOINTERFACE;
    }

protected:
    IComSrvQI<IUnknown>() {}
    virtual ~IComSrvQI<IUnknown>() {}
};


template<typename BASE, typename OBJ>
    class IComSrvBase : public IComSrvQI<BASE>
{
    typedef IComSrvQI<BASE> super;

protected:
    IComSrvBase(REFIID uuid_base)
     :  super(uuid_base)
    {
    }

public:
    STDMETHODIMP_(ULONG) AddRef() {return static_cast<OBJ*>(this)->IncRef();}
    STDMETHODIMP_(ULONG) Release() {return static_cast<OBJ*>(this)->DecRef();}
};



struct ShellFolder;



struct CommonDesktop
{
    CommonDesktop()
    {
        _desktop = 0;
    }

    ~CommonDesktop();

    void init();

    operator ShellFolder&()
    {
        return *_desktop;
    }

protected:
    ShellFolder* _desktop;
};


#ifndef _NO_COMUTIL // _com_ptr available?

struct ShellFolder : public IShellFolderPtr // IShellFolderPtr uses intrinsic extensions of the VC++ compiler.
{
    typedef IShellFolderPtr super;

    ShellFolder();  // desktop folder
    ShellFolder(IShellFolder* p);
    ShellFolder(IShellFolder* parent, LPCITEMIDLIST pidl);
    ShellFolder(LPCITEMIDLIST pidl);

    void    attach(IShellFolder* parent, LPCITEMIDLIST pidl);
    String  get_name(LPCITEMIDLIST pidl=NULL, SHGDNF flags=SHGDN_NORMAL) const;

    bool    empty() const {return !operator bool();}    //NOTE: see SIfacePtr::empty()
};

#ifdef UNICODE
#define IShellLinkPtr IShellLinkWPtr
#else
#define IShellLinkPtr IShellLinkAPtr
#endif

struct ShellLinkPtr : public IShellLinkPtr
{
    typedef IShellLinkPtr super;

    ShellLinkPtr(IShellLink* p)
     :  super(p)
    {
        p->AddRef();
    }

    bool    empty() const {return !operator bool();}    //NOTE: see SIfacePtr::empty()
};

#else // _com_ptr not available -> use SIfacePtr

struct ShellFolder : public SIfacePtr<IShellFolder>
{
    typedef SIfacePtr<IShellFolder> super;

    ShellFolder();
    ShellFolder(IShellFolder* p);
    ShellFolder(IShellFolder* parent, LPCITEMIDLIST pidl);
    ShellFolder(LPCITEMIDLIST pidl);

    void    attach(IShellFolder* parent, LPCITEMIDLIST pidl);
    String  get_name(LPCITEMIDLIST pidl, SHGDNF flags=SHGDN_NORMAL) const;
};

struct ShellLinkPtr : public SIfacePtr<IShellLink>
{
    typedef SIfacePtr<IShellLink> super;

    ShellLinkPtr(IShellLink* p)
     :  super(p)
    {
        _p->AddRef();
    }

};

#endif


extern ShellFolder& GetDesktopFolder();


#ifdef UNICODE
#define path_from_pidl path_from_pidlW
#else
#define path_from_pidl path_from_pidlA
#endif

extern HRESULT path_from_pidlA(IShellFolder* folder, LPCITEMIDLIST pidl, LPSTR buffer, int len);
extern HRESULT path_from_pidlW(IShellFolder* folder, LPCITEMIDLIST pidl, LPWSTR buffer, int len);
extern HRESULT name_from_pidl(IShellFolder* folder, LPCITEMIDLIST pidl, LPTSTR buffer, int len, SHGDNF flags);


 // ILGetSize() was missing in previous versions of MinGW and is not exported from shell32.dll on Windows 2000.
extern "C" UINT ILGetSize_local(LPCITEMIDLIST pidl);
#define ILGetSize ILGetSize_local

#if 0
#ifdef UNICODE      // CFSTR_FILENAME was defined wrong in previous versions of MinGW.
#define CFSTR_FILENAMEW TEXT("FileNameW")
#undef CFSTR_FILENAME
#define CFSTR_FILENAME CFSTR_FILENAMEW
#endif
#endif



struct ShellPath : public SShellPtr<ITEMIDLIST>
{
    typedef SShellPtr<ITEMIDLIST> super;

    ShellPath()
    {
    }

    ShellPath(IShellFolder* folder, LPCWSTR path)
    {
        CONTEXT("ShellPath::ShellPath(IShellFolder*, LPCWSTR)");

        if (path)
            CHECKERROR(folder->ParseDisplayName(0, NULL, (LPOLESTR)path, NULL, &_p, NULL));
        else
            _p = NULL;
    }

    ShellPath(LPCWSTR path)
    {
        OBJ_CONTEXT("ShellPath::ShellPath(LPCWSTR)", path);

        if (path)
            CHECKERROR(GetDesktopFolder()->ParseDisplayName(0, NULL, (LPOLESTR)path, NULL, &_p, NULL));
        else
            _p = NULL;
    }

    ShellPath(IShellFolder* folder, LPCSTR path)
    {
        CONTEXT("ShellPath::ShellPath(IShellFolder*, LPCSTR)");

        WCHAR b[MAX_PATH];

        if (path) {
            MultiByteToWideChar(CP_ACP, 0, path, -1, b, COUNTOF(b));
            CHECKERROR(folder->ParseDisplayName(0, NULL, b, NULL, &_p, NULL));
        } else
            _p = NULL;
    }

    ShellPath(LPCSTR path)
    {
        CONTEXT("ShellPath::ShellPath(LPCSTR)");

        WCHAR b[MAX_PATH];

        if (path) {
            MultiByteToWideChar(CP_ACP, 0, path, -1, b, COUNTOF(b));
            CHECKERROR(GetDesktopFolder()->ParseDisplayName(0, NULL, b, NULL, &_p, NULL));
        } else
            _p = NULL;
    }

    ShellPath(const ShellPath& o)
     :  super(NULL)
    {
        //CONTEXT("ShellPath::ShellPath(const ShellPath&)");

        if (o._p) {
            int l = ILGetSize(o._p);
            _p = (ITEMIDLIST*) _malloc->Alloc(l);
            if (_p) memcpy(_p, o._p, l);
        }
    }

    explicit ShellPath(LPITEMIDLIST p)
     :  super(p)
    {
    }

    ShellPath(LPCITEMIDLIST p)
    {
        //CONTEXT("ShellPath::ShellPath(LPCITEMIDLIST)");

        if (p) {
            int l = ILGetSize(p);
            _p = (ITEMIDLIST*) _malloc->Alloc(l);
            if (_p) memcpy(_p, p, l);
        }
    }

    void operator=(const ShellPath& o)
    {
        //CONTEXT("ShellPath::operator=(const ShellPath&)");

        ITEMIDLIST* h = _p;

        if (o._p) {
            int l = ILGetSize(o._p);

            _p = (ITEMIDLIST*) _malloc->Alloc(l);
            if (_p) memcpy(_p, o._p, l);
        }
        else
            _p = NULL;

        _malloc->Free(h);
    }

    void operator=(ITEMIDLIST* p)
    {
        //CONTEXT("ShellPath::operator=(ITEMIDLIST*)");

        ITEMIDLIST* h = _p;

        if (p) {
            int l = ILGetSize(p);
            _p = (ITEMIDLIST*) _malloc->Alloc(l);
            if (_p) memcpy(_p, p, l);
        }
        else
            _p = NULL;

        _malloc->Free(h);
    }

    void operator=(const SHITEMID& o)
    {
        ITEMIDLIST* h = _p;

        LPBYTE p = (LPBYTE)_malloc->Alloc(o.cb+2);
        if (p) *(PWORD)((LPBYTE)memcpy(p, &o, o.cb)+o.cb) = 0;
        _p = (ITEMIDLIST*)p;

        _malloc->Free(h);
    }

    void operator+=(const SHITEMID& o)
    {
        int l0 = ILGetSize(_p);
        LPBYTE p = (LPBYTE)_malloc->Alloc(l0+o.cb);
        int l = l0 - 2;

        if (p) {
            memcpy(p, _p, l);
            *(PWORD)((LPBYTE)memcpy(p+l, &o, o.cb)+o.cb) = 0;
        }

        _malloc->Free(_p);
        _p = (ITEMIDLIST*)p;
    }

    friend bool operator<(const ShellPath& a, const ShellPath& b)
    {
        int la = ILGetSize(a._p);
        int lb = ILGetSize(b._p);

        int r = memcmp(a._p, b._p, min(la, lb));
        if (r)
            return r < 0;
        else
            return la < lb;
    }

    void assign(LPCITEMIDLIST pidl, size_t size)
    {
        //CONTEXT("ShellPath::assign(LPCITEMIDLIST, size_t)");

        ITEMIDLIST* h = _p;

        _p = (ITEMIDLIST*) _malloc->Alloc(size+sizeof(USHORT/*SHITEMID::cb*/));

        if (_p) {
            memcpy(_p, pidl, size);
            ((ITEMIDLIST*)((LPBYTE)_p+size))->mkid.cb = 0; // terminator
        }

        _malloc->Free(h);
    }

    void assign(LPCITEMIDLIST pidl)
    {
        //CONTEXT("ShellPath::assign(LPCITEMIDLIST)");

        ITEMIDLIST* h = _p;

        if (pidl) {
            int l = ILGetSize(pidl);
            _p = (ITEMIDLIST*) _malloc->Alloc(l);
            if (_p) memcpy(_p, pidl, l);
        } else
            _p = NULL;

        _malloc->Free(h);
    }

    void split(ShellPath& parent, ShellPath& obj) const;

    void GetUIObjectOf(REFIID riid, LPVOID* ppvOut, HWND hWnd=0, ShellFolder& sf=GetDesktopFolder());

    ShellFolder get_folder()
    {
        return ShellFolder(_p);
    }

    ShellFolder get_folder(IShellFolder* parent)
    {
        CONTEXT("ShellPath::get_folder()");
        return ShellFolder(parent, _p);
    }

     // convert an item id list from relative to absolute (=relative to the desktop) format
    ShellPath create_absolute_pidl(LPCITEMIDLIST parent_pidl) const;
};


#if defined(__WINE__) && defined(NONAMELESSUNION)   // Wine doesn't know of unnamed union members and uses some macros instead.
#define UNION_MEMBER(x) DUMMYUNIONNAME.##x
#else
#define UNION_MEMBER(x) x
#endif


 // encapsulation of STRRET structure for easy string retrieval with conversion

#ifdef UNICODE
#define StrRet StrRetW
//#define   tcscpyn wcscpyn
#else
#define StrRet StrRetA
//#define   tcscpyn strcpyn
#endif

//extern LPSTR strcpyn(LPSTR dest, LPCSTR source, size_t count);
//extern LPWSTR wcscpyn(LPWSTR dest, LPCWSTR source, size_t count);

struct StrRetA : public STRRET
{
    ~StrRetA()
    {
        if (uType == STRRET_WSTR)
            ShellMalloc()->Free(pOleStr);
    }

    void GetString(const SHITEMID& shiid, LPSTR b, int l)
    {
        switch(uType) {
          case STRRET_WSTR:
            WideCharToMultiByte(CP_ACP, 0, UNION_MEMBER(pOleStr), -1, b, l, NULL, NULL);
            break;

          case STRRET_OFFSET:
            lstrcpynA(b, (LPCSTR)&shiid+UNION_MEMBER(uOffset), l);
            break;

          case STRRET_CSTR:
            lstrcpynA(b, UNION_MEMBER(cStr), l);
        }
    }
};

struct StrRetW : public STRRET
{
    ~StrRetW()
    {
        if (uType == STRRET_WSTR)
            ShellMalloc()->Free(pOleStr);
    }

    void GetString(const SHITEMID& shiid, LPWSTR b, int l)
    {
        switch(uType) {
          case STRRET_WSTR:
            lstrcpynW(b, UNION_MEMBER(pOleStr), l);
            break;

          case STRRET_OFFSET:
            MultiByteToWideChar(CP_ACP, 0, (LPCSTR)&shiid+UNION_MEMBER(uOffset), -1, b, l);
            break;

          case STRRET_CSTR:
            MultiByteToWideChar(CP_ACP, 0, UNION_MEMBER(cStr), -1, b, l);
        }
    }
};


class FileSysShellPath : public ShellPath
{
    TCHAR   _fullpath[MAX_PATH];

protected:
    FileSysShellPath() {_fullpath[0] = '\0';}

public:
    FileSysShellPath(const ShellPath& o) : ShellPath(o) {_fullpath[0] = '\0';}

    operator LPCTSTR() {if (!SHGetPathFromIDList(_p, _fullpath)) return NULL; return _fullpath;}
};


struct FolderBrowser : public FileSysShellPath
{
    FolderBrowser(HWND owner, UINT flags, LPCTSTR title, LPCITEMIDLIST root=0)
    {
        _displayname[0] = '\0';
        _browseinfo.hwndOwner = owner;
        _browseinfo.pidlRoot = root;
        _browseinfo.pszDisplayName = _displayname;
        _browseinfo.lpszTitle = title;
        _browseinfo.ulFlags = flags;
        _browseinfo.lpfn = 0;
        _browseinfo.lParam = 0;
        _browseinfo.iImage = 0;

        _p = SHBrowseForFolder(&_browseinfo);
    }

    LPCTSTR GetDisplayName()
    {
        return _displayname;
    }

    bool IsOK()
    {
        return _p != 0;
    }

private:
    BROWSEINFO _browseinfo;
    TCHAR   _displayname[MAX_PATH];
};


struct SpecialFolderPath : public ShellPath
{
    SpecialFolderPath(int folder, HWND hwnd)
    {
        HRESULT hr = SHGetSpecialFolderLocation(hwnd, folder, &_p);
        CHECKERROR(hr);
    }
};

struct DesktopFolderPath : public SpecialFolderPath
{
    DesktopFolderPath()
     :  SpecialFolderPath(CSIDL_DESKTOP, 0)
    {
    }
};

struct SpecialFolder : public ShellFolder
{
    SpecialFolder(int folder, HWND hwnd)
     :  ShellFolder(GetDesktopFolder(), SpecialFolderPath(folder, hwnd))
    {
    }
};

struct DesktopFolder : public ShellFolder
{
};


struct SpecialFolderFSPath
{
    SpecialFolderFSPath(int folder/*e.g. CSIDL_DESKTOP*/, HWND hwnd);

    operator LPCTSTR()
    {
        return _fullpath;
    }

protected:
    TCHAR   _fullpath[MAX_PATH];
};

/*
struct SpecialFolderFSPath : public FileSysShellPath
{
    SpecialFolderFSPath(int folder, HWND hwnd)
    {
        CONTEXT("SpecialFolderFSPath::SpecialFolderFSPath()");

        HRESULT hr = SHGetSpecialFolderLocation(hwnd, folder, &_p);
        CHECKERROR(hr);
    }
};
*/



struct ShellItemEnumerator : public SIfacePtr<IEnumIDList>
{
    ShellItemEnumerator(IShellFolder* folder, DWORD flags=SHCONTF_FOLDERS|SHCONTF_NONFOLDERS|SHCONTF_INCLUDEHIDDEN)
    {
        CONTEXT("ShellItemEnumerator::ShellItemEnumerator()");

        CHECKERROR(folder->EnumObjects(0, flags, &_p));
    }
};


struct PIDList
{
    PIDList()
    {
        memset(&_stgm, 0, sizeof(STGMEDIUM));
    }

    ~PIDList()
    {
        if (_stgm.hGlobal) {
            GlobalUnlock(_stgm.hGlobal);
            ReleaseStgMedium(&_stgm);
        }
    }

    HRESULT GetData(IDataObject* selection)
    {
        static UINT CF_IDLIST = RegisterClipboardFormat(CFSTR_SHELLIDLIST);

        FORMATETC fetc;
        fetc.cfFormat = CF_IDLIST;
        fetc.ptd = NULL;
        fetc.dwAspect = DVASPECT_CONTENT;
        fetc.lindex = -1;
        fetc.tymed = TYMED_HGLOBAL;

        HRESULT hr = selection->QueryGetData(&fetc);
        if (FAILED(hr))
            return hr;

        hr = selection->GetData(&fetc, &_stgm);
        if (FAILED(hr))
            return hr;

        _pIDList = (LPIDA)GlobalLock(_stgm.hGlobal);

        return hr;
    }

    operator LPIDA() {return _pIDList;}

protected:
    STGMEDIUM _stgm;
    LPIDA _pIDList;
};


struct CtxMenuInterfaces
{
    CtxMenuInterfaces()
    {
        reset();
    }

    void    reset();
    bool    HandleMenuMsg(UINT nmsg, WPARAM wparam, LPARAM lparam);
    IContextMenu* query_interfaces(IContextMenu* pcm1);

    IContextMenu2*  _pctxmenu2;

    IContextMenu3*  _pctxmenu3;
};

template<typename BASE> struct ExtContextMenuHandlerT
 : public BASE
{
    typedef BASE super;

    ExtContextMenuHandlerT(HWND hwnd)
     :  super(hwnd)
    {
    }

    template<typename PARA> ExtContextMenuHandlerT(HWND hwnd, const PARA& info)
     :  super(hwnd, info)
    {
    }

    LRESULT WndProc(UINT nmsg, WPARAM wparam, LPARAM lparam)
    {
        switch(nmsg) {
          case WM_DRAWITEM:
          case WM_MEASUREITEM:
            if (!wparam)    // Is the message menu-related?
                if (_cm_ifs.HandleMenuMsg(nmsg, wparam, lparam))
                    return TRUE;

            break;

          case WM_INITMENUPOPUP:
            if (_cm_ifs.HandleMenuMsg(nmsg, wparam, lparam))
                return 0;

            break;

          case WM_MENUCHAR: // only supported by IContextMenu3
           if (_cm_ifs._pctxmenu3) {
               LRESULT lResult = 0;

               _cm_ifs._pctxmenu3->HandleMenuMsg2(nmsg, wparam, lparam, &lResult);

               return lResult;
           }

           return 0;
        }

        return super::WndProc(nmsg, wparam, lparam);
    }

protected:
    CtxMenuInterfaces _cm_ifs;
};


extern HRESULT ShellFolderContextMenu(IShellFolder* shell_folder, HWND hwndParent, int cidl,
                                        LPCITEMIDLIST* ppidl, int x, int y, CtxMenuInterfaces& cm_ifs);