comutil.h

Go to the documentation of this file.

/***
* comutil.h - Native C++ compiler COM support - BSTR, VARIANT wrappers header
*
* Copyright (c) Microsoft Corporation. All rights reserved.
*
****/

#if _MSC_VER > 1000
#pragma once
#endif

#ifdef _M_CEE_PURE
#error comutil.h header cannot be included under /clr:safe or /clr:pure
#endif

#if !defined(_INC_COMUTIL)
#define _INC_COMUTIL

#include <ole2.h>

#if !defined(_COM_ASSERT)
# if defined(_DEBUG)
# include <assert.h>
# define _COM_ASSERT(x) assert(x)
# else
# define _COM_ASSERT(x) ((void)0)
# endif
#endif

#if !defined(_SECURE_COMPILER_COM)
/* use secure versions by default if not specified otherwise */
#define _SECURE_COMPILER_COM 1
#endif

#if _SECURE_COMPILER_COM && defined(__GOT_SECURE_LIB__) && __GOT_SECURE_LIB__ >= 200402L

#include <stdio.h>

# define _COM_MEMCPY_S(dest, destsize, src, count) memcpy_s(dest, destsize, src, count)
# if defined(UNICODE)
#  define _COM_PRINTF_S_1(dest, destsize, format, arg1) swprintf_s(dest, destsize, format, arg1)
# else
#  define _COM_PRINTF_S_1(dest, destsize, format, arg1) sprintf_s(dest, destsize, format, arg1)
# endif

#else

# define _COM_MEMCPY_S(dest, destsize, src, count) memcpy(dest, src, count)
# define _COM_PRINTF_S_1(dest, destsize, format, arg1) wsprintf(dest, format, arg1)

#endif

#pragma warning(push)
#pragma warning(disable: 4290)
#pragma warning(disable: 4310)

#pragma push_macro("new")
#undef new

/* Add macros if the macros were not defined. */
#ifndef S_OK
#define S_OK                            ((HRESULT)0L)
#endif
#ifndef INTSAFE_E_ARITHMETIC_OVERFLOW
#define INTSAFE_E_ARITHMETIC_OVERFLOW   ((HRESULT)0x80070216L)  // 0x216 = 534 = ERROR_ARITHMETIC_OVERFLOW
#endif
#ifndef INTSAFE_UINT_MAX
#define INTSAFE_UINT_MAX                0xffffffff
#endif
#ifndef FAILED
#define FAILED(hr) (((HRESULT)(hr)) < 0)
#endif

class _com_error;

void __declspec(noreturn) __stdcall _com_issue_error(HRESULT);

//
// Forward class declarations
//

class _bstr_t;
class _variant_t;

//
// Error checking routines
//

namespace _com_util {
    inline void CheckError(HRESULT hr)
    {
        if (FAILED(hr)) {
            _com_issue_error(hr);
        }
    }
    static HRESULT UIntAdd(UINT uAugend, UINT uAddend, UINT *puResult)
    {
        if((uAugend + uAddend) < uAddend)
        {
            return INTSAFE_E_ARITHMETIC_OVERFLOW;
        }
        *puResult = uAugend + uAddend;
        return S_OK;
    }

    static HRESULT UIntMult(UINT uMultiplicand, UINT uMultiplier, UINT *puResult)
    {
        ULONGLONG ull64Result = UInt32x32To64(uMultiplicand, uMultiplier);
        if(ull64Result <= INTSAFE_UINT_MAX)
        {
            *puResult = (UINT)ull64Result;
            return S_OK;
        }
        return INTSAFE_E_ARITHMETIC_OVERFLOW;
    }
}

//
// Routines for handling conversions between BSTR and char*
//

namespace _com_util {
    // Convert char * to BSTR
    //
    BSTR __stdcall ConvertStringToBSTR(const char* pSrc) ;

    // Convert BSTR to char *
    //
    char* __stdcall ConvertBSTRToString(BSTR pSrc) ;
}

//
// Wrapper class for BSTR
//

class _bstr_t {
public:
    // Constructors
    //
    _bstr_t() throw();
    _bstr_t(const _bstr_t& s) throw();
    _bstr_t(const char* s) ;
    _bstr_t(const wchar_t* s) ;
    _bstr_t(const _variant_t& var) ;
    _bstr_t(BSTR bstr, bool fCopy) ;

    // Destructor
    //
    ~_bstr_t() throw();

    // Assignment operators
    //
    _bstr_t& operator=(const _bstr_t& s) throw();
    _bstr_t& operator=(const char* s) ;
    _bstr_t& operator=(const wchar_t* s) ;
    _bstr_t& operator=(const _variant_t& var) ;

    // Operators
    //
    _bstr_t& operator+=(const _bstr_t& s) ;
    _bstr_t operator+(const _bstr_t& s) const ;

    // Friend operators
    //
    friend _bstr_t operator+(const char* s1, const _bstr_t& s2) ;
    friend _bstr_t operator+(const wchar_t* s1, const _bstr_t& s2) ;

    // Extractors
    //
    operator const wchar_t*() const throw();
    operator wchar_t*() const throw();
    operator const char*() const ;
    operator char*() const ;

    // Comparison operators
    //
    bool operator!() const throw();
    bool operator==(const _bstr_t& str) const throw();
    bool operator!=(const _bstr_t& str) const throw();
    bool operator<(const _bstr_t& str) const throw();
    bool operator>(const _bstr_t& str) const throw();
    bool operator<=(const _bstr_t& str) const throw();
    bool operator>=(const _bstr_t& str) const throw();

    // Low-level helper functions
    //
    BSTR copy(bool fCopy = true) const ;
    unsigned int length() const throw();

    // Binary string assign
    //
    void Assign(BSTR s) ;

    // Get the physical BSTR
    //
    BSTR& GetBSTR() ;
    BSTR* GetAddress() ;

    // Attach to the internal BSTR w/o copying
    //
    void Attach(BSTR s) ;

    // Detach the internal BSTR
    //
    BSTR Detach();

private:
    // Referenced counted wrapper
    //
    class Data_t {
    public:
        // Constructors
        //
        Data_t(const char* s) ;
        Data_t(const wchar_t* s) ;
        Data_t(BSTR bstr, bool fCopy) ;
        Data_t(const _bstr_t& s1, const _bstr_t& s2) ;

        // Reference counting routines
        //
        unsigned long AddRef() throw();
        unsigned long Release() throw();
        unsigned long RefCount() const throw();

        // Extractors
        //
        operator const wchar_t*() const throw();
        operator const char*() const ;

        // Low-level helper functions
        //
        const wchar_t* GetWString() const throw();
        wchar_t*& GetWString() throw();
        const char* GetString() const ;

        BSTR Copy() const ;
        void Assign(BSTR s) ;
        void Attach(BSTR s) throw();
        unsigned int Length() const throw();
        int Compare(const Data_t& str) const throw();

        // Exception agnostic wrapper for new
        //
        void* operator new(size_t sz);          

    private:
        BSTR            m_wstr;
        mutable char*   m_str;
        unsigned long   m_RefCount;

        // Never allow default construction
        //
        Data_t() throw();

        // Never allow copy
        //
        Data_t(const Data_t& s) throw();

        // Prevent deletes from outside. Release() must be used.
        //
        ~Data_t() throw();

        void _Free() throw();
    };

private:
    // Reference counted representation
    //
    Data_t* m_Data;

private:
    // Low-level utilities
    //
    void _AddRef() throw();
    void _Free() throw();
    int _Compare(const _bstr_t& str) const throw();
};

//
// Constructors
//

// Default constructor
//
inline _bstr_t::_bstr_t() throw()
    : m_Data(NULL)
{
}

// Copy constructor
//
inline _bstr_t::_bstr_t(const _bstr_t& s) throw()
    : m_Data(s.m_Data)
{
    _AddRef();
}

// Construct a _bstr_t from a const char*
//
inline _bstr_t::_bstr_t(const char* s) 
    : m_Data(new Data_t(s))
{
    if (m_Data == NULL) {
        _com_issue_error(E_OUTOFMEMORY);
    }
}

// Construct a _bstr_t from a const whar_t*
//
inline _bstr_t::_bstr_t(const wchar_t* s) 
    : m_Data(new Data_t(s))
{
    if (m_Data == NULL) {
        _com_issue_error(E_OUTOFMEMORY);
    }
}

// Construct a _bstr_t from a BSTR.  If fCopy is FALSE, give control of
// data to the _bstr_t without making a new copy.
//
inline _bstr_t::_bstr_t(BSTR bstr, bool fCopy) 
    : m_Data(new Data_t(bstr, fCopy))
{
    if (m_Data == NULL) {
        _com_issue_error(E_OUTOFMEMORY);
    }
}

// Destructor
//
inline _bstr_t::~_bstr_t() throw()
{
    _Free();
}

//
// Assignment operators
//

// Default assign operator
//
inline _bstr_t& _bstr_t::operator=(const _bstr_t& s) throw()
{
    if (this != &s) {
        _Free();

        m_Data = s.m_Data;
        _AddRef();
    }

    return *this;
}

// Assign a const char* to a _bstr_t
//
inline _bstr_t& _bstr_t::operator=(const char* s) 
{
    _COM_ASSERT(s == NULL || static_cast<const char*>(*this) != s);

    if (s == NULL || static_cast<const char*>(*this) != s)
    {
        _Free();

        m_Data = new Data_t(s);
        if (m_Data == NULL) {
            _com_issue_error(E_OUTOFMEMORY);
        }
    }

    return *this;
}

// Assign a const wchar_t* to a _bstr_t
//
inline _bstr_t& _bstr_t::operator=(const wchar_t* s) 
{
    _COM_ASSERT(s == NULL || static_cast<const wchar_t*>(*this) != s);

    if (s == NULL || static_cast<const wchar_t*>(*this) != s)
    {
        _Free();

        m_Data = new Data_t(s);
        if (m_Data == NULL) {
            _com_issue_error(E_OUTOFMEMORY);
        }
    }

    return *this;
}

//
// Operators
//

// Concatenate a _bstr_t onto this _bstr_t
//
inline _bstr_t& _bstr_t::operator+=(const _bstr_t& s) 
{
    Data_t* newData = new Data_t(*this, s);
    if (newData == NULL) {
        _com_issue_error(E_OUTOFMEMORY);
    }
    else {
        _Free();
        m_Data = newData;
    }

    return *this;
}

// Return the concatenation of this _bstr_t with another _bstr_t
//
inline _bstr_t _bstr_t::operator+(const _bstr_t& s) const 
{
    _bstr_t b = *this;
    b += s;

    return b;
}

//
// Friend Operators
//

// Return the concatenation of a const char* with a _bstr_t
//
inline _bstr_t operator+(const char* s1, const _bstr_t& s2) 
{
    _bstr_t b = s1; 
    b += s2;

    return b;
}

// Return the concatenation of a const char* with a _bstr_t
//
inline _bstr_t operator+(const wchar_t* s1, const _bstr_t& s2) 
{
    _bstr_t b = s1; 
    b += s2;

    return b;
}

//
// Extractors
//

// Extract a const wchar_t*
//
inline _bstr_t::operator const wchar_t*() const throw()
{
    return (m_Data != NULL) ? m_Data->GetWString() : NULL;
}

// Extract a wchar_t*
//
inline _bstr_t::operator wchar_t*() const throw()
{
    return const_cast<wchar_t*>((m_Data != NULL) ? m_Data->GetWString() : NULL);
}

// Extract a const char_t*
//
inline _bstr_t::operator const char*() const 
{
    return (m_Data != NULL) ? m_Data->GetString() : NULL;
}

// Extract a char_t*
//
inline _bstr_t::operator char*() const 
{
    return const_cast<char*>((m_Data != NULL) ? m_Data->GetString() : NULL);
}

//
// Comparison operators
//

inline bool _bstr_t::operator!() const throw()
{
    return (m_Data != NULL) ? !m_Data->GetWString() : true;
}

inline bool _bstr_t::operator==(const _bstr_t& str) const throw()
{
    return _Compare(str) == 0;
}

inline bool _bstr_t::operator!=(const _bstr_t& str) const throw()
{
    return _Compare(str) != 0;
}

inline bool _bstr_t::operator<(const _bstr_t& str) const throw()
{
    return _Compare(str) < 0;
}

inline bool _bstr_t::operator>(const _bstr_t& str) const throw()
{
    return _Compare(str) > 0;
}

inline bool _bstr_t::operator<=(const _bstr_t& str) const throw()
{
    return _Compare(str) <= 0;
}

inline bool _bstr_t::operator>=(const _bstr_t& str) const throw()
{
    return _Compare(str) >= 0;
}

//
// Low-level help functions
//

// Extract a copy of the wrapped BSTR
//
inline BSTR _bstr_t::copy(bool fCopy) const 
{
    return (m_Data != NULL) ? (fCopy ? m_Data->Copy() : m_Data->GetWString()) : NULL;
}

// Return the length of the wrapped BSTR
//
inline unsigned int _bstr_t::length() const throw()
{
    return (m_Data != NULL) ? m_Data->Length() : 0;
}

// Binary string assign
//
inline void _bstr_t::Assign(BSTR s) 
{
    _COM_ASSERT(s == NULL || m_Data == NULL || m_Data->GetWString() != s);
    
    if (s == NULL || m_Data == NULL || m_Data->GetWString() != s)
    {
        _Free();

        m_Data = new Data_t(s, TRUE);
        if (m_Data == NULL) {
            _com_issue_error(E_OUTOFMEMORY);
        }
    }
}

// Get the physical BSTR
//
inline BSTR& _bstr_t::GetBSTR()  
{
    if (m_Data == NULL) {
        m_Data = new Data_t(0, FALSE);
        if (m_Data == NULL) {
            _com_issue_error(E_OUTOFMEMORY);
        }
    }
    return m_Data->GetWString();
}

// Get the address of the physical BSTR to pass as an 'out'-parameter
//
inline BSTR* _bstr_t::GetAddress()  
{
    Attach(0);
    return &m_Data->GetWString();
}

// Attach to the internal BSTR w/o copying
//
inline void _bstr_t::Attach(BSTR s) 
{
    _Free();

    m_Data = new Data_t(s, FALSE);
    if (m_Data == NULL) {
        _com_issue_error(E_OUTOFMEMORY);
    }
}

// Detach the internal BSTR
//
inline BSTR _bstr_t::Detach()
{
    _COM_ASSERT(m_Data != NULL && m_Data->RefCount() == 1);

    if (m_Data != NULL && m_Data->RefCount() == 1) {
        BSTR b = m_Data->GetWString();
        m_Data->GetWString() = NULL;
        _Free();
        return b;
    } 
    else {
        _com_issue_error(E_POINTER);        
    }
}

// AddRef the BSTR
//
inline void _bstr_t::_AddRef() throw()
{
    if (m_Data != NULL) {
        m_Data->AddRef();
    }
}

// Free the BSTR
//
inline void _bstr_t::_Free() throw()
{
    if (m_Data != NULL) {
        m_Data->Release();
        m_Data = NULL;
    }
}

// Compare two _bstr_t objects
//
inline int _bstr_t::_Compare(const _bstr_t& str) const throw()
{
    if (m_Data == str.m_Data) {
        return 0;
    }

    if (m_Data == NULL) {
        if (str.length() == 0) {
            return 0;
        }
        else {
            return -1;
        }
    }

    if (str.m_Data == NULL){
        if (this->length() == 0) {
            return 0;
        }
        else {
            return 1;
        }
    }

    return m_Data->Compare(*str.m_Data);
}

//
// Reference counted wrapper - Constructors
//

// Construct a Data_t from a const char*
//
inline _bstr_t::Data_t::Data_t(const char* s) 
    : m_str(NULL), m_RefCount(1)
{
    m_wstr = _com_util::ConvertStringToBSTR(s);
}

// Construct a Data_t from a const wchar_t*
//
inline _bstr_t::Data_t::Data_t(const wchar_t* s) 
    : m_str(NULL), m_RefCount(1)
{
    m_wstr = ::SysAllocString(s);

    if (m_wstr == NULL && s != NULL) {
        _com_issue_error(E_OUTOFMEMORY);
    }
}

// Construct a Data_t from a BSTR.  If fCopy is FALSE, give control of
// data to the Data_t without doing a SysAllocStringByteLen.
//
inline _bstr_t::Data_t::Data_t(BSTR bstr, bool fCopy) 
    : m_str(NULL), m_RefCount(1)
{
    if (fCopy && bstr != NULL) {
        m_wstr = ::SysAllocStringByteLen(reinterpret_cast<char*>(bstr),
                                         ::SysStringByteLen(bstr));

        if (m_wstr == NULL) {
            _com_issue_error(E_OUTOFMEMORY);
        }
    }
    else {
        m_wstr = bstr;
    }
}

// Construct a Data_t from the concatenation of two _bstr_t objects
//
inline _bstr_t::Data_t::Data_t(const _bstr_t& s1, const _bstr_t& s2) 
    : m_str(NULL), m_RefCount(1)
{
    const unsigned int l1 = s1.length();
    const unsigned int l2 = s2.length();
    unsigned int l3;

    if (FAILED(_com_util::UIntAdd(l1, l2, &l3)) ||
        FAILED(_com_util::UIntMult(l3, sizeof(wchar_t), &l3)))
    {
        _com_issue_error(E_OUTOFMEMORY);
        return;
    }
    
    m_wstr = ::SysAllocStringByteLen(NULL, (l1 + l2) * sizeof(wchar_t));
    if (m_wstr == NULL) 
    {
        if (l1 + l2 == 0)
        {
            return;
        }
        _com_issue_error(E_OUTOFMEMORY);
        return;
    }

    const wchar_t* wstr1 = static_cast<const wchar_t*>(s1);

    if (wstr1 != NULL) 
    {
        _COM_MEMCPY_S(m_wstr, (l1 + l2 + 1) * sizeof(wchar_t), wstr1, (l1 + 1) * sizeof(wchar_t));
    }

    const wchar_t* wstr2 = static_cast<const wchar_t*>(s2);

    if (wstr2 != NULL) 
    {
        _COM_MEMCPY_S(m_wstr + l1, (l2 + 1) * sizeof(wchar_t), wstr2, (l2 + 1) * sizeof(wchar_t));
    }
}

//
// Reference counted wrapper - reference counting routines
//

inline unsigned long _bstr_t::Data_t::AddRef() throw()
{
    InterlockedIncrement(reinterpret_cast<long*>(&m_RefCount));
    return m_RefCount;
}

inline unsigned long _bstr_t::Data_t::Release() throw()
{
    unsigned long cRef = InterlockedDecrement(reinterpret_cast<long*>(&m_RefCount));
    if (cRef == 0) {
        delete this;
    }

    return cRef;
}

inline unsigned long _bstr_t::Data_t::RefCount() const throw()
{
    return m_RefCount;
}

//
// Reference counted wrapper - extractors
//

// Extract a const wchar_t*
//
inline _bstr_t::Data_t::operator const wchar_t*() const throw()
{
    return m_wstr;
}

// Extract a const char_t*
//
inline _bstr_t::Data_t::operator const char*() const 
{
    return GetString();
}

//
// Reference counted wrapper - helper functions
//

inline const wchar_t* _bstr_t::Data_t::GetWString() const throw()
{
    return m_wstr;
}

inline wchar_t*& _bstr_t::Data_t::GetWString() throw()
{
    return m_wstr;
}

inline const char* _bstr_t::Data_t::GetString() const 
{
    if (m_str == NULL) {
        m_str = _com_util::ConvertBSTRToString(m_wstr);
    }

    return m_str;
}

// Return a copy of the wrapped BSTR
//
inline BSTR _bstr_t::Data_t::Copy() const 
{
    if (m_wstr != NULL) {
        BSTR bstr = ::SysAllocStringByteLen(reinterpret_cast<char*>(m_wstr), ::SysStringByteLen(m_wstr));

        if (bstr == NULL) {
            _com_issue_error(E_OUTOFMEMORY);
        }

        return bstr;
    }

    return NULL;
}

inline void _bstr_t::Data_t::Assign(BSTR s) 
{
    _Free();

    if (s != NULL) {
        m_wstr = ::SysAllocStringByteLen(reinterpret_cast<char*>(s), ::SysStringByteLen(s));
        m_str = 0;
    }
}

inline void _bstr_t::Data_t::Attach(BSTR s) throw()
{
    _Free();

    m_wstr = s;
    m_str = 0;
    m_RefCount = 1;
}

// Return the length of the wrapper BSTR
//
inline unsigned int _bstr_t::Data_t::Length() const throw()
{
    return m_wstr ? ::SysStringLen(m_wstr) : 0;
}

// Compare two wrapped BSTRs
//
inline int _bstr_t::Data_t::Compare(const _bstr_t::Data_t& str) const throw()
{
    // Dont need to check for NULL here, because 
    // SysStringLen will return 0 if you pass in NULL
    const unsigned int l1 = ::SysStringLen(m_wstr);
    const unsigned int l2 = ::SysStringLen(str.m_wstr);

    unsigned int len = l1;
    if (len > l2) {
        len = l2;
    }

    BSTR bstr1 = m_wstr;
    BSTR bstr2 = str.m_wstr;

    while (len-- > 0) {
        if (*bstr1++ != *bstr2++) {
            return bstr1[-1] - bstr2[-1];
        }
    }

    return (l1 < l2) ? -1 : (l1 == l2) ? 0 : 1;
}

// Exception agnostic wrapper for new
//
#ifdef _COM_OPERATOR_NEW_THROWS
inline void* _bstr_t::Data_t::operator new(size_t sz) 
{
    try {
        return ::operator new(sz);
    }
    catch (...) {
        return NULL;
    }
}
#else // _COM_OPERATOR_NEW_THROWS
inline void* _bstr_t::Data_t::operator new(size_t sz) 
{
    return ::operator new(sz);
}
#endif // _COM_OPERATOR_NEW_THROWS

// Destruct this object
//
inline _bstr_t::Data_t::~Data_t() throw()
{
    _Free();
}

// Free up this object
//
inline void _bstr_t::Data_t::_Free() throw()
{
    if (m_wstr != NULL) {
        ::SysFreeString(m_wstr);
        m_wstr = NULL;
    }

    if (m_str != NULL) {
        delete [] m_str;
        m_str = NULL;
    }
}

//
// Wrapper class for VARIANT
//

/*
 * VARENUM usage key,
 *
 * * [V] - may appear in a VARIANT
 * * [T] - may appear in a TYPEDESC
 * * [P] - may appear in an OLE property set
 * * [S] - may appear in a Safe Array
 * * [C] - supported by class _variant_t
 *
 *
 *  VT_EMPTY            [V]   [P]        nothing
 *  VT_NULL             [V]   [P]        SQL style Null
 *  VT_I2               [V][T][P][S][C]  2 byte signed int
 *  VT_I4               [V][T][P][S][C]  4 byte signed int
 *  VT_R4               [V][T][P][S][C]  4 byte real
 *  VT_R8               [V][T][P][S][C]  8 byte real
 *  VT_CY               [V][T][P][S][C]  currency
 *  VT_DATE             [V][T][P][S][C]  date
 *  VT_BSTR             [V][T][P][S][C]  OLE Automation string
 *  VT_DISPATCH         [V][T][P][S][C]  IDispatch *
 *  VT_ERROR            [V][T]   [S][C]  SCODE
 *  VT_BOOL             [V][T][P][S][C]  True=-1, False=0
 *  VT_VARIANT          [V][T][P][S]     VARIANT *
 *  VT_UNKNOWN          [V][T]   [S][C]  IUnknown *
 *  VT_DECIMAL          [V][T]   [S][C]  16 byte fixed point
 *  VT_I1                  [T]           signed char
 *  VT_UI1              [V][T][P][S][C]  unsigned char
 *  VT_UI2                 [T][P]        unsigned short
 *  VT_UI4                 [T][P]        unsigned short
 *  VT_I8                  [T][P]        signed 64-bit int
 *  VT_UI8                 [T][P]        unsigned 64-bit int
 *  VT_INT                 [T]           signed machine int
 *  VT_UINT                [T]           unsigned machine int
 *  VT_VOID                [T]           C style void
 *  VT_HRESULT             [T]           Standard return type
 *  VT_PTR                 [T]           pointer type
 *  VT_SAFEARRAY           [T]          (use VT_ARRAY in VARIANT)
 *  VT_CARRAY              [T]           C style array
 *  VT_USERDEFINED         [T]           user defined type
 *  VT_LPSTR               [T][P]        null terminated string
 *  VT_LPWSTR              [T][P]        wide null terminated string
 *  VT_FILETIME               [P]        FILETIME
 *  VT_BLOB                   [P]        Length prefixed bytes
 *  VT_STREAM                 [P]        Name of the stream follows
 *  VT_STORAGE                [P]        Name of the storage follows
 *  VT_STREAMED_OBJECT        [P]        Stream contains an object
 *  VT_STORED_OBJECT          [P]        Storage contains an object
 *  VT_BLOB_OBJECT            [P]        Blob contains an object
 *  VT_CF                     [P]        Clipboard format
 *  VT_CLSID                  [P]        A Class ID
 *  VT_VECTOR                 [P]        simple counted array
 *  VT_ARRAY            [V]              SAFEARRAY*
 *  VT_BYREF            [V]              void* for local use
 */

class _variant_t : public ::tagVARIANT {
public:
    // Constructors
    //
    _variant_t() throw();

    _variant_t(const VARIANT& varSrc) ;
    _variant_t(const VARIANT* pSrc) ;
    _variant_t(const _variant_t& varSrc) ;

    _variant_t(VARIANT& varSrc, bool fCopy) ;          // Attach VARIANT if !fCopy

    _variant_t(short sSrc, VARTYPE vtSrc = VT_I2) ;    // Creates a VT_I2, or a VT_BOOL
    _variant_t(long lSrc, VARTYPE vtSrc = VT_I4) ;     // Creates a VT_I4, a VT_ERROR, or a VT_BOOL
    _variant_t(float fltSrc) throw();                                   // Creates a VT_R4
    _variant_t(double dblSrc, VARTYPE vtSrc = VT_R8) ; // Creates a VT_R8, or a VT_DATE
    _variant_t(const CY& cySrc) throw();                                // Creates a VT_CY
    _variant_t(const _bstr_t& bstrSrc) ;               // Creates a VT_BSTR
    _variant_t(const wchar_t *pSrc) ;                  // Creates a VT_BSTR
    _variant_t(const char* pSrc) ;                     // Creates a VT_BSTR
    _variant_t(IDispatch* pSrc, bool fAddRef = true) throw();           // Creates a VT_DISPATCH
    _variant_t(bool boolSrc) throw();                                   // Creates a VT_BOOL
    _variant_t(IUnknown* pSrc, bool fAddRef = true) throw();            // Creates a VT_UNKNOWN
    _variant_t(const DECIMAL& decSrc) throw();                          // Creates a VT_DECIMAL
    _variant_t(BYTE bSrc) throw();                                      // Creates a VT_UI1

    _variant_t(char cSrc) throw();                                      // Creates a VT_I1
    _variant_t(unsigned short usSrc) throw();                           // Creates a VT_UI2
    _variant_t(unsigned long ulSrc) throw();                            // Creates a VT_UI4
    _variant_t(int iSrc) throw();                                       // Creates a VT_INT
    _variant_t(unsigned int uiSrc) throw();                             // Creates a VT_UINT
#if (_WIN32_WINNT >= 0x0501)
    _variant_t(__int64 i8Src) throw();                                  // Creates a VT_I8
    _variant_t(unsigned __int64 ui8Src) throw();                        // Creates a VT_UI8
#endif

    // Destructor
    //
    ~_variant_t() throw() ;

    // Extractors
    //
    operator short() const ;                           // Extracts a short from a VT_I2
    operator long() const ;                            // Extracts a long from a VT_I4
    operator float() const ;                           // Extracts a float from a VT_R4
    operator double() const ;                          // Extracts a double from a VT_R8
    operator CY() const ;                              // Extracts a CY from a VT_CY
    operator _bstr_t() const ;                         // Extracts a _bstr_t from a VT_BSTR
    operator IDispatch*() const ;                      // Extracts a IDispatch* from a VT_DISPATCH
    operator bool() const ;                            // Extracts a bool from a VT_BOOL
    operator IUnknown*() const ;                       // Extracts a IUnknown* from a VT_UNKNOWN
    operator DECIMAL() const ;                         // Extracts a DECIMAL from a VT_DECIMAL
    operator BYTE() const ;                            // Extracts a BTYE (unsigned char) from a VT_UI1
    operator VARIANT() const throw();

    operator char() const ;                            // Extracts a char from a VT_I1
    operator unsigned short() const ;                  // Extracts a unsigned short from a VT_UI2
    operator unsigned long() const ;                   // Extracts a unsigned long from a VT_UI4
    operator int() const ;                             // Extracts a int from a VT_INT
    operator unsigned int() const ;                    // Extracts a unsigned int from a VT_UINT
#if (_WIN32_WINNT >= 0x0501)
    operator __int64() const ;                         // Extracts a __int64 from a VT_I8
    operator unsigned __int64() const ;                // Extracts a unsigned __int64 from a VT_UI8
#endif

    // Assignment operations
    //
    _variant_t& operator=(const VARIANT& varSrc) ;
    _variant_t& operator=(const VARIANT* pSrc) ;
    _variant_t& operator=(const _variant_t& varSrc) ;

    _variant_t& operator=(short sSrc) ;                // Assign a VT_I2, or a VT_BOOL
    _variant_t& operator=(long lSrc) ;                 // Assign a VT_I4, a VT_ERROR or a VT_BOOL
    _variant_t& operator=(float fltSrc) ;              // Assign a VT_R4
    _variant_t& operator=(double dblSrc) ;             // Assign a VT_R8, or a VT_DATE
    _variant_t& operator=(const CY& cySrc) ;           // Assign a VT_CY
    _variant_t& operator=(const _bstr_t& bstrSrc) ;    // Assign a VT_BSTR
    _variant_t& operator=(const wchar_t* pSrc) ;       // Assign a VT_BSTR
    _variant_t& operator=(const char* pSrc) ;          // Assign a VT_BSTR
    _variant_t& operator=(IDispatch* pSrc) ;           // Assign a VT_DISPATCH
    _variant_t& operator=(bool boolSrc) ;              // Assign a VT_BOOL
    _variant_t& operator=(IUnknown* pSrc) ;            // Assign a VT_UNKNOWN
    _variant_t& operator=(const DECIMAL& decSrc) ;     // Assign a VT_DECIMAL
    _variant_t& operator=(BYTE bSrc) ;                 // Assign a VT_UI1

    _variant_t& operator=(char cSrc) ;                 // Assign a VT_I1
    _variant_t& operator=(unsigned short usSrc) ;      // Assign a VT_UI2
    _variant_t& operator=(unsigned long ulSrc) ;       // Assign a VT_UI4
    _variant_t& operator=(int iSrc) ;                  // Assign a VT_INT
    _variant_t& operator=(unsigned int uiSrc) ;        // Assign a VT_UINT
#if (_WIN32_WINNT >= 0x0501)
    _variant_t& operator=(__int64 i8Src) ;             // Assign a VT_I8
    _variant_t& operator=(unsigned __int64 ui8Src) ;   // Assign a VT_UI8
#endif

    // Comparison operations
    //
    bool operator==(const VARIANT& varSrc) const throw();
    bool operator==(const VARIANT* pSrc) const throw();

    bool operator!=(const VARIANT& varSrc) const throw();
    bool operator!=(const VARIANT* pSrc) const throw();

    // Low-level operations
    //
    void Clear() ;

    void Attach(VARIANT& varSrc) ;
    VARIANT Detach() throw();

    VARIANT& GetVARIANT() throw();
    VARIANT* GetAddress() ;

    void ChangeType(VARTYPE vartype, const _variant_t* pSrc = NULL) ;

    void SetString(const char* pSrc) ; // used to set ANSI string
};

//
// Constructors
//

// Default constructor
//
inline _variant_t::_variant_t() throw()
{
    ::VariantInit(this);
}

// Construct a _variant_t from a const VARIANT&
//
inline _variant_t::_variant_t(const VARIANT& varSrc) 
{
    ::VariantInit(this);
    _com_util::CheckError(::VariantCopy(this, const_cast<VARIANT*>(&varSrc)));
}

// Construct a _variant_t from a const VARIANT*
//
inline _variant_t::_variant_t(const VARIANT* pSrc) 
{
    if (pSrc == NULL) {
        _com_issue_error(E_POINTER);
    }
    else {
        ::VariantInit(this);
        _com_util::CheckError(::VariantCopy(this, const_cast<VARIANT*>(pSrc)));
    }
}

// Construct a _variant_t from a const _variant_t&
//
inline _variant_t::_variant_t(const _variant_t& varSrc) 
{
    ::VariantInit(this);
    _com_util::CheckError(::VariantCopy(this, const_cast<VARIANT*>(static_cast<const VARIANT*>(&varSrc))));
}

// Construct a _variant_t from a VARIANT&.  If fCopy is FALSE, give control of
// data to the _variant_t without doing a VariantCopy.
//
inline _variant_t::_variant_t(VARIANT& varSrc, bool fCopy) 
{
    if (fCopy) {
        ::VariantInit(this);
        _com_util::CheckError(::VariantCopy(this, &varSrc));
    } 
    else {
        _COM_MEMCPY_S(this, sizeof(varSrc), &varSrc, sizeof(varSrc));
        V_VT(&varSrc) = VT_EMPTY;
    }
}

// Construct either a VT_I2 VARIANT or a VT_BOOL VARIANT from
// a short (the default is VT_I2)
//
inline _variant_t::_variant_t(short sSrc, VARTYPE vtSrc) 
{
    if ((vtSrc != VT_I2) && (vtSrc != VT_BOOL)) {
        _com_issue_error(E_INVALIDARG);
        return;
    }

    if (vtSrc == VT_BOOL) {
        V_VT(this) = VT_BOOL;
        V_BOOL(this) = (sSrc ? VARIANT_TRUE : VARIANT_FALSE);
    }
    else {
        V_VT(this) = VT_I2;
        V_I2(this) = sSrc;
    }
}

// Construct either a VT_I4 VARIANT, a VT_BOOL VARIANT, or a
// VT_ERROR VARIANT from a long (the default is VT_I4)
//
inline _variant_t::_variant_t(long lSrc, VARTYPE vtSrc) 
{
    if ((vtSrc != VT_I4) && (vtSrc != VT_ERROR) && (vtSrc != VT_BOOL)) {
        _com_issue_error(E_INVALIDARG);
        return;
    }

    if (vtSrc == VT_ERROR) {
        V_VT(this) = VT_ERROR;
        V_ERROR(this) = lSrc;
    }
    else if (vtSrc == VT_BOOL) {
        V_VT(this) = VT_BOOL;
        V_BOOL(this) = (lSrc ? VARIANT_TRUE : VARIANT_FALSE);
    }
    else {
        V_VT(this) = VT_I4;
        V_I4(this) = lSrc;
    }
}

// Construct a VT_R4 VARIANT from a float
//
inline _variant_t::_variant_t(float fltSrc) throw()
{
    V_VT(this) = VT_R4;
    V_R4(this) = fltSrc;
}

// Construct either a VT_R8 VARIANT, or a VT_DATE VARIANT from
// a double (the default is VT_R8)
//
inline _variant_t::_variant_t(double dblSrc, VARTYPE vtSrc) 
{
    if ((vtSrc != VT_R8) && (vtSrc != VT_DATE)) {
        _com_issue_error(E_INVALIDARG);
        return;
    }

    if (vtSrc == VT_DATE) {
        V_VT(this) = VT_DATE;
        V_DATE(this) = dblSrc;
    }
    else {
        V_VT(this) = VT_R8;
        V_R8(this) = dblSrc;
    }
}

// Construct a VT_CY from a CY
//
inline _variant_t::_variant_t(const CY& cySrc) throw()
{
    V_VT(this) = VT_CY;
    V_CY(this) = cySrc;
}

// Construct a VT_BSTR VARIANT from a const _bstr_t&
//
inline _variant_t::_variant_t(const _bstr_t& bstrSrc) 
{
    V_VT(this) = VT_BSTR;

    BSTR bstr = static_cast<wchar_t*>(bstrSrc);
    if (bstr == NULL) {
        V_BSTR(this) = NULL;
    }
    else {
        V_BSTR(this) = ::SysAllocStringByteLen(reinterpret_cast<char*>(bstr),
                                               ::SysStringByteLen(bstr));
        if (V_BSTR(this) == NULL) {
            _com_issue_error(E_OUTOFMEMORY);
        }
    }
}

// Construct a VT_BSTR VARIANT from a const wchar_t*
//
inline _variant_t::_variant_t(const wchar_t* pSrc) 
{
    V_VT(this) = VT_BSTR;

    V_BSTR(this) = ::SysAllocString(pSrc);

    if (V_BSTR(this) == NULL && pSrc != NULL) {
            _com_issue_error(E_OUTOFMEMORY);
    }
}

// Construct a VT_BSTR VARIANT from a const char*
//
inline _variant_t::_variant_t(const char* pSrc) 
{
    V_VT(this) = VT_BSTR;
    V_BSTR(this) = _com_util::ConvertStringToBSTR(pSrc);
}

// Construct a VT_DISPATCH VARIANT from an IDispatch*
//
inline _variant_t::_variant_t(IDispatch* pSrc, bool fAddRef) throw()
{
    V_VT(this) = VT_DISPATCH;
    V_DISPATCH(this) = pSrc;

    // Need the AddRef() as VariantClear() calls Release(), unless fAddRef
    // false indicates we're taking ownership
    //
    if (fAddRef) {
        if (V_DISPATCH(this) != NULL) {
            V_DISPATCH(this)->AddRef();
        }
    }
}

// Construct a VT_BOOL VARIANT from a bool
//
inline _variant_t::_variant_t(bool boolSrc) throw()
{
    V_VT(this) = VT_BOOL;
    V_BOOL(this) = (boolSrc ? VARIANT_TRUE : VARIANT_FALSE);
}

// Construct a VT_UNKNOWN VARIANT from an IUnknown*
//
inline _variant_t::_variant_t(IUnknown* pSrc, bool fAddRef) throw()
{
    V_VT(this) = VT_UNKNOWN;
    V_UNKNOWN(this) = pSrc;

    // Need the AddRef() as VariantClear() calls Release(), unless fAddRef
    // false indicates we're taking ownership
    //
    if (fAddRef) {
        if (V_UNKNOWN(this) != NULL) {
            V_UNKNOWN(this)->AddRef();
        }
    }
}

// Construct a VT_DECIMAL VARIANT from a DECIMAL
//
inline _variant_t::_variant_t(const DECIMAL& decSrc) throw()
{
    // Order is important here! Setting V_DECIMAL wipes out the entire VARIANT
    //
    V_DECIMAL(this) = decSrc;
    V_VT(this) = VT_DECIMAL;
}

// Construct a VT_UI1 VARIANT from a BYTE (unsigned char)
//
inline _variant_t::_variant_t(BYTE bSrc) throw()
{
    V_VT(this) = VT_UI1;
    V_UI1(this) = bSrc;
}

// Construct a VT_I1 VARIANT from a char 
//
inline _variant_t::_variant_t(char cSrc) throw() 
{
    V_VT(this) = VT_I1;
    V_I1(this) = cSrc;
}

// Construct a VT_UI2 VARIANT from a unsigned short 
//
inline _variant_t::_variant_t(unsigned short usSrc) throw()
{
    V_VT(this) = VT_UI2;
    V_UI2(this) = usSrc;
}

// Construct a VT_UI4 VARIANT from a unsigned long 
//
inline _variant_t::_variant_t(unsigned long ulSrc) throw()
{
    V_VT(this) = VT_UI4;
    V_UI4(this) = ulSrc;
}

// Construct a VT_INT VARIANT from a int 
//
inline _variant_t::_variant_t(int iSrc) throw()
{
    V_VT(this) = VT_INT;
    V_INT(this) = iSrc;
}

// Construct a VT_UINT VARIANT from a unsigned int 
//
inline _variant_t::_variant_t(unsigned int uiSrc) throw()
{
    V_VT(this) = VT_UINT;
    V_UINT(this) = uiSrc;
}

#if (_WIN32_WINNT >= 0x0501)
// Construct a VT_I8 VARIANT from a __int64 
//
inline _variant_t::_variant_t(__int64 i8Src) throw()
{
    V_VT(this) = VT_I8;
    V_I8(this) = i8Src;
}

// Construct a VT_UI8 VARIANT from a unsigned __int64 
//
inline _variant_t::_variant_t(unsigned __int64 ui8Src) throw()
{
    V_VT(this) = VT_UI8;
    V_UI8(this) = ui8Src;
}
#endif

//
// Extractors
//

// Extracts a VT_I2 into a short
//
inline _variant_t::operator short() const 
{
    if (V_VT(this) == VT_I2) {
        return V_I2(this); 
    }

    _variant_t varDest;
    varDest.ChangeType(VT_I2, this);

    return V_I2(&varDest);
}

// Extracts a VT_I4 into a long
//
inline _variant_t::operator long() const 
{
    if (V_VT(this) == VT_I4) {
        return V_I4(this); 
    }

    _variant_t varDest;
    varDest.ChangeType(VT_I4, this);

    return V_I4(&varDest);
}

// Extracts a VT_R4 into a float
//
inline _variant_t::operator float() const 
{
    if (V_VT(this) == VT_R4) {
        return V_R4(this); 
    }

    _variant_t varDest;
    varDest.ChangeType(VT_R4, this);

    return V_R4(&varDest);
}

// Extracts a VT_R8 into a double
//
inline _variant_t::operator double() const 
{
    if (V_VT(this) == VT_R8) {
        return V_R8(this); 
    }

    _variant_t varDest;
    varDest.ChangeType(VT_R8, this);

    return V_R8(&varDest);
}

// Extracts a VT_CY into a CY
//
inline _variant_t::operator CY() const 
{
    if (V_VT(this) == VT_CY) {
        return V_CY(this); 
    }

    _variant_t varDest;
    varDest.ChangeType(VT_CY, this);

    return V_CY(&varDest);
}

// Extracts a VT_BSTR into a _bstr_t
//
inline _variant_t::operator _bstr_t() const 
{
    if (V_VT(this) == VT_BSTR) {
        return V_BSTR(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_BSTR, this);

    return V_BSTR(&varDest);
}

// Extracts a VT_DISPATCH into an IDispatch*
//
inline _variant_t::operator IDispatch*() const 
{
    if (V_VT(this) == VT_DISPATCH) {
        if (V_DISPATCH(this) != NULL) {
            V_DISPATCH(this)->AddRef();
        }
        return V_DISPATCH(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_DISPATCH, this);
    
    if (V_DISPATCH(&varDest) != NULL) {
        V_DISPATCH(&varDest)->AddRef();
    }

    return V_DISPATCH(&varDest);
}

// Extract a VT_BOOL into a bool
//
inline _variant_t::operator bool() const 
{
    if (V_VT(this) == VT_BOOL) {
        return V_BOOL(this) ? true : false;
    }

    _variant_t varDest;
    varDest.ChangeType(VT_BOOL, this);

    return (V_BOOL(&varDest) == VARIANT_TRUE) ? true : false;
}

// Extracts a VT_UNKNOWN into an IUnknown*
//
inline _variant_t::operator IUnknown*() const 
{
    if (V_VT(this) == VT_UNKNOWN) {
        if (V_UNKNOWN(this) != NULL) {
            V_UNKNOWN(this)->AddRef();
        }
        return V_UNKNOWN(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_UNKNOWN, this);

    if (V_UNKNOWN(&varDest) != NULL) {
        V_UNKNOWN(&varDest)->AddRef();
    }

    return V_UNKNOWN(&varDest);
}

// Extracts a VT_DECIMAL into a DECIMAL
//
inline _variant_t::operator DECIMAL() const 
{
    if (V_VT(this) == VT_DECIMAL) {
        return V_DECIMAL(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_DECIMAL, this);

    return V_DECIMAL(&varDest);
}

// Extracts a VT_UI1 into a BYTE (unsigned char)
//
inline _variant_t::operator BYTE() const 
{
    if (V_VT(this) == VT_UI1) {
        return V_UI1(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_UI1, this);

    return V_UI1(&varDest);
}

// Extract the physical VARIANT
//
inline _variant_t::operator VARIANT() const throw()
{
    return *(VARIANT*) this;
}

// Extracts a VT_I1 into a char
//
inline _variant_t::operator char() const  
{
    if (V_VT(this) == VT_I1) {
        return V_I1(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_I1, this);

    return V_I1(&varDest);
}

// Extracts a VT_UI2 into a unsigned short
//
inline _variant_t::operator unsigned short() const  
{
    if (V_VT(this) == VT_UI2) {
        return V_UI2(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_UI2, this);

    return V_UI2(&varDest);
}

// Extracts a VT_UI4 into a unsigned long
//
inline _variant_t::operator unsigned long() const  
{
    if (V_VT(this) == VT_UI4) {
        return V_UI4(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_UI4, this);

    return V_UI4(&varDest);
}

// Extracts a VT_INT into a int
//
inline _variant_t::operator int() const  
{
    if (V_VT(this) == VT_INT) {
        return V_INT(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_INT, this);

    return V_INT(&varDest);
}

// Extracts a VT_UINT into a unsigned int
//
inline _variant_t::operator unsigned int() const  
{
    if (V_VT(this) == VT_UINT) {
        return V_UINT(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_UINT, this);

    return V_UINT(&varDest);
}

#if (_WIN32_WINNT >= 0x0501)
// Extracts a VT_I8 into a __int64
//
inline _variant_t::operator __int64() const  
{
    if (V_VT(this) == VT_I8) {
        return V_I8(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_I8, this);

    return V_I8(&varDest);
}

// Extracts a VT_UI8 into a unsigned __int64
//
inline _variant_t::operator unsigned __int64() const  
{
    if (V_VT(this) == VT_UI8) {
        return V_UI8(this);
    }

    _variant_t varDest;
    varDest.ChangeType(VT_UI8, this);

    return V_UI8(&varDest);
}
#endif

//
// Assignment operations
//

// Assign a const VARIANT& (::VariantCopy handles everything)
//
inline _variant_t& _variant_t::operator=(const VARIANT& varSrc) 
{
    _com_util::CheckError(::VariantCopy(this, const_cast<VARIANT*>(&varSrc)));

    return *this;
}

// Assign a const VARIANT* (::VariantCopy handles everything)
//
inline _variant_t& _variant_t::operator=(const VARIANT* pSrc) 
{
    if (pSrc == NULL) {
        _com_issue_error(E_POINTER);
    }
    else {
        _com_util::CheckError(::VariantCopy(this, const_cast<VARIANT*>(pSrc)));
    }

    return *this;
}

// Assign a const _variant_t& (::VariantCopy handles everything)
//
inline _variant_t& _variant_t::operator=(const _variant_t& varSrc) 
{
    _com_util::CheckError(::VariantCopy(this, const_cast<VARIANT*>(static_cast<const VARIANT*>(&varSrc))));

    return *this;
}

// Assign a short creating either VT_I2 VARIANT or a 
// VT_BOOL VARIANT (VT_I2 is the default)
//
inline _variant_t& _variant_t::operator=(short sSrc) 
{
    if (V_VT(this) == VT_I2) {
        V_I2(this) = sSrc;
    }
    else if (V_VT(this) == VT_BOOL) {
        V_BOOL(this) = (sSrc ? VARIANT_TRUE : VARIANT_FALSE);
    }
    else {
        // Clear the VARIANT and create a VT_I2
        //
        Clear();

        V_VT(this) = VT_I2;
        V_I2(this) = sSrc;
    }

    return *this;
}

// Assign a long creating either VT_I4 VARIANT, a VT_ERROR VARIANT
// or a VT_BOOL VARIANT (VT_I4 is the default)
//
inline _variant_t& _variant_t::operator=(long lSrc) 
{
    if (V_VT(this) == VT_I4) {
        V_I4(this) = lSrc;
    }
    else if (V_VT(this) == VT_ERROR) {
        V_ERROR(this) = lSrc;
    }
    else if (V_VT(this) == VT_BOOL) {
        V_BOOL(this) = (lSrc ? VARIANT_TRUE : VARIANT_FALSE);
    }
    else {
        // Clear the VARIANT and create a VT_I4
        //
        Clear();

        V_VT(this) = VT_I4;
        V_I4(this) = lSrc;
    }

    return *this;
}

// Assign a float creating a VT_R4 VARIANT 
//
inline _variant_t& _variant_t::operator=(float fltSrc) 
{
    if (V_VT(this) != VT_R4) {
        // Clear the VARIANT and create a VT_R4
        //
        Clear();

        V_VT(this) = VT_R4;
    }

    V_R4(this) = fltSrc;

    return *this;
}

// Assign a double creating either a VT_R8 VARIANT, or a VT_DATE
// VARIANT (VT_R8 is the default)
//
inline _variant_t& _variant_t::operator=(double dblSrc) 
{
    if (V_VT(this) == VT_R8) {
        V_R8(this) = dblSrc;
    }
    else if(V_VT(this) == VT_DATE) {
        V_DATE(this) = dblSrc;
    }
    else {
        // Clear the VARIANT and create a VT_R8
        //
        Clear();

        V_VT(this) = VT_R8;
        V_R8(this) = dblSrc;
    }

    return *this;
}

// Assign a CY creating a VT_CY VARIANT 
//
inline _variant_t& _variant_t::operator=(const CY& cySrc) 
{
    if (V_VT(this) != VT_CY) {
        // Clear the VARIANT and create a VT_CY
        //
        Clear();

        V_VT(this) = VT_CY;
    }

    V_CY(this) = cySrc;

    return *this;
}

// Assign a const _bstr_t& creating a VT_BSTR VARIANT
//
inline _variant_t& _variant_t::operator=(const _bstr_t& bstrSrc) 
{
    _COM_ASSERT(V_VT(this) != VT_BSTR || (BSTR) bstrSrc == NULL || V_BSTR(this) != (BSTR) bstrSrc);

    // Clear the VARIANT (This will SysFreeString() any previous occupant)
    //
    Clear();

    V_VT(this) = VT_BSTR;

    if (!bstrSrc) {
        V_BSTR(this) = NULL;
    }
    else {
        BSTR bstr = static_cast<wchar_t*>(bstrSrc);
        V_BSTR(this) = ::SysAllocStringByteLen(reinterpret_cast<char*>(bstr),
                                               ::SysStringByteLen(bstr));

        if (V_BSTR(this) == NULL) {
            _com_issue_error(E_OUTOFMEMORY);
        }
    }

    return *this;
}

// Assign a const wchar_t* creating a VT_BSTR VARIANT
//
inline _variant_t& _variant_t::operator=(const wchar_t* pSrc) 
{
    _COM_ASSERT(V_VT(this) != VT_BSTR || pSrc == NULL || V_BSTR(this) != pSrc);

    // Clear the VARIANT (This will SysFreeString() any previous occupant)
    //
    Clear();

    V_VT(this) = VT_BSTR;

    if (pSrc == NULL) {
        V_BSTR(this) = NULL;
    }
    else {
        V_BSTR(this) = ::SysAllocString(pSrc);

        if (V_BSTR(this) == NULL) {
            _com_issue_error(E_OUTOFMEMORY);
        }
    }

    return *this;
}

// Assign a const char* creating a VT_BSTR VARIANT
//
inline _variant_t& _variant_t::operator=(const char* pSrc) 
{
    _COM_ASSERT(V_VT(this) != (VT_I1 | VT_BYREF) || pSrc == NULL || V_I1REF(this) != pSrc);

    // Clear the VARIANT (This will SysFreeString() any previous occupant)
    //
    Clear();

    V_VT(this) = VT_BSTR;
    V_BSTR(this) = _com_util::ConvertStringToBSTR(pSrc);

    return *this;
}

// Assign an IDispatch* creating a VT_DISPATCH VARIANT 
//
inline _variant_t& _variant_t::operator=(IDispatch* pSrc) 
{
    _COM_ASSERT(V_VT(this) != VT_DISPATCH || pSrc == 0 || V_DISPATCH(this) != pSrc);

    // Clear the VARIANT (This will Release() any previous occupant)
    //
    Clear();

    V_VT(this) = VT_DISPATCH;
    V_DISPATCH(this) = pSrc;

    if (V_DISPATCH(this) != NULL) {
        // Need the AddRef() as VariantClear() calls Release()
        //
        V_DISPATCH(this)->AddRef();
    }

    return *this;
}

// Assign a bool creating a VT_BOOL VARIANT 
//
inline _variant_t& _variant_t::operator=(bool boolSrc) 
{
    if (V_VT(this) != VT_BOOL) {
        // Clear the VARIANT and create a VT_BOOL
        //
        Clear();

        V_VT(this) = VT_BOOL;
    }

    V_BOOL(this) = (boolSrc ? VARIANT_TRUE : VARIANT_FALSE);

    return *this;
}

// Assign an IUnknown* creating a VT_UNKNOWN VARIANT 
//
inline _variant_t& _variant_t::operator=(IUnknown* pSrc) 
{
    _COM_ASSERT(V_VT(this) != VT_UNKNOWN || pSrc == NULL || V_UNKNOWN(this) != pSrc);

    // Clear VARIANT (This will Release() any previous occupant)
    //
    Clear();

    V_VT(this) = VT_UNKNOWN;
    V_UNKNOWN(this) = pSrc;

    if (V_UNKNOWN(this) != NULL) {
        // Need the AddRef() as VariantClear() calls Release()
        //
        V_UNKNOWN(this)->AddRef();
    }

    return *this;
}

// Assign a DECIMAL creating a VT_DECIMAL VARIANT
//
inline _variant_t& _variant_t::operator=(const DECIMAL& decSrc) 
{
    if (V_VT(this) != VT_DECIMAL) {
        // Clear the VARIANT
        //
        Clear();
    }

    // Order is important here! Setting V_DECIMAL wipes out the entire VARIANT
    V_DECIMAL(this) = decSrc;
    V_VT(this) = VT_DECIMAL;

    return *this;
}

// Assign a BTYE (unsigned char) creating a VT_UI1 VARIANT
//
inline _variant_t& _variant_t::operator=(BYTE bSrc) 
{
    if (V_VT(this) != VT_UI1) {
        // Clear the VARIANT and create a VT_UI1
        //
        Clear();

        V_VT(this) = VT_UI1;
    }

    V_UI1(this) = bSrc;

    return *this;
}

// Assign a char creating a VT_I1 VARIANT
//
inline _variant_t& _variant_t::operator=(char cSrc) 
{
    if (V_VT(this) != VT_I1) {
        // Clear the VARIANT and create a VT_I1
        //
        Clear();

        V_VT(this) = VT_I1;
    }

    V_I1(this) = cSrc;

    return *this;
}

// Assign a char creating a VT_UI2 VARIANT
//
inline _variant_t& _variant_t::operator=(unsigned short usSrc) 
{
    if (V_VT(this) != VT_UI2) {
        // Clear the VARIANT and create a VT_UI2
        //
        Clear();

        V_VT(this) = VT_UI2;
    }

    V_UI2(this) = usSrc;

    return *this;
}

// Assign a char creating a VT_UI4 VARIANT
//
inline _variant_t& _variant_t::operator=(unsigned long ulSrc) 
{
    if (V_VT(this) != VT_UI4) {
        // Clear the VARIANT and create a VT_UI4
        //
        Clear();

        V_VT(this) = VT_UI4;
    }

    V_UI4(this) = ulSrc;

    return *this;
}

// Assign a char creating a VT_INT VARIANT
//
inline _variant_t& _variant_t::operator=(int iSrc) 
{
    if (V_VT(this) != VT_INT) {
        // Clear the VARIANT and create a VT_INT
        //
        Clear();

        V_VT(this) = VT_INT;
    }

    V_INT(this) = iSrc;

    return *this;
}

// Assign a char creating a VT_UINT VARIANT
//
inline _variant_t& _variant_t::operator=(unsigned int uiSrc) 
{
    if (V_VT(this) != VT_UINT) {
        // Clear the VARIANT and create a VT_UINT
        //
        Clear();

        V_VT(this) = VT_UINT;
    }

    V_UINT(this) = uiSrc;

    return *this;
}

#if (_WIN32_WINNT >= 0x0501)
// Assign a char creating a VT_I8 VARIANT
//
inline _variant_t& _variant_t::operator=(__int64 i8Src) 
{
    if (V_VT(this) != VT_I8) {
        // Clear the VARIANT and create a VT_I8
        //
        Clear();

        V_VT(this) = VT_I8;
    }

    V_I8(this) = i8Src;

    return *this;
}

// Assign a char creating a VT_UI8 VARIANT
//
inline _variant_t& _variant_t::operator=(unsigned __int64 ui8Src) 
{
    if (V_VT(this) != VT_UI8) {
        // Clear the VARIANT and create a VT_UI8
        //
        Clear();

        V_VT(this) = VT_UI8;
    }

    V_UI8(this) = ui8Src;

    return *this;
}
#endif

//
// Comparison operations
//

// Compare a _variant_t against a const VARIANT& for equality
//
inline bool _variant_t::operator==(const VARIANT& varSrc) const throw()
{
    return *this == &varSrc;
}

#pragma warning(push)
#pragma warning(disable: 4702) // unreachable code

// Compare a _variant_t against a const VARIANT* for equality
//
inline bool _variant_t::operator==(const VARIANT* pSrc) const throw()
{
    if (pSrc == NULL) {
        return false;
    }

    if (this == pSrc) {
        return true;
    }

    //
    // Variants not equal if types don't match
    //
    if (V_VT(this) != V_VT(pSrc)) {
        return false;
    }

    //
    // Check type specific values
    //
    switch (V_VT(this)) {
        case VT_EMPTY:
        case VT_NULL:
            return true;

        case VT_I2:
            return V_I2(this) == V_I2(pSrc);

        case VT_I4:
            return V_I4(this) == V_I4(pSrc);

        case VT_R4:
            return V_R4(this) == V_R4(pSrc);

        case VT_R8:
            return V_R8(this) == V_R8(pSrc);

        case VT_CY:
            return memcmp(&(V_CY(this)), &(V_CY(pSrc)), sizeof(CY)) == 0;

        case VT_DATE:
            return V_DATE(this) == V_DATE(pSrc);

        case VT_BSTR:
            return (::SysStringByteLen(V_BSTR(this)) == ::SysStringByteLen(V_BSTR(pSrc))) &&
                    (memcmp(V_BSTR(this), V_BSTR(pSrc), ::SysStringByteLen(V_BSTR(this))) == 0);

        case VT_DISPATCH:
            return V_DISPATCH(this) == V_DISPATCH(pSrc);

        case VT_ERROR:
            return V_ERROR(this) == V_ERROR(pSrc);

        case VT_BOOL:
            return V_BOOL(this) == V_BOOL(pSrc);

        case VT_UNKNOWN:
            return V_UNKNOWN(this) == V_UNKNOWN(pSrc);

        case VT_DECIMAL:
            return memcmp(&(V_DECIMAL(this)), &(V_DECIMAL(pSrc)), sizeof(DECIMAL)) == 0;

        case VT_UI1:
            return V_UI1(this) == V_UI1(pSrc);

        case VT_I1:
            return V_I1(this) == V_I1(pSrc);

        case VT_UI2:
            return V_UI2(this) == V_UI2(pSrc);

        case VT_UI4:
            return V_UI4(this) == V_UI4(pSrc);

        case VT_INT:
            return V_INT(this) == V_INT(pSrc);

        case VT_UINT:
            return V_UINT(this) == V_UINT(pSrc);

#if (_WIN32_WINNT >= 0x0501)
        case VT_I8:
            return V_I8(this) == V_I8(pSrc);

        case VT_UI8:
            return V_UI8(this) == V_UI8(pSrc);
#endif

        default:
            _com_issue_error(E_INVALIDARG);
            // fall through
    }

    return false;
}

#pragma warning(pop)

// Compare a _variant_t against a const VARIANT& for in-equality
//
inline bool _variant_t::operator!=(const VARIANT& varSrc) const throw()
{
    return !(*this == &varSrc);
}

// Compare a _variant_t against a const VARIANT* for in-equality
//
inline bool _variant_t::operator!=(const VARIANT* pSrc) const throw()
{
    return !(*this == pSrc);
}

//
// Low-level operations
//

// Clear the _variant_t
//
inline void _variant_t::Clear() 
{
    _com_util::CheckError(::VariantClear(this));
}

inline void _variant_t::Attach(VARIANT& varSrc) 
{
    //
    // Free up previous VARIANT
    //
    Clear();

    //
    // Give control of data to _variant_t
    //
    _COM_MEMCPY_S(this, sizeof(varSrc), &varSrc, sizeof(varSrc));
    V_VT(&varSrc) = VT_EMPTY;
}

inline VARIANT _variant_t::Detach() throw()
{
    VARIANT varResult = *this;
    V_VT(this) = VT_EMPTY;

    return varResult;
}

inline VARIANT& _variant_t::GetVARIANT() throw() 
{
    return *(VARIANT*) this;
}

inline VARIANT* _variant_t::GetAddress() 
{
    Clear();
    return (VARIANT*) this;
}

// Change the type and contents of this _variant_t to the type vartype and
// contents of pSrc
//
inline void _variant_t::ChangeType(VARTYPE vartype, const _variant_t* pSrc) 
{
    //
    // If pDest is NULL, convert type in place
    //
    if (pSrc == NULL) {
        pSrc = this;
    }

    if ((this != pSrc) || (vartype != V_VT(this))) {
        _com_util::CheckError(::VariantChangeType(static_cast<VARIANT*>(this),
                                                  const_cast<VARIANT*>(static_cast<const VARIANT*>(pSrc)),
                                                  0, vartype));
    }
}

inline void _variant_t::SetString(const char* pSrc) 
{
    operator=(pSrc);
}

//
// Destructor
//

inline _variant_t::~_variant_t() throw()
{
    ::VariantClear(this);
}

//
// Mutually-dependent definitions
//

// Construct a _bstr_t from a const _variant_t&
//
inline _bstr_t::_bstr_t(const _variant_t &var) 
    : m_Data(NULL)
{
    if (V_VT(&var) == VT_BSTR) {
        *this = V_BSTR(&var);
        return;
    }

    _variant_t varDest;
    varDest.ChangeType(VT_BSTR, &var);

    *this = V_BSTR(&varDest);
}

// Assign a const _variant_t& to a _bstr_t
//
inline _bstr_t& _bstr_t::operator=(const _variant_t &var) 
{
    if (V_VT(&var) == VT_BSTR) {
        *this = V_BSTR(&var);
        return *this;
    }

    _variant_t varDest;
    varDest.ChangeType(VT_BSTR, &var);

    *this = V_BSTR(&varDest);

    return *this;
}

extern _variant_t vtMissing;

#ifndef _USE_RAW
#define bstr_t _bstr_t
#define variant_t _variant_t
#endif

#pragma pop_macro("new")

#pragma warning(pop)

#endif  // _INC_COMUTIL