Registry.h

// sktoolslib - common files for SK tools

// Copyright (C) 2012, 2017-2018, 2020-2021 - Stefan Kueng

// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.

// This program 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 General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software Foundation,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
#pragma once
#include <string>
#include <memory>
#include "shlwapi.h"
#include "FormatMessageWrapper.h"

#ifndef ASSERT
#    define ASSERT(x)
#endif

/**
 * \ingroup Utils
 * Base class for the registry classes.
 *
 * \par requirements
 * - winXP or later
 * - import library Shlwapi.lib
 */

template <class S>
class CRegBaseCommon
{
protected:
    /**
     * String type specific operations.
     */

    virtual LPCWSTR GetPlainString(const S& s) const = 0;
    virtual DWORD   GetLength(const S& s) const      = 0;

public:
    //methods
    /** Default constructor.
     */
    CRegBaseCommon();
    /**
     * Constructor.
     * \param key the path to the key, including the key. example: "Software\\Company\\SubKey\\MyValue"
     * \param force set to TRUE if no cache should be used, i.e. always read and write directly from/to registry
     * \param base a predefined base key like HKEY_LOCAL_MACHINE. see the SDK documentation for more information.
     */
    CRegBaseCommon(const S& key, bool force, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);
    virtual ~CRegBaseCommon() = default;

    /**
     * Removes the whole registry key including all values. So if you set the registry
     * entry to be HKCU\Software\Company\Product\key\value there will only be
     * HKCU\Software\Company\Product key in the registry.
     * \return ERROR_SUCCESS or an nonzero error code. Use FormatMessage() to get an error description.
     */
    DWORD removeKey();
    /**
     * Removes the value of the registry object. If you set the registry entry to
     * be HKCU\Software\Company\Product\key\value there will only be
     * HKCU\Software\Company\Product\key\ in the registry.
     * \return ERROR_SUCCESS or an nonzero error code. Use FormatMessage() to get an error description.
     */
    LONG removeValue();

    /**
     * Returns the string of the last error occurred.
     */
    virtual S getErrorString()
    {
        CFormatMessageWrapper errorMessage(m_lastError);
        S                     result(static_cast<LPCWSTR>(errorMessage));
        return result;
    }

    /// get failure info for last operation

    LONG GetLastError() const
    {
        return m_lastError;
    }

    /// used in subclass templates to specify the correct string type

    typedef S StringT;

protected:
    //members
    HKEY   m_base;      ///< handle to the registry base
    S      m_key;       ///< the name of the value
    S      m_path;      ///< the path to the key
    LONG   m_lastError; ///< the value of the last error occurred
    REGSAM m_sam;       ///< the security attributes to pass to the registry command

    bool m_read;   ///< indicates if the value has already been attempted read from the registry
    bool m_force;  ///< indicates if no cache should be used, i.e. always read and write directly from registry
    bool m_exists; ///< true, if the registry value actually exists
};

// implement CRegBaseCommon<> members

template <class S>
CRegBaseCommon<S>::CRegBaseCommon()
    : m_base(HKEY_CURRENT_USER)
    , m_key()
    , m_path()
    , m_lastError(ERROR_SUCCESS)
    , m_sam(0)
    , m_read(false)
    , m_force(false)
    , m_exists(false)
{
}

template <class S>
CRegBaseCommon<S>::CRegBaseCommon(const S& key, bool force, HKEY base, REGSAM sam)
    : m_base(base)
    , m_key(key)
    , m_path()
    , m_lastError(ERROR_SUCCESS)
    , m_sam(sam)
    , m_read(false)
    , m_force(force)
    , m_exists(false)
{
}

template <class S>
DWORD CRegBaseCommon<S>::removeKey()
{
    m_exists = false;
    m_read   = true;

    HKEY hKey = nullptr;
    RegOpenKeyEx(m_base, GetPlainString(m_path), 0, KEY_WRITE | m_sam, &hKey);
    auto ret = SHDeleteKey(m_base, GetPlainString(m_path));
    RegCloseKey(hKey);
    return ret;
}

template <class S>
LONG CRegBaseCommon<S>::removeValue()
{
    m_exists = false;
    m_read   = true;

    HKEY hKey = nullptr;
    RegOpenKeyEx(m_base, GetPlainString(m_path), 0, KEY_WRITE | m_sam, &hKey);
    auto ret = RegDeleteValue(hKey, GetPlainString(m_key));
    RegCloseKey(hKey);
    return ret;
}

/**
 * \ingroup Utils
 * Base class for MFC type registry classes.
 */

#ifdef __CSTRINGT_H__
class CRegBase : public CRegBaseCommon<CString>
{
protected:
    /**
     * String type specific operations.
     */

    virtual LPCWSTR GetPlainString(const CString& s) const { return (LPCWSTR)s; }
    virtual DWORD   GetLength(const CString& s) const { return s.GetLength(); }

public: //methods
    /** Default constructor.
     */
    CRegBase();
    /**
     * Constructor.
     * \param key the path to the key, including the key. example: "Software\\Company\\SubKey\\MyValue"
     * \param force set to TRUE if no cache should be used, i.e. always read and write directly from/to registry
     * \param base a predefined base key like HKEY_LOCAL_MACHINE. see the SDK documentation for more information.
     */
    CRegBase(const CString& key, bool force, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);

    /**
     * Returns the string of the last error occurred.
     */
    CString getErrorString()
    {
        CString error = CRegBaseCommon<CString>::getErrorString();
#    if defined IDS_REG_ERROR
        CString sTemp;
        sTemp.FormatMessage(IDS_REG_ERROR, (LPCWSTR)m_key, (LPCWSTR)error);
        return sTemp;
#    else
        return error;
#    endif
    };
};
#endif

/**
 * \ingroup Utils
 * Base class for STL string type registry classes.
 */

class CRegStdBase : public CRegBaseCommon<std::wstring>
{
protected:
    /**
     * String type specific operations.
     */

    LPCWSTR GetPlainString(const std::wstring& s) const override { return s.c_str(); }
    DWORD   GetLength(const std::wstring& s) const override { return static_cast<DWORD>(s.size()); }

public: //methods
    /** Default constructor.
     */
    CRegStdBase();
    /**
     * Constructor.
     * \param key the path to the key, including the key. example: "Software\\Company\\SubKey\\MyValue"
     * \param force set to TRUE if no cache should be used, i.e. always read and write directly from/to registry
     * \param base a predefined base key like HKEY_LOCAL_MACHINE. see the SDK documentation for more information.
     */
    CRegStdBase(const std::wstring& key, bool force, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);
};

/**
 * \ingroup Utils
 * DWORD value in registry. with this class you can use DWORD values in registry
 * like normal DWORD variables in your program.
 * Usage:
 * in your header file, declare your registry DWORD variable:
 * \code
 * CRegDWORD regvalue;
 * \endcode
 * next initialize the variable e.g. in the constructor of your class:
 * \code
 * regvalue = CRegDWORD("Software\\Company\\SubKey\\MyValue", 100);
 * \endcode
 * this will set the registry value "MyValue" under HKEY_CURRENT_USER with path
 * "Software\Company\SubKey" to the variable. If the key does not yet exist or
 * an error occurred during read from the registry, a default
 * value of 100 is used when accessing the variable.
 * now the variable can be used like any other DWORD variable:
 * \code
 * regvalue = 200;                      //stores the value 200 in the registry
 * int temp = regvalue + 300;           //temp has value 500 now
 * regvalue += 300;                     //now the registry has the value 500 too
 * \endcode
 * to avoid too much access to the registry the value is cached inside the object.
 * once the value is read, no more read accesses to the registry will be made.
 * this means the variable will contain a wrong value if the corresponding registry
 * entry is changed by anything else than this variable! If you think that could happen
 * then use
 * \code
 * regvalue.read();
 * \endcode
 * to force a refresh of the variable with the registry.
 * a write to the registry is only made if the new value assigned with the variable
 * is different than the last assigned value.
 * to force a write use the method write();
 * another option to force reads and writes to the registry is to specify TRUE as the
 * third parameter in the constructor.
 */
template <class T, class Base>
class CRegTypedBase : public Base
{
private:
    T m_value;        ///< the cached value of the registry
    T m_defaultValue; ///< the default value to use

    /**
     * time stamp of the last registry lookup, i.e \ref read() call
     */

    ULONGLONG lastRead;

    /**
     * \ref read() will be called, if \ref lastRead differs from the
     * current time stamp by more than this.
     * (DWORD)(-1) -> no automatic refresh.
     */

    ULONGLONG lookupInterval;

    /**
     * Check time stamps etc.
     * If the current data is out-dated, reset the \ref m_read flag.
     */

    void HandleAutoRefresh();

    /**
     * sub-classes must provide type-specific code to extract data from
     * and write data to an open registry key.
     */

    virtual void InternalRead(HKEY hKey, T& value)        = 0;
    virtual void InternalWrite(HKEY hKey, const T& value) = 0;

public:
    /**
     * Make the value type accessible to others.
     */

    typedef T ValueT;

    /**
     * Constructor.
     * We use this instead of a default constructor because not all
     * data types may provide an adequate default constructor.
     */
    CRegTypedBase(const T& def);

    /**
     * Constructor.
     * \param key the path to the key, including the key. example: "Software\\Company\\SubKey\\MyValue"
     * \param def the default value used when the key does not exist or a read error occurred
     * \param force set to TRUE if no cache should be used, i.e. always read and write directly from/to registry
     * \param base a predefined base key like HKEY_LOCAL_MACHINE. see the SDK documentation for more information.
     */
    CRegTypedBase(const typename Base::StringT& key, const T& def, bool force = FALSE, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);

    /**
     * Constructor.
     * \param updateInterval time in msec between registry lookups caused by operator const T&
     * \param key the path to the key, including the key. example: "Software\\Company\\SubKey\\MyValue"
     * \param def the default value used when the key does not exist or a read error occurred
     * \param force set to TRUE if no cache should be used, i.e. always read and write directly from/to registry
     * \param base a predefined base key like HKEY_LOCAL_MACHINE. see the SDK documentation for more information.
     */
    CRegTypedBase(DWORD updateInterval, const typename Base::StringT& key, const T& def, bool force = FALSE, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);

    /**
     * reads the assigned value from the registry. Use this method only if you think the registry
     * value could have been altered without using the CRegDWORD object.
     * \return the read value
     */
    void read();  ///< reads the value from the registry
    void write(); ///< writes the value to the registry

    bool     exists();             ///< test whether registry entry exits
    const T& defaultValue() const; ///< return the default passed to the constructor

    /**
     * Data access.
     */

                                    operator const T&();
    virtual CRegTypedBase<T, Base>& operator=(const T& rhs);
};

// implement CRegTypedBase<> members

template <class T, class Base>
void CRegTypedBase<T, Base>::HandleAutoRefresh()
{
    if (Base::m_read && (lookupInterval != static_cast<ULONGLONG>(-1)))
    {
        auto currentTime = GetTickCount64();
        if ((currentTime < lastRead) || (currentTime > lastRead + lookupInterval))
        {
            Base::m_read = false;
        }
    }
}

template <class T, class Base>
CRegTypedBase<T, Base>::CRegTypedBase(const T& def)
    : m_value(def)
    , m_defaultValue(def)
    , lastRead(0)
    , lookupInterval(static_cast<ULONGLONG>(-1))
{
}

template <class T, class Base>
CRegTypedBase<T, Base>::CRegTypedBase(const typename Base::StringT& key, const T& def, bool force, HKEY base, REGSAM sam)
    : Base(key, force, base, sam)
    , m_value(def)
    , m_defaultValue(def)
    , lastRead(0)
    , lookupInterval(static_cast<DWORD>(-1))
{
}

template <class T, class Base>
CRegTypedBase<T, Base>::CRegTypedBase(DWORD updateInterval, const typename Base::StringT& key, const T& def, bool force, HKEY base, REGSAM sam)
    : Base(key, force, base, sam)
    , m_value(def)
    , m_defaultValue(def)
    , lastRead(0)
    , lookupInterval(updateInterval)
{
}

template <class T, class Base>
void CRegTypedBase<T, Base>::read()
{
    m_value        = m_defaultValue;
    Base::m_exists = false;

    HKEY hKey = nullptr;
    if ((Base::m_lastError = RegOpenKeyEx(Base::m_base, Base::GetPlainString(Base::m_path), 0, STANDARD_RIGHTS_READ | KEY_QUERY_VALUE | Base::m_sam, &hKey)) == ERROR_SUCCESS)
    {
        T value = m_defaultValue;
        InternalRead(hKey, value);

        if (Base::m_lastError == ERROR_SUCCESS)
        {
            Base::m_exists = true;
            m_value        = value;
        }

        Base::m_lastError = RegCloseKey(hKey);
    }

    Base::m_read = true;
    lastRead     = GetTickCount64();
}

template <class T, class Base>
void CRegTypedBase<T, Base>::write()
{
    HKEY hKey = nullptr;

    DWORD disp = 0;
    if ((Base::m_lastError = RegCreateKeyEx(Base::m_base, Base::GetPlainString(Base::m_path), 0, nullptr, REG_OPTION_NON_VOLATILE, KEY_WRITE | Base::m_sam, nullptr, &hKey, &disp)) != ERROR_SUCCESS)
    {
        return;
    }

    InternalWrite(hKey, m_value);
    if (Base::m_lastError == ERROR_SUCCESS)
    {
        Base::m_read   = true;
        Base::m_exists = true;
    }
    Base::m_lastError = RegCloseKey(hKey);

    lastRead = GetTickCount64();
}

template <class T, class Base>
bool CRegTypedBase<T, Base>::exists()
{
    if (!Base::m_read && (Base::m_lastError == ERROR_SUCCESS))
        read();

    return Base::m_exists;
}

template <class T, class Base>
const T& CRegTypedBase<T, Base>::defaultValue() const
{
    return m_defaultValue;
}

template <class T, class Base>
CRegTypedBase<T, Base>::operator const T&()
{
    HandleAutoRefresh();
    if ((Base::m_read) && (!Base::m_force))
    {
        Base::m_lastError = ERROR_SUCCESS;
    }
    else
    {
        read();
    }

    return m_value;
}

template <class T, class Base>
CRegTypedBase<T, Base>& CRegTypedBase<T, Base>::operator=(const T& d)
{
    if (Base::m_read && (d == m_value) && !Base::m_force)
    {
        //no write to the registry required, its the same value
        Base::m_lastError = ERROR_SUCCESS;
        return *this;
    }
    m_value = d;
    write();
    return *this;
}

/**
 * \ingroup Utils
 * DWORD value in registry. with this class you can use DWORD values in registry
 * like normal DWORD variables in your program.
 * Usage:
 * in your header file, declare your registry DWORD variable:
 * \code
 * CRegDWORD regvalue;
 * \endcode
 * next initialize the variable e.g. in the constructor of your class:
 * \code
 * regvalue = CRegDWORD("Software\\Company\\SubKey\\MyValue", 100);
 * \endcode
 * this will set the registry value "MyValue" under HKEY_CURRENT_USER with path
 * "Software\Company\SubKey" to the variable. If the key does not yet exist or
 * an error occurred during read from the registry, a default
 * value of 100 is used when accessing the variable.
 * now the variable can be used like any other DWORD variable:
 * \code
 * regvalue = 200;                      //stores the value 200 in the registry
 * int temp = regvalue + 300;           //temp has value 500 now
 * regvalue += 300;                     //now the registry has the value 500 too
 * \endcode
 * to avoid too much access to the registry the value is cached inside the object.
 * once the value is read, no more read accesses to the registry will be made.
 * this means the variable will contain a wrong value if the corresponding registry
 * entry is changed by anything else than this variable! If you think that could happen
 * then use
 * \code
 * regvalue.read();
 * \endcode
 * to force a refresh of the variable with the registry.
 * a write to the registry is only made if the new value assigned with the variable
 * is different than the last assigned value.
 * to force a write use the method write();
 * another option to force reads and writes to the registry is to specify TRUE as the
 * third parameter in the constructor.
 */
template <class Base>
class CRegDWORDCommon : public CRegTypedBase<DWORD, Base>
{
private:
    /**
     * provide type-specific code to extract data from and write data to an open registry key.
     */

    void InternalRead(HKEY hKey, DWORD& value) override;
    void InternalWrite(HKEY hKey, const DWORD& value) override;

public:
    CRegDWORDCommon();
    /**
     * Constructor.
     * \param key the path to the key, including the key. example: "Software\\Company\\SubKey\\MyValue"
     * \param def the default value used when the key does not exist or a read error occurred
     * \param force set to TRUE if no cache should be used, i.e. always read and write directly from/to registry
     * \param base a predefined base key like HKEY_LOCAL_MACHINE. see the SDK documentation for more information.
     */
    CRegDWORDCommon(const typename Base::StringT& key, DWORD def = 0, bool force = false, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);
    CRegDWORDCommon(DWORD lookupInterval, const typename Base::StringT& key, DWORD def = 0, bool force = false, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);

    CRegDWORDCommon& operator=(DWORD rhs)
    {
        CRegTypedBase<DWORD, Base>::operator=(rhs);
        return *this;
    }
    CRegDWORDCommon& operator+=(DWORD d) { return *this = *this + d; }
    CRegDWORDCommon& operator-=(DWORD d) { return *this = *this - d; }
    CRegDWORDCommon& operator*=(DWORD d) { return *this = *this * d; }
    CRegDWORDCommon& operator/=(DWORD d) { return *this = *this / d; }
    CRegDWORDCommon& operator%=(DWORD d) { return *this = *this % d; }
    CRegDWORDCommon& operator<<=(DWORD d) { return *this = *this << d; }
    CRegDWORDCommon& operator>>=(DWORD d) { return *this = *this >> d; }
    CRegDWORDCommon& operator&=(DWORD d) { return *this = *this & d; }
    CRegDWORDCommon& operator|=(DWORD d) { return *this = *this | d; }
    CRegDWORDCommon& operator^=(DWORD d) { return *this = *this ^ d; }
};

// implement CRegDWORDCommon<> methods

template <class Base>
CRegDWORDCommon<Base>::CRegDWORDCommon()
    : CRegTypedBase<DWORD, Base>(0)
{
}

template <class Base>
CRegDWORDCommon<Base>::CRegDWORDCommon(const typename Base::StringT& key, DWORD def, bool force, HKEY base, REGSAM sam)
    : CRegTypedBase<DWORD, Base>(key, def, force, base, sam)
{
}

template <class Base>
CRegDWORDCommon<Base>::CRegDWORDCommon(DWORD lookupInterval, const typename Base::StringT& key, DWORD def, bool force, HKEY base, REGSAM sam)
    : CRegTypedBase<DWORD, Base>(lookupInterval, key, def, force, base, sam)
{
}

template <class Base>
void CRegDWORDCommon<Base>::InternalRead(HKEY hKey, DWORD& value)
{
    DWORD size = sizeof(value);
    DWORD type = 0;
    if ((Base::m_lastError = RegQueryValueEx(hKey, Base::GetPlainString(Base::m_key), nullptr, &type, reinterpret_cast<BYTE*>(&value), &size)) == ERROR_SUCCESS)
    {
        ASSERT(type == REG_DWORD);
    }
}

template <class Base>
void CRegDWORDCommon<Base>::InternalWrite(HKEY hKey, const DWORD& value)
{
    Base::m_lastError = RegSetValueEx(hKey, Base::GetPlainString(Base::m_key), 0, REG_DWORD, reinterpret_cast<const BYTE*>(&value), sizeof(value));
}

/**
 * \ingroup Utils
 * CString value in registry. with this class you can use CString values in registry
 * almost like normal CString variables in your program.
 * Usage:
 * in your header file, declare your registry CString variable:
 * \code
 * CRegString regvalue;
 * \endcode
 * next initialize the variable e.g. in the constructor of your class:
 * \code
 * regvalue = CRegString("Software\\Company\\SubKey\\MyValue", "default");
 * \endcode
 * this will set the registry value "MyValue" under HKEY_CURRENT_USER with path
 * "Software\Company\SubKey" to the variable. If the key does not yet exist or
 * an error occurred during read from the registry, a default
 * value of "default" is used when accessing the variable.
 * now the variable can be used like any other CString variable:
 * \code
 * regvalue = "some string";            //stores the value "some string" in the registry
 * CString temp = regvalue + "!!";      //temp has value "some string!!" now
 * \endcode
 * to use the normal methods of the CString class, just typecast the CRegString to a CString
 * and do whatever you want with the string:
 * \code
 * ((CString)regvalue).GetLength();
 * ((CString)regvalue).Trim();
 * \endcode
 * please be aware that in the second line the change in the string won't be written
 * to the registry! To force a write use the write() method. A write() is only needed
 * if you change the String with Methods not overloaded by CRegString.
 * to avoid too much access to the registry the value is cached inside the object.
 * once the value is read, no more read accesses to the registry will be made.
 * this means the variable will contain a wrong value if the corresponding registry
 * entry is changed by anything else than this variable! If you think that could happen
 * then use
 * \code
 * regvalue.read();
 * \endcode
 * to force a refresh of the variable with the registry.
 * a write to the registry is only made if the new value assigned with the variable
 * is different than the last assigned value.
 * to force a write use the method write();
 * another option to force reads and writes to the registry is to specify TRUE as the
 * third parameter in the constructor.
 */
template <class Base>
class CRegStringCommon : public CRegTypedBase<typename Base::StringT, Base>
{
private:
    /**
     * provide type-specific code to extract data from and write data to an open registry key.
     */

    void InternalRead(HKEY hKey, typename Base::StringT& value) override;
    void InternalWrite(HKEY hKey, const typename Base::StringT& value) override;

public:
    CRegStringCommon();
    /**
     * Constructor.
     * \param key the path to the key, including the key. example: "Software\\Company\\SubKey\\MyValue"
     * \param def the default value used when the key does not exist or a read error occurred
     * \param force set to TRUE if no cache should be used, i.e. always read and write directly from/to registry
     * \param base a predefined base key like HKEY_LOCAL_MACHINE. see the SDK documentation for more information.
     */
    CRegStringCommon(const typename Base::StringT& key, const typename Base::StringT& def = L"", bool force = false, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);
    CRegStringCommon(DWORD lookupInterval, const typename Base::StringT& key, const typename Base::StringT& def = L"", bool force = false, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);

    CRegStringCommon& operator=(const typename Base::StringT& rhs) override
    {
        CRegTypedBase<typename Base::StringT, Base>::operator=(rhs);
        return *this;
    }
    CRegStringCommon& operator+=(const typename Base::StringT& s) { return *this = static_cast<typename Base::StringT>(*this) + s; }
};

// implement CRegDWORD<> methods

template <class Base>
CRegStringCommon<Base>::CRegStringCommon()
    : CRegTypedBase<typename Base::StringT, Base>(typename Base::StringT())
{
}

template <class Base>
CRegStringCommon<Base>::CRegStringCommon(const typename Base::StringT& key, const typename Base::StringT& def, bool force, HKEY base, REGSAM sam)
    : CRegTypedBase<typename Base::StringT, Base>(key, def, force, base, sam)
{
}

template <class Base>
CRegStringCommon<Base>::CRegStringCommon(DWORD lookupInterval, const typename Base::StringT& key, const typename Base::StringT& def, bool force, HKEY base, REGSAM sam)
    : CRegTypedBase<typename Base::StringT, Base>(lookupInterval, key, def, force, base, sam)
{
}

template <class Base>
void CRegStringCommon<Base>::InternalRead(HKEY hKey, typename Base::StringT& value)
{
    DWORD size        = 0;
    DWORD type        = 0;
    Base::m_lastError = RegQueryValueEx(hKey, Base::GetPlainString(Base::m_key), nullptr, &type, nullptr, &size);

    if (Base::m_lastError == ERROR_SUCCESS)
    {
        auto pStr = std::make_unique<wchar_t[]>(size);
        if ((Base::m_lastError = RegQueryValueEx(hKey, Base::GetPlainString(Base::m_key), nullptr, &type, reinterpret_cast<BYTE*>(pStr.get()), &size)) == ERROR_SUCCESS)
        {
            ASSERT(type == REG_SZ || type == REG_EXPAND_SZ);
            value = Base::StringT(pStr.get());
        }
    }
}

template <class Base>
void CRegStringCommon<Base>::InternalWrite(HKEY hKey, const typename Base::StringT& value)
{
    Base::m_lastError = RegSetValueEx(hKey, Base::GetPlainString(Base::m_key), 0, REG_SZ, reinterpret_cast<BYTE*>(const_cast<LPWSTR>(Base::GetPlainString(value))), (Base::GetLength(value) + 1) * sizeof(wchar_t));
}

/**
 * \ingroup Utils
 * CRect value in registry. with this class you can use CRect values in registry
 * almost like normal CRect variables in your program.
 * Usage:
 * in your header file, declare your registry CString variable:
 * \code
 * CRegRect regvalue;
 * \endcode
 * next initialize the variable e.g. in the constructor of your class:
 * \code
 * regvalue = CRegRect("Software\\Company\\SubKey\\MyValue", CRect(100,100,200,200));
 * \endcode
 * this will set the registry value "MyValue" under HKEY_CURRENT_USER with path
 * "Software\Company\SubKey" to the variable. If the key does not yet exist or
 * an error occurred during read from the registry, a default
 * value of 100,100,200,200 is used when accessing the variable.
 * now the variable can be used like any other CRect variable:
 * \code
 * regvalue = CRect(40,20,300,500);             //stores the value in the registry
 * CRect temp = regvalue + CPoint(1,1);
 * temp |= CSize(5,5);
 * \endcode
 * to use the normal methods of the CRect class, just typecast the CRegRect to a CRect
 * and do whatever you want with the rect:
 * \code
 * ((CRect)regvalue).MoveToX(100);
 * ((CRect)regvalue).DeflateRect(10,10);
 * \endcode
 * please be aware that in the second line the change in the CRect won't be written
 * to the registry! To force a write use the write() method. A write() is only needed
 * if you change the CRect with Methods not overloaded by CRegRect.
 * to avoid too much access to the registry the value is cached inside the object.
 * once the value is read, no more read accesses to the registry will be made.
 * this means the variable will contain a wrong value if the corresponding registry
 * entry is changed by anything else than this variable! If you think that could happen
 * then use
 * \code
 * regvalue.read();
 * \endcode
 * to force a refresh of the variable with the registry.
 * a write to the registry is only made if the new value assigned with the variable
 * is different than the last assigned value.
 * to force a write use the method write();
 * another option to force reads and writes to the registry is to specify TRUE as the
 * third parameter in the constructor.
 */

#ifdef __ATLTYPES_H__ // defines CRect
class CRegRect : public CRegTypedBase<CRect, CRegBase>
{
private:
    /**
     * provide type-specific code to extract data from and write data to an open registry key.
     */

    virtual void InternalRead(HKEY hKey, CRect& value);
    virtual void InternalWrite(HKEY hKey, const CRect& value);

public:
    CRegRect();
    /**
     * Constructor.
     * \param key the path to the key, including the key. example: "Software\\Company\\SubKey\\MyValue"
     * \param def the default value used when the key does not exist or a read error occurred
     * \param force set to TRUE if no cache should be used, i.e. always read and write directly from/to registry
     * \param base a predefined base key like HKEY_LOCAL_MACHINE. see the SDK documentation for more information.
     */
    CRegRect(const CString& key, const CRect& def = CRect(), bool force = false, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);
    ~CRegRect(void) {}

    CRegRect& operator=(const CRect& rhs)
    {
        CRegTypedBase<CRect, CRegBase>::operator=(rhs);
        return *this;
    }
              operator LPCRECT() { return (LPCRECT)(CRect) * this; }
              operator LPRECT() { return (LPRECT)(CRect) * this; }
    CRegRect& operator+=(POINT r) { return *this = (CRect) * this + r; }
    CRegRect& operator+=(SIZE r) { return *this = (CRect) * this + r; }
    CRegRect& operator+=(LPCRECT r) { return *this = (CRect) * this + r; }
    CRegRect& operator-=(POINT r) { return *this = (CRect) * this - r; }
    CRegRect& operator-=(SIZE r) { return *this = (CRect) * this - r; }
    CRegRect& operator-=(LPCRECT r) { return *this = (CRect) * this - r; }

    CRegRect& operator&=(CRect r) { return *this = r & *this; }
    CRegRect& operator|=(CRect r) { return *this = r | *this; }
};
#endif

/**
 * \ingroup Utils
 * CPoint value in registry. with this class you can use CPoint values in registry
 * almost like normal CPoint variables in your program.
 * Usage:
 * in your header file, declare your registry CPoint variable:
 * \code
 * CRegPoint regvalue;
 * \endcode
 * next initialize the variable e.g. in the constructor of your class:
 * \code
 * regvalue = CRegPoint("Software\\Company\\SubKey\\MyValue", CPoint(100,100));
 * \endcode
 * this will set the registry value "MyValue" under HKEY_CURRENT_USER with path
 * "Software\Company\SubKey" to the variable. If the key does not yet exist or
 * an error occurred during read from the registry, a default
 * value of 100,100 is used when accessing the variable.
 * now the variable can be used like any other CPoint variable:
 * \code
 * regvalue = CPoint(40,20);                    //stores the value in the registry
 * CPoint temp = regvalue + CPoint(1,1);
 * temp += CSize(5,5);
 * \endcode
 * to use the normal methods of the CPoint class, just typecast the CRegPoint to a CPoint
 * and do whatever you want with the point:
 * \code
 * ((CRect)regvalue).Offset(100,10);
 * \endcode
 * please be aware that in the above example the change in the CPoint won't be written
 * to the registry! To force a write use the write() method. A write() is only needed
 * if you change the CPoint with Methods not overloaded by CRegPoint.
 * to avoid too much access to the registry the value is cached inside the object.
 * once the value is read, no more read accesses to the registry will be made.
 * this means the variable will contain a wrong value if the corresponding registry
 * entry is changed by anything else than this variable! If you think that could happen
 * then use
 * \code
 * regvalue.read();
 * \endcode
 * to force a refresh of the variable with the registry.
 * a write to the registry is only made if the new value assigned with the variable
 * is different than the last assigned value.
 * to force a write use the method write();
 * another option to force reads and writes to the registry is to specify TRUE as the
 * third parameter in the constructor.
 */

#ifdef __ATLTYPES_H__ // defines CPoint
class CRegPoint : public CRegTypedBase<CPoint, CRegBase>
{
private:
    /**
     * provide type-specific code to extract data from and write data to an open registry key.
     */

    virtual void InternalRead(HKEY hKey, CPoint& value);
    virtual void InternalWrite(HKEY hKey, const CPoint& value);

public:
    CRegPoint();
    /**
     * Constructor.
     * \param key the path to the key, including the key. example: "Software\\Company\\SubKey\\MyValue"
     * \param def the default value used when the key does not exist or a read error occurred
     * \param force set to TRUE if no cache should be used, i.e. always read and write directly from/to registry
     * \param base a predefined base key like HKEY_LOCAL_MACHINE. see the SDK documentation for more information.
     */
    CRegPoint(const CString& key, const CPoint& def = CPoint(), bool force = false, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);
    ~CRegPoint(void) {}

    CRegPoint& operator=(const CPoint& rhs)
    {
        CRegTypedBase<CPoint, CRegBase>::operator=(rhs);
        return *this;
    }
    CRegPoint& operator+=(CPoint p) { return *this = p + *this; }
    CRegPoint& operator-=(CPoint p) { return *this = p - *this; }
};
#endif

/**
 * \ingroup Utils
 * Manages a registry key (not a value). Provides methods to create and remove the
 * key and to query the list of values and sub keys.
 */

#ifdef __AFXCOLL_H__ // defines CStringList
class CRegistryKey
{
public: //methods
    /**
     * Constructor.
     * \param key the path to the key, including the key. example: "Software\\Company\\SubKey"
     * \param base a predefined base key like HKEY_LOCAL_MACHINE. see the SDK documentation for more information.
     */
    CRegistryKey(const CString& key, HKEY base = HKEY_CURRENT_USER, REGSAM sam = 0);
    ~CRegistryKey();

    /**
     * Creates the registry key if it does not already exist.
     * \return ERROR_SUCCESS or an nonzero error code. Use FormatMessage() to get an error description.
     */
    DWORD createKey();
    /**
     * Removes the whole registry key including all values. So if you set the registry
     * entry to be HKCU\Software\Company\Product\key there will only be
     * HKCU\Software\Company\Product key in the registry.
     * \return ERROR_SUCCESS or an nonzero error code. Use FormatMessage() to get an error description.
     */
    DWORD removeKey();

    bool getValues(CStringList& values);   ///< returns the list of values
    bool getSubKeys(CStringList& subkeys); ///< returns the list of sub keys

public:             //members
    HKEY    m_base; ///< handle to the registry base
    HKEY    m_hKey; ///< handle to the open registry key
    REGSAM  m_sam;  ///< the security attributes to pass to the registry command
    CString m_path; ///< the path to the key
};
#endif

#ifdef _MAP_
template <class T>
class CKeyList
{
private:
    /// constructor parameters

    typename T::StringT key;
    typename T::ValueT  defaultValue;
    HKEY                base;

    /// per-index defaults

    typedef std::map<int, typename T::ValueT> TDefaults;
    TDefaults                                 defaults;

    /// the indices accessed so far

    typedef std::map<int, T*> TElements;
    mutable TElements         elements;

    /// auto-insert

    const typename T::ValueT& GetDefault(int index) const;
    T&                        GetAt(int index) const;

public:
    /// construction

    CKeyList(const typename T::StringT& key, const typename T::ValueT& defaultValue, HKEY base = HKEY_CURRENT_USER)
        : key(key)
        , defaultValue(defaultValue)
        , base(base)
    {
    }

    /// destruction: delete all elements

    ~CKeyList()
    {
        for (auto iter = elements.begin(), end = elements.end(); iter != end; ++iter)
        {
            delete iter->second;
        }
    }

    /// data access

    const T& operator[](int index) const
    {
        return GetAt(index);
    }

    T& operator[](int index)
    {
        return GetAt(index);
    }

    const TDefaults& GetDefaults() const
    {
        return defaults;
    }

    TDefaults& GetDefaults()
    {
        return defaults;
    }

    const typename T::ValueT& GetDefault() const
    {
        return defaultValue;
    }
};

/// auto-insert

template <class T>
const typename T::ValueT& CKeyList<T>::GetDefault(int index) const
{
    auto iter = defaults.find(index);
    return iter == defaults.end() ? defaultValue : iter->second;
}

template <class T>
T& CKeyList<T>::GetAt(int index) const
{
    auto iter = elements.find(index);
    if (iter == elements.end())
    {
        typename T::StringT indexKey = key + '\\' + std::to_wstring(index);

        T* newElement = new T(indexKey, GetDefault(index), false, base);
        iter          = elements.insert(std::make_pair(index, newElement)).first;
    }

    return *iter->second;
};

#endif

    /**
 * Instantiate templates for common (data type, string type) combinations.
 */

#ifdef __CSTRINGT_H__
typedef CRegDWORDCommon<CRegBase>  CRegDWORD;
typedef CRegStringCommon<CRegBase> CRegString;

#    ifdef _MAP_
typedef CKeyList<CRegDWORD>  CRegDWORDList;
typedef CKeyList<CRegString> CRegStringList;
#    endif
#endif

typedef CRegDWORDCommon<CRegStdBase>  CRegStdDWORD;
typedef CRegStringCommon<CRegStdBase> CRegStdString;

#ifdef _MAP_
typedef CKeyList<CRegStdDWORD>  CRegStdDWORDList;
typedef CKeyList<CRegStdString> CRegStdStringList;
#endif

// to avoid a C4505 compiler warning, this dummy
// function is added.
inline void CRegStdCompilerWarningDummyFunction()
{
    std::wstring(CRegStdString(L"TEST")).clear();
    CRegStdDWORD(L"TEST");
}