Source: kconfigbase.h

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    /*
       This file is part of the KDE libraries
       Copyright (c) 1999 Preston Brown <pbrown@kde.org>
       Copyright (c) 1997 Matthias Kalle Dalheimer <kalle@kde.org>

       This library is free software; you can redistribute it and/or
       modify it under the terms of the GNU Library General Public
       License as published by the Free Software Foundation; either
       version 2 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
       Library General Public License for more details.

       You should have received a copy of the GNU Library General Public License
       along with this library; see the file COPYING.LIB.  If not, write to
       the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
       Boston, MA 02111-1307, USA.
    */

    // $Id: kconfigbase.h,v 1.49 2000/09/25 03:53:04 waba Exp $

    #ifndef _KCONFIGBASE_H
    #define _KCONFIGBASE_H

    #include <qobject.h>
    #include <qcolor.h>
    #include <qfont.h>
    #include <qdatetime.h>
    #include <qstrlist.h>
    #include <qstringlist.h>
    #include <qvariant.h>
    #include <qmap.h>

    #include "kconfigdata.h"

    class KConfigBasePrivate;

    /**
     * Abstract base class for KDE configuration entries.
     *
     * This class forms the base for all KDE configuration. It is an
     * abstract base class, meaning that you cannot directly instantiate
     * objects of this class. Either use @ref KConfig (for usual KDE
     * configuration) or @ref KSimpleConfig (for special needs as in ksamba), or
     * even @ref KSharedConfig (stores values in shared memory).
     *
     * All configuration entries are key, value pairs.  Each entry also
     * belongs to a specific group of related entries.  All configuration
     * entries that do not explicitly specify which group they are in are
     * in a special group called the default group.
     *
     * If there is a $ character in an entry, @ref KConfigBase tries to expand
     * environment variable and uses its value instead of its name. You
     * can avoid this feature by having two consecutive $ characters in
     * your config file which get expanded to one.
     *
     * @author Kalle Dalheimer <kalle@kde.org>, Preston Brown <pbrown@kde.org>
     * @version $Id: kconfigbase.h,v 1.49 2000/09/25 03:53:04 waba Exp $
     * @see  KApplication::getConfig()  KConfig  KSimpleConfig
     * @short KDE Configuration Management abstract base class
     */
    class KConfigBase : public QObject
    {
      Q_OBJECT

      friend class KConfigBackEnd;
      friend class KConfigINIBackEnd;

    public:
      /**
       * Construct a KConfigBase object.
       */
      KConfigBase();

      /**
       * Destructor.
       */
      virtual ~KConfigBase();

      /**
       * Specify the group in which keys will be searched.
       *
       *  Subsequent
       * calls to @ref readEntry() will look only for keys in the currently
       * activated group.
       *
       * Switch back to the default group by passing an empty string.
       * @param pGroup The name of the new group.
       */
      void setGroup( const QString& pGroup );

      /**
       * Set the group to the "Desktop Entry" group used for
       * desktop configuration files for applications, mime types, etc.
       */
      void setDesktopGroup();

      /**
       * Retrieve the name of the group in which we are
       *  searching for keys and from which we are retrieving entries.
       *
       * @return The current group.
       */
      QString group() const;

      /**
       * Returns @p true if the specified group is known about.
       *
       * @param _pGroup The group to search for.
       * @returns Whether the group exists.
       */
      virtual bool hasGroup(const QString &_pGroup) const = 0;

      /**
       * Retrieve a list of groups that are known about.
       *
       * @returns The list of groups.
       **/
      virtual QStringList groupList() const = 0;

      /**
       * Retrieve a the current locale.
       *
       * @return A string representing the current locale.
       */
      QString locale() const;

      /**
       * Read the value of an entry specified by @p pKey in the current group.
       *
       * @param pKey The key to search for.
       * @param aDefault A default value returned if the key was not found.
       * @return The value for this key or a null string if no value
       *      was found.
       */
       QString readEntry( const QString& pKey,
                         const QString& aDefault = QString::null ) const;
       QString readEntry( const char *pKey,
                         const QString& aDefault = QString::null ) const;

      /**
       * Read the value of an entry specified by @p pKey in the current group.
       * The value is treated as if it is of the given type.
       *
       * @return An empty property or error.
       */
      QVariant readPropertyEntry( const QString& pKey, QVariant::Type ) const;
      QVariant readPropertyEntry( const char *pKey, QVariant::Type ) const;

      /**
       * Read a list of strings.
       *
       * @deprecated
       *
       * @param pKey The key to search for
       * @param list In this object, the read list will be returned.
       * @param sep  The list separator (default ",")
       * @return The number of entries in the list.
       */
      int readListEntry( const QString& pKey, QStrList &list, char sep = ',' ) const;
      int readListEntry( const char *pKey, QStrList &list, char sep = ',' ) const;

      /**
       * Read a list of strings.
       *
       * @param pKey The key to search for.
       * @param sep  The list separator (default is ",").
       * @return The list.
       */
      QStringList readListEntry( const QString& pKey, char sep = ',' ) const;
      QStringList readListEntry( const char *pKey, char sep = ',' ) const;

      /**
       * Read a list of Integers.
       *
       * @param pKey The key to search for.
       * @return The list.
       */
      QValueList<int> readIntListEntry( const QString& pKey ) const;
      QValueList<int> readIntListEntry( const char *pKey ) const;

      /**
       * Read a path.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it as a path. This means, dollar expansion is activated
       * for this value, so that e.g. $HOME gets expanded.
       *
       * @param pKey The key to search for.
       * @param aDefault A default value returned if the key was not found.
       * @return The value for this key or a null string if no value was found.
       */
      QString readPathEntry( const QString& pKey, const QString & aDefault = QString::null ) const;
      QString readPathEntry( const char *pKey, const QString & aDefault = QString::null ) const;

      /**
       * Read a numerical value.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it numerically.
       *
       * @param pKey The key to search for.
       * @param nDefault A default value returned if the key was not found.
       * @return The value for this key or 0 if no value was found.
       */
      int readNumEntry( const QString& pKey, int nDefault = 0 ) const;
      int readNumEntry( const char *pKey, int nDefault = 0 ) const;

      /**
       * Read a numerical value.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it numerically.
       *
       * @param pKey The key to search for.
       * @param nDefault A default value returned if the key was not found.
       * @return The value for this key or 0 if no value was found.
       */
      unsigned int readUnsignedNumEntry( const QString& pKey, unsigned int nDefault = 0 ) const;
      unsigned int readUnsignedNumEntry( const char *pKey, unsigned int nDefault = 0 ) const;

      /**
       * Read a numerical value.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it numerically.
       *
       * @param pKey The key to search for.
       * @param nDefault A default value returned if the key was not found.
       * @return The value for this key or 0 if no value was found.
       */
      long readLongNumEntry( const QString& pKey, long nDefault = 0 ) const;
      long readLongNumEntry( const char *pKey, long nDefault = 0 ) const;

      /**
       * Read a numerical value.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it numerically.
       *
       * @param pKey The key to search for.
       * @param nDefault A default value returned if the key was not found.
       * @return The value for this key or 0 if no value was found.
       */
      unsigned long readUnsignedLongNumEntry( const QString& pKey, unsigned long nDefault = 0 ) const;
      unsigned long readUnsignedLongNumEntry( const char *pKey, unsigned long nDefault = 0 ) const;

      /**
       * Read a numerical value.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it numerically.
       *
       * @param pKey The key to search for.
       * @param nDefault A default value returned if the key was not found.
       * @return The value for this key or 0 if no value was found.
       */
      double readDoubleNumEntry( const QString& pKey, double nDefault = 0.0 ) const;
      double readDoubleNumEntry( const char *pKey, double nDefault = 0.0 ) const;

      /**
       * Read a @ref QFont.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it as a font object.
       *
       * @param pKey                The key to search for.
       * @param pDefault    A default value returned if the key was not found.
       * @return The value for this key or a default font if no value was found.
       */
      QFont readFontEntry( const QString& pKey, const QFont* pDefault = 0L ) const;
      QFont readFontEntry( const char *pKey, const QFont* pDefault = 0L ) const;

      /**
       * Read a boolean entry.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it as a boolean value. Currently "on" and "true" are
       * accepted as true, everything else if false.
       *
       * @param pKey                The key to search for
       * @param bDefault    A default value returned if the key was not
       *                                    found.
       * @return The value for this key or a default value if no value was
       * found.
       */
      bool readBoolEntry( const QString& pKey, const bool bDefault = false ) const;
      bool readBoolEntry( const char *pKey, const bool bDefault = false ) const;

      /**
       * Read a rect entry.
       *
       * Read the value of an entry specified by pKey in the current group
       * and interpret it as a @ref QRect object.
       *
       * @param pKey                The key to search for
       * @param pDefault    A default value returned if the key was not
       *                                    found.
       * @return The value for this key or a default rectangle if no value
       * was found.
       */
      QRect readRectEntry( const QString& pKey, const QRect* pDefault = 0L ) const;
      QRect readRectEntry( const char *pKey, const QRect* pDefault = 0L ) const;

      /**
       * Read a point entry.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it as a @ref QPoint object.
       *
       * @param pKey                The key to search for
       * @param pDefault    A default value returned if the key was not
       *                                    found.
       * @return The value for this key or a default point if no value
       * was found.
       */
      QPoint readPointEntry( const QString& pKey, const QPoint* pDefault = 0L ) const;
      QPoint readPointEntry( const char *pKey, const QPoint* pDefault = 0L ) const;

      /**
       * Read a size entry.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it as a @ref QSize object.
       *
       * @param pKey                The key to search for
       * @param pDefault    A default value returned if the key was not
       *                                    found.
       * @return The value for this key or a default point if no value
       * was found.
       */
      QSize readSizeEntry( const QString& pKey, const QSize* pDefault = 0L ) const;
      QSize readSizeEntry( const char *pKey, const QSize* pDefault = 0L ) const;

      /**
       * Read a @ref QColor.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it as a color.
       *
       * @param pKey                The key to search for.
       * @param pDefault    A default value returned if the key was not found.
       * @return The value for this key or a default color if no value
       * was found.
       */
      QColor readColorEntry( const QString& pKey, const QColor* pDefault = 0L ) const;
      QColor readColorEntry( const char *pKey, const QColor* pDefault = 0L ) const;

      /**
       * Read a @ref QDateTime.
       *
       * Read the value of an entry specified by @p pKey in the current group
       * and interpret it as a date and time.
       *
       * @param pKey                The key to search for.
       * @param pDefault    A default value returned if the key was not found.
       * @return The value for this key or a @ref currentDateTime()
       *  (Qt global function) if no value was found.
       */
      QDateTime readDateTimeEntry( const QString& pKey, const QDateTime* pDefault = 0L ) const;
      QDateTime readDateTimeEntry( const char *pKey, const QDateTime* pDefault = 0L ) const;

      /**
       * Write the key/value pair.
       *
       * This is stored in the most specific config file when destroying the
       * config object or when calling @ref sync().
       *
       * @param pKey         The key to write.
       * @param pValue       The value to write.
       * @param bPersistent  If @p bPersistent is false, the entry's dirty
       *                     flag will not be set and thus the entry will
       *                     not be written to disk at deletion time.
       * @param bGlobal      If @p bGlobal is true, the pair is not saved to the
       *                     application specific config file, but to the
       *                     global KDE config file.
       * @param bNLS         If @p bNLS is true, the locale tag is added to the key
       *                     when writing it back.
       * @return The old value for this key. If this key did not
       *         exist, a null string is returned.
       */
      QString writeEntry( const QString& pKey, const QString& pValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );
      QString writeEntry( const char *pKey, const QString& pValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );

      /**
       * @ref writeEntry() Overridden to accept a property.
       *
       * Note: Unlike the other @ref writeEntry() functions, the old value is
       * _not_ returned here!
       *
       * @param pKey The key to write
       * @param rValue The property to write
       * @param bPersistent If @p bPersistent is false, the entry's dirty flag
       *                    will not be set and thus the entry will not be
       *                    written to disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *                    application specific config file, but to the
       *                    global KDE config file.
       * @param bNLS If @p bNLS is true, the locale tag is added to the key
       *             when writing it back.
       *
       * @see  writeEntry()
       */
      void writeEntry( const QString& pKey, const QVariant& rValue,
                        bool bPersistent = true, bool bGlobal = false,
                        bool bNLS = false );
      void writeEntry( const char *pKey, const QVariant& rValue,
                        bool bPersistent = true, bool bGlobal = false,
                        bool bNLS = false );

      /**
       * @ref writeEntry() overriden to accept a list of strings.
       *
       * Note: Unlike the other @ref writeEntry() functions, the old value is
       * _not_ returned here!
       *
       * @param pKey The key to write
       * @param rValue The list to write
       * @param bPersistent If @p bPersistent is false, the entry's dirty flag
       *                    will not be set and thus the entry will not be
       *                    written to disk at deletion time.
       * @param bGlobal If @p bGlobal is true, the pair is not saved to the
       *                application specific config file, but to the
       *                global KDE config file.
       * @param bNLS If @p bNLS is true, the locale tag is added to the key
       *             when writing it back.
       *
       * @see  writeEntry()
       */
      void writeEntry( const QString& pKey, const QStrList &rValue,
    		   char sep = ',', bool bPersistent = true, bool bGlobal = false, bool bNLS = false );
      void writeEntry( const char *pKey, const QStrList &rValue,
    		   char sep = ',', bool bPersistent = true, bool bGlobal = false, bool bNLS = false );

      /**
       * @ref writeEntry() overridden to accept a list of strings.
       *
       * Note: Unlike the other @ref writeEntry() functions, the old value is
       * _not_ returned here!
       *
       * @param pKey The key to write
       * @param rValue The list to write
       * @param bPersistent If @p bPersistent is false, the entry's dirty flag
       *                    will not be set and thus the entry will not be
       *                    written to disk at deletion time.
       * @param bGlobal If @p bGlobal is true, the pair is not saved to the
       *                application specific config file, but to the
       *                global KDE config file.
       * @param bNLS If @p bNLS is true, the locale tag is added to the key
       *             when writing it back.
       *
       * @see  writeEntry()
       */
      void writeEntry( const QString& pKey, const QStringList &rValue,
    		   char sep = ',', bool bPersistent = true, bool bGlobal = false, bool bNLS = false );
      void writeEntry( const char *pKey, const QStringList &rValue,
    		   char sep = ',', bool bPersistent = true, bool bGlobal = false, bool bNLS = false );

     /**
       * @ref writeEntry() overridden to accept a list of Integers.
       *
       * Note: Unlike the other @ref writeEntry() functions, the old value is
       * _not_ returned here!
       *
       * @param pKey The key to write
       * @param rValue The list to write
       * @param bPersistent If @p bPersistent is false, the entry's dirty flag
       *                    will not be set and thus the entry will not be
       *                    written to disk at deletion time.
       * @param bGlobal If @p bGlobal is true, the pair is not saved to the
       *                application specific config file, but to the
       *                global KDE config file.
       * @param bNLS If @p bNLS is true, the locale tag is added to the key
       *             when writing it back.
       *
       * @see  writeEntry()
       */
      void writeEntry( const QString& pKey, const QValueList<int>& rValue,
    		   bool bPersistent = true, bool bGlobal = false, bool bNLS = false );
      void writeEntry( const char *pKey, const QValueList<int>& rValue,
    		   bool bPersistent = true, bool bGlobal = false, bool bNLS = false );

      /**
       * Write the key/value pair.
       *
       * This is stored to the most specific config file when destroying the
       * config object or when calling @ref sync().
       *
       *  @param pKey               The key to write.
       *  @param pValue     The value to write.
       *  @param bPersistent        If @p bPersistent is false, the entry's dirty
       *                    flag will not be set and thus the entry will
       *                    not be written to disk at deletion time.
       *  @param bGlobal    If @p bGlobal is true, the pair is not saved to the
       *                    application specific config file, but to the
       *                    global KDE config file.
       *  @param bNLS       If @p bNLS is true, the locale tag is added to the key
       *                    when writing it back.
       *  @return The old value for this key. If this key did not
       *          exist, a null string is returned.
       */
      QString writeEntry( const QString& pKey, const char *pValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false )
        { return writeEntry(pKey, QString::fromLatin1(pValue), bPersistent, bGlobal, bNLS); }
      QString writeEntry( const char *pKey, const char *pValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false )
        { return writeEntry(pKey, QString::fromLatin1(pValue), bPersistent, bGlobal, bNLS); }

      /**
       * Write the key value pair.
       * Same as above, but write a numerical value.
       *
       * @param pKey The key to write.
       * @param nValue The value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *                    application specific config file, but to the
       *                    global KDE config file.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *                    when writing it back.
       * @return The old value for this key. If this key did not
       *         exist, a null string is returned.
       */
      QString writeEntry( const QString& pKey, int nValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );
      QString writeEntry( const char *pKey, int nValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );

      /**
       * Write the key value pair.
       * Same as above, but write an unsigned numerical value.
       *
       * @param pKey The key to write.
       * @param nValue The value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *                    application specific config file, but to the
       *                    global KDE config file.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *                    when writing it back.
       * @return The old value for this key. If this key did not
       *         exist, a null string is returned.
       */
      QString writeEntry( const QString& pKey, unsigned int nValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );
      QString writeEntry( const char *pKey, unsigned int nValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );

      /**
       * Write the key value pair.
       * Same as above, but write a long numerical value.
       *
       * @param pKey The key to write.
       * @param nValue The value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *  application specific config file, but to the global KDE config file.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *  when writing it back.
       * @return The old value for this key. If this key did not
       * exist, a null string is returned.
       */
      QString writeEntry( const QString& pKey, long nValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );
      QString writeEntry( const char *pKey, long nValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );

      /**
       * Write the key value pair.
       * Same as above, but write an unsigned long numerical value.
       *
       * @param pKey The key to write.
       * @param nValue The value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *  application specific config file, but to the global KDE config file.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *  when writing it back.
       * @return The old value for this key. If this key did not
       * exist, a null string is returned.
       */
      QString writeEntry( const QString& pKey, unsigned long nValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );
      QString writeEntry( const char *pKey, unsigned long nValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );

      /**
       * Write the key value pair.
       * Same as above, but write a floating-point value.*
       * @param pKey The key to write.
       * @param nValue The value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *  application specific config file, but to the global KDE config file.
       * @param format      @p format determines the format to which the value
       *  is converted. Default is 'g'.
       * @param precision   @p precision sets the precision with which the
       *  value is converted. Default is 6 as in QString.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *  when writing it back.
       * @return The old value for this key. If this key did not
       * exist, a null string is returned.
       */
      QString writeEntry( const QString& pKey, double nValue,
                          bool bPersistent = true, bool bGlobal = false,
                          char format = 'g', int precision = 6,
                          bool bNLS = false );
      QString writeEntry( const char *pKey, double nValue,
                          bool bPersistent = true, bool bGlobal = false,
                          char format = 'g', int precision = 6,
                          bool bNLS = false );

      /**
       * Write the key value pair.
       * Same as above, but write a boolean value.
       *
       * @param pKey The key to write.
       * @param bValue The value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *  application specific config file, but to the global KDE config file.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *  when writing it back.
       * @return The old value for this key. If this key did not
       * exist, a null string is returned.
       */
      QString writeEntry( const QString& pKey, bool bValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );
      QString writeEntry( const char *pKey, bool bValue,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );

      /**
       * Write the key value pair.
       * Same as above, but write a font
       *
       * @param pKey The key to write.
       * @param rFont The font value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *  application specific config file, but to the global KDE config file.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *  when writing it back.
       * @return The old value for this key. If this key did not
       * exist, a null string is returned.
       */
      QString writeEntry( const QString& pKey, const QFont& rFont,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );
      QString writeEntry( const char *pKey, const QFont& rFont,
                          bool bPersistent = true, bool bGlobal = false,
                          bool bNLS = false );

      /**
       * Write the key value pair.
       * Same as above, but write a color.
       *
       * Note: Unlike the other @ref writeEntry() functions, the old value is
       * _not_ returned here!
       *
       * @param pKey The key to write.
       * @param rValue The color value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *  application specific config file, but to the global KDE config file.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *  when writing it back.
       */
      void writeEntry( const QString& pKey, const QColor& rColor,
                       bool bPersistent = true, bool bGlobal = false,
                       bool bNLS = false );
      void writeEntry( const char *pKey, const QColor& rColor,
                       bool bPersistent = true, bool bGlobal = false,
                       bool bNLS = false );

      /**
       * Write the key value pair.
       * Same as above, but write a date and time.
       *
       * Note: Unlike the other @ref writeEntry() functions, the old value is
       * @em not returned here!
       *
       * @param pKey The key to write.
       * @param rValue The date and time value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *  application specific config file, but to the global KDE config file.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *  when writing it back.
       */
      void writeEntry( const QString& pKey, const QDateTime& rDateTime,
                       bool bPersistent = true, bool bGlobal = false,
                       bool bNLS = false );
      void writeEntry( const char *pKey, const QDateTime& rDateTime,
                       bool bPersistent = true, bool bGlobal = false,
                       bool bNLS = false );

      /**
       * Write the key value pair.
       * Same as above, but write a rectangle.
       *
       * Note: Unlike the other @ref writeEntry() functions, the old value is
       * _not_ returned here!
       *
       * @param pKey The key to write.
       * @param rValue The rectangle value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *  application specific config file, but to the global KDE config file.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *  when writing it back.
       */
      void writeEntry( const QString& pKey, const QRect& rValue,
                       bool bPersistent = true, bool bGlobal = false,
                       bool bNLS = false );
      void writeEntry( const char *pKey, const QRect& rValue,
                       bool bPersistent = true, bool bGlobal = false,
                       bool bNLS = false );

      /**
       * Write the key value pair.
       * Same as above, but write a point.
       *
       * Note: Unlike the other @ref writeEntry() functions, the old value is
       * _not_ returned here!
       *
       * @param pKey The key to write.
       * @param rValue The point value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *  application specific config file, but to the global KDE config file.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *  when writing it back.
       */
      void writeEntry( const QString& pKey, const QPoint& rValue,
                       bool bPersistent = true, bool bGlobal = false,
                       bool bNLS = false );
      void writeEntry( const char *pKey, const QPoint& rValue,
                       bool bPersistent = true, bool bGlobal = false,
                       bool bNLS = false );

      /**
       * Write the key value pair.
       * Same as above, but write a size.
       *
       * Note: Unlike the other @ref writeEntry() functions, the old value is
       * _not_ returned here!
       *
       * @param pKey The key to write.
       * @param rValue The size value to write.
       * @param bPersistent If @p bPersistent is false, the entry's dirty
       * flag will not be set and thus the entry will not be written to
       * disk at deletion time.
       * @param bGlobal     If @p bGlobal is true, the pair is not saved to the
       *  application specific config file, but to the global KDE config file.
       * @param bNLS        If @p bNLS is true, the locale tag is added to the key
       *  when writing it back.
       */
      void writeEntry( const QString& pKey, const QSize& rValue,
                       bool bPersistent = true, bool bGlobal = false,
                       bool bNLS = false );
      void writeEntry( const char *pKey, const QSize& rValue,
                       bool bPersistent = true, bool bGlobal = false,
                       bool bNLS = false );

      /**
       * Turns on or off "dollar  expansion" (see @ref KConfigBase introduction)
       *  when reading config entries.
       * Dollar sign expansion is initially OFF.
       *
       * @param _bExpand Tf true, dollar expansion is turned on.
       */
      void setDollarExpansion( bool _bExpand = true ) { bExpand = _bExpand; }

      /**
       * Returns whether dollar expansion is on or off.  It is initially OFF.
       *
       * @return true if dollar expansion is on.
       */
      bool isDollarExpansion() const { return bExpand; }

      /**
       * Mark the config object as "clean," i.e. don't write dirty entries
       * at destruction time. If @p bDeep is false, only the global dirty
       * flag of the KConfig object gets cleared. If you then call
       * @ref writeEntry() again, the global dirty flag is set again and all
       * dirty entries will be written at a subsequent @ref sync() call.
       *
       * Classes that derive from @ref KConfigObject should override this
       * method and implement storage-specific behaviour, as well as
       * calling the @ref KConfigBase::rollback() explicitly in the initializer.
       *
       * @param bDeep If @p true, the dirty flags of all entries are cleared,
       *        as well as the global dirty flag.
       */
      virtual void rollback( bool bDeep = true );

      /**
       * Flush all changes that currently reside only in memory
       * back to disk / permanent storage. Dirty configuration entries are
       * written to the most specific file available.
       *
       * Asks the back end to flush out all pending writes, and then calls
       * @ref rollback().  No changes are made if the object has @p readOnly
       * status.
       *
       * You should call this from your destructor in derivative classes.
       *
       * @see  rollback(),  isReadOnly()
       */
      virtual void sync();

      /**
       * @returns @p true if the config file has any dirty (modified) entries.
       */
      bool isDirty() const { return bDirty; }

      /**
       * Set the config object's read-only status.
       *
       * @param _ro If @p true, the config object will not write out any
       *        changes to disk even if it is destroyed or @ref sync() is called.
       *
       */
      virtual void setReadOnly(bool _ro) { bReadOnly = _ro; }

       /**
        * Queries the read-only status of the config object.
        *
        * @return The read-only status.
        */
      bool isReadOnly() const { return bReadOnly; }

      /**
       * Check whether the key has an entry in the currently active group.
       * Use this to determine whether a key is not specified for the current
       * group (hasKey() returns false). Keys with null data are considered
       * nonexistent.
       *
       * @param pKey The key to search for.
       * @return If @ref true, the key is available.
       */
      virtual bool hasKey( const QString& pKey ) const = 0;

      /**
       * Return a map (tree) of entries for all entries in a particular
       * group.  Only the actual entry string is returned, none of the
       * other internal data should be included.
       *
       * @param pGroup A group to get keys from.
       * @return A map of entries in the group specified, indexed by key.
       *         The returned map may be empty if the group is not found.
       * @see   QMap
       */
      virtual QMap<QString, QString> entryMap(const QString &pGroup) const = 0;

      /**
       * Reparses all configuration files. This is useful for programs
       * that use standalone graphical configuration tools. The base
       * method implemented here only clears the group list and then
       * appends the default group.
       *
       * Derivative classes should clear any internal data structures and
       * then simply call @ref parseConfigFiles() when implementing this
       * method.
       *
       * @see  parseConfigFiles()
       */
      virtual void reparseConfiguration() = 0;

      /**
       * Possible return values for @ref getConfigState().
       *
       * @see  getConfigState()
       */
      enum ConfigState { NoAccess, ReadOnly, ReadWrite };

      /**
       * Retrieve the state of the app-config object.
       *
       * Possible return values
       * are NoAccess (the application-specific config file could not be
       * opened neither read-write nor read-only), ReadOnly (the
       * application-specific config file is opened read-only, but not
       * read-write) and ReadWrite (the application-specific config
       * file is opened read-write).
       *
       * @see  ConfigState()
       */
      ConfigState getConfigState() const;

    protected:
      /**
       * Read the locale and put in the configuration data struct.
       * Note that this should be done in the constructor, but this is not
       * possible due to some mutual dependencies in @ref KApplication::init()
       */
      void setLocale();

      /**
       * Sets the global dirty flag of the config object
       *
       * @param _bDirty How to mark the object's dirty status
       */
      virtual void setDirty(bool _bDirty = true) { bDirty = _bDirty; }

      /**
       * Parse all configuration files for a configuration object.
       *
       * The actual parsing is done by the associated KConfigBackEnd.
       */
      virtual void parseConfigFiles();

      /**
       * Returns an map (tree) of the entries in the specified group.
       * This may or may not return all entries that belong to the
       * config object.  The only guarantee that you are given is that
       * any entries that are dirty (i.e. modified and not yet written back
       * to the disk) will be contained in the map.  Some derivative
       * classes may choose to return everything.
       *
       * Do not use this function, the implementation / return type are
       * subject to change.
       *
       * @param pGroup The group to provide a KEntryMap for.
       * @return The map of the entries in the group.
       * @internal
       */
      virtual KEntryMap internalEntryMap( const QString& pGroup ) const = 0;

      /**
       * Returns an map (tree) of the entries in the tree.
       *
       * Do not use this function, the implementation / return type are
       * subject to change.
       *
       * @return A map of the entries in the tree.
       *
       * @internal
       *
       */
      virtual KEntryMap internalEntryMap() const = 0;

      /**
       * Insert a key,value pair into the internal storage mechanism of
       * the configuration object. Classes that derive from KConfigBase
       * will need to implement this method in a storage-specific manner.
       *
       * Do not use this function, the implementation / return type are
       * subject to change.
       *
       * @param _key The key to insert.  It contains information both on
       *        the group of the key and the key itself. If the key already
       *        exists, the old value will be replaced.
       * @param _data the KEntry that is to be stored.
       * @internal
       */
      virtual void putData(const KEntryKey &_key, const KEntry &_data) = 0;

      /**
       * Look up an entry in the config object's internal structure.
       * Classes that derive from KConfigBase will need to implement this
       * method in a storage-specific manner.
       *
       * Do not use this function, the implementation and return type are
       * subject to change.
       *
       * @param _key The key to look up  It contains information both on
       *        the group of the key and the entry's key itself.
       * @return The @ref KEntry value (data) found for the key.  @p KEntry.aValue
       * will be the null string if nothing was located.
       * @internal
       */
      virtual KEntry lookupData(const KEntryKey &_key) const = 0;

      /**
       * A back end for loading/saving to disk in a particular format.
       */
      KConfigBackEnd *backEnd;
    public:
      /**
       * Overloaded public methods:
       */
      void setGroup( const QCString &pGroup );
      void setGroup( const char *pGroup );
      virtual bool hasGroup(const QCString &_pGroup) const = 0;
      virtual bool hasGroup(const char *_pGroup) const = 0;
      virtual bool hasKey( const char *pKey ) const = 0;

    protected:
      QCString readEntryUtf8( const char *pKey) const;

      /**
       * The currently selected group. */
      QCString mGroup;

      /**
       * The locale to retrieve keys under if possible, i.e en_US or fr.  */
      QCString aLocaleString;

      /**
       * Indicates whether there are any dirty entries in the config object
       * that need to be written back to disk. */
      bool bDirty;

      bool bLocaleInitialized;
      bool bReadOnly;           // currently only used by KSimpleConfig
      bool bExpand;             // whether dollar expansion is used

      KConfigBasePrivate *d;
    };

    // we put this here instead of in the declaration above to
    // avoid warnings about the unused parameter.
    inline void KConfigBase::rollback( bool /*bDeep = true*/ )
    {
      bDirty = false;
    }

    class KConfigGroupSaverPrivate;

    /**
      * Helper class to facilitate working with @ref KConfig / @ref KSimpleConfig
      * groups.
      *
      * Careful programmers always set the group of a
      * @ref KConfig @ref KSimpleConfig object to the group they want to read from
      * and set it back to the old one of afterwards. This is usually
      * written as:
      * <pre>
      *
      * QString oldgroup config->group();
      * config->setGroup( "TheGroupThatIWant" );
      * ...
      * config->writeEntry( "Blah", "Blubb" );
      *
      * config->setGroup( oldgroup );
      * </pre>
      *
      * In order to facilitate this task, you can use
      * KConfigGroupSaver. Simply construct such an object ON THE STACK
      * when you want to switch to a new group. Then, when the object goes
      * out of scope, the group will automatically be restored. If you
      * want to use several different groups within a function or method,
      * you can still use KConfigGroupSaver: Simply enclose all work with
      * one group (including the creation of the KConfigGroupSaver object)
      * in one block.
      *
      * @author Matthias Kalle Dalheimer <kalle@kde.org>
      * @version $Id: kconfigbase.h,v 1.49 2000/09/25 03:53:04 waba Exp $
      * @see KConfigBase, KConfig, KSimpleConfig
      * @short Helper class for easier use of KConfig/KSimpleConfig groups
      */

    class KConfigGroupSaver
    {
    public:
      /**
       * Constructor. You pass a pointer to the KConfigBase-derived
       * object you want to work with and a string indicating the _new_
       * group.
       * @param config The KConfigBase-derived object this
       *               KConfigGroupSaver works on.
       * @param group  The new group that the config object should switch to.
       */
      KConfigGroupSaver( KConfigBase* config, QString group )
          : _config(config), _oldgroup(config->group())
            { _config->setGroup( group ); }

      KConfigGroupSaver( KConfigBase* config, const char *group )
          : _config(config), _oldgroup(config->group())
            { _config->setGroup( group ); }

      KConfigGroupSaver( KConfigBase* config, const QCString &group )
          : _config(config), _oldgroup(config->group())
            { _config->setGroup( group ); }

      ~KConfigGroupSaver() { _config->setGroup( _oldgroup ); }

        KConfigBase* config() { return _config; };

    private:
      KConfigBase* _config;
      QString _oldgroup;

      KConfigGroupSaver(const KConfigGroupSaver&);
      KConfigGroupSaver& operator=(const KConfigGroupSaver&);

      KConfigGroupSaverPrivate *d;
    };

    #endif