/*
 * $Id$
 */

/*
 * Harbour Project source code:
 *   STRSWAP() CT3 string function
 *
 * Copyright 2001 IntTec GmbH, Neunlindenstr 32, 79106 Freiburg, Germany
 *        Author: Martin Vogel <vogel@inttec.de>
 *
 * www - http://www.harbour-project.org
 *
 * 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, 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 software; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307 USA (or visit the web site http://www.gnu.org/).
 *
 * As a special exception, the Harbour Project gives permission for
 * additional uses of the text contained in its release of Harbour.
 *
 * The exception is that, if you link the Harbour libraries with other
 * files to produce an executable, this does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * Your use of that executable is in no way restricted on account of
 * linking the Harbour library code into it.
 *
 * This exception does not however invalidate any other reasons why
 * the executable file might be covered by the GNU General Public License.
 *
 * This exception applies only to the code released by the Harbour
 * Project under the name Harbour.  If you copy code from other
 * Harbour Project or Free Software Foundation releases into a copy of
 * Harbour, as the General Public License permits, the exception does
 * not apply to the code that you add in this way.  To avoid misleading
 * anyone as to the status of such modified files, you must delete
 * this exception notice from them.
 *
 * If you write modifications of your own for Harbour, it is your choice
 * whether to permit this exception to apply to your modifications.
 * If you do not wish that, delete this exception notice.
 *
 */


#include "ct.h"


/*  $DOC$
 *  $FUNCNAME$
 *      STRSWAP()
 *  $CATEGORY$
 *      CT3 string functions
 *  $ONELINER$
 *      Swap the contents of two strings
 *  $SYNTAX$
 *      STRSWAP (<[@]cString1>, <[@]cString2>) -> cString
 *  $ARGUMENTS$
 *  $RETURNS$
 *  $DESCRIPTION$
 *      TODO: add documentation
 *  $EXAMPLES$
 *  $TESTS$
 *  $STATUS$
 *      Started
 *  $COMPLIANCE$
 *      STRSWAP() is compatible with CT3's STRSWAP().
 *  $PLATFORMS$
 *      All
 *  $FILES$
 *      Source is strswap.c, library is libct.
 *  $SEEALSO$
 *  $END$
 */

HB_FUNC( STRSWAP )
{
   size_t sStrLen1, sStrLen2;

   /* param check */
   if( ( sStrLen1 = ( size_t ) hb_parclen( 1 ) ) > 0 &&
       ( sStrLen2 = ( size_t ) hb_parclen( 2 ) ) > 0 )
   {
      /* get parameters */
      char *pcString1 = ( char * ) hb_parc( 1 );
      char *pcString2 = ( char * ) hb_parc( 2 );
      char *pcRet1 = NULL, *pcRet2 = NULL;
      int iChange1, iChange2;
      size_t sIndex, sCmpLen;

      if( ( iChange1 = ISBYREF( 1 ) ) != 0 )
      {
         pcRet1 = ( char * ) hb_xgrab( sStrLen1 );
         hb_xmemcpy( pcRet1, pcString1, sStrLen1 );
      }

      if( ( iChange2 = ISBYREF( 2 ) ) != 0 )
      {
         pcRet2 = ( char * ) hb_xgrab( sStrLen2 );
         hb_xmemcpy( pcRet2, pcString2, sStrLen2 );
      }

      sCmpLen = ( sStrLen1 < sStrLen2 ? sStrLen1 : sStrLen2 );
      for( sIndex = 0; sIndex < sCmpLen; sIndex++ )
      {
         char cExchange;

         if( iChange1 )
         {
            cExchange = *( pcString1 + sIndex );
            *( pcRet1 + sIndex ) = *( pcString2 + sIndex );
            if( iChange2 )
            {
               *( pcRet2 + sIndex ) = cExchange;
            }
         }
         else
         {
            *( pcRet2 + sIndex ) = *( pcString1 + sIndex );
         }
      }

      /* strings */
      if( iChange1 )
      {
         hb_storclen( pcRet1, sStrLen1, 1 );
         hb_xfree( pcRet1 );
      }

      if( iChange2 )
      {
         hb_storclen( pcRet2, sStrLen2, 2 );
         hb_xfree( pcRet2 );
      }

      hb_retc( NULL );
   }
   else  /* ( sStrLen1 = ( size_t ) hb_parclen( 1 ) ) > 0 &&
            ( sStrLen2 = ( size_t ) hb_parclen( 2 ) ) > 0 */
   {
      PHB_ITEM pSubst = NULL;
      int iArgErrorMode = ct_getargerrormode();

      if( iArgErrorMode != CT_ARGERR_IGNORE )
      {
         pSubst = ct_error_subst( ( USHORT ) iArgErrorMode, EG_ARG,
                                  CT_ERROR_STRSWAP, NULL, "STRSWAP", 0,
                                  EF_CANSUBSTITUTE, HB_ERR_ARGS_BASEPARAMS );
      }

      if( pSubst != NULL )
         hb_itemReturnRelease( pSubst );
      else
         hb_retc( NULL );
   }
}
