105 lines
3.1 KiB
C
105 lines
3.1 KiB
C
/*
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* $Id$
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*/
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/*
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* Harbour Project source code:
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* DESCEND() function
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*
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* Copyright 1999 Jose Lalin <dezac@corevia.com>
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* www - http://www.harbour-project.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version, with one exception:
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*
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* The exception is that if you link the Harbour Runtime Library (HRL)
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* and/or the Harbour Virtual Machine (HVM) with other files to produce
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* an executable, this does not by itself cause the resulting executable
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* to be covered by the GNU General Public License. Your use of that
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* executable is in no way restricted on account of linking the HRL
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* and/or HVM code into it.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA (or visit
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* their web site at http://www.gnu.org/).
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*
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*/
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/* $DOC$
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* $FUNCNAME$
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* DESCEND
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* $CATEGORY$
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*
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* $ONELINER$
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* Inverts an expression of string, logical, date or numeric type.
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* $SYNTAX$
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* DESCEND( <xExp> ) --> <xExpInverted>
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* $ARGUMENTS$
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* <xExp> is any valid expression.
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* $RETURNS$
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* Inverted value of the same type as passed.
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* $DESCRIPTION$
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* This function converts an expression in his inverted form. It is
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* useful to build descending indexes.
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* $EXAMPLES$
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* // Seek for Smith in a descending index
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* SEEK DESCEND( "SMITH" )
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* $TESTS$
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* DATA->( DBSEEK( DESCEND( "SMITH" ) ) )
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* will seek "SMITH" into a descending index.
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* $STATUS$
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* C
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* $COMPLIANCE$
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* DESCEND is fully CA-Clipper compliant.
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* $SEEALSO$
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* INDEX, SEEK
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* $END$
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*/
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#include "extend.h"
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#include "itemapi.h"
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void hb_strDescend( char * szStringTo, const char * szStringFrom, ULONG ulLen )
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{
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HB_TRACE(HB_TR_DEBUG, ("hb_strDescend(%s, %s, %lu)", szStringTo, szStringFrom, ulLen));
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if( ulLen == 1 && szStringFrom[ 0 ] == '\0' )
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szStringTo[ 0 ] = '\0';
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else
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{
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for(; ulLen--; ++szStringTo, ++szStringFrom )
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*szStringTo = 256 - *szStringFrom;
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}
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}
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HARBOUR HB_DESCEND( void )
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{
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PHB_ITEM pItem = hb_param( 1, IT_ANY );
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if( pItem )
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{
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if( IS_STRING( pItem ) )
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{
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ULONG ulLen = hb_itemGetCLen( pItem );
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char * szBuffer = ( char * ) hb_xgrab( ulLen );
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hb_strDescend( szBuffer, hb_itemGetCPtr( pItem ), ulLen );
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hb_retclen( szBuffer, ulLen );
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hb_xfree( szBuffer );
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}
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else if( IS_DATE( pItem ) )
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hb_retnl( 5231808 - hb_itemGetNL( pItem ) );
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else if( IS_NUMERIC( pItem ) )
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hb_retnd( -1 * hb_itemGetND( pItem ) );
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else if( IS_LOGICAL( pItem ) )
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hb_retl( ! hb_itemGetL( pItem ) );
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}
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}
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