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/* $Id: stack.cpp,v 1.5 2000/11/10 19:04:17 dbryson Exp $
Xbase project source code
This file contains logic for handling basic stack functions.
Copyright (C) 1997 Startech, Gary A. Kunkel
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Contact:
Mail:
Technology Associates, Inc.
XBase Project
1455 Deming Way #11
Sparks, NV 89434
USA
Email:
xbase@techass.com
See our website at:
xdb.sourceforge.net
V 1.0 10/10/97 - Initial release of software
V 1.5 1/2/97 - Added memo field support
V 1.6a 4/1/98 - Added expression support
V 1.6b 4/8/98 - Added expression support
*/
#ifdef __GNUG__
#pragma implementation "xstack.h"
#endif
#ifdef __WIN32__
#include <xbase/xbconfigw32.h>
#else
#include <xbase/xbconfig.h>
#endif
#include <xbase/xbase.h>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <xbase/xstack.h>
/*! \file stack.cpp
*/
/*************************************************************************/
//! Short description.
/*!
*/
xbStack::xbStack( void )
{
First = NULL;
Last = NULL;
Free = NULL;
StackDepth = 0;;
}
/*************************************************************************/
//! Short description.
/*!
*/
void xbStack::InitStack( void )
{
if( !First || !Last ) return;
if( Free )
{
Last->Next = Free;
Free->Previous = Last;
}
Free = First;
First = NULL;
Last = NULL;
StackDepth = 0;
return;
}
/*************************************************************************/
//! Short description.
/*!
*/
xbStackElement * xbStack::GetStackElement( void )
{
xbStackElement * Temp;
/* check the free chain for an empty Stack element, if not found,
allocate one from memory */
if( Free )
{
Temp = Free;
Free = Free->Next;
}
else
if((( Temp = (xbStackElement *) malloc( sizeof( xbStackElement )))==NULL))
return NULL;
memset( Temp, 0x00, sizeof( xbStackElement ));
return Temp;
}
/*************************************************************************/
//! Short description.
/*!
\param e
*/
void xbStack::FreeStackElement( xbStackElement * e )
{
e->Previous = NULL;
e->Next = Free;
if( Free ) Free->Previous = e;
Free = e;
}
/*************************************************************************/
//! Short description.
/*!
\param p
*/
xbShort xbStack::Push( void * p )
{
xbStackElement * Temp;
if(( Temp = GetStackElement()) == NULL )
return 102;
Temp->UserPtr = p;
if( !First )
{
First = Temp;
Last = Temp;
StackDepth = 1;
}
else
{
Last->Next = Temp;
Temp->Previous = Last;
Last = Temp;
StackDepth++;
}
return 0;
}
/*************************************************************************/
//! Short description.
/*!
*/
void * xbStack::Pop( void )
{
void * p;
xbStackElement * Save;
if( StackDepth == 0 )
return NULL;
else
{
p = Last->UserPtr;
if( StackDepth == 1 )
{
FreeStackElement( First );
First = NULL;
Last = NULL;
}
else /* number of items in Stack must be > 1 */
{
Last->Previous->Next = NULL;
Save = Last;
Last = Last->Previous;
FreeStackElement( Save );
}
StackDepth--;
return p;
}
}
/*************************************************************************/
//! Short description.
/*!
*/
#ifdef XBASE_DEBUG
void xbStack::DumpStack( void )
{
xbStackElement * e;
if( StackDepth == 0 )
{
std::cout << "\nStack is empty...";
return;
}
std::cout << "\nThere are " << StackDepth << " entries.";
std::cout << "\nFirst = " << First << " Last = " << Last;
e = First;
while( e )
{
std::cout << "\n*****************************";
std::cout << "\nThis = " << e;
std::cout << "\nNext = " << e->Next;
std::cout << "\nPrevious = " << e->Previous;
std::cout << "\nUser Pointer = " << e->UserPtr;
e = e->Next;
}
std::cout << "\nFree list follows...";
e = Free;
while( e )
{
std::cout << "\n*****************************";
std::cout << "\nThis = " << e;
std::cout << "\nNext = " << e->Next;
std::cout << "\nPrevious = " << e->Previous;
std::cout << "\nUser Pointer = " << e->UserPtr;
e = e->Next;
}
return;
}
#endif
/*************************************************************************/
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