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/******************************************************************************
*H* ValueStack.m {Maintain push down stack of double values } V0.0, 09-FEB-91 *
*C* V0.0 09-FEB-91 Initial version --MDM *
******************************************************************************/
/* Standard C Library includes */
#import <stdio.h> /* Standard I/O functions and definitions */
#import <stdlib.h> /* Standard C memory allocation prototypes */
#import "ValueStack.h" /* ValueStack interface specification */
@implementation ValueStack
/* Private Object Wide Definitions */
#define OCnullStack (OTvalueStackItem *) 0
/******************************************************************************
* METHOD:- init *
* Initialize a new instance of a ValueStack class. *
******************************************************************************/
- init
{/* BEGIN:-init */
self = [super init];
OVstackTop = OCnullStack;
return self;
}/* END:-init */
/******************************************************************************
*** I N S T A N C E M E T H O D S ***
******************************************************************************/
/******************************************************************************
* METHOD:- free *
* All data currently on the ValueStack is poped and freed, returning the *
* allocated memory back to the system pool. *
******************************************************************************/
- free
{ /* Local Variables */
OTvalueStackItem *tmp_blink;
/* BEGIN free */
while (OVstackTop != OCnullStack)
{/* Get pointer to lower stack item and free top item */
tmp_blink = OVstackTop->blink;
free( (char *) OVstackTop );
OVstackTop = tmp_blink;
OVstackSize = 0;
}
/* Request super class to perform its free method */
return [super free];
}/* END free */
/******************************************************************************
* METHOD:- ClearStack *
* Pop and free each element on the stack until the stack is empty. *
******************************************************************************/
- ClearStack
{ /* Local Variables */
OTvalueStackItem *tmp_blink;
/* BEGIN ClearStack */
while ( OVstackTop )
{/* Stack is not empty, free top item */
tmp_blink = OVstackTop->blink;
free ( (char *) OVstackTop );
OVstackTop = tmp_blink;
}
OVstackSize = 0;
return self;
}/* END ClearStack */
/******************************************************************************
* METHOD:- GetSize *
* Return the current number of items in the Value Stack. *
******************************************************************************/
- (unsigned long) GetSize
{/* BEGIN GetSize */
return OVstackSize;
}/* END GetSize */
/******************************************************************************
* METHOD:- Peek *
* Return the value on the top of the stack without removing it from the *
* stack. *
******************************************************************************/
- Peek: (double *) value
{/* BEGIN Peek */
if ( OVstackTop )
{/* The stack is not empty return top stack value */
*value = OVstackTop->value;
return self;
}
else
{/* Report illegal reference to standard error */
#ifdef DEBUG
fprintf(stderr, "ValueStack: Peek on empty stack returning 0.0\n");
#endif
*value = 0.0;
return nil;
}
}/* END Peek */
/******************************************************************************
* METHOD:- Pop *
* Return the value on the top of the stack and free top stack item. *
******************************************************************************/
- Pop: (double *) value
{ /* Local Variables */
OTvalueStackItem *tmp_blink;
/* BEGIN Pop */
if ( OVstackTop )
{/* Stack is not empty, free top item and return top value */
*value = OVstackTop->value;
tmp_blink = OVstackTop->blink;
free ( (char *) OVstackTop );
OVstackTop = tmp_blink;
OVstackSize--;
return self; /* successful status */
}
else
{/* Stack is empty report error, return 0.0 */
#ifdef DEBUG
fprintf(stderr, "ValueStack: Pop on empty stack returning 0.0\n");
#endif
*value = 0.0;
return nil; /* failure status */
}
}/* END Pop */
/******************************************************************************
* METHOD:- Push *
* Push a double float value on the stack. We allocate a new stack item *
* setting its value field to the supplied value and its blink field to point *
* to the current stack top. If a new stack item cannot be allocated an error *
* message is written to stderr. *
******************************************************************************/
- Push: (double) value
{ /* Local Variables */
OTvalueStackItem *new_item;
/* BEGIN Push */
/* Allocate a new stack item */
new_item = (OTvalueStackItem *) malloc(sizeof(OTvalueStackItem));
if ( new_item )
{/* New stack item allocated, initialize and link in new stack top */
new_item->value = value;
new_item->blink = OVstackTop;
OVstackTop = new_item;
OVstackSize++;
return self;
}
else
{/* Allocation failed, report error to stderr */
#ifdef DEBUG
fprintf(stderr, "ValueStack: Push allocation failure\n");
#endif
return nil;
}
}/* END Push */
/******************************************************************************
* METHOD:- PrintStack *
* Print out the contents of the stack to standard output. *
******************************************************************************/
- PrintStack
{ /* Local Variables */
OTvalueStackItem *trace_link;
long level;
/* BEGIN PrintStack */
if ( OVstackTop )
{/* The stack is not empty so dump its contents */
trace_link = OVstackTop;
level = 0;
while ( trace_link )
{/* Not at bottom, print this item */
#ifdef DEBUG
printf("%2f : (%ld)\n", trace_link->value, level--);
#endif
trace_link = trace_link->blink;
}
}
else
{/* Stack is empty so print a message */
#ifdef DEBUG
printf("ValueStack: stack empty\n");
#endif
}
return self;
}/* END PrintStack */
@end /* ValueStack Implementation */
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.