Category : Word Processors
Archive   : STEVIE.ZIP
Filename : PTRFUNC.C

/*
* STevie - ST editor for VI enthusiasts. ...Tim Thompson...twitch!tjt...
*
* Extensive modifications by: Tony Andrews onecom!wldrdg!tony
*
*/

#include "stevie.h"

/*
* The routines in this file attempt to imitate many of the operations
* that used to be performed on simple character pointers and are now
* performed on LPTR's. This makes it easier to modify other sections
* of the code. Think of an LPTR as representing a position in the file.
* Positions can be incremented, decremented, compared, etc. through
* the functions implemented here.
*/

/*
* inc(p)
*
* Increment the line pointer 'p' crossing line boundaries as necessary.
* Return 1 when crossing a line, -1 when at end of file, 0 otherwise.
*/
int
inc(lp)
register LPTR *lp;
{
register char *p = &(lp->linep->s[lp->index]);

if (*p != NUL) { /* still within line */
lp->index++;
return ((p[1] != NUL) ? 0 : 1);
}

if (lp->linep->next != Fileend->linep) { /* there is a next line */
lp->index = 0;
lp->linep = lp->linep->next;
return 1;
}

return -1;
}

/*
* dec(p)
*
* Decrement the line pointer 'p' crossing line boundaries as necessary.
* Return 1 when crossing a line, -1 when at start of file, 0 otherwise.
*/
int
dec(lp)
register LPTR *lp;
{
if (lp->index > 0) { /* still within line */
lp->index--;
return 0;
}

if (lp->linep->prev != NULL) { /* there is a prior line */
lp->linep = lp->linep->prev;
lp->index = strlen(lp->linep->s);
return 1;
}

return -1; /* at start of file */
}

/*
* gchar(lp) - get the character at position "lp"
*/
int
gchar(lp)
register LPTR *lp;
{
return (lp->linep->s[lp->index]);
}

/*
* pchar(lp, c) - put character 'c' at position 'lp'
*/
void
pchar(lp, c)
register LPTR *lp;
char c;
{
lp->linep->s[lp->index] = c;
}

/*
* pswap(a, b) - swap two position pointers
*/
void
pswap(a, b)
register LPTR *a, *b;
{
LPTR tmp;

tmp = *a;
*a = *b;
*b = tmp;
}

/*
* Position comparisons
*/

bool_t
lt(a, b)
register LPTR *a, *b;
{
register int an, bn;

an = LINEOF(a);
bn = LINEOF(b);

if (an != bn)
return (an < bn);
else
return (a->index < b->index);
}

bool_t
gt(a, b)
LPTR *a, *b;
{
register int an, bn;

an = LINEOF(a);
bn = LINEOF(b);

if (an != bn)
return (an > bn);
else
return (a->index > b->index);
}

bool_t
equal(a, b)
register LPTR *a, *b;
{
return (a->linep == b->linep && a->index == b->index);
}

bool_t
ltoreq(a, b)
register LPTR *a, *b;
{
return (lt(a, b) || equal(a, b));
}

bool_t
gtoreq(a, b)
LPTR *a, *b;
{
return (gt(a, b) || equal(a, b));
}