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PTRFUNC.C
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C/C++ Source or Header
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1992-07-28
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3KB
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118 lines
/* Copyright (c) 1990,1991,1992 Chris and John Downey */
#ifndef lint
static char *sccsid = "@(#)ptrfunc.c 2.2 (Chris & John Downey) 8/28/92";
#endif
/***
* program name:
xvi
* function:
PD version of UNIX "vi" editor, with extensions.
* module name:
ptrfunc.c
* module function:
Primitive functions on "Posn"s.
* history:
STEVIE - ST Editor for VI Enthusiasts, Version 3.10
Originally by Tim Thompson (twitch!tjt)
Extensive modifications by Tony Andrews (onecom!wldrdg!tony)
Heavily modified by Chris & John Downey
***/
#include "xvi.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 Posn's. This makes it easier to modify other sections
* of the code. Think of a Posn as representing a position in the file.
* Posns can be incremented, decremented, compared, etc. through the
* functions implemented here.
*
* Note that some functions are now implemented as macros, in ptrfunc.h.
*/
/*
* inc(p)
*
* Increment the line pointer 'p' crossing line boundaries as
* necessary. Return mv_CHLINE when crossing a line, mv_NOMOVE when at
* end of file, mv_SAMELINE otherwise.
*/
enum mvtype
inc(lp)
register Posn *lp;
{
register char *p;
p = &(lp->p_line->l_text[lp->p_index]);
if (*p != '\0') { /* still within line */
lp->p_index++;
return((p[1] != '\0') ? mv_SAMELINE : mv_EOL);
}
if (!is_lastline(lp->p_line->l_next)) {
lp->p_index = 0;
lp->p_line = lp->p_line->l_next;
return(mv_CHLINE);
}
return(mv_NOMOVE);
}
/*
* dec(p)
*
* Decrement the line pointer 'p' crossing line boundaries as
* necessary. Return mv_CHLINE when crossing a line, mv_NOMOVE when at
* start of file, mv_SAMELINE otherwise.
*/
enum mvtype
dec(lp)
register Posn *lp;
{
if (lp->p_index > 0) { /* still within line */
lp->p_index--;
return(mv_SAMELINE);
}
if (!is_line0(lp->p_line->l_prev)) {
lp->p_line = lp->p_line->l_prev;
lp->p_index = strlen(lp->p_line->l_text);
return(mv_CHLINE);
}
return(mv_NOMOVE); /* at start of file */
}
/*
* pswap(a, b) - swap two position pointers.
*/
void
pswap(a, b)
register Posn *a, *b;
{
register Posn tmp;
tmp = *a;
*a = *b;
*b = tmp;
}
/*
* Posn comparisons.
*/
bool_t
lt(a, b)
register Posn *a, *b;
{
if (a->p_line != b->p_line) {
return(earlier(a->p_line, b->p_line));
} else {
return(a->p_index < b->p_index);
}
}