/*      subst.c */
#include <stdio.h>
#include "tools.h"
#include "ed.h"

int subst(pat, sub, gflg, pflag)
TOKEN *pat;
char *sub;
int gflg, pflag;
{
  int lin, chngd, nchngd;
  char *txtptr, *txt;
  char *lastm, *m, *new, buf[MAXLINE];

  if (line1 <= 0) return(ERR);
  nchngd = 0;                   /* reset count of lines changed */
  for (lin = line1; lin <= line2; lin++) {
        txt = txtptr = gettxt(lin);
        new = buf;
        chngd = 0;
        lastm = NULL;
        while (*txtptr) {
                if (gflg || !chngd)
                        m = amatch(txtptr, pat, txt);
                else
                        m = NULL;
                if (m != NULL && lastm != m) {
                        chngd++;
                        new = catsub(txtptr, m, sub, new,
                                     buf + MAXLINE);
                        lastm = m;
                }
                if (m == NULL || m == txtptr) {
                        *new++ = *txtptr++;
                } else {
                        txtptr = m;
                }
        }
        if (chngd) {
                if (new >= buf + MAXLINE) return(ERR);
                *new++ = EOS;
                del(lin, lin);
                ins(buf);
                nchngd++;
                if (pflag) doprnt(curln, curln);
        }
  }
  if (nchngd == 0 && !gflg) {
        return(ERR);
  }
  return(nchngd);
}