import-wisdom-from-file.c

/*
 * Copyright (c) 2003, 2007-14 Matteo Frigo
 * Copyright (c) 2003, 2007-14 Massachusetts Institute of Technology
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include "api.h"
#include <stdio.h>

/* getc()/putc() are *unbelievably* slow on linux.  Looks like glibc
   is grabbing a lock for each call to getc()/putc(), or something
   like that.  You pay the price for these idiotic posix threads
   whether you use them or not.

   So, we do our own buffering.  This completely defeats the purpose
   of having stdio in the first place, of course.
*/
  
#define BUFSZ 256

typedef struct {
     scanner super;
     FILE *f;
     char buf[BUFSZ];
     char *bufr, *bufw;
} S;

static int getchr_file(scanner * sc_)
{
     S *sc = (S *) sc_;

     if (sc->bufr >= sc->bufw) {
	  sc->bufr = sc->buf;
	  sc->bufw = sc->buf + fread(sc->buf, 1, BUFSZ, sc->f);
	  if (sc->bufr >= sc->bufw)
	       return EOF;
     }

     return *(sc->bufr++);
}

static scanner *mkscanner_file(FILE *f)
{
     S *sc = (S *) X(mkscanner)(sizeof(S), getchr_file);
     sc->f = f;
     sc->bufr = sc->bufw = sc->buf;
     return &sc->super;
}

int X(import_wisdom_from_file)(FILE *input_file)
{
     scanner *s = mkscanner_file(input_file);
     planner *plnr = X(the_planner)();
     int ret = plnr->adt->imprt(plnr, s);
     X(scanner_destroy)(s);
     return ret;
}

int X(import_wisdom_from_filename)(const char *filename)
{
     FILE *f = fopen(filename, "r");
     int ret;
     if (!f) return 0; /* error opening file */
     ret = X(import_wisdom_from_file)(f);
     if (fclose(f)) ret = 0; /* error closing file */
     return ret;
}