Usenet 1994 October/usenetsourcesnewsgroupsinfomagicoctober1994disk2.iso/misc/volume10/get_grammar

Text File | 1990-01-08 | 5.1 KB | 224 lines

Newsgroups: comp.sources.misc
subject: v10i003: Extract a grammar from a YACC file
From: [e-mail] (Robert Lupton)
Sender: [e-mail] (Brandon S. Allbery - comp.sources.misc)

Posting-number: Volume 10, Issue 3
Submitted-by: [e-mail] (Robert Lupton)
Archive-name: get_grammar

Here's a simple programme to take a yacc (or bison) file and convert it
to a readable form by stripping out all of the C. If given the -t flag
it'll produce TeX output (and strip comments; I couldn't be bothered to
figure out how to make them look nice)

            Robert

: =-=-=-=-=-=-=-=-=-=-= Cut Here =-=-=-=-=-=-=-=-=-=-=
PATH=/bin:/usr/bin:/usr/ucb:/etc:$PATH
export PATH
echo Extracting get_grammar.c
if [ -w get_grammar.c ]; then
    echo File already exists - saving as get_grammar.c.old
    mv get_grammar.c get_grammar.c.old
    chmod 444 get_grammar.c.old
fi
sed 's/^X//' <<'//go.sysin dd *' >get_grammar.c
X/*
 * Extract the grammar from a set of yacc rules
 * Syntax: get_grammar [-t] [infile] [outfile]
 *
 * Options:
 *    t    write a file suitable for TeX
 *
 * If files are omitted, use standard in/output
 *
 * You are welcome to make any use you like of this code, providing that
 * my name remains on it, and that you don't make any money out of it.
 *
 *    Robert Lupton ([e-mail])
 */
#include <stdio.h>
#include <ctype.h>
#define ISSPECIAL(C) ((C) == '{' || (C) == '}' || (C) == '_' ||              \
                              (C) == '&' || (C) == '%')
#define SIZE 82

static int TeX = 0;            /* produce a TeX file? */

main(ac,av)
int ac;
char **av;
{
   char line[SIZE],
       *lptr;                /* pointer to line */
   FILE *infil = stdin,
       *outfil = stdout;
   int ctr,                /* counter for {} */
       print_on = 1,            /* Should I print line? */
       rule;                /* is this line a rule? */

   if(ac >= 2 && av[1][0] == '-') {
      if(av[1][1] == 't') {
     TeX = 1;
      } else {
     fprintf(stderr,"Unknown flag %s\n",av[1]);
      }
      ac--;
      av++;
   }

   if(ac >= 2) {
      if((infil = fopen(av[1],"r")) == NULL) {
     fprintf(stderr,"Can't open %s\n",av[1]);
     exit();
      }
   }
   if(ac >= 3) {
      if((outfil = fopen(av[2],"w")) == NULL) {
     fprintf(stderr,"Can't open %s\n",av[2]);
     fclose(infil);
     exit();
      }
   }

   if(TeX) {
      fprintf(outfil,"%\n% YACC grammar from %s\n%\n",(ac > 1)?av[1]:"?");
      fprintf(outfil,
          "{\\tt\\obeylines\\obeyspaces\\parskip=0pt\\parindent=0pt\n");
      fprintf(outfil,"\\settabs\\+\\ \\ \\ \\ \\ \\ &\\cr\n");
   }

   while(fgets(line,SIZE,infil) != NULL) {
      rule = 0;
      if(line[0] == '%') {
     if(line[1] == '{' || line[1] == '%') {
        print_on = 0;
     } else if(line[1] == '}') {
        print_on = 1;
     }
     line_out(line,outfil);
     continue;
      }
      if(print_on) {
     line_out(line,outfil);
     continue;
      }

      lptr = line;
      if(!isspace(line[0])) {        /* probably start of new rule */
     while(*lptr != '\0' && !isspace(*lptr)) {    /* skip word */
        lptr++;
     }
     while(isspace(*lptr)) lptr++;    /* skip white space */
     if(*lptr == ':') {
        rule = 1;
     }
     lptr = line;
      }

      while(isspace(*lptr)) lptr++;    /* skip white space */
      if(rule || *lptr == '|') {    /* a rule */
     if(TeX) {
        fprintf(outfil,"\\+");
        if(isspace(line[0])) {
           fprintf(outfil,"&");
        }
     }
     if(!TeX) {            /* we don't want it for TeX */
        lptr = line;
     }
     while(*lptr != '\0') {
        while(*lptr != '\0') {
           if(TeX) {
          if(ISSPECIAL(*lptr)) {
             putc('\\',outfil);
          } else if(*lptr == '/' && *(lptr + 1) == '*') {
             while(!(*++lptr == '*' && *(lptr + 1) == '/')) ;
             if(*lptr == '*' && *(lptr + 1) == '/') lptr += 2;
          }
          if(*lptr == '\n') {
             fprintf(outfil,"\\cr");
          }
           }
           putc(*lptr,outfil);
           if(*lptr == '{' && *(lptr - 1) != '\'') {
             ctr = 0;        /* we'll see that { again */
          break;
           } else {
          lptr++;
           }
        }
        while(*lptr != '\0') {
           if(*lptr == '}') {
          if(--ctr == 0) {
             break;
          }
           } else if(*lptr == '{') {
          ctr++;
           }
           lptr++;
        }
     }
      } else if(*lptr == ';') {
     line_out(line,outfil);
     if(TeX) {
        fprintf(outfil,"\\+\\cr");
     }
     putc('\n',outfil);
      }
   }

   if(TeX) {
      fprintf(outfil,"}\n");
   }

   fclose(infil); fclose(outfil);
}


line_out(line,fil)
char *line;
FILE *fil;
{
   if(line[0] == '\0' || !TeX) {
      fputs(line,fil);
      return;
   }

   fprintf(fil,"\\+");
   if(isspace(*line)) {
      fprintf(fil,"&");
      while(isspace(*++line)) ;
   }

   for(;*line != '\0';line++) {
      if(ISSPECIAL(*line)) {
     putc('\\',fil);
      } else if(*line == '/' && *(line + 1) == '*') {
     while(!(*++line == '*' && *(line + 1) == '/')) ;
     if(*line == '*' && *(line + 1) == '/') line += 2;
      }
      if(*line == '\n') {
     break;
      }
      putc(*line,fil);
   }
   fprintf(fil,"\\cr\n");
}
//go.sysin dd *
if [ `wc -c < get_grammar.c` != 3985 ]; then
made=FALSE
echo error transmitting get_grammar.c --
echo length should be 3985, not `wc -c < get_grammar.c`
else
    made=TRUE
fi
if [ $made = TRUE ]; then
    chmod 755 get_grammar.c
    echo -n  ; ls -ld get_grammar.c
fi