ack/util/LLgen/src/savegram.c

/* Copyright (c) 1991 by the Vrije Universiteit, Amsterdam, the Netherlands.
 * All rights reserved.
 */

#ifdef NON_CORRECTING

/*
 *  L L G E N
 *
 *  An Extended LL(1) Parser Generator
 *
 *  Author : Ceriel J.H. Jacobs
 */

/*
 * savegram.c
 * Save the input grammar for non-correcting error recovery
 *
 * Grammar rules are `flattened' by introducing anonymous nonterminals.
 * [B]? becomes X; X: B | {empty}
 * [B]+ becomes X: B Y; Y: X | {empty}
 * [B]* becomes X; X: B X | {empty}
 * [B | C] becomes X; X: B | C
 * [B | C]* becomes X; X: B X | C X | {empty}  etc.
 */


#include <stdlib.h>
#include  <stdio.h>
# include "types.h"
# include "extern.h"
# include "io.h"
# include "assert.h"
# include "sets.h"

#define LLALT 9999

static int nt_highest;
extern int nbytes;
extern p_mem alloc();
extern p_set start_firsts;
extern p_set setalloc();
extern p_gram search();

STATIC void save_rule();
STATIC void save_set();

/* t_list will contain terms to be `flattened' */
static struct t_list {
	p_term term;
	int t_nt_num;
} *t_list;

/* Subparse list will contain symbols in %substart */
static struct subparse_list {
	p_gram sub_action;
	int sub_nt_num;
} *sub_list;

/* Index in t_list */
static int t_list_index;

/* Index in subparse_list */
static int sub_list_index;

/* File to save grammar to */
static FILE *fgram;

/* Nonterminal number to simulate parsers that get called in actions
   used when LLgen called with -n -s options */
int act_nt;

void save_grammar(FILE *f)
{
	/*
	 * Save the grammar
	 */
	register p_nont		p;
	register p_start	st;
	register int		nt_nr;

	fgram = f;

	/* Compute highest nonterminal nr. */
	nt_highest = nnonterms + assval - 1;


	/* Generate some constants in the grammar file */

	/* Allocate terms list */
	t_list = (struct t_list *) alloc(nterms * sizeof(struct t_list));
	t_list_index = 0;

	sub_list = (struct subparse_list *) alloc(nsubstarts * sizeof(struct subparse_list));

	fputs("static ", fgram);
	fputs((prefix ? prefix : "LL"), fgram);
	fputs("grammar[] = {\n", fgram);

	/* Check if -n -s option is on */
	if (subpars_sim) {

		/* Allocate action simulation nt */

		act_nt = ++nt_highest;

		/* write simualtion rule */
		fprintf(fgram, "/* Simulation rule */\n");
		fprintf(fgram, "%d,\n", act_nt);

		/* Put a firstset and a fake followset */
		/* Followset optimization is not implemented for
		   -s because it would be hard, and does not
		   bring enough improvement to jutify the effort
		 */
		save_set(start_firsts);
		save_set(start_firsts);
		/* Simulation rule procudes empty */
		fprintf(fgram, "%d,\n", 1);
		for (st = start; st; st = st->ff_next)
		{
			fprintf(fgram, "%d, %d, %d, \n", st->ff_nont + assval,
								act_nt, LLALT);
		}
		fprintf(fgram, "%d, \n", 0);

	}

	/* Now process all rules */
	for (p = nonterms, nt_nr = assval; p < maxnt; p++, nt_nr++) {
		fprintf(fgram, "/* nr. %d %s */\n", nt_nr, p->n_name);
		fprintf(fgram, "%d, ",nt_nr);
		if (! p->n_rule) {	/* undefined */
			f_input = p->n_string;
			error(p->n_lineno,"Nonterminal %s not defined",
				p->n_name);
		}

		/* Save the first_set and follow set */
		save_set(p->n_nc_first);
		save_set(p->n_nc_follow);

		if (p->n_flags & EMPTY)
			fprintf(fgram, "%d,\n", 1);
		else
			fprintf(fgram, "%d,\n", 0);

		save_rule(p->n_rule, 0);

		fprintf(fgram, "%d,\n", 0);
	}

	/* Resolve terms, they are on t_list */

	fprintf(fgram, "/* Fresh nonterminals */\n");

	{ int i;
	for (i = 0; i < t_list_index; i++)
	{

	/* Terms of the form [] without + ? * or number produce
	 a NIL pointer in the term-list */
		if ((t_list + i)->term == (struct term *) 0) {
			continue;
		}

		fprintf(fgram, "%d, ", (t_list + i)->t_nt_num);

		/* Save the first and follow sets */

		save_set((t_list + i)->term->t_nc_first);
		save_set((t_list + i)->term->t_nc_follow);

		/* NOTE: A VARIABLE REPETITION COUNT TERMS RULE IS NOT
		   ALLOWED TO PRODUCE EMPTY IN LLGEN
		 */

		switch(r_getkind((t_list + i)->term)) {
		case FIXED:
		/* Already done by repeating new nonterminal */

			/* FIXED term-rule may produce empty */
			if (empty((t_list +i)->term->t_rule))
				fprintf(fgram, "%d,\n", 1);
			else
				fprintf(fgram, "%d,\n", 0);

			save_rule((t_list + i)->term->t_rule, 0);
			fprintf(fgram, "%d,\n", 0);
			break;
		case STAR:
		/* Save the rule, appending the new lhs for this rule */

			/* Star rules always produce empty */
			fprintf(fgram, "1,\n");

			save_rule((t_list + i)->term->t_rule,
						(t_list + i)->t_nt_num);
			fprintf(fgram, "%d,\n%d,\n", LLALT, 0);
			/* ALT EMPTY*/
			break;
		case PLUS:
		/* Save the rule appending a fresh nonterminal */

			fprintf(fgram, "%d,\n", 0);

			save_rule((t_list + i)->term->t_rule, ++nt_highest);
			fprintf(fgram, "%d,\n", 0); /* EOR */
			fprintf(fgram, "%d, ", nt_highest);
			/* First set of the extra nonterm is same as
			   for the term */
			/* Except that the new nonterm also produces empty ! */
			save_set((t_list + i)->term->t_nc_first);
			save_set((t_list + i)->term->t_nc_follow);
			fprintf(fgram, "1,\n");
			fprintf(fgram, "%d, ", (t_list+i)->t_nt_num);
			fprintf(fgram, "%d,\n%d,\n", LLALT, 0); /* ALT EMPTY */
			break;
		case OPT:
			fprintf(fgram, "1,\n");
			save_rule((t_list + i)->term->t_rule, 0);
			fprintf(fgram, "%d,\n%d,\n", LLALT, 0); /* ALT EMPTY */
			break;
		}
	}
	}

	/* Resolve %substarts */
	if (!subpars_sim) {
		int i,s,check;
		p_start ff, gg;
		p_set temp_set;

		for (i = 0; i < sub_list_index; i++) {
			fprintf(fgram, "%d, ", (sub_list + i)->sub_nt_num);
			/* Compute the first set */
			temp_set = setalloc();
			for (ff = g_getsubparse((sub_list + i)->sub_action);
							ff; ff = ff->ff_next){
			s = setunion(temp_set,
					(&nonterms[ff->ff_nont])->n_first);
			check = 0;
			for (gg =start; gg; gg = gg->ff_next)
				if (ff->ff_nont == gg->ff_nont)
					check = 1;
			if (check == 0)
			warning((sub_list + i)->sub_action->g_lineno,
					"\"%s\" is not a startsymbol",
					(&nonterms[ff->ff_nont])->n_name);
		}
		save_set(temp_set);
		save_set(temp_set);
		free(temp_set);

		/* Produces empty */
		fprintf(fgram, "1,\n");

		ff = g_getsubparse((sub_list + i)->sub_action);

		for (; ff; ff = ff->ff_next)
			fprintf(fgram, "%d, %d, %d, \n", ff->ff_nont + assval,
						(sub_list + i)->sub_nt_num,
									LLALT);
		fprintf(fgram, "%d, \n", 0);
		}
	}

	fprintf(fgram, "%d\n};\n", 0);
	fprintf(fgram, "#define LLNNONTERMINALS %d\n", nt_highest - assval + 1);
}

STATIC void save_rule(register p_gram p, int tail)
{
/*
 Walk through rule p, saving it. The non-terminal tail is
 appended to the rule. It needs to be appended in this function
 to process alt-rules correctly. Tail == 0 means don't append.
 */

	int in_alt;
	int illegal_num;
	/* Processing an alt needs some special care. When processing the
	   first alternative, we don't want to write the alt-code;
	   When appending something to the alt, it needs to be appended to
	   every alternative and not at the end of the rule.
	*/

	/* Look up the ILLEGAL token number */
	illegal_num = tokens[g_getcont(illegal_gram)].t_tokno;

	in_alt = 0;
	for (;;) {
		switch(g_gettype(p)) {
		case ALTERNATION :
			if (in_alt)
				fprintf(fgram, "%d,\n", LLALT);
			else
				in_alt = 1;
			save_rule(g_getlink(p)->l_rule, tail);
			break;
		case TERM :
			/* Make entry in term list */
			(t_list + t_list_index)->term = g_getterm(p);
			/* Test for [] without specifier */
			if (g_getterm(p) == (struct term *) 0) {
				t_list_index++;
				break;
			}
			(t_list + t_list_index++)->t_nt_num = ++nt_highest;
			fprintf(fgram, "%d, ", nt_highest);
			/* Check if repetition,	 if so handle here */
			if (r_getkind(g_getterm(p)) == FIXED)
			{
				int k;
				for (k = 1; k < r_getnum(g_getterm(p)); k++)
					fprintf(fgram, "%d, ", nt_highest);
			}
			break;
		case NONTERM :
			fprintf(fgram, "%d, ", g_getcont(p) + assval);
			break;
		case TERMINAL:
			if (g_getcont(p) == g_getcont(illegal_gram)) {
				/* %illegal. Ignore. */
				break;
			}
			if (p->g_erroneous)
				fprintf(fgram, "%d, ", illegal_num);
			else
				fprintf(fgram, "%d, ",
						tokens[g_getcont(p)].t_tokno);
			break;
		case LITERAL:
			if (p->g_erroneous)
				fprintf(fgram, "%d, ", illegal_num);
			else
				fprintf(fgram, "%d, ",
						tokens[g_getcont(p)].t_tokno);
			break;
		case ACTION:
			if (subpars_sim) {
				fprintf(fgram, "%d, ", act_nt);
			}
			else if (g_getsubparse(p)) {
				/* Allocate nonterminal that will simulate
				   subparser
				 */
				(sub_list + sub_list_index)->sub_nt_num =
								++nt_highest;
				(sub_list + sub_list_index++)->sub_action = p;

				fprintf(fgram, "%d, ", nt_highest);
			}
			break;
		case EORULE :
			if ((! in_alt) && tail )
			/* If this rule is not an alt, append tail now.
			   If it is an alt, the recursive call of this function
			   has appended tail to each alternative
			 */
			fprintf(fgram, "%d, ", tail);
			return;
		}
		p++;
	}
}

STATIC void save_set(p_set p)
{
	register int k;
	register unsigned i;
	int j;

	j = nbytes;
	for (;;) {
		i = (unsigned) *p++;
		for (k = 0; k < sizeof(int); k++) {
			fprintf(fgram,"0%o,",(int)(i & 0377));
			i >>= 8;
			if (--j == 0) {
				fputs("\n",fgram);
				return;
			}
		}
	}
	/* NOTREACHED */
}
#endif