ack/util/topgen/symtab.c

/* $Id$ */
/*
 * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
 * See the copyright notice in the ACK home directory, in the file "Copyright".
 */
/* s y m t a b . c 
 *
 * Contains the routine findident, which builds the symbol table and
 * searches identifiers
 */

#include <stdlib.h>
#include <string.h>
#include "symtab.h"

struct symtab *idtable, *deftable;

extern void error(char *s, char* s1);

struct symtab * findident(char *s, int mode, struct symtab **table)
{
	/*
	 * Look for identifier s in the symboltable referred to by *table.
	 * If mode = LOOKING, no new entry's will be made.
	 * If mode = ENTERING, a new entry will be made if s is not in the
	 * table yet, otherwise an error results
	 */
	register struct symtab *p;
	register int n;

	if (!*table)
	{ /* No entry for this symbol */
		if (mode == LOOKING)
			return (struct symtab *) 0;
		/*
		 * Make new entry
		 */
		p = (struct symtab *) malloc(sizeof *p);
		p->s_left = p->s_right = (struct symtab *) 0;
		p->s_name = malloc((unsigned) (strlen(s) + 1));
		strcpy(p->s_name, s);
		*table = p;
		return p;
	}
	else
	{
		p = *table;
		if ((n = strcmp(p->s_name, s)) == 0)
		{ /* This is it! */
			if (mode == ENTERING)
			{
				error("Identifier %s redefined", s);
			}
			return p;
		}
		/* Binary tree ..... */
		if (n < 0)
			return findident(s, mode, &(p->s_left));
		return findident(s, mode, &(p->s_right));
	}
	/* NOTREACHED */
}