source: trunk/minix/commands/m4/look.c@ 15

/*
 * look.c
 * Facility: m4 macro processor
 * by: oz
 */

#include "mdef.h"
#include "extr.h"

/*
 *  hash - compute hash value using the proverbial
 *         hashing function. Taken from K&R.
 */
int hash (name)
register char *name;
{
        register int h = 0;
        while (*name)
                h += *name++;
        return (h % HASHSIZE);
}

/*
 * lookup - find name in the hash table
 *
 */
ndptr lookup(name)
char *name;
{
        register ndptr p;

        for (p = hashtab[hash(name)]; p != nil; p = p->nxtptr)
                if (strcmp(name, p->name) == 0)
                        break;
        return (p);
}

/*
 * addent - hash and create an entry in the hash
 *          table. The new entry is added in front
 *          of a hash bucket.
 */
ndptr addent(name)
char *name;
{
        register int h;
        ndptr p;

        h = hash(name);
        if ((p = (ndptr) malloc(sizeof(struct ndblock))) != NULL) {
                p->nxtptr = hashtab[h];
                hashtab[h] = p;
                p->name = strsave(name);
        }
        else
                error("m4: no more memory.");
        return p;
}

/*
 * remhash - remove an entry from the hashtable
 *
 */
void remhash(name, all)
char *name;
int all;
{
        register int h;
        register ndptr xp, tp, mp;

        h = hash(name);
        mp = hashtab[h];
        tp = nil;
        while (mp != nil) {
                if (strcmp(mp->name, name) == 0) {
                        mp = mp->nxtptr;
                        if (tp == nil) {
                                freent(hashtab[h]);
                                hashtab[h] = mp;
                        }
                        else {
                                xp = tp->nxtptr;
                                tp->nxtptr = mp;
                                freent(xp);
                        }
                        if (!all)
                                break;
                }
                else {
                        tp = mp;
                        mp = mp->nxtptr;
                }
        }
}

/*
 * freent - free a hashtable information block
 *
 */
void freent(p)
ndptr p;
{
        if (!(p->type & STATIC)) {
                free(p->name);
                if (p->defn != null)
                        free(p->defn);
        }
        free(p);
}