diff options
Diffstat (limited to 'hash.c')
| -rw-r--r-- | hash.c | 31 |
1 files changed, 31 insertions, 0 deletions
@@ -1735,6 +1735,36 @@ val hash_revget(val hash, val value, val test, val keyfun) return nil; } +val hash_invert(val hash, val joinfun, val unitfun, struct args *hashv_args) +{ + val self = lit("hash-invert"); + val hout = hashv(hashv_args); + val iter = hash_begin(hash); + val jfun = default_arg(joinfun, identity_star_f); + val ufun = default_arg(unitfun, identity_f); + val cell; + + if (jfun == identity_star_f && ufun == identity_f) { + while ((cell = hash_next(iter)) != nil) { + us_cons_bind(k, v, cell); + sethash(hout, v, k); + } + } else { + while ((cell = hash_next(iter)) != nil) { + us_cons_bind(k, v, cell); + val new_p; + loc place = gethash_l(self, hout, v, mkcloc(new_p)); + val ukey = funcall1(ufun, k); + if (new_p) + set(place, ukey); + else + set(place, funcall2(jfun, deref(place), ukey)); + } + } + + return hout; +} + static val set_hash_traversal_limit(val lim) { val old = num(hash_traversal_limit); @@ -1809,6 +1839,7 @@ void hash_init(void) reg_fun(intern(lit("hash-update-1"), user_package), func_n4o(hash_update_1, 3)); reg_fun(intern(lit("hash-revget"), user_package), func_n4o(hash_revget, 2)); + reg_fun(intern(lit("hash-invert"), user_package), func_n3ov(hash_invert, 1)); reg_fun(intern(lit("hash-begin"), user_package), func_n1(hash_begin)); reg_fun(intern(lit("hash-next"), user_package), func_n1(hash_next)); reg_fun(intern(lit("hash-peek"), user_package), func_n1(hash_peek)); |