Hash#rehash

VALUE
rb_hash_rehash(VALUE hash)
{
    VALUE tmp;
    st_table *tbl;

    if (hash_iterating_p(hash)) {
        rb_raise(rb_eRuntimeError, "rehash during iteration");
    }
    rb_hash_modify_check(hash);
    if (RHASH_AR_TABLE_P(hash)) {
        tmp = hash_alloc_capa(0, RHASH_SIZE(hash));
        if (RHASH_IDENTHASH_P(hash)) {
            FL_SET_RAW(tmp, RHASH_COMPARE_BY_IDENTITY);
        }
        rb_hash_foreach(hash, rb_hash_rehash_i, (VALUE)tmp);

        hash_ar_free_and_clear_table(hash);
        ar_copy(hash, tmp);
    }
    else if (RHASH_ST_TABLE_P(hash)) {
        st_table *old_tab = RHASH_ST_TABLE(hash);
        tmp = hash_alloc_capa(0, 0);
        if (old_tab->type == &identhash) {
            FL_SET_RAW(tmp, RHASH_COMPARE_BY_IDENTITY);
        }

        hash_st_table_init(tmp, old_tab->num_entries);
        RHASH_ST_TABLE(tmp)->type = old_tab->type;
        tbl = RHASH_ST_TABLE(tmp);

        rb_hash_foreach(hash, rb_hash_rehash_i, (VALUE)tmp);

        hash_st_free(hash);
        rb_hash_st_table_set(hash, tbl);
        RHASH_ST_CLEAR(tmp);
    }
    hash_verify(hash);
    return hash;
}