local_variables

static VALUE
rb_f_local_variables(void)
{
    VALUE ary = rb_ary_new();
    rb_thread_t *th = GET_THREAD();
    rb_control_frame_t *cfp =
        vm_get_ruby_level_caller_cfp(th, RUBY_VM_PREVIOUS_CONTROL_FRAME(th->cfp));
    int i;

    while (cfp) {
        if (cfp->iseq) {
            for (i = 0; i < cfp->iseq->local_table_size; i++) {
                ID lid = cfp->iseq->local_table[i];
                if (lid) {
                    const char *vname = rb_id2name(lid);
                    /* should skip temporary variable */
                    if (vname) {
                        rb_ary_push(ary, ID2SYM(lid));
                    }
                }
            }
        }
        if (cfp->lfp != cfp->dfp) {
            /* block */
            VALUE *dfp = GC_GUARDED_PTR_REF(cfp->dfp[0]);

            if (vm_collect_local_variables_in_heap(th, dfp, ary)) {
                break;
            }
            else {
                while (cfp->dfp != dfp) {
                    cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
                }
            }
        }
        else {
            break;
        }
    }
    return ary;
}