py: Add iter_buf to getiter type method.

Allows to iterate over the following without allocating on the heap:
- tuple
- list
- string, bytes
- bytearray, array
- dict (not dict.keys, dict.values, dict.items)
- set, frozenset

Allows to call the following without heap memory:
- all, any, min, max, sum

TODO: still need to allocate stack memory in bytecode for iter_buf.

1 files changed, 6 insertions, 5 deletions

diff --git a/py/objrange.c b/py/objrange.c
index 79459316b..dd074a98a 100644
--- a/py/objrange.c
+++ b/py/objrange.c
@@ -55,12 +55,13 @@ STATIC mp_obj_t range_it_iternext(mp_obj_t o_in) {
 STATIC const mp_obj_type_t range_it_type = {
     { &mp_type_type },
     .name = MP_QSTR_iterator,
-    .getiter = mp_identity,
+    .getiter = mp_identity_getiter,
     .iternext = range_it_iternext,
 };
 
-STATIC mp_obj_t mp_obj_new_range_iterator(mp_int_t cur, mp_int_t stop, mp_int_t step) {
-    mp_obj_range_it_t *o = m_new_obj(mp_obj_range_it_t);
+STATIC mp_obj_t mp_obj_new_range_iterator(mp_int_t cur, mp_int_t stop, mp_int_t step, mp_obj_iter_buf_t *iter_buf) {
+    assert(sizeof(mp_obj_range_it_t) <= sizeof(mp_obj_iter_buf_t));
+    mp_obj_range_it_t *o = (mp_obj_range_it_t*)iter_buf;
     o->base.type = &range_it_type;
     o->cur = cur;
     o->stop = stop;
@@ -161,9 +162,9 @@ STATIC mp_obj_t range_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
     }
 }
 
-STATIC mp_obj_t range_getiter(mp_obj_t o_in) {
+STATIC mp_obj_t range_getiter(mp_obj_t o_in, mp_obj_iter_buf_t *iter_buf) {
     mp_obj_range_t *o = MP_OBJ_TO_PTR(o_in);
-    return mp_obj_new_range_iterator(o->start, o->stop, o->step);
+    return mp_obj_new_range_iterator(o->start, o->stop, o->step, iter_buf);
 }