commit ae8d86758631e62466a55d179897d2111c3cb1c1
author Damien George <damien.p.george@gmail.com> Sat Jan 09 23:14:54 2016 +0000
committer Damien George <damien.p.george@gmail.com> Thu Feb 16 18:38:06 2017 +1100
tree 1852733b57cd4334727203e11d5af76243615636
parent 101886f5291fdbef07ba70d386c5e3e644b71cfb

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.

py/objdict.c

diff --git a/py/objdict.c b/py/objdict.c
index 640df7b..c52403f 100644
--- a/py/objdict.c
+++ b/py/objdict.c
@@ -210,8 +210,9 @@
     }
 }
 
-STATIC mp_obj_t dict_getiter(mp_obj_t self_in) {
-    mp_obj_dict_it_t *o = m_new_obj(mp_obj_dict_it_t);
+STATIC mp_obj_t dict_getiter(mp_obj_t self_in, mp_obj_iter_buf_t *iter_buf) {
+    assert(sizeof(mp_obj_dict_it_t) <= sizeof(mp_obj_iter_buf_t));
+    mp_obj_dict_it_t *o = (mp_obj_dict_it_t*)iter_buf;
     o->base.type = &mp_type_polymorph_iter;
     o->iternext = dict_it_iternext;
     o->dict = self_in;
@@ -249,7 +250,8 @@
 
 // this is a classmethod
 STATIC mp_obj_t dict_fromkeys(size_t n_args, const mp_obj_t *args) {
-    mp_obj_t iter = mp_getiter(args[1]);
+    mp_obj_iter_buf_t iter_buf;
+    mp_obj_t iter = mp_getiter(args[1], &iter_buf);
     mp_obj_t value = mp_const_none;
     mp_obj_t next = MP_OBJ_NULL;
 
@@ -375,10 +377,12 @@
             }
         } else {
             // update from a generic iterable of pairs
-            mp_obj_t iter = mp_getiter(args[1]);
+            mp_obj_iter_buf_t iter_buf;
+            mp_obj_t iter = mp_getiter(args[1], &iter_buf);
             mp_obj_t next = MP_OBJ_NULL;
             while ((next = mp_iternext(iter)) != MP_OBJ_STOP_ITERATION) {
-                mp_obj_t inneriter = mp_getiter(next);
+                mp_obj_iter_buf_t inner_iter_buf;
+                mp_obj_t inneriter = mp_getiter(next, &inner_iter_buf);
                 mp_obj_t key = mp_iternext(inneriter);
                 mp_obj_t value = mp_iternext(inneriter);
                 mp_obj_t stop = mp_iternext(inneriter);
@@ -457,14 +461,15 @@
 STATIC const mp_obj_type_t dict_view_it_type = {
     { &mp_type_type },
     .name = MP_QSTR_iterator,
-    .getiter = mp_identity,
+    .getiter = mp_identity_getiter,
     .iternext = dict_view_it_iternext,
 };
 
-STATIC mp_obj_t dict_view_getiter(mp_obj_t view_in) {
+STATIC mp_obj_t dict_view_getiter(mp_obj_t view_in, mp_obj_iter_buf_t *iter_buf) {
+    assert(sizeof(mp_obj_dict_view_it_t) <= sizeof(mp_obj_iter_buf_t));
     mp_check_self(MP_OBJ_IS_TYPE(view_in, &dict_view_type));
     mp_obj_dict_view_t *view = MP_OBJ_TO_PTR(view_in);
-    mp_obj_dict_view_it_t *o = m_new_obj(mp_obj_dict_view_it_t);
+    mp_obj_dict_view_it_t *o = (mp_obj_dict_view_it_t*)iter_buf;
     o->base.type = &dict_view_it_type;
     o->kind = view->kind;
     o->dict = view->dict;
@@ -479,7 +484,8 @@
     bool first = true;
     mp_print_str(print, mp_dict_view_names[self->kind]);
     mp_print_str(print, "([");
-    mp_obj_t self_iter = dict_view_getiter(self_in);
+    mp_obj_iter_buf_t iter_buf;
+    mp_obj_t self_iter = dict_view_getiter(self_in, &iter_buf);
     mp_obj_t next = MP_OBJ_NULL;
     while ((next = dict_view_it_iternext(self_iter)) != MP_OBJ_STOP_ITERATION) {
         if (!first) {