Implemented set.discard

py/map.c

@@ -146,10 +146,10 @@ static void mp_set_rehash(mp_set_t *set) {
     m_del(mp_obj_t, old_table, old_alloc);
 }
 
-mp_obj_t mp_set_lookup(mp_set_t *set, mp_obj_t index, bool add_if_not_found) {
+mp_obj_t mp_set_lookup(mp_set_t *set, mp_obj_t index, mp_map_lookup_kind_t lookup_kind) {
     int hash = mp_obj_hash(index);
     if (set->alloc == 0) {
-        if (add_if_not_found) {
+        if (lookup_kind == MP_MAP_LOOKUP_ADD_IF_NOT_FOUND) {
             mp_set_rehash(set);
         } else {
             return NULL;
@@ -160,7 +160,7 @@ mp_obj_t mp_set_lookup(mp_set_t *set, mp_obj_t index, bool add_if_not_found) {
         mp_obj_t elem = set->table[pos];
         if (elem == MP_OBJ_NULL) {
             // not in table
-            if (add_if_not_found) {
+            if (lookup_kind == MP_MAP_LOOKUP_ADD_IF_NOT_FOUND) {
                 if (set->used + 1 >= set->alloc) {
                     // not enough room in table, rehash it
                     mp_set_rehash(set);
@@ -176,6 +176,11 @@ mp_obj_t mp_set_lookup(mp_set_t *set, mp_obj_t index, bool add_if_not_found) {
             }
         } else if (mp_obj_equal(elem, index)) {
             // found it
+            if (lookup_kind == MP_MAP_LOOKUP_REMOVE_IF_FOUND) {
+                set->used--;
+                set->table[pos] = NULL;
+                return elem;
+            }
             return elem;
         } else {
             // not yet found, keep searching in this table

py/map.h

@@ -31,5 +31,5 @@ mp_map_elem_t* mp_map_lookup(mp_map_t *map, mp_obj_t index, mp_map_lookup_kind_t
 void mp_map_clear(mp_map_t *map);
 
 void mp_set_init(mp_set_t *set, int n);
-mp_obj_t mp_set_lookup(mp_set_t *set, mp_obj_t index, bool add_if_not_found);
+mp_obj_t mp_set_lookup(mp_set_t *set, mp_obj_t index, mp_map_lookup_kind_t lookup_kind);
 void mp_set_clear(mp_set_t *set);

py/objset.c

@@ -100,7 +100,7 @@ static mp_obj_t set_getiter(mp_obj_t set_in) {
 static mp_obj_t set_add(mp_obj_t self_in, mp_obj_t item) {
     assert(MP_OBJ_IS_TYPE(self_in, &set_type));
     mp_obj_set_t *self = self_in;
-    mp_set_lookup(&self->set, item, true);
+    mp_set_lookup(&self->set, item, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
     return mp_const_none;
 }
 static MP_DEFINE_CONST_FUN_OBJ_2(set_add_obj, set_add);
@@ -129,6 +129,13 @@ static mp_obj_t set_copy(mp_obj_t self_in) {
 }
 static MP_DEFINE_CONST_FUN_OBJ_1(set_copy_obj, set_copy);
 
+static mp_obj_t set_discard(mp_obj_t self_in, mp_obj_t item) {
+    assert(MP_OBJ_IS_TYPE(self_in, &set_type));
+    mp_obj_set_t *self = self_in;
+    mp_set_lookup(&self->set, item, MP_MAP_LOOKUP_REMOVE_IF_FOUND);
+    return mp_const_none;
+}
+static MP_DEFINE_CONST_FUN_OBJ_2(set_discard_obj, set_discard);
 
 /******************************************************************************/
 /* set constructors & public C API                                            */
@@ -138,6 +145,7 @@ static const mp_method_t set_type_methods[] = {
     { "add", &set_add_obj },
     { "clear", &set_clear_obj },
     { "copy", &set_copy_obj },
+    { "discard", &set_discard_obj },
     { NULL, NULL }, // end-of-list sentinel
 };
 
@@ -155,7 +163,7 @@ mp_obj_t mp_obj_new_set(int n_args, mp_obj_t *items) {
     o->base.type = &set_type;
     mp_set_init(&o->set, n_args);
     for (int i = 0; i < n_args; i++) {
-        mp_set_lookup(&o->set, items[i], true);
+        mp_set_lookup(&o->set, items[i], MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
     }
     return o;
 }
@@ -163,5 +171,5 @@ mp_obj_t mp_obj_new_set(int n_args, mp_obj_t *items) {
 void mp_obj_set_store(mp_obj_t self_in, mp_obj_t item) {
     assert(MP_OBJ_IS_TYPE(self_in, &set_type));
     mp_obj_set_t *self = self_in;
-    mp_set_lookup(&self->set, item, true);
+    mp_set_lookup(&self->set, item, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
 }

tests/basics/tests/set_discard.py

@@ -0,0 +1,3 @@
+s = {1, 2}
+print(s.discard(1))
+print(list(s))