Implements list.insert. Fixes issue #61.

py/obj.h

@@ -46,6 +46,7 @@ struct _mp_obj_base_t {
 #define MP_DEFINE_CONST_FUN_OBJ_0(obj_name, fun_name) const mp_obj_fun_native_t obj_name = {{&fun_native_type}, 0, 0, fun_name}
 #define MP_DEFINE_CONST_FUN_OBJ_1(obj_name, fun_name) const mp_obj_fun_native_t obj_name = {{&fun_native_type}, 1, 1, fun_name}
 #define MP_DEFINE_CONST_FUN_OBJ_2(obj_name, fun_name) const mp_obj_fun_native_t obj_name = {{&fun_native_type}, 2, 2, fun_name}
+#define MP_DEFINE_CONST_FUN_OBJ_3(obj_name, fun_name) const mp_obj_fun_native_t obj_name = {{&fun_native_type}, 3, 3, fun_name}
 #define MP_DEFINE_CONST_FUN_OBJ_VAR(obj_name, n_args_min, fun_name) const mp_obj_fun_native_t obj_name = {{&fun_native_type}, n_args_min, (~((machine_uint_t)0)), fun_name}
 #define MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(obj_name, n_args_min, n_args_max, fun_name) const mp_obj_fun_native_t obj_name = {{&fun_native_type}, n_args_min, n_args_max, fun_name}
 
@@ -54,6 +55,7 @@ struct _mp_obj_base_t {
 typedef mp_obj_t (*mp_fun_0_t)(void);
 typedef mp_obj_t (*mp_fun_1_t)(mp_obj_t);
 typedef mp_obj_t (*mp_fun_2_t)(mp_obj_t, mp_obj_t);
+typedef mp_obj_t (*mp_fun_3_t)(mp_obj_t, mp_obj_t, mp_obj_t);
 typedef mp_obj_t (*mp_fun_t)(void);
 typedef mp_obj_t (*mp_fun_var_t)(int n, const mp_obj_t *);
 

py/objfun.c

@@ -38,6 +38,9 @@ mp_obj_t fun_native_call_n(mp_obj_t self_in, int n_args, const mp_obj_t *args) {
             case 2:
                 return ((mp_fun_2_t)self->fun)(args[1], args[0]);
 
+            case 3:
+                return ((mp_fun_3_t)self->fun)(args[2], args[1], args[0]);
+
             default:
                 assert(0);
                 return mp_const_none;
@@ -106,6 +109,15 @@ mp_obj_t rt_make_function_2(mp_fun_2_t fun) {
     return o;
 }
 
+mp_obj_t rt_make_function_3(mp_fun_3_t fun) {
+    mp_obj_fun_native_t *o = m_new_obj(mp_obj_fun_native_t);
+    o->base.type = &fun_native_type;
+    o->n_args_min = 3;
+    o->n_args_max = 3;
+    o->fun = fun;
+    return o;
+}
+
 mp_obj_t rt_make_function_var(int n_args_min, mp_fun_var_t fun) {
     mp_obj_fun_native_t *o = m_new_obj(mp_obj_fun_native_t);
     o->base.type = &fun_native_type;

py/objlist.c

@@ -173,11 +173,37 @@ static mp_obj_t list_index(int n_args, const mp_obj_t *args) {
     nlr_jump(mp_obj_new_exception_msg(rt_q_ValueError, "Object not in list."));
 }
 
+static mp_obj_t list_insert(mp_obj_t self_in, mp_obj_t idx, mp_obj_t obj) {
+    assert(MP_OBJ_IS_TYPE(self_in, &list_type));
+    mp_obj_list_t *self = self_in;
+    // insert has its own strange index logic
+    int index = MP_OBJ_SMALL_INT_VALUE(idx);
+    if (index < 0) {
+         index += self->len;
+    }
+    if (index < 0) {
+         index = 0;
+    }
+    if (index > self->len) {
+         index = self->len;
+    }
+
+    mp_obj_list_append(self_in, mp_const_none);
+
+    for (int i = self->len-1; i > index; i--) {
+         self->items[i] = self->items[i-1];
+    }
+    self->items[index] = obj;
+
+    return mp_const_none;
+}
+
 static MP_DEFINE_CONST_FUN_OBJ_2(list_append_obj, mp_obj_list_append);
 static MP_DEFINE_CONST_FUN_OBJ_1(list_clear_obj, list_clear);
 static MP_DEFINE_CONST_FUN_OBJ_1(list_copy_obj, list_copy);
 static MP_DEFINE_CONST_FUN_OBJ_2(list_count_obj, list_count);
 static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(list_index_obj, 2, 4, list_index);
+static MP_DEFINE_CONST_FUN_OBJ_3(list_insert_obj, list_insert);
 static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(list_pop_obj, 1, 2, list_pop);
 static MP_DEFINE_CONST_FUN_OBJ_2(list_sort_obj, list_sort);
 
@@ -196,6 +222,7 @@ const mp_obj_type_t list_type = {
         { "copy", &list_copy_obj },
         { "count", &list_count_obj },
         { "index", &list_index_obj },
+        { "insert", &list_insert_obj },
         { "pop", &list_pop_obj },
         { "sort", &list_sort_obj },
         { NULL, NULL }, // end-of-list sentinel

tests/basics/tests/list_insert.py

+a = [1, 2, 3]
+a.insert(1, 42)
+print(a)
+a.insert(-1, -1)
+print(a)
+a.insert(99, 99)
+print(a)
+a.insert(-99, -99)
+print(a)