/*
   * This file is part of the MicroPython project, http://micropython.org/
   *
   * The MIT License (MIT)
   *
   * Copyright (c) 2013, 2014 Damien P. George
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  #include <string.h>
  #include <assert.h>
  
  #include "py/objlist.h"
  #include "py/runtime.h"
  #include "py/stackctrl.h"
  
  STATIC mp_obj_t mp_obj_new_list_iterator(mp_obj_t list, size_t cur, mp_obj_iter_buf_t *iter_buf);
  STATIC mp_obj_list_t *list_new(size_t n);
  STATIC mp_obj_t list_extend(mp_obj_t self_in, mp_obj_t arg_in);
  STATIC mp_obj_t list_pop(size_t n_args, const mp_obj_t *args);
  
  // TODO: Move to mpconfig.h
  #define LIST_MIN_ALLOC 4
  
  /******************************************************************************/
  /* list                                                                       */
  
  STATIC void list_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
      mp_obj_list_t *o = MP_OBJ_TO_PTR(o_in);
      if (!(MICROPY_PY_UJSON && kind == PRINT_JSON)) {
          kind = PRINT_REPR;
      }
      mp_print_str(print, "[");
      for (size_t i = 0; i < o->len; i++) {
          if (i > 0) {
              mp_print_str(print, ", ");
          }
          mp_obj_print_helper(print, o->items[i], kind);
      }
      mp_print_str(print, "]");
  }
  
  STATIC mp_obj_t list_extend_from_iter(mp_obj_t list, mp_obj_t iterable) {
      mp_obj_t iter = mp_getiter(iterable, NULL);
      mp_obj_t item;
      while ((item = mp_iternext(iter)) != MP_OBJ_STOP_ITERATION) {
          mp_obj_list_append(list, item);
      }
      return list;
  }
  
  STATIC mp_obj_t list_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
      (void)type_in;
      mp_arg_check_num(n_args, n_kw, 0, 1, false);
  
      switch (n_args) {
          case 0:
              // return a new, empty list
              return mp_obj_new_list(0, NULL);
  
          case 1:
          default: {
              // make list from iterable
              // TODO: optimize list/tuple
              mp_obj_t list = mp_obj_new_list(0, NULL);
              return list_extend_from_iter(list, args[0]);
          }
      }
  }
  
  STATIC mp_obj_t list_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
      mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
      switch (op) {
          case MP_UNARY_OP_BOOL: return mp_obj_new_bool(self->len != 0);
          case MP_UNARY_OP_LEN: return MP_OBJ_NEW_SMALL_INT(self->len);
          #if MICROPY_PY_SYS_GETSIZEOF
          case MP_UNARY_OP_SIZEOF: {
              size_t sz = sizeof(*self) + sizeof(mp_obj_t) * self->alloc;
              return MP_OBJ_NEW_SMALL_INT(sz);
          }
          #endif
          default: return MP_OBJ_NULL; // op not supported
      }
  }
  
  STATIC mp_obj_t list_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
      mp_obj_list_t *o = MP_OBJ_TO_PTR(lhs);
      switch (op) {
          case MP_BINARY_OP_ADD: {
              if (!MP_OBJ_IS_TYPE(rhs, &mp_type_list)) {
                  return MP_OBJ_NULL; // op not supported
              }
              mp_obj_list_t *p = MP_OBJ_TO_PTR(rhs);
              mp_obj_list_t *s = list_new(o->len + p->len);
              mp_seq_cat(s->items, o->items, o->len, p->items, p->len, mp_obj_t);
              return MP_OBJ_FROM_PTR(s);
          }
          case MP_BINARY_OP_INPLACE_ADD: {
              list_extend(lhs, rhs);
              return lhs;
          }
          case MP_BINARY_OP_MULTIPLY: {
              mp_int_t n;
              if (!mp_obj_get_int_maybe(rhs, &n)) {
                  return MP_OBJ_NULL; // op not supported
              }
              if (n < 0) {
                  n = 0;
              }
              mp_obj_list_t *s = list_new(o->len * n);
              mp_seq_multiply(o->items, sizeof(*o->items), o->len, n, s->items);
              return MP_OBJ_FROM_PTR(s);
          }
          case MP_BINARY_OP_EQUAL:
          case MP_BINARY_OP_LESS:
          case MP_BINARY_OP_LESS_EQUAL:
          case MP_BINARY_OP_MORE:
          case MP_BINARY_OP_MORE_EQUAL: {
              if (!MP_OBJ_IS_TYPE(rhs, &mp_type_list)) {
                  if (op == MP_BINARY_OP_EQUAL) {
                      return mp_const_false;
                  }
                  return MP_OBJ_NULL; // op not supported
              }
  
              mp_obj_list_t *another = MP_OBJ_TO_PTR(rhs);
              bool res = mp_seq_cmp_objs(op, o->items, o->len, another->items, another->len);
              return mp_obj_new_bool(res);
          }
  
          default:
              return MP_OBJ_NULL; // op not supported
      }
  }
  
  STATIC mp_obj_t list_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
      if (value == MP_OBJ_NULL) {
          // delete
  #if MICROPY_PY_BUILTINS_SLICE
          if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) {
              mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
              mp_bound_slice_t slice;
              if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice)) {
                  mp_raise_NotImplementedError(NULL);
              }
  
              mp_int_t len_adj = slice.start - slice.stop;
              //printf("Len adj: %d\n", len_adj);
              assert(len_adj <= 0);
              mp_seq_replace_slice_no_grow(self->items, self->len, slice.start, slice.stop, self->items/*NULL*/, 0, sizeof(*self->items));
              // Clear "freed" elements at the end of list
              mp_seq_clear(self->items, self->len + len_adj, self->len, sizeof(*self->items));
              self->len += len_adj;
              return mp_const_none;
          }
  #endif
          mp_obj_t args[2] = {self_in, index};
          list_pop(2, args);
          return mp_const_none;
      } else if (value == MP_OBJ_SENTINEL) {
          // load
          mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
  #if MICROPY_PY_BUILTINS_SLICE
          if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) {
              mp_bound_slice_t slice;
              if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice)) {
                  return mp_seq_extract_slice(self->len, self->items, &slice);
              }
              mp_obj_list_t *res = list_new(slice.stop - slice.start);
              mp_seq_copy(res->items, self->items + slice.start, res->len, mp_obj_t);
              return MP_OBJ_FROM_PTR(res);
          }
  #endif
          size_t index_val = mp_get_index(self->base.type, self->len, index, false);
          return self->items[index_val];
      } else {
  #if MICROPY_PY_BUILTINS_SLICE
          if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) {
              mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
              size_t value_len; mp_obj_t *value_items;
              mp_obj_get_array(value, &value_len, &value_items);
              mp_bound_slice_t slice_out;
              if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice_out)) {
                  mp_raise_NotImplementedError(NULL);
              }
              mp_int_t len_adj = value_len - (slice_out.stop - slice_out.start);
              //printf("Len adj: %d\n", len_adj);
              if (len_adj > 0) {
                  if (self->len + len_adj > self->alloc) {
                      // TODO: Might optimize memory copies here by checking if block can
                      // be grown inplace or not
                      self->items = m_renew(mp_obj_t, self->items, self->alloc, self->len + len_adj);
                      self->alloc = self->len + len_adj;
                  }
                  mp_seq_replace_slice_grow_inplace(self->items, self->len,
                      slice_out.start, slice_out.stop, value_items, value_len, len_adj, sizeof(*self->items));
              } else {
                  mp_seq_replace_slice_no_grow(self->items, self->len,
                      slice_out.start, slice_out.stop, value_items, value_len, sizeof(*self->items));
                  // Clear "freed" elements at the end of list
                  mp_seq_clear(self->items, self->len + len_adj, self->len, sizeof(*self->items));
                  // TODO: apply allocation policy re: alloc_size
              }
              self->len += len_adj;
              return mp_const_none;
          }
  #endif
          mp_obj_list_store(self_in, index, value);
          return mp_const_none;
      }
  }
  
  STATIC mp_obj_t list_getiter(mp_obj_t o_in, mp_obj_iter_buf_t *iter_buf) {
      return mp_obj_new_list_iterator(o_in, 0, iter_buf);
  }
  
  mp_obj_t mp_obj_list_append(mp_obj_t self_in, mp_obj_t arg) {
      mp_check_self(MP_OBJ_IS_TYPE(self_in, &mp_type_list));
      mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
      if (self->len >= self->alloc) {
          self->items = m_renew(mp_obj_t, self->items, self->alloc, self->alloc * 2);
          self->alloc *= 2;
          mp_seq_clear(self->items, self->len + 1, self->alloc, sizeof(*self->items));
      }
      self->items[self->len++] = arg;
      return mp_const_none; // return None, as per CPython
  }
  
  STATIC mp_obj_t list_extend(mp_obj_t self_in, mp_obj_t arg_in) {
      mp_check_self(MP_OBJ_IS_TYPE(self_in, &mp_type_list));
      if (MP_OBJ_IS_TYPE(arg_in, &mp_type_list)) {
          mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
          mp_obj_list_t *arg = MP_OBJ_TO_PTR(arg_in);
  
          if (self->len + arg->len > self->alloc) {
              // TODO: use alloc policy for "4"
              self->items = m_renew(mp_obj_t, self->items, self->alloc, self->len + arg->len + 4);
              self->alloc = self->len + arg->len + 4;
              mp_seq_clear(self->items, self->len + arg->len, self->alloc, sizeof(*self->items));
          }
  
          memcpy(self->items + self->len, arg->items, sizeof(mp_obj_t) * arg->len);
          self->len += arg->len;
      } else {
          list_extend_from_iter(self_in, arg_in);
      }
      return mp_const_none; // return None, as per CPython
  }
  
  STATIC mp_obj_t list_pop(size_t n_args, const mp_obj_t *args) {
      mp_check_self(MP_OBJ_IS_TYPE(args[0], &mp_type_list));
      mp_obj_list_t *self = MP_OBJ_TO_PTR(args[0]);
      if (self->len == 0) {
          mp_raise_msg(&mp_type_IndexError, "pop from empty list");
      }
      size_t index = mp_get_index(self->base.type, self->len, n_args == 1 ? MP_OBJ_NEW_SMALL_INT(-1) : args[1], false);
      mp_obj_t ret = self->items[index];
      self->len -= 1;
      memmove(self->items + index, self->items + index + 1, (self->len - index) * sizeof(mp_obj_t));
      // Clear stale pointer from slot which just got freed to prevent GC issues
      self->items[self->len] = MP_OBJ_NULL;
      if (self->alloc > LIST_MIN_ALLOC && self->alloc > 2 * self->len) {
          self->items = m_renew(mp_obj_t, self->items, self->alloc, self->alloc/2);
          self->alloc /= 2;
      }
      return ret;
  }
  
  STATIC void mp_quicksort(mp_obj_t *head, mp_obj_t *tail, mp_obj_t key_fn, mp_obj_t binop_less_result) {
      MP_STACK_CHECK();
      while (head < tail) {
          mp_obj_t *h = head - 1;
          mp_obj_t *t = tail;
          mp_obj_t v = key_fn == MP_OBJ_NULL ? tail[0] : mp_call_function_1(key_fn, tail[0]); // get pivot using key_fn
          for (;;) {
              do ++h; while (h < t && mp_binary_op(MP_BINARY_OP_LESS, key_fn == MP_OBJ_NULL ? h[0] : mp_call_function_1(key_fn, h[0]), v) == binop_less_result);
              do --t; while (h < t && mp_binary_op(MP_BINARY_OP_LESS, v, key_fn == MP_OBJ_NULL ? t[0] : mp_call_function_1(key_fn, t[0])) == binop_less_result);
              if (h >= t) break;
              mp_obj_t x = h[0];
              h[0] = t[0];
              t[0] = x;
          }
          mp_obj_t x = h[0];
          h[0] = tail[0];
          tail[0] = x;
          // do the smaller recursive call first, to keep stack within O(log(N))
          if (t - head < tail - h - 1) {
              mp_quicksort(head, t, key_fn, binop_less_result);
              head = h + 1;
          } else {
              mp_quicksort(h + 1, tail, key_fn, binop_less_result);
              tail = t;
          }
      }
  }
  
  // TODO Python defines sort to be stable but ours is not
  mp_obj_t mp_obj_list_sort(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
      static const mp_arg_t allowed_args[] = {
          { MP_QSTR_key, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
          { MP_QSTR_reverse, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
      };
  
      // parse args
      struct {
          mp_arg_val_t key, reverse;
      } args;
      mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args,
          MP_ARRAY_SIZE(allowed_args), allowed_args, (mp_arg_val_t*)&args);
  
      mp_check_self(MP_OBJ_IS_TYPE(pos_args[0], &mp_type_list));
      mp_obj_list_t *self = MP_OBJ_TO_PTR(pos_args[0]);
  
      if (self->len > 1) {
          mp_quicksort(self->items, self->items + self->len - 1,
                       args.key.u_obj == mp_const_none ? MP_OBJ_NULL : args.key.u_obj,
                       args.reverse.u_bool ? mp_const_false : mp_const_true);
      }
  
      return mp_const_none;
  }
  
  STATIC mp_obj_t list_clear(mp_obj_t self_in) {
      mp_check_self(MP_OBJ_IS_TYPE(self_in, &mp_type_list));
      mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
      self->len = 0;
      self->items = m_renew(mp_obj_t, self->items, self->alloc, LIST_MIN_ALLOC);
      self->alloc = LIST_MIN_ALLOC;
      mp_seq_clear(self->items, 0, self->alloc, sizeof(*self->items));
      return mp_const_none;
  }
  
  STATIC mp_obj_t list_copy(mp_obj_t self_in) {
      mp_check_self(MP_OBJ_IS_TYPE(self_in, &mp_type_list));
      mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
      return mp_obj_new_list(self->len, self->items);
  }
  
  STATIC mp_obj_t list_count(mp_obj_t self_in, mp_obj_t value) {
      mp_check_self(MP_OBJ_IS_TYPE(self_in, &mp_type_list));
      mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
      return mp_seq_count_obj(self->items, self->len, value);
  }
  
  STATIC mp_obj_t list_index(size_t n_args, const mp_obj_t *args) {
      mp_check_self(MP_OBJ_IS_TYPE(args[0], &mp_type_list));
      mp_obj_list_t *self = MP_OBJ_TO_PTR(args[0]);
      return mp_seq_index_obj(self->items, self->len, n_args, args);
  }
  
  STATIC mp_obj_t list_insert(mp_obj_t self_in, mp_obj_t idx, mp_obj_t obj) {
      mp_check_self(MP_OBJ_IS_TYPE(self_in, &mp_type_list));
      mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
      // insert has its own strange index logic
      mp_int_t index = MP_OBJ_SMALL_INT_VALUE(idx);
      if (index < 0) {
           index += self->len;
      }
      if (index < 0) {
           index = 0;
      }
      if ((size_t)index > self->len) {
           index = self->len;
      }
  
      mp_obj_list_append(self_in, mp_const_none);
  
      for (mp_int_t i = self->len-1; i > index; i--) {
           self->items[i] = self->items[i-1];
      }
      self->items[index] = obj;
  
      return mp_const_none;
  }
  
  mp_obj_t mp_obj_list_remove(mp_obj_t self_in, mp_obj_t value) {
      mp_check_self(MP_OBJ_IS_TYPE(self_in, &mp_type_list));
      mp_obj_t args[] = {self_in, value};
      args[1] = list_index(2, args);
      list_pop(2, args);
  
      return mp_const_none;
  }
  
  STATIC mp_obj_t list_reverse(mp_obj_t self_in) {
      mp_check_self(MP_OBJ_IS_TYPE(self_in, &mp_type_list));
      mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
  
      mp_int_t len = self->len;
      for (mp_int_t i = 0; i < len/2; i++) {
           mp_obj_t a = self->items[i];
           self->items[i] = self->items[len-i-1];
           self->items[len-i-1] = a;
      }
  
      return mp_const_none;
  }
  
  STATIC MP_DEFINE_CONST_FUN_OBJ_2(list_append_obj, mp_obj_list_append);
  STATIC MP_DEFINE_CONST_FUN_OBJ_2(list_extend_obj, list_extend);
  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_remove_obj, mp_obj_list_remove);
  STATIC MP_DEFINE_CONST_FUN_OBJ_1(list_reverse_obj, list_reverse);
  STATIC MP_DEFINE_CONST_FUN_OBJ_KW(list_sort_obj, 1, mp_obj_list_sort);
  
  STATIC const mp_rom_map_elem_t list_locals_dict_table[] = {
      { MP_ROM_QSTR(MP_QSTR_append), MP_ROM_PTR(&list_append_obj) },
      { MP_ROM_QSTR(MP_QSTR_clear), MP_ROM_PTR(&list_clear_obj) },
      { MP_ROM_QSTR(MP_QSTR_copy), MP_ROM_PTR(&list_copy_obj) },
      { MP_ROM_QSTR(MP_QSTR_count), MP_ROM_PTR(&list_count_obj) },
      { MP_ROM_QSTR(MP_QSTR_extend), MP_ROM_PTR(&list_extend_obj) },
      { MP_ROM_QSTR(MP_QSTR_index), MP_ROM_PTR(&list_index_obj) },
      { MP_ROM_QSTR(MP_QSTR_insert), MP_ROM_PTR(&list_insert_obj) },
      { MP_ROM_QSTR(MP_QSTR_pop), MP_ROM_PTR(&list_pop_obj) },
      { MP_ROM_QSTR(MP_QSTR_remove), MP_ROM_PTR(&list_remove_obj) },
      { MP_ROM_QSTR(MP_QSTR_reverse), MP_ROM_PTR(&list_reverse_obj) },
      { MP_ROM_QSTR(MP_QSTR_sort), MP_ROM_PTR(&list_sort_obj) },
  };
  
  STATIC MP_DEFINE_CONST_DICT(list_locals_dict, list_locals_dict_table);
  
  const mp_obj_type_t mp_type_list = {
      { &mp_type_type },
      .name = MP_QSTR_list,
      .print = list_print,
      .make_new = list_make_new,
      .unary_op = list_unary_op,
      .binary_op = list_binary_op,
      .subscr = list_subscr,
      .getiter = list_getiter,
      .locals_dict = (mp_obj_dict_t*)&list_locals_dict,
  };
  
  void mp_obj_list_init(mp_obj_list_t *o, size_t n) {
      o->base.type = &mp_type_list;
      o->alloc = n < LIST_MIN_ALLOC ? LIST_MIN_ALLOC : n;
      o->len = n;
      o->items = m_new(mp_obj_t, o->alloc);
      mp_seq_clear(o->items, n, o->alloc, sizeof(*o->items));
  }
  
  STATIC mp_obj_list_t *list_new(size_t n) {
      mp_obj_list_t *o = m_new_obj(mp_obj_list_t);
      mp_obj_list_init(o, n);
      return o;
  }
  
  mp_obj_t mp_obj_new_list(size_t n, mp_obj_t *items) {
      mp_obj_list_t *o = list_new(n);
      if (items != NULL) {
          for (size_t i = 0; i < n; i++) {
              o->items[i] = items[i];
          }
      }
      return MP_OBJ_FROM_PTR(o);
  }
  
  void mp_obj_list_get(mp_obj_t self_in, size_t *len, mp_obj_t **items) {
      mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
      *len = self->len;
      *items = self->items;
  }
  
  void mp_obj_list_set_len(mp_obj_t self_in, size_t len) {
      // trust that the caller knows what it's doing
      // TODO realloc if len got much smaller than alloc
      mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
      self->len = len;
  }
  
  void mp_obj_list_store(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
      mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
      size_t i = mp_get_index(self->base.type, self->len, index, false);
      self->items[i] = value;
  }
  
  /******************************************************************************/
  /* list iterator                                                              */
  
  typedef struct _mp_obj_list_it_t {
      mp_obj_base_t base;
      mp_fun_1_t iternext;
      mp_obj_t list;
      size_t cur;
  } mp_obj_list_it_t;
  
  STATIC mp_obj_t list_it_iternext(mp_obj_t self_in) {
      mp_obj_list_it_t *self = MP_OBJ_TO_PTR(self_in);
      mp_obj_list_t *list = MP_OBJ_TO_PTR(self->list);
      if (self->cur < list->len) {
          mp_obj_t o_out = list->items[self->cur];
          self->cur += 1;
          return o_out;
      } else {
          return MP_OBJ_STOP_ITERATION;
      }
  }
  
  mp_obj_t mp_obj_new_list_iterator(mp_obj_t list, size_t cur, mp_obj_iter_buf_t *iter_buf) {
      assert(sizeof(mp_obj_list_it_t) <= sizeof(mp_obj_iter_buf_t));
      mp_obj_list_it_t *o = (mp_obj_list_it_t*)iter_buf;
      o->base.type = &mp_type_polymorph_iter;
      o->iternext = list_it_iternext;
      o->list = list;
      o->cur = cur;
      return MP_OBJ_FROM_PTR(o);
  }