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       1                 :            : /*
       2                 :            :  * This file is part of the MicroPython project, http://micropython.org/
       3                 :            :  *
       4                 :            :  * The MIT License (MIT)
       5                 :            :  *
       6                 :            :  * Copyright (c) 2014 Damien P. George
       7                 :            :  *
       8                 :            :  * Permission is hereby granted, free of charge, to any person obtaining a copy
       9                 :            :  * of this software and associated documentation files (the "Software"), to deal
      10                 :            :  * in the Software without restriction, including without limitation the rights
      11                 :            :  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
      12                 :            :  * copies of the Software, and to permit persons to whom the Software is
      13                 :            :  * furnished to do so, subject to the following conditions:
      14                 :            :  *
      15                 :            :  * The above copyright notice and this permission notice shall be included in
      16                 :            :  * all copies or substantial portions of the Software.
      17                 :            :  *
      18                 :            :  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
      19                 :            :  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
      20                 :            :  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
      21                 :            :  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
      22                 :            :  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
      23                 :            :  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
      24                 :            :  * THE SOFTWARE.
      25                 :            :  */
      26                 :            : 
      27                 :            : #include <stdlib.h>
      28                 :            : #include <assert.h>
      29                 :            : 
      30                 :            : #include "py/runtime.h"
      31                 :            : 
      32                 :            : #if MICROPY_PY_BUILTINS_REVERSED
      33                 :            : 
      34                 :            : typedef struct _mp_obj_reversed_t {
      35                 :            :     mp_obj_base_t base;
      36                 :            :     mp_obj_t seq;           // sequence object that we are reversing
      37                 :            :     mp_uint_t cur_index;    // current index, plus 1; 0=no more, 1=last one (index 0)
      38                 :            : } mp_obj_reversed_t;
      39                 :            : 
      40                 :         44 : static mp_obj_t reversed_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
      41                 :         44 :     mp_arg_check_num(n_args, n_kw, 1, 1, false);
      42                 :            : 
      43                 :            :     // check if __reversed__ exists, and if so delegate to it
      44                 :         44 :     mp_obj_t dest[2];
      45                 :         44 :     mp_load_method_maybe(args[0], MP_QSTR___reversed__, dest);
      46         [ +  + ]:         44 :     if (dest[0] != MP_OBJ_NULL) {
      47                 :          4 :         return mp_call_method_n_kw(0, 0, dest);
      48                 :            :     }
      49                 :            : 
      50                 :         40 :     mp_obj_reversed_t *o = mp_obj_malloc(mp_obj_reversed_t, type);
      51                 :         40 :     o->seq = args[0];
      52                 :         40 :     o->cur_index = mp_obj_get_int(mp_obj_len(args[0])); // start at the end of the sequence
      53                 :            : 
      54                 :         40 :     return MP_OBJ_FROM_PTR(o);
      55                 :            : }
      56                 :            : 
      57                 :        120 : static mp_obj_t reversed_iternext(mp_obj_t self_in) {
      58                 :        120 :     mp_check_self(mp_obj_is_type(self_in, &mp_type_reversed));
      59                 :        120 :     mp_obj_reversed_t *self = MP_OBJ_TO_PTR(self_in);
      60                 :            : 
      61                 :            :     // "raise" stop iteration if we are at the end (the start) of the sequence
      62         [ +  + ]:        120 :     if (self->cur_index == 0) {
      63                 :            :         return MP_OBJ_STOP_ITERATION;
      64                 :            :     }
      65                 :            : 
      66                 :            :     // pre-decrement and index sequence
      67                 :         80 :     self->cur_index -= 1;
      68                 :         80 :     return mp_obj_subscr(self->seq, MP_OBJ_NEW_SMALL_INT(self->cur_index), MP_OBJ_SENTINEL);
      69                 :            : }
      70                 :            : 
      71                 :            : MP_DEFINE_CONST_OBJ_TYPE(
      72                 :            :     mp_type_reversed,
      73                 :            :     MP_QSTR_reversed,
      74                 :            :     MP_TYPE_FLAG_ITER_IS_ITERNEXT,
      75                 :            :     make_new, reversed_make_new,
      76                 :            :     iter, reversed_iternext
      77                 :            :     );
      78                 :            : 
      79                 :            : #endif // MICROPY_PY_BUILTINS_REVERSED