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
34typedef 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
40STATIC 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 mp_arg_check_num(n_args, n_kw, 1, 1, false);
42
43 // check if __reversed__ exists, and if so delegate to it
44 mp_obj_t dest[2];
45 mp_load_method_maybe(args[0], MP_QSTR___reversed__, dest);
46 if (dest[0] != MP_OBJ_NULL) {
47 return mp_call_method_n_kw(0, 0, dest);
48 }
49
50 mp_obj_reversed_t *o = m_new_obj(mp_obj_reversed_t);
51 o->base.type = type;
52 o->seq = args[0];
53 o->cur_index = mp_obj_get_int(mp_obj_len(args[0])); // start at the end of the sequence
54
55 return MP_OBJ_FROM_PTR(o);
56}
57
58STATIC mp_obj_t reversed_iternext(mp_obj_t self_in) {
59 mp_check_self(mp_obj_is_type(self_in, &mp_type_reversed));
60 mp_obj_reversed_t *self = MP_OBJ_TO_PTR(self_in);
61
62 // "raise" stop iteration if we are at the end (the start) of the sequence
63 if (self->cur_index == 0) {
64 return MP_OBJ_STOP_ITERATION;
65 }
66
67 // pre-decrement and index sequence
68 self->cur_index -= 1;
69 return mp_obj_subscr(self->seq, MP_OBJ_NEW_SMALL_INT(self->cur_index), MP_OBJ_SENTINEL);
70}
71
72const mp_obj_type_t mp_type_reversed = {
73 { &mp_type_type },
74 .name = MP_QSTR_reversed,
75 .make_new = reversed_make_new,
76 .getiter = mp_identity_getiter,
77 .iternext = reversed_iternext,
78};
79
80#endif // MICROPY_PY_BUILTINS_REVERSED
81