micropython/py/objreversed.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 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 <stdlib.h>
#include <assert.h>
#include "py/runtime.h"
#if MICROPY_PY_BUILTINS_REVERSED
typedef struct _mp_obj_reversed_t {
mp_obj_base_t base;
mp_obj_t seq; // sequence object that we are reversing
mp_uint_t cur_index; // current index, plus 1; 0=no more, 1=last one (index 0)
} mp_obj_reversed_t;
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) {
mp_arg_check_num(n_args, n_kw, 1, 1, false);
// check if __reversed__ exists, and if so delegate to it
mp_obj_t dest[2];
mp_load_method_maybe(args[0], MP_QSTR___reversed__, dest);
if (dest[0] != MP_OBJ_NULL) {
return mp_call_method_n_kw(0, 0, dest);
}
mp_obj_reversed_t *o = m_new_obj(mp_obj_reversed_t);
o->base.type = type;
o->seq = args[0];
o->cur_index = mp_obj_get_int(mp_obj_len(args[0])); // start at the end of the sequence
return MP_OBJ_FROM_PTR(o);
}
STATIC mp_obj_t reversed_iternext(mp_obj_t self_in) {
mp_check_self(mp_obj_is_type(self_in, &mp_type_reversed));
mp_obj_reversed_t *self = MP_OBJ_TO_PTR(self_in);
// "raise" stop iteration if we are at the end (the start) of the sequence
if (self->cur_index == 0) {
return MP_OBJ_STOP_ITERATION;
}
// pre-decrement and index sequence
self->cur_index -= 1;
return mp_obj_subscr(self->seq, MP_OBJ_NEW_SMALL_INT(self->cur_index), MP_OBJ_SENTINEL);
}
const mp_obj_type_t mp_type_reversed = {
{ &mp_type_type },
.name = MP_QSTR_reversed,
.make_new = reversed_make_new,
.getiter = mp_identity_getiter,
.iternext = reversed_iternext,
};
#endif // MICROPY_PY_BUILTINS_REVERSED