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#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <assert.h>
#include "nlr.h"
#include "misc.h"
#include "mpconfig.h"
#include "obj.h"
#include "runtime0.h"
#if MICROPY_ENABLE_SLICE
// TODO: This implements only variant of slice with 2 integer args only.
// CPython supports 3rd arg (step), plus args can be arbitrary Python objects.
typedef struct _mp_obj_slice_t {
mp_obj_base_t base;
machine_int_t start;
machine_int_t stop;
} mp_obj_slice_t;
void slice_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t o_in) {
mp_obj_slice_t *o = o_in;
print(env, "slice(" INT_FMT ", " INT_FMT ")", o->start, o->stop);
}
const mp_obj_type_t slice_type = {
{ &mp_const_type },
"slice",
slice_print,
NULL, // call_n
NULL, // unary_op
NULL, // binary_op
NULL, // getiter
NULL, // iternext
{ { NULL, NULL }, }, // method list
};
// TODO: Make sure to handle "empty" values, which are signified by None in CPython
mp_obj_t mp_obj_new_slice(mp_obj_t ostart, mp_obj_t ostop, mp_obj_t ostep) {
assert(ostep == NULL);
machine_int_t start = 0, stop = 0;
if (ostart != mp_const_none) {
start = mp_obj_get_int(ostart);
}
if (ostop != mp_const_none) {
stop = mp_obj_get_int(ostop);
if (stop == 0) {
// [x:0] is a special case - in our slice object, stop = 0 means
// "end of sequence". Fortunately, [x:0] is an empty seqence for
// any x (including negative). [x:x] is also always empty sequence.
// but x also can be 0. But note that b""[x:x] is b"" for any x (i.e.
// no IndexError, at least in Python 3.3.3). So, we just use -1's to
// signify that. -1 is catchy "special" number in case someone will
// try to print [x:0] slice ever.
start = stop = -1;
}
}
mp_obj_slice_t *o = m_new(mp_obj_slice_t, 1);
o->base.type = &slice_type;
o->start = start;
o->stop = stop;
return (mp_obj_t)o;
}
void mp_obj_slice_get(mp_obj_t self_in, machine_int_t *start, machine_int_t *stop, machine_int_t *step) {
assert(MP_OBJ_IS_TYPE(self_in, &slice_type));
mp_obj_slice_t *self = self_in;
*start = self->start;
*stop = self->stop;
*step = 1;
}
#endif
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