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| author | Damien George <damien.p.george@gmail.com> | 2014-01-03 17:03:19 -0800 |
|---|---|---|
| committer | Damien George <damien.p.george@gmail.com> | 2014-01-03 17:03:19 -0800 |
| commit | b95d90b2f37e00a39a7cca46c24c9d496bb1e342 (patch) | |
| tree | dee120c28b998e528b1ba9f7a72d7dee2df7e12f /py/objslice.c | |
| parent | 9ba9589ef71920132cd6ec5c3a948e9c605b50f7 (diff) | |
| parent | f8b9d3c41addea79851c355f014db9f0f256cdaf (diff) | |
| download | micropython-b95d90b2f37e00a39a7cca46c24c9d496bb1e342.tar.gz micropython-b95d90b2f37e00a39a7cca46c24c9d496bb1e342.zip | |
Merge pull request #59 from pfalcon/slice
Implement basic slice object and string slicing
Diffstat (limited to 'py/objslice.c')
| -rw-r--r-- | py/objslice.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/py/objslice.c b/py/objslice.c new file mode 100644 index 0000000000..03607e4c3e --- /dev/null +++ b/py/objslice.c @@ -0,0 +1,74 @@ +#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 |