From 5fd5af98d0292e06f42e0e0dc6ea8278219cdd6e Mon Sep 17 00:00:00 2001 From: Paul Sokolovsky Date: Sun, 25 May 2014 22:12:56 +0300 Subject: [PATCH] objlist: Implement support for arbitrary (3-arg) slices. --- py/obj.h | 1 + py/objarray.c | 3 ++- py/objlist.c | 2 +- py/objstr.c | 3 ++- py/objtuple.c | 3 ++- py/sequence.c | 23 +++++++++++++++++++++-- tests/basics/list_slice_3arg.py | 4 ++++ 7 files changed, 33 insertions(+), 6 deletions(-) create mode 100644 tests/basics/list_slice_3arg.py diff --git a/py/obj.h b/py/obj.h index 6bcebcf6ef..b1d9be2096 100644 --- a/py/obj.h +++ b/py/obj.h @@ -579,6 +579,7 @@ bool mp_seq_cmp_bytes(int op, const byte *data1, uint len1, const byte *data2, u bool mp_seq_cmp_objs(int op, const mp_obj_t *items1, uint len1, const mp_obj_t *items2, uint len2); mp_obj_t mp_seq_index_obj(const mp_obj_t *items, uint len, uint n_args, const mp_obj_t *args); mp_obj_t mp_seq_count_obj(const mp_obj_t *items, uint len, mp_obj_t value); +mp_obj_t mp_seq_extract_slice(uint len, const mp_obj_t *seq, mp_bound_slice_t *indexes); // Helper to clear stale pointers from allocated, but unused memory, to preclude GC problems #define mp_seq_clear(start, len, alloc_len, item_sz) memset((byte*)(start) + (len) * (item_sz), 0, ((alloc_len) - (len)) * (item_sz)) #define mp_seq_replace_slice_no_grow(dest, dest_len, beg, end, slice, slice_len, item_t) \ diff --git a/py/objarray.c b/py/objarray.c index da57709ece..91fcec624a 100644 --- a/py/objarray.c +++ b/py/objarray.c @@ -178,7 +178,8 @@ STATIC mp_obj_t array_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value } mp_bound_slice_t slice; if (!mp_seq_get_fast_slice_indexes(o->len, index_in, &slice)) { - assert(0); + nlr_raise(mp_obj_new_exception_msg(&mp_type_NotImplementedError, + "Only slices with step=1 (aka None) are supported")); } mp_obj_array_t *res = array_new(o->typecode, slice.stop - slice.start); int sz = mp_binary_get_size('@', o->typecode, NULL); diff --git a/py/objlist.c b/py/objlist.c index 8643be41a1..647096f0dd 100644 --- a/py/objlist.c +++ b/py/objlist.c @@ -178,7 +178,7 @@ STATIC mp_obj_t list_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) { if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) { mp_bound_slice_t slice; if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice)) { - assert(0); + return mp_seq_extract_slice(self->len, self->items, &slice); } mp_obj_list_t *res = list_new(slice.stop - slice.start); mp_seq_copy(res->items, self->items + slice.start, res->len, mp_obj_t); diff --git a/py/objstr.c b/py/objstr.c index 84a6f30aad..f5939d1b1f 100644 --- a/py/objstr.c +++ b/py/objstr.c @@ -353,7 +353,8 @@ STATIC mp_obj_t str_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) { if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) { mp_bound_slice_t slice; if (!mp_seq_get_fast_slice_indexes(self_len, index, &slice)) { - assert(0); + nlr_raise(mp_obj_new_exception_msg(&mp_type_NotImplementedError, + "Only slices with step=1 (aka None) are supported")); } return str_new(type, self_data + slice.start, slice.stop - slice.start); } diff --git a/py/objtuple.c b/py/objtuple.c index ffc94b5d27..c0a33dad7e 100644 --- a/py/objtuple.c +++ b/py/objtuple.c @@ -165,7 +165,8 @@ mp_obj_t mp_obj_tuple_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) { if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) { mp_bound_slice_t slice; if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice)) { - assert(0); + nlr_raise(mp_obj_new_exception_msg(&mp_type_NotImplementedError, + "Only slices with step=1 (aka None) are supported")); } mp_obj_tuple_t *res = mp_obj_new_tuple(slice.stop - slice.start, NULL); mp_seq_copy(res->items, self->items + slice.start, res->len, mp_obj_t); diff --git a/py/sequence.c b/py/sequence.c index db5eed4c8e..c940d9f69f 100644 --- a/py/sequence.c +++ b/py/sequence.c @@ -95,8 +95,6 @@ bool mp_seq_get_fast_slice_indexes(machine_uint_t len, mp_obj_t slice, mp_bound_ indexes->stop = stop; if (ostep != mp_const_none && ostep != MP_OBJ_NEW_SMALL_INT(1)) { - nlr_raise(mp_obj_new_exception_msg(&mp_type_NotImplementedError, - "Only slices with step=1 (aka None) are supported")); indexes->step = MP_OBJ_SMALL_INT_VALUE(ostep); return false; } @@ -104,6 +102,27 @@ bool mp_seq_get_fast_slice_indexes(machine_uint_t len, mp_obj_t slice, mp_bound_ return true; } +mp_obj_t mp_seq_extract_slice(uint len, const mp_obj_t *seq, mp_bound_slice_t *indexes) { + machine_int_t start = indexes->start, stop = indexes->stop; + machine_int_t step = indexes->step; + + mp_obj_t res = mp_obj_new_list(0, NULL); + + if (step < 0) { + stop--; + while (start <= stop) { + mp_obj_list_append(res, seq[stop]); + stop += step; + } + } else { + while (start < stop) { + mp_obj_list_append(res, seq[start]); + start += step; + } + } + return res; +} + // Special-case comparison function for sequences of bytes // Don't pass MP_BINARY_OP_NOT_EQUAL here bool mp_seq_cmp_bytes(int op, const byte *data1, uint len1, const byte *data2, uint len2) { diff --git a/tests/basics/list_slice_3arg.py b/tests/basics/list_slice_3arg.py new file mode 100644 index 0000000000..1320e79236 --- /dev/null +++ b/tests/basics/list_slice_3arg.py @@ -0,0 +1,4 @@ +x = list(range(10)) +print(x[::-1]) +print(x[::2]) +print(x[::-2])