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author | Rob Browning <rlb@defaultvalue.org> | 2024-07-18 03:23:27 -0500 |
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committer | Rob Browning <rlb@defaultvalue.org> | 2024-07-30 19:28:37 -0500 |
commit | a94b4406b76082d2a98842a404b7a068729dcf58 (patch) | |
tree | 9d3fbef864ae6546c2b112402aef3de107fcd36f /libguile/srfi-1.c | |
parent | 51e15d448f705a7aa0aa2f26744f9b2b793535d2 (diff) | |
download | guile-a94b4406b76082d2a98842a404b7a068729dcf58.tar.gz |
srfi-1 delete-duplicates!: move from C to Scheme
* libguile/srfi-1.c (scm_srfi1_delete-duplicates_x): delete.
* libguile/srfi-1.h (scm_srfi1_delete-duplicates_x): delete.
* module/srfi/srfi-1.scm: add delete-duplicates!.
Diffstat (limited to 'libguile/srfi-1.c')
-rw-r--r-- | libguile/srfi-1.c | 83 |
1 files changed, 0 insertions, 83 deletions
diff --git a/libguile/srfi-1.c b/libguile/srfi-1.c index 56e12296b..ba48e3425 100644 --- a/libguile/srfi-1.c +++ b/libguile/srfi-1.c @@ -189,89 +189,6 @@ SCM_DEFINE (scm_srfi1_delete_duplicates, "delete-duplicates", 1, 1, 0, } #undef FUNC_NAME - -SCM_DEFINE (scm_srfi1_delete_duplicates_x, "delete-duplicates!", 1, 1, 0, - (SCM lst, SCM pred), - "Return a list containing the elements of @var{lst} but without\n" - "duplicates.\n" - "\n" - "When elements are equal, only the first in @var{lst} is\n" - "retained. Equal elements can be anywhere in @var{lst}, they\n" - "don't have to be adjacent. The returned list will have the\n" - "retained elements in the same order as they were in @var{lst}.\n" - "\n" - "Equality is determined by @var{pred}, or @code{equal?} if not\n" - "given. Calls @code{(pred x y)} are made with element @var{x}\n" - "being before @var{y} in @var{lst}. A call is made at most once\n" - "for each combination, but the sequence of the calls across the\n" - "elements is unspecified.\n" - "\n" - "@var{lst} may be modified to construct the returned list.\n" - "\n" - "In the worst case, this is an @math{O(N^2)} algorithm because\n" - "it must check each element against all those preceding it. For\n" - "long lists it is more efficient to sort and then compare only\n" - "adjacent elements.") -#define FUNC_NAME s_scm_srfi1_delete_duplicates_x -{ - scm_t_trampoline_2 equal_p; - SCM ret, endret, item, l; - - /* ret is the return list, constructed from the pairs in lst. endret is - the last pair of ret, initially the first pair. lst is advanced as - elements are considered. */ - - /* skip to end if an empty list (or something invalid) */ - ret = lst; - if (scm_is_pair (lst)) - { - if (SCM_UNBNDP (pred)) - equal_p = equal_trampoline; - else - { - SCM_VALIDATE_PROC (SCM_ARG2, pred); - equal_p = scm_call_2; - } - - endret = ret; - - /* loop over lst elements starting from second */ - for (;;) - { - lst = SCM_CDR (lst); - if (! scm_is_pair (lst)) - break; - item = SCM_CAR (lst); - - /* is item equal to any element from ret to endret (inclusive)? */ - l = ret; - for (;;) - { - if (scm_is_true (equal_p (pred, SCM_CAR (l), item))) - break; /* equal, forget this element */ - - if (scm_is_eq (l, endret)) - { - /* not equal to any, so append this pair */ - scm_set_cdr_x (endret, lst); - endret = lst; - break; - } - l = SCM_CDR (l); - } - } - - /* terminate, in case last element was deleted */ - scm_set_cdr_x (endret, SCM_EOL); - } - - /* demand that lst was a proper list */ - SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, SCM_ARG1, FUNC_NAME, "list"); - - return ret; -} -#undef FUNC_NAME - void scm_register_srfi_1 (void) |