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;;;; SPLIT-SEQUENCE
;;;
;;; This code was based on Arthur Lemmens' in
;;; <URL:http://groups.google.com/groups?as_umsgid=39F36F1A.B8F19D20%40simplex.nl>;
;;;
;;; changes include:
;;;
;;; * altering the behaviour of the :from-end keyword argument to
;;; return the subsequences in original order, for consistency with
;;; CL:REMOVE, CL:SUBSTITUTE et al. (:from-end being non-NIL only
;;; affects the answer if :count is less than the number of
;;; subsequences, by analogy with the above-referenced functions).
;;;
;;; * changing the :maximum keyword argument to :count, by analogy
;;; with CL:REMOVE, CL:SUBSTITUTE, and so on.
;;;
;;; * naming the function SPLIT-SEQUENCE rather than PARTITION rather
;;; than SPLIT.
;;;
;;; * adding SPLIT-SEQUENCE-IF and SPLIT-SEQUENCE-IF-NOT.
;;;
;;; * The second return value is now an index rather than a copy of a
;;; portion of the sequence; this index is the `right' one to feed to
;;; CL:SUBSEQ for continued processing.
;;; There's a certain amount of code duplication here, which is kept
;;; to illustrate the relationship between the SPLIT-SEQUENCE
;;; functions and the CL:POSITION functions.
;;; Examples:
;;;
;;; * (split-sequence #\; "a;;b;c")
;;; -> ("a" "" "b" "c"), 6
;;;
;;; * (split-sequence #\; "a;;b;c" :from-end t)
;;; -> ("a" "" "b" "c"), 0
;;;
;;; * (split-sequence #\; "a;;b;c" :from-end t :count 1)
;;; -> ("c"), 4
;;;
;;; * (split-sequence #\; "a;;b;c" :remove-empty-subseqs t)
;;; -> ("a" "b" "c"), 6
;;;
;;; * (split-sequence-if (lambda (x) (member x '(#\a #\b))) "abracadabra")
;;; -> ("" "" "r" "c" "d" "" "r" ""), 11
;;;
;;; * (split-sequence-if-not (lambda (x) (member x '(#\a #\b))) "abracadabra")
;;; -> ("ab" "a" "a" "ab" "a"), 11
;;;
;;; * (split-sequence #\; ";oo;bar;ba;" :start 1 :end 9)
;;; -> ("oo" "bar" "b"), 9
;; cl-utilities note: the license of this file is unclear, and I don't
;; even know whom to contact to clarify it. If anybody objects to my
;; assumption that it is public domain, please contact me so I can do
;; something about it. Previously I required the split-sequence
; package as a dependency, but that was so unwieldy that it was *the*
;; sore spot sticking out in the design of cl-utilities. -Peter Scott
(in-package :utils-kt)
(export! split-sequence)
(defun split-sequence (delimiter seq &key (count nil) (remove-empty-subseqs nil) (from-end nil)
(start 0) (end nil) (test nil test-supplied) (test-not nil test-not-supplied) (key nil key-supplied))
(let ((len (length seq))
(other-keys (nconc (when test-supplied
(list :test test))
(when test-not-supplied
(list :test-not test-not))
(when key-supplied
(list :key key)))))
(unless end (setq end len))
(if from-end
(loop for right = end then left
for left = (max (or (apply #'position delimiter seq
:end right
:from-end t
other-keys)
-1)
(1- start))
unless (and (= right (1+ left))
remove-empty-subseqs) ; empty subseq we don't want
if (and count (>= nr-elts count))
;; We can't take any more. Return now.
return (values (nreverse subseqs) right)
else
collect (subseq seq (1+ left) right) into subseqs
and sum 1 into nr-elts
until (< left start)
finally (return (values (nreverse subseqs) (1+ left))))
(loop for left = start then (+ right 1)
for right = (min (or (apply #'position delimiter seq
:start left
other-keys)
len)
end)
unless (and (= right left)
remove-empty-subseqs) ; empty subseq we don't want
if (and count (>= nr-elts count))
;; We can't take any more. Return now.
return (values subseqs left)
else
collect (subseq seq left right) into subseqs
and sum 1 into nr-elts
until (>= right end)
finally (return (values subseqs right))))))
(defun split-sequence-if (predicate seq &key (count nil) (remove-empty-subseqs nil) (from-end nil) (start 0) (end nil) (key nil key-supplied))
(let ((len (length seq))
(other-keys (when key-supplied
(list :key key))))
(unless end (setq end len))
(if from-end
(loop for right = end then left
for left = (max (or (apply #'position-if predicate seq
:end right
:from-end t
other-keys)
-1)
(1- start))
unless (and (= right (1+ left))
remove-empty-subseqs) ; empty subseq we don't want
if (and count (>= nr-elts count))
;; We can't take any more. Return now.
return (values (nreverse subseqs) right)
else
collect (subseq seq (1+ left) right) into subseqs
and sum 1 into nr-elts
until (< left start)
finally (return (values (nreverse subseqs) (1+ left))))
(loop for left = start then (+ right 1)
for right = (min (or (apply #'position-if predicate seq
:start left
other-keys)
len)
end)
unless (and (= right left)
remove-empty-subseqs) ; empty subseq we don't want
if (and count (>= nr-elts count))
;; We can't take any more. Return now.
return (values subseqs left)
else
collect (subseq seq left right) into subseqs
and sum 1 into nr-elts
until (>= right end)
finally (return (values subseqs right))))))
(defun split-sequence-if-not (predicate seq &key (count nil) (remove-empty-subseqs nil) (from-end nil) (start 0) (end nil) (key nil key-supplied))
(let ((len (length seq))
(other-keys (when key-supplied
(list :key key))))
(unless end (setq end len))
(if from-end
(loop for right = end then left
for left = (max (or (apply #'position-if-not predicate seq
:end right
:from-end t
other-keys)
-1)
(1- start))
unless (and (= right (1+ left))
remove-empty-subseqs) ; empty subseq we don't want
if (and count (>= nr-elts count))
;; We can't take any more. Return now.
return (values (nreverse subseqs) right)
else
collect (subseq seq (1+ left) right) into subseqs
and sum 1 into nr-elts
until (< left start)
finally (return (values (nreverse subseqs) (1+ left))))
(loop for left = start then (+ right 1)
for right = (min (or (apply #'position-if-not predicate seq
:start left
other-keys)
len)
end)
unless (and (= right left)
remove-empty-subseqs) ; empty subseq we don't want
if (and count (>= nr-elts count))
;; We can't take any more. Return now.
return (values subseqs left)
else
collect (subseq seq left right) into subseqs
and sum 1 into nr-elts
until (>= right end)
finally (return (values subseqs right))))))
(pushnew :split-sequence *features*)