original-message.txt - clic - Clic is an command line interactive client for gopher written in Common LISP
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original-message.txt (4492B)
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1 From ...
2 Path: supernews.google.com!sn-xit-02!sn-xit-03!supernews.com!news.tele.dk!193.190.198.17!newsfeeds.belnet.be!
3 news.belnet.be!skynet.be!newsfeed2.news.nl.uu.net!sun4nl!not-for-mail
4 From: Arthur Lemmens <lemmens@simplex.nl>
5 Newsgroups: comp.lang.lisp
6 Subject: Re: Q: on hashes and counting
7 Date: Mon, 23 Oct 2000 00:50:02 +0200
8 Organization: Kikashi Software
9 Lines: 129
10 Message-ID: <39F36F1A.B8F19D20@simplex.nl>
11 References: <8sl58e$ivq$1@nnrp1.deja.com> <878zrlp1cr.fsf@orion.bln.pmsf.de>
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20 Xref: supernews.google.com comp.lang.lisp:2515
21
22
23 Pierre R. Mai wrote:
24
25 > ;;; The following functions are based on the versions by Arthur
26 > ;;; Lemmens of the original code by Bernard Pfahringer posted to
27 > ;;; comp.lang.lisp. I only renamed and diddled them a bit.
28 >
29 > (defun partition
30
31 [snip]
32
33 > ;; DO: Find a more efficient way to take care of :from-end T.
34 > (when from-end
35 > (setf seq (reverse seq))
36 > (psetf start (- len end)
37 > end (- len start)))
38
39 I've written a different version now for dealing with :FROM-END T.
40 It doesn't call REVERSE anymore, which makes it more efficient.
41 Also, I prefer the new semantics. Stuff like
42 (split #\space "one two three " :from-end t)
43 now returns
44 ("three" "two" "one")
45 which I find a lot more useful than
46 ("eerht" "owt" "eno")
47 If you prefer the latter, it's easy enough to use
48 (split #\space (reverse "one two three "))
49
50
51 Here it is (feel free to use this code any way you like):
52
53 (defun SPLIT (delimiter seq
54 &key (maximum nil)
55 (keep-empty-subseqs nil)
56 (from-end nil)
57 (start 0)
58 (end nil)
59 (test nil test-supplied)
60 (test-not nil test-not-supplied)
61 (key nil key-supplied))
62
63 "Return a list of subsequences in <seq> delimited by <delimiter>.
64 If :keep-empty-subseqs is true, empty subsequences will be included
65 in the result; otherwise they will be discarded.
66 If :maximum is supplied, the result will contain no more than :maximum
67 (possibly empty) subsequences. The second result value contains the
68 unsplit rest of the sequence.
69 All other keywords work analogously to those for CL:POSITION."
70
71 ;; DO: Make ":keep-delimiters t" include the delimiters in the result (?).
72
73 (let ((len (length seq))
74 (other-keys (nconc (when test-supplied
75 (list :test test))
76 (when test-not-supplied
77 (list :test-not test-not))
78 (when key-supplied
79 (list :key key)))))
80
81 (unless end (setq end len))
82 (if from-end
83 (loop for right = end then left
84 for left = (max (or (apply #'position delimiter seq
85 :end right
86 :from-end t
87 other-keys)
88 -1)
89 (1- start))
90 unless (and (= right (1+ left) )
91 (not keep-empty-subseqs)) ; empty subseq we don't want
92 if (and maximum (>= nr-elts maximum))
93 ;; We can't take any more. Return now.
94 return (values subseqs (subseq seq start right))
95 else
96 collect (subseq seq (1+ left) right) into subseqs
97 and sum 1 into nr-elts
98 until (<= left start)
99 finally return (values subseqs (subseq seq start (1+ left))))
100 (loop for left = start then (+ right 1)
101 for right = (min (or (apply #'position delimiter seq
102 :start left
103 other-keys)
104 len)
105 end)
106 unless (and (= right left)
107 (not keep-empty-subseqs)) ; empty subseq we don't want
108 if (and maximum (>= nr-elts maximum))
109 ;; We can't take any more. Return now.
110 return (values subseqs (subseq seq left end))
111 else
112 collect (subseq seq left right) into subseqs
113 and sum 1 into nr-elts
114 until (= right end)
115 finally return (values subseqs (subseq seq right end))))))
116
117
118
119 Here are some examples of how you can use this:
120
121
122 CL-USER 2 > (split #\space "word1 word2 word3")
123 ("word1" "word2" "word3")
124 ""
125
126 CL-USER 3 > (split #\space "word1 word2 word3" :from-end t)
127 ("word3" "word2" "word1")
128 ""
129
130 CL-USER 4 > (split nil '(a b nil c d e nil nil nil nil f) :maximum 2)
131 ((A B) (C D E))
132 (F)
133
134 CL-USER 5 > (split #\space "Nospaceshere.")
135 ("Nospaceshere.")
136 ""
137
138 CL-USER 6 > (split #\; "12;13;;14" :keep-empty-subseqs t)
139
140 ("12" "13" "" "14")
141 ""
142
143 CL-USER 7 > (split #\; "12;13;;14" :keep-empty-subseqs t :from-end t)
144
145 ("14" "" "13" "12")
146 ""
147
148 CL-USER 8 > (split #\space "Nospaceshere. ")
149 ("Nospaceshere.")
150 ""