From Newsgroup: comp.lang.lisp
B. Pym wrote:
Madhu wrote:
I would like to parse color names in X11's rgb.txt. They look like this:
119 136 153 light slate gray
119 136 153 LightSlateGray
When parsing each line, I would like to get the color triplet, and the
name. I tried it like this:
(let ((color-scanner
(cl-ppcre:create-scanner
"^ +([0-9]{0,2}) +([0-9]{0,2}) +([0-9]{0,2}) +([ a-zA-Z0-9]+)")))
(cl-ppcre:scan-to-strings color-scanner " 1 2 3 foo bar baz "))
This gives #("1" "2" "3" "foo bar baz ") for the substrings. How can
I get rid of the trailing spaces?
Use the right tool for the job :)
(defun parse-rgb-line (string &key (start 0) end)
(multiple-value-bind (r endr)
(parse-integer string :start start :end end :junk-allowed t)
(multiple-value-bind (g endg)
(parse-integer string :start (1+ endr) :end end :junk-allowed t)
(multiple-value-bind (b endb)
(parse-integer string :start (1+ endg) :end end :junk-allowed t)
(let ((name-startpos
(position-if-not (lambda (c) (case c ((#\Tab #\Space) t)))
string :start (1+ endb))))
(values (format nil "#~2,'0X~2,'0X~2,'0X" r g b)
(subseq string name-startpos end)))))))
Gauche Scheme
(use srfi-13) ;; string-trim-both
(define (parse-rgb-line line)
(with-input-from-string line
(lambda()
(append
(list (read) (read) (read))
(list (string-trim-both (read-line)))))))
(parse-rgb-line " 255 88 6 yes no ")
===>
(255 88 6 "yes no")
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