Madhu wrote:

> * Tamas Papp <87hcnwaky1.fsf@pu100877.student.princeton.edu> :
>
> | Hi,
> |
> | 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)))))))
>

Testing under SBCL:

* (parse-rgb-line " 62 128 255 light blue ")

"#3E80FF"
"light blue "

Pure crap.

Gauche Scheme:

(use gauche.generator)

(define (parse-rgb-line line)
(define tokens
(with-input-from-string line (cut generator->list read)))
(list (take tokens 3)
(string-join (map symbol->string (drop tokens 3)) " ")))

(parse-rgb-line " 62 128 255 light blue ")
===>
((62 128 255) "light blue")

(parse-rgb-line "62 128 255 LightBlue")
===>
((62 128 255) "LightBlue")

Robert L. <No_spamming@noWhere_7073.org> wrote:

> (define (parse-rgb-line line)
> (define tokens
> (with-input-from-string line (cut generator->list read)))
> (list (take tokens 3)
> (string-join (map symbol->string (drop tokens 3)) " ")))
>

He is using read. Because that is a good idea.
--
the small snake