Re: removeText

B. Pym wrote:

Peter Seibel wrote:
 

Kenny Tilton <ktilton@nyc.rr.com> writes:
 

Cool. Now here is a version using loop:
 
(defun remove-text (text-to-remove text)
     (loop with remove-length = (length text-to-remove)
         for i = (search text-to-remove text)
         then (search text-to-remove text :start2 i)
         while i
         do (setq text (concatenate 'string
                         (subseq text 0 i)
                         (subseq text (+ i remove-length))))
         finally (return text)))

 
Just to point out a useful LOOP idiom, here's another way:
 
  (defun remove-text (text-to-remove text)
    (with-output-to-string (s)
      (loop
         with remove-length = (length text-to-remove)
         for prev-end       = 0 then (+ start remove-length)
         for start          = (search text-to-remove text :start2 prev-end)
         do (write-string text s :start prev-end :end start)
         while start)))

 
If we use a Lispy language instead of CL, then we can
make the solution shorter by simply using recursion
instead of a macro whose source measures more than
60 kilobytes.
 
Gauche Scheme
 
(use srfi-13)  ;; string-contains
 
(define (remove-text victim text)
  (let1 victim-length (string-length victim)
    (with-output-to-string
      (lambda()
        (let go ((start 0))
          (let1 p (string-contains text victim start)
            (display (string-copy text start p))
            (when p (go (+ p victim-length)))))))))
 
(remove-text " not" "CL is not bad and not a nightmare.")
  ===>
"CL is bad and a nightmare."

Using "do":

(define (remove-text victim text)
  (let ((victim-length (string-length victim)) (p 0))
    (with-output-to-string
      (lambda()
        (do ((start 0 (+ p victim-length)))
          ((begin
             (set! p (string-contains text victim start))
             (display (string-copy text start p))
             (not p))))))))