Align columns: Difference between revisions

=={{header|Common Lisp}}==

<lang lisp>(defun nonempty (seq)

(position-if (lambda (x) (declare (ignore x)) t) seq))

(defun split (delim seq)

"Splits seq on delim into a list of subsequences. Trailing empty

subsequences are removed."

(labels

((f (seq &aux (pos (position delim seq)))

(if pos

(cons

(subseq seq 0 pos)

(f (subseq seq (1+ pos))))

(list seq))))

(let*

((list (f seq))

(end (position-if #'nonempty list :from-end t)))

(subseq list 0 (1+ end)))))

(defun lengthen (list minlen filler-elem &aux (len (length list)))

"Destructively pads list with filler-elem up to minlen."

(if (< len minlen)

(nconc list (make-list

(- minlen len) :initial-element filler-elem))

list))

(defun align-columns (text &key (align :left) &aux

(fmtmod (case align

(:left "@")

(:right ":")

(:center "@:")

(t (error "Invalid alignment."))))

(fields (mapcar

(lambda (line) (split #\$ line))

(split #\Newline text)))

(mostcols (loop for l in fields maximize (length l)))

widest)

(setf fields (mapcar

(lambda (l) (lengthen l mostcols ""))

fields))

(setf widest (loop

for col below (length (first fields))

collect (loop

for row in fields maximize (length (elt row col)))))

(format nil

(with-output-to-string (s)

(princ "~{~{" s)

(dolist (w widest)

(format s "~~~d~a<~~a~~>" (1+ w) fmtmod))

(princ "~}~%~}" s))

fields))</lang>