Emacs Lisp 3 - 暇つぶし2ch

Emacs Lisp 3 at TECH

108:デフォルトの名無しさん
08/12/03 17:02:51
;; >>106 エスパーして作ってみた
(mapc 'require (cl el-expectations))

(defun co (x lst &optional acc)
(assert (listp lst))
(macrolet
((recur (&rest lst) `(co ,@lst)))
(let ((cur (car lst)))
(cond ((null cur) nil)
((and (atom cur)) (if (eq x cur) (cons 'car acc)
(recur x (cdr lst) (cons 'cdr acc))))
((listp cur) (or (recur x (car lst) (cons 'car acc))
(recur x (cdr lst) (cons 'cdr acc))))
(t (error "unexpected lst: %s" cur))))))
;; test cases
(expectations
(error (co 'a '()))
(expect (co 'not-found '()))
(expect (co 'a '(a)) '(car))
(expect (co 'b '(a b c)) '(car cdr))
(expect (co 'c '(a b c)) '(car cdr cdr))
(expect (co 'x '((x) a b c)) '(car car))
(expect (co 'x '((a b c x) d e f)) '(car cdr cdr cdr car))
(expect (co 'x '(a b (c x d) e f)) '(car cdr car cdr cdr)))

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