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  1. ; your code goes here
  2. ;; PCL chapter 3
  3.  
  4. (defvar *db* nil)
  5.  
  6. (defun add-record (cd) (push cd *db*))
  7.  
  8. (defun dump-db()
  9.   (dolist (cd *db*)
  10.     (format t "~{~a:~10t~a~%~}~%" cd)))
  11.  
  12. (defun prompt-read (prompt)
  13.   (format *query-io* "~a: " prompt)
  14.   (force-output *query-io*)
  15.   (read-line *query-io*))
  16.  
  17. (defun prompt-for-cd ()
  18.   (make-cd
  19.    (prompt-read "Title")
  20.    (prompt-read "Artist")
  21.    (or
  22.     (parse-integer (prompt-read "Rating") :junk-allowed t)
  23.     0)
  24.    (y-or-n-p "Ripped [y/n]: ")))
  25.  
  26. (defun add-cds()
  27.   (loop (add-record (prompt-for-cd))
  28.      (if (not (y-or-n-p "Another? [y/n]: ")) (return))))
  29.  
  30. (defun save-db (filename)
  31.   (with-open-file (out filename
  32.                        :direction :output
  33.                        :if-exists :supersede)
  34.     (with-standard-io-syntax
  35.       (print *db* out))))
  36.  
  37. (defun load-db (filename)
  38.   (with-open-file (in filename)
  39.     (with-standard-io-syntax
  40.       (setf *db* (read in)))))
  41.  
  42. (defun select (selector-fn)
  43.   (remove-if-not selector-fn *db*))
  44.  
  45. (defmacro where (&rest clauses)
  46.   `#'(lambda (cd) (and ,@(make-comparison-list clauses))))
  47.  
  48. (defun make-comparison-list (fields)
  49.   (loop while fields
  50.      collecting (make-comparison-expr (pop fields) (pop fields))))
  51.  
  52. (defun make-comparison-expr (field value)
  53.   `(equal (getf cd ,field) ,value))
  54.  
  55. (defun update (selector-fn &key title artist rating (ripped nil ripped-p))
  56.   (setf *db*
  57.         (mapcar
  58.          #'(lambda (row)
  59.              (when (funcall selector-fn row)
  60.                (if title (setf (getf row :title) title))
  61.                (if artist (setf (getf row :artist) artist))
  62.                (if rating (setf (getf row :rating) rating))
  63.                (if ripped-p (setf (getf row :ripped) ripped)))
  64.              row) *db*)))
  65.  
  66. (defun delete-rows (selector-fn)
  67.   (setf *db* (remove-if selector-fn *db*)))
  68.  
  69. (defun make-cd (title artist rating ripped)
  70.   (list :title title :artist artist :rating rating :ripped ripped))
  71.  
Success #stdin #stdout 0.01s 10552KB
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stdout 
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https://ideone.com/DZxArH
language:
Common Lisp (clisp 2.49.92)
created:
8 years ago
visibility:
secret

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