cd_project.lisp

(defun make-cd (title artist rating ripped)
    (list :title title :artist artist :rating rating :ripped ripped))

(defvar *db* nil)

(defun add-record (cd) (push cd *db*))

(defun dump-db ()
    (format t "~{~{~a:~10t~a~%~}~%~}" *db*))

(defun prompt-read (prompt)
    (format *query-io* "~a: " prompt)
    (force-output *query-io*)
    (read-line *query-io*))

(defun prompt-for-cd ()
    (make-cd 
        (prompt-read "Title")
        (prompt-read "Artist")
        (or (parse-integer (prompt-read "Rating") :junk-allowed t) 0)
        (y-or-n-p "Ripped [y/n]")))

(defun add-cds ()
    (loop (add-record (prompt-for-cd))
        (if (not (y-or-n-p "Another? [y/n]: ")) (return))))

(defun save-db (filename)
    (with-open-file (out filename 
                        :direction :output
                        :if-exists :supersede)
                    (with-standard-io-syntax
                        (print *db* out))))

(defun load-db (filename)
    (with-open-file (in filename)
        (with-standard-io-syntax
            (setf *db* (read in)))))

(defun select (selector-fn)
    (remove-if-not selector-fn *db*))

(defun where (&key title artist rating (ripped nil ripped-p))
    #'(lambda (cd)
        (and
            (if title    (equal (getf cd :title)  title) t)
            (if artist   (equal (getf cd :artist) artist) t)
            (if rating   (equal (getf cd :rating) rating) t)
            (if ripped-p (equal (getf cd :ripped) ripped) t))))

(defun update (selector-fn &key title artist rating (ripped nil ripped-p))
    (setf *db* 
        (mapcar 
        #'(lambda (row)
            (when (funcall selector-fn row)
                (if title    (setf (getf row :title) title))
                (if artist   (setf (getf row :artist) artist))
                (if rating   (setf (getf row :rating) rating))
                (if ripped-p (setf (getf row :ripped) ripped)))
            row) *db*)))

(defun delete-rows (selector-fn)
    (setf *db* (remove-if selector-fn *db*)))