;;; dir-iterate-files --- iterate directory files

;;; Commentary:
;;
;; .-----------------------------------------------.
;;  \  dir-iterate-files - iterate directory files  \
;;   \     by Emanuel Berg                           \
;;   /     embe8573 AT&T student DOS uu DOS se       /
;;  /      updated: Thu Jan  8 02:47:47 CET 2015    /
;; '-----------------------------------------------'
;;
;; Iterate  the  contents  of  the  directory  of  the
;; current buffer file.
;;
;; This  can be  used  for many  things,  but the  one
;; primarily in mind  is when there are  many files in
;; the same directory, and  those files must be sorted
;; as a function of their contents, and thus be viewed
;; before it can be determined where they should go.
;;
;; This package,  in combination with a  function that
;; sends files in different directions, would speed up
;; such work considerably, and  make it more enjoyable
;; and fun.
;;
;; Note  that  it  is   all  but  compulsory  to  bind
;; `dir-next-file'  to  a  key  or  key  sequence,  as
;; otherwise selecting  the next file most  other ways
;; would be just as fast (or slow).

;;; Code:

(require 'cl-lib)

(defun drop-sublist (l drop-l)
  "Every element that is in L, but isn't in DROP-L."
  (cl-remove-if #'(lambda (e) (member e drop-l)) l) )

(defun dir-common-files ()
  "Get a list of all files in the directory of the current buffer file,
except for '.' and '..'."
  (let*((dir (file-name-directory (buffer-file-name)))
        (all-files (directory-files dir))
        (files (drop-sublist all-files '("." ".."))) )
    files))

(defun dir-next-file ()
  "Go to the next file in the list returned by `dir-common-files'.
If the current buffer file is the last file already, start over.
If the current buffer file isn't in `dir-common-files', start with the first one."
  (interactive)
  (let*((files (dir-common-files))
        (this-file-forward (member (buffer-name) files)) )
    (if this-file-forward
        (find-file
         (if (eq (length this-file-forward) 1) (car files)
           (cadr this-file-forward) ))
      (find-file (car files)) )))

(provide 'iterate-files)

;;; iterate-files.el ends here