bswitch.el

;;;; Hydra for quickly switching among the 8 most recent buffers
;;;; by using the home row keys.

;; This is the command that toggles the hydra.
;; Change the keybinding if you like
(global-set-key (kbd "C-c j") 'hydra-bswitch/body)

(defvar bswitch-map (list 1 "a"
                          2 "s"
                          3 "d"
                          4 "f"
                          5 "j"
                          6 "k"
                          7 "l"
                          8 ";"))

(defvar bswitch-offset 15)
(defvar bswitch-key-buffer-spacing 5)

(defun bswitch-repeat (number &optional str)
  (if (< number 1)
      str
    (bswitch-repeat (1- number) (concat " " str))))

(defun bswitch-get-beginning ()
  (bswitch-repeat (- (/ (window-body-width) 2) bswitch-offset)))

(defun bswitch-get-end (beg mid)
  (bswitch-repeat (- (window-body-width)
                     (+ (length mid)
                        (length beg)))))

(defun bswitch-get-header-display-line ()
  (let* ((beg (bswitch-get-beginning))
         (mid (concat "Key"
                      (bswitch-repeat
                       (+ -2 bswitch-key-buffer-spacing))
                      "Buffer"))
         (end (bswitch-get-end beg mid)))
    (concat beg mid end)))


(defun bswitch-get-buffer-display-line (index)
  (let* ((blist (buffer-list)))
    (if (< index (length blist))
        (let* ((beg (bswitch-get-beginning))
               (mid (concat (plist-get bswitch-map index)
                            (bswitch-repeat bswitch-key-buffer-spacing)
                            (buffer-name (nth index (buffer-list)))))
               (end (bswitch-get-end beg mid))) 
          
          (concat beg mid end))
      (let* ((beg (bswitch-get-beginning))
             (mid (format "No buffer at index %s yet" index))
             (end (bswitch-get-end beg mid)))
        (concat beg mid end)))))

(defun bswitch-switch (index)
  (if (< index (length (buffer-list)))
      (switch-to-buffer (nth index (buffer-list)))
    (message "Cannot switch since there is no buffer at index %s yet" index)))

(defhydra hydra-bswitch (:hint nil :exit t)
  "

%(bswitch-get-header-display-line)

%(bswitch-get-buffer-display-line 1)

%(bswitch-get-buffer-display-line 2)

%(bswitch-get-buffer-display-line 3)

%(bswitch-get-buffer-display-line 4)

%(bswitch-get-buffer-display-line 5)

%(bswitch-get-buffer-display-line 6)

%(bswitch-get-buffer-display-line 7)

%(bswitch-get-buffer-display-line 8)

"
  ("a" (bswitch-switch 1))
  ("s" (bswitch-switch 2))
  ("d" (bswitch-switch 3))
  ("f" (bswitch-switch 4))
  ("j" (bswitch-switch 5))
  ("k" (bswitch-switch 6))
  ("l" (bswitch-switch 7))
  (";" (bswitch-switch 8))
  )