Add reading-mode

1 files changed, 83 insertions, 0 deletions

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+;;; reading.el --- minor mode for reading -*- lexical-binding: t; -*-
+
+;;; Code:
+
+(defgroup reading nil
+  "Group for Reading mode customizations."
+  :prefix "reading-"
+  :group 'convenience)
+
+(defcustom reading-vars '((indicate-empty-lines . nil)
+                          (indicate-buffer-boundaries . nil))
+  "Alist of variables to set in function `reading-mode'.
+The car of each cell is the variable name, and the cdr is the
+value to set it to."
+  :type '(alist :key-type variable
+                :value-type sexp))
+
+(defcustom reading-modes '((display-fill-column-indicator-mode . -1)
+                           (blink-cursor-mode . -1))
+  "Alist of modes to set in function `reading-mode'.
+The car of each cell is the function name, and the cdr is the
+value to call it with."
+  :type '(alist :key-type function
+                :value-type sexp))
+
+;;; Internal
+
+(defvar reading--remembered-template "reading--remembered-%s-value"
+  "The template passed to `format' for remembered modes and variables.")
+
+(defun reading--remember (things func)
+  "Apply FUNC to THINGS, remembering their previous value for later."
+  (declare (indent 1))
+  (unless (listp things)
+    (setq things (list things)))
+  (dolist (thing things)
+    (set (make-local-variable
+          (intern (format reading--remembered-template thing)))
+         (and (boundp thing)
+              (symbol-value thing)))
+    (funcall func thing)))
+
+(defun reading--recall (things func)
+  "Recall previously remembered THINGS by applying FUNC to them.
+FUNC should be a function with the signature (THING REMEMBERED-SETTING)."
+  (declare (indent 1))
+  (unless (listp things)
+    (setq things (list things)))
+  (dolist (thing things)
+    (with-demoted-errors "reading--recall: %S"
+      (let ((value (symbol-value
+                    (intern
+                     (format reading--remembered-template thing)))))
+        (funcall func thing value)))))
+
+;;; Mode
+
+;;;###autoload
+(define-minor-mode reading-mode
+  "A mode for reading."
+  :init-value nil
+  :lighter " Read"
+  :keymap (make-sparse-keymap)
+  (if reading-mode
+      ;; turn on
+      (progn
+        (reading--remember (mapcar #'car reading-vars)
+          (lambda (var)
+            (set (make-local-variable var)
+                 (cdr (assoc var reading-vars)))))
+        (reading--remember (mapcar #'car reading-modes)
+          (lambda (mode)
+            (funcall mode (cdr (assoc mode reading-modes))))))
+    ;; turn off
+    (reading--recall (mapcar #'car reading-vars)
+      (lambda (var orig-val)
+        (set (make-local-variable var) orig-val)))
+    (reading--recall (mapcar #'car reading-modes)
+      (lambda (mode orig-setting)
+        (funcall mode (if orig-setting +1 -1))))))
+
+(provide 'reading)
+;;; reading.el ends here