feat: visual format buffer (early WIP)

Author: abougouffa

elisp/visual-format.el

@@ -0,0 +1,84 @@
+(defun visual-format--cleanup (start end)
+  (while (and (< start end)
+              (setq start (text-property-any start end 'display visual-format--space)))
+    (remove-text-properties
+     start
+     (setq start (or (text-property-not-all start end 'display visual-format--space)
+                     end))
+     '(display nil))))
+
+(require 'treesit)
+
+(defvar-local visual-format--buffer nil)
+(defvar-local visual-format--buffer-formatted nil)
+
+(defmacro visual-format--with-buff (&rest body)
+  `(with-current-buffer visual-format--buffer
+    ,@body))
+
+(defmacro visual-format--with-buff-fmt (&rest body)
+  `(with-current-buffer visual-format--buffer-formatted
+    ,@body))
+
+(defun visual-format--depth-first-walk (&optional node node-fmt prev-node prev-node-fmt depth)
+  (let ((node (or node (visual-format--with-buff (treesit-buffer-root-node))))
+        (node-fmt (or node-fmt (visual-format--with-buff-fmt (treesit-buffer-root-node))))
+        (prev-leaf prev-node)
+        (prev-leaf-fmt prev-node-fmt)
+        (depth (or depth 0)))
+    (cl-assert (= (treesit-node-child-count node) (treesit-node-child-count node-fmt)))
+    (dotimes (i (treesit-node-child-count node))
+      (let* ((n (treesit-node-child node i))
+             (n-fmt (treesit-node-child node-fmt i)))
+        (if (zerop (treesit-node-child-count n)) ; leaf
+            (let* ((pos-beg
+                    (visual-format--with-buff
+                     (or (and prev-leaf (max 1 (1- (treesit-node-end prev-leaf))))
+                         (point-min))))
+                   (pos-end (treesit-node-start n))
+                   (pos-beg-fmt
+                    (visual-format--with-buff-fmt
+                     (or (and prev-leaf-fmt (max 1 (1- (treesit-node-end prev-leaf-fmt))))
+                         (point-min))))
+                   (pos-end-fmt (treesit-node-start n-fmt))
+                   (fmt-spaces (visual-format--with-buff-fmt (buffer-substring pos-beg-fmt pos-end-fmt))))
+              (visual-format--with-buff
+               (message "Token at (%d):\t %s \t\t\t\t Prev: %s"
+                        depth
+                        (treesit-node-text n t)
+                        (treesit-node-text prev-leaf t))
+               (unless (string= (buffer-substring pos-beg pos-end) fmt-spaces)
+                 (put-text-property pos-beg pos-end 'display fmt-spaces)))
+              (setq prev-leaf n
+                    prev-leaf-fmt n-fmt))
+          (let ((last-nodes (visual-format--depth-first-walk n n-fmt prev-leaf prev-leaf-fmt (1+ depth))))
+            (setq prev-leaf (car last-nodes)
+                  prev-leaf-fmt (cdr last-nodes))))))
+    (cons prev-leaf prev-leaf-fmt)))
+
+(defvar visual-format-function #'apheleia-format-buffer)
+
+(defun visual-format-buffer ()
+  "Visually format the buffer without modifing it."
+  (interactive)
+  (visual-format--cleanup (point-min) (point-max))
+  (let ((visual-format--buffer (current-buffer))
+        (visual-format--buffer-formatted (get-buffer-create (format " *visual-format: %s*" (buffer-name))))
+        (buf-str (buffer-string))
+        (buf-mode major-mode))
+    (visual-format--with-buff-fmt
+     (delay-mode-hooks (funcall buf-mode))
+     (delete-region (point-min) (point-max))
+     (insert buf-str)
+     (call-interactively visual-format-function))
+    (with-silent-modifications
+      (visual-format--depth-first-walk))))
+
+;;;###autoload
+(define-minor-mode visual-format-mode
+  "Format code without modifying the buffer."
+  :lighter " VFmt"
+  :global nil
+  (if visual-format-mode
+      (visual-format-buffer)
+    (visual-format--cleanup (point-min) (point-max))))