Temporary fix for sluggishness while scanning big forms

1 files changed, 13 insertions, 10 deletions

diff --git a/elisp/geiser-syntax.el b/elisp/geiser-syntax.el
index f057d9d..f5d8cfa 100644
--- a/elisp/geiser-syntax.el
+++ b/elisp/geiser-syntax.el
@@ -229,22 +229,25 @@
   (if (cdr (last p)) (1+ (safe-length p)) (length p)))
 
 (defun geiser-syntax--scan-sexps (&optional begin)
-  (let* ((fst (geiser-syntax--symbol-at-point))
+  (let* ((start (point))
+         (go-on t)
+         (fst (geiser-syntax--symbol-at-point))
          (smth (or fst (not (looking-at-p "[\s \s)\s>\s<\n]"))))
          (path (and fst `((,fst 0)))))
     (save-excursion
       (geiser-syntax--skip-comment/string)
-      (while (not (zerop (geiser-syntax--nesting-level)))
+      (while (and go-on (not (zerop (geiser-syntax--nesting-level))))
         (let ((boundary (1+ (point))))
           (backward-up-list)
-          (let ((form
-                 (nth-value 0 (geiser-syntax--form-after-point boundary))))
-            (when (and (listp form) (car form) (symbolp (car form)))
-              (let* ((len (geiser-syntax--pair-length form))
-                     (pos (if smth (1- len) (progn (setq smth t) len)))
-                     (prev (and (> pos 1) (nth (1- pos) form)))
-                     (prev (and (keywordp prev) (list prev))))
-                (push `(,(car form) ,pos ,@prev) path)))))))
+          (when (setq go-on (< (- start (point)) 2000))
+            (let ((form
+                   (nth-value 0 (geiser-syntax--form-after-point boundary))))
+              (when (and (listp form) (car form) (symbolp (car form)))
+                (let* ((len (geiser-syntax--pair-length form))
+                       (pos (if smth (1- len) (progn (setq smth t) len)))
+                       (prev (and (> pos 1) (nth (1- pos) form)))
+                       (prev (and (keywordp prev) (list prev))))
+                  (push `(,(car form) ,pos ,@prev) path))))))))
     (nreverse path)))
 
 (defsubst geiser-syntax--binding-form-p (bfs sbfs f)