Subject: bug#60256: 29.0.60; Maybe improve tree sitter default treesit-language-at function

From: Wilhelm H Kirschbaum <[email-masked]>
Date: Thu, 22 Dec 2022 12:30:09 +0200

We can detect the language from treesit-parser-included-ranges, so
instead of taking the first parser from the list what about taking 
the
first parser within known ranges?

diff --git a/lisp/treesit.el b/lisp/treesit.el
index 6407669118..f08bb1cd40 100644
--- a/lisp/treesit.el
+++ b/lisp/treesit.el
@@ -136,8 +136,20 @@ treesit-language-at
 parser in `treesit-parser-list', or nil if there is no parser."
   (if treesit-language-at-point-function
       (funcall treesit-language-at-point-function position)
-    (when-let ((parser (car (treesit-parser-list))))
-      (treesit-parser-language parser))))
+    (let ((language-in-range
+         (cl-loop
+          for parser in (treesit-parser-list)
+          do (setq range
+                   (cl-loop
+                    for range in (treesit-parser-included-ranges 
parser)
+                    if (and (>= point (car range)) (<= point (cdr 
range)))
+                    return parser))
+          if range
+          return (treesit-parser-language parser))))
+    (if (null language-in-range)
+        (when-let ((parser (car (treesit-parser-list))))
+          (treesit-parser-language parser))
+      language-in-range))))

Maybe there is a better way of doing this, but seems like it can 
be
generic enough to make this work without having to set
treesit-language-at-point-function for the majority of the cases.

Wilhelm