emacs-29 7ca71d66dc7 4/5: Fix various problems in treesit-explore-mode (bug#60800)

[Yuan Fu]

branch: emacs-29
commit 7ca71d66dc7365a3dd8dd5f20638b4fa612fdc5e
Author: Yuan Fu <casouri@gmail.com>
Commit: Yuan Fu <casouri@gmail.com>

    Fix various problems in treesit-explore-mode (bug#60800)
    
    * lisp/treesit.el:
    (treesit--explorer-kill-explorer-buffer): New function.
    (treesit-explore-mode):
    1. Move prompt for language earlier, and terminate early if language
    not available.
    2. Make sure desktop-save doesn't save the explorer buffer.
    3. Kill the explorer buffer when the source buffer is killed.
---
 lisp/treesit.el | 59 ++++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 40 insertions(+), 19 deletions(-)

diff --git a/lisp/treesit.el b/lisp/treesit.el
index 5a65d565236..660039cc7cc 100644
--- a/lisp/treesit.el
+++ b/lisp/treesit.el
@@ -2621,6 +2621,11 @@ leaves point at the end of the last line of NODE."
       (when (not named)
         (overlay-put ov 'face 'treesit-explorer-anonymous-node)))))
 
+(defun treesit--explorer-kill-explorer-buffer ()
+  "Kill the explorer buffer of this buffer."
+  (when (buffer-live-p treesit--explorer-buffer)
+    (kill-buffer treesit--explorer-buffer)))
+
 (define-derived-mode treesit--explorer-tree-mode special-mode
   "TS Explorer"
   "Mode for displaying syntax trees for `treesit-explore-mode'."
@@ -2632,30 +2637,46 @@ Pops up a window showing the syntax tree of the source 
in the
 current buffer in real time.  The corresponding node enclosing
 the text in the active region is highlighted in the explorer
 window."
-  :lighter " TSplay"
+  :lighter " TSexplore"
   (if treesit-explore-mode
-      (progn
-        (unless (buffer-live-p treesit--explorer-buffer)
-          (setq-local treesit--explorer-buffer
-                      (get-buffer-create
-                       (format "*tree-sitter explorer for %s*"
-                               (buffer-name))))
-          (setq-local treesit--explorer-language
-                      (intern (completing-read
+      (let ((language (intern (completing-read
                                "Language: "
                                (mapcar #'treesit-parser-language
-                                       (treesit-parser-list)))))
-          (with-current-buffer treesit--explorer-buffer
-            (treesit--explorer-tree-mode)))
-        (display-buffer treesit--explorer-buffer
-                        (cons nil '((inhibit-same-window . t))))
-        (treesit--explorer-refresh)
-        (add-hook 'post-command-hook
-                  #'treesit--explorer-post-command 0 t)
-        (setq-local treesit--explorer-last-node nil))
+                                       (treesit-parser-list))))))
+        (if (not (treesit-language-available-p language))
+            (user-error "Cannot find tree-sitter grammar for %s: %s"
+                        language (cdr (treesit-language-available-p
+                                       language t)))
+          ;; Create explorer buffer.
+          (unless (buffer-live-p treesit--explorer-buffer)
+            (setq-local treesit--explorer-buffer
+                        (get-buffer-create
+                         (format "*tree-sitter explorer for %s*"
+                                 (buffer-name))))
+            (setq-local treesit--explorer-language language)
+            (with-current-buffer treesit--explorer-buffer
+              (treesit--explorer-tree-mode)))
+          (display-buffer treesit--explorer-buffer
+                          (cons nil '((inhibit-same-window . t))))
+          (treesit--explorer-refresh)
+          ;; Setup variables and hooks.
+          (add-hook 'post-command-hook
+                    #'treesit--explorer-post-command 0 t)
+          (add-hook 'kill-buffer-hook
+                    #'treesit--explorer-kill-explorer-buffer 0 t)
+          (setq-local treesit--explorer-last-node nil)
+          ;; Tell `desktop-save' to not save explorer buffers.
+          (when (boundp 'desktop-modes-not-to-save)
+            (unless (memq 'treesit--explorer-tree-mode
+                          desktop-modes-not-to-save)
+              (push 'treesit--explorer-tree-mode
+                    desktop-modes-not-to-save)))))
+    ;; Turn off explore mode.
     (remove-hook 'post-command-hook
                  #'treesit--explorer-post-command t)
-    (kill-buffer treesit--explorer-buffer)))
+    (remove-hook 'post-command-hook
+                 #'treesit--explorer-kill-explorer-buffer t)
+    (treesit--explorer-kill-explorer-buffer)))
 
 ;;; Install & build language grammar