From 45a84160d5557ee2004fa7e045f52854b9c8e3c5 Mon Sep 17 00:00:00 2001
From: Joost Kremers <joostkremers@fastmail.com>
Date: Thu, 30 May 2024 13:28:00 +0200
Subject: [PATCH 1/3] Allow empty vtable

* lisp/emacs-lisp/vtable.el (vtable--compute-widths): Set default width
  for columns that have no explicit width and no data.
---
 lisp/emacs-lisp/vtable.el | 67 ++++++++++++++++++++++++---------------
 1 file changed, 41 insertions(+), 26 deletions(-)

diff --git a/lisp/emacs-lisp/vtable.el b/lisp/emacs-lisp/vtable.el
index cb7ea397314..07ef7d20020 100644
--- a/lisp/emacs-lisp/vtable.el
+++ b/lisp/emacs-lisp/vtable.el
@@ -850,32 +850,47 @@ vtable--compute-width
     (error "Invalid spec: %s" spec))))
 
 (defun vtable--compute-widths (table cache)
-  "Compute the display widths for TABLE."
-  (seq-into
-   (seq-map-indexed
-    (lambda (column index)
-      (let ((width
-             (or
-              ;; Explicit widths.
-              (and (vtable-column-width column)
-                   (vtable--compute-width table (vtable-column-width column)))
-              ;; Compute based on the displayed widths of
-              ;; the data.
-              (seq-max (seq-map (lambda (elem)
-                                  (nth 1 (elt (cdr elem) index)))
-                                cache)))))
-        ;; Let min-width/max-width specs have their say.
-        (when-let ((min-width (and (vtable-column-min-width column)
-                                   (vtable--compute-width
-                                    table (vtable-column-min-width column)))))
-          (setq width (max width min-width)))
-        (when-let ((max-width (and (vtable-column-max-width column)
-                                   (vtable--compute-width
-                                    table (vtable-column-max-width column)))))
-          (setq width (min width max-width)))
-        width))
-    (vtable-columns table))
-   'vector))
+  "Compute the display widths for TABLE.
+CACHE is TABLE's cache data as returned by `vtable--compute-cache'."
+  (let ((widths (seq-map-indexed
+                 (lambda (column index)
+                   (let ((width
+                          (or
+                           ;; Explicit widths.
+                           (and (vtable-column-width column)
+                                (vtable--compute-width table (vtable-column-width column)))
+                           ;; If the vtable is empty and no explicit width is given,
+                           ;; set its width to 0 and deal with it below.
+                           (if (null cache)
+                               0)
+                           ;; Otherwise, compute based on the displayed widths of the
+                           ;; data.
+                           (seq-max (seq-map (lambda (elem)
+                                               (nth 1 (elt (cdr elem) index)))
+                                             cache)))))
+                     ;; Let min-width/max-width specs have their say.
+                     (when-let ((min-width (and (vtable-column-min-width column)
+                                                (vtable--compute-width
+                                                 table (vtable-column-min-width column)))))
+                       (setq width (max width min-width)))
+                     (when-let ((max-width (and (vtable-column-max-width column)
+                                                (vtable--compute-width
+                                                 table (vtable-column-max-width column)))))
+                       (setq width (min width max-width)))
+                     width))
+                 (vtable-columns table))))
+    ;; If there are any zero-width columns, divide the remaining window
+    ;; width evenly over them.
+    (when (member 0 widths)
+      (let* ((combined-width (apply #'+ widths))
+             (n-0cols (length (seq-keep #'zerop widths)))
+             (default-width (/ (- (window-width nil t) combined-width) n-0cols)))
+        (setq widths (mapcar (lambda (width)
+                               (if (zerop width)
+                                   default-width
+                                 width))
+                             widths))))
+    (seq-into widths 'vector)))
 
 (defun vtable--compute-cache (table)
   (seq-map
-- 
2.45.1