[elpa] externals/indent-bars dbbd7fb1ed 218/431: Add (custom-inherit): Improve inheritance for partial plists

[ELPA Syncer]

branch: externals/indent-bars
commit dbbd7fb1ed2a57f6b9b0ded8ce62acdb8dcb2b52
Author: JD Smith <93749+jdtsmith@users.noreply.github.com>
Commit: JD Smith <93749+jdtsmith@users.noreply.github.com>

    Add (custom-inherit): Improve inheritance for partial plists
    
    Some variables only end in a plist, but have atoms before it.  Treat
    those, as well as the atom value 'unspecified, correctly.
---
 indent-bars.el | 37 +++++++++++++++++++++++++++++++------
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/indent-bars.el b/indent-bars.el
index a7f270125d..8eaf7d8a98 100644
--- a/indent-bars.el
+++ b/indent-bars.el
@@ -748,22 +748,47 @@ inheritance of the plist is handled.  If style is the 
symbol
               indent-bars--styles)
     (indent-bars--style1 style name)))
 
+(defun indent-bars--custom-inherit (old new)
+  "Inherit the values of NEW and OLD, which can be values or lists.
+NEW and OLD must have the same form, composed of atoms
+and (optionally) a final plist.  The symbol \\='unspecified in
+NEW indicates that that value should be replaced by the
+corresponding value in OLD.  Any trailing PLIST in NEW and OLD
+will be merged (with NEW taking precedence).  The merged value is
+returned."
+  (cond
+   ((and (atom old) (atom new))
+    (if (eq new 'unspecified) old new))
+   
+   ((and (consp old) (consp new))
+    (let ((n new) (o old) lo)
+      (while (and n o)
+       (if (and (plistp n) (plistp o) (keywordp (car o)))
+           (let ((m (map-merge 'plist o n)))
+             (if lo (setcdr lo m) (setq old m))
+             (setq o nil))             ; signify list complete
+         (unless (eq (car n) 'unspecified)
+           (setcar o (car n))))
+       (setq lo o n (cdr n) o (cdr o))))
+    old)
+
+   (t new)))
 
 (defun indent-bars--style1 (style name)
-  "Return the value of style variable NAME for STYLE."
+  "Return the value of style variable NAME for STYLE.
+Considers ([no-]inherit . rest) inheritance."
   (let* ((tag (indent-bars-style-tag style))
         (sym (indent-bars--alt name tag))
         (val (symbol-value sym))
-        (inhrt t))                     ; inherit by default
+        (inhrt t))  ; inherit by default
     (when tag
       ;; Check for the ([no-]inherit . actual-val) form
       (when (and (consp val) (memq (car val) '(inherit no-inherit)))
        (setq inhrt (and (car val) (not (eq (car val) 'no-inherit)))
              val (cdr val)))
-      (when-let (((and inhrt (plistp val) (keywordp (car val)))) ;only :key 
plists
-                (main-val (symbol-value (indent-bars--alt name nil)))
-                ((plistp main-val)))
-       (setq val (map-merge 'plist main-val val))))
+      (when inhrt
+       (setq val (indent-bars--custom-inherit
+                  (symbol-value (indent-bars--alt name nil)) val))))
     val))
 
 ;;;; Indentation and Drawing