>From 68fb034a60f74ea3cab9acd8e35bdf52ba9d5024 Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <jp@neverwas.me>
Date: Thu, 3 Aug 2023 22:24:57 -0700
Subject: [PATCH] [POC] Honor invisible text-prop list values in count-lines

* lisp/simple.el (count-lines): Use `invisible-p' when
`ignore-invisible-lines' parameter is non-nil.
* test/lisp/simple-tests.el (simple-tests-count-lines/invisible/interval,
simple-tests-count-lines/invisible/list/single,
simple-tests-count-lines/invisible/list/tail): Add tests.
(Bug#23675)
---
 lisp/simple.el            | 19 ++++--------
 test/lisp/simple-tests.el | 62 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 14 deletions(-)

diff --git a/lisp/simple.el b/lisp/simple.el
index 6dc08ff0eb0..5c414fb364f 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -1782,20 +1782,11 @@ count-lines
 		   done))))
 	    (ignore-invisible-lines
              (goto-char (point-min))
-	     (save-match-data
-	       (- (buffer-size)
-                  (forward-line (buffer-size))
-		  (let ((invisible-count 0)
-		        prop)
-		    (goto-char (point-min))
-		    (while (re-search-forward "\n\\|\r[^\n]" nil t)
-		      (setq prop (get-char-property (1- (point)) 'invisible))
-		      (if (if (eq buffer-invisibility-spec t)
-			      prop
-			    (or (memq prop buffer-invisibility-spec)
-			        (assq prop buffer-invisibility-spec)))
-			  (setq invisible-count (1+ invisible-count))))
-		    invisible-count))))
+             (let ((count (if (eobp) 0 1)))
+               (while (and (zerop (forward-line)) (not (eobp)))
+                 (unless (invisible-p (1- (point)))
+                   (cl-incf count)))
+               count))
 	    (t
              (goto-char (point-max))
              (if (bolp)
diff --git a/test/lisp/simple-tests.el b/test/lisp/simple-tests.el
index 7dabb735522..e8e83c9a5cd 100644
--- a/test/lisp/simple-tests.el
+++ b/test/lisp/simple-tests.el
@@ -67,6 +67,68 @@ simple-test-count-lines/ignore-invisible-lines
     (insert (propertize "\nbar\nbaz\nzut" 'invisible t))
     (should (= (count-lines (point-min) (point-max) t) 2))))
 
+(ert-deftest simple-tests-count-lines/invisible/interval ()
+  (with-current-buffer (get-buffer-create "*count-lines/invisible/interval*")
+    (should (= 0 (count-lines (point-min) (point-max) t))) ; invisible
+    (insert "pre\n"
+            "before\n"
+            (propertize "0\n" 'invisible t)
+            (propertize "1\n" 'invisible t)
+            (propertize "2\n" 'invisible t)
+            (propertize "3\n" 'invisible t)
+            "after\n"
+            "post\n")
+    (should (equal buffer-invisibility-spec 't))
+    (with-restriction 5 (- (point-max) 5)
+      (goto-char (point-min))
+      (should (looking-at "before"))
+      (goto-char (point-max))
+      (should (looking-back "after\n")))
+    (should (= 6 (count-lines 5 (- (point-max) 5))))
+    (should (= 2 (count-lines 5 (- (point-max) 5) t))) ; invisible
+    (when noninteractive (kill-buffer))))
+
+(ert-deftest simple-tests-count-lines/invisible/list/single ()
+  (with-current-buffer (get-buffer-create "*count-lines/invisible/list/head*")
+    (insert "before\n"
+            (propertize "0\n" 'invisible '(0))
+            (propertize "1\n" 'invisible '(1))
+            (propertize "2\n" 'invisible '(2))
+            (propertize "3\n" 'invisible '(3))
+            "after\n")
+    (setq buffer-invisibility-spec '(0 1 (2 . t) 3 t))
+    (should (= 6 (count-lines (point-min) (point-max))))
+    (should (= 2 (count-lines (point-min) (point-max) t))) ; invisible
+    (when noninteractive (kill-buffer)))
+
+  (with-current-buffer (get-buffer-create "*count-lines/invisible/list/alt*")
+    (insert "before\n"
+            (propertize "0\n" 'invisible '(0))
+            "a\n"
+            (propertize "1\n" 'invisible '(1))
+            "b\n"
+            (propertize "2\n" 'invisible '(2))
+            "c\n"
+            (propertize "3\n" 'invisible '(3))
+            "after\n")
+    (setq buffer-invisibility-spec '(0 1 (2 . t) 3 t))
+    (should (= 9 (count-lines (point-min) (point-max))))
+    (should (= 5 (count-lines (point-min) (point-max) t))) ; invisible
+    (when noninteractive (kill-buffer))))
+
+(ert-deftest simple-tests-count-lines/invisible/list/tail ()
+  (with-current-buffer (get-buffer-create "*count-lines/invisible/list/tail*")
+    (insert "before\n"
+            (propertize "0\n" 'invisible '(x 0))
+            (propertize "1\n" 'invisible '(x 1))
+            (propertize "2\n" 'invisible '(x 2))
+            (propertize "3\n" 'invisible '(x 3))
+            "after\n")
+    (setq buffer-invisibility-spec '(0 (1 . t) 2 3 t))
+    (should (= 6 (count-lines (point-min) (point-max))))
+    (should (= 2 (count-lines (point-min) (point-max) t))) ; invisible
+    (when noninteractive (kill-buffer))))
+
 (ert-deftest simple-text-count-lines-non-ascii ()
   (with-temp-buffer
     (insert "あ\nい\nう\nえ\nお\n")
-- 
2.41.0