Support rectangular regions in capitalize-region and capitalize-dwim.

* lisp/simple.el (capitalize-dwim): Add arg region-noncontiguous-p
in capitalize-region call.

* src/casefiddle.c (Fcapitalize_region): Add arg region-noncontiguous-p.
If non-nil, operate on multiple chunks.  (Bug#37477)
(Fdowncase_region): Use builtin symbol Qregion_extract_function
rather than calling intern.

etc/NEWS

@@ -487,8 +487,8 @@ interface that's more like functions like 'search-forward'.
 
 ---
 ** More commands support noncontiguous rectangular regions, namely
-'upcase-dwim', 'downcase-dwim', 'replace-string', 'replace-regexp',
-and 'delimit-columns-region'.
+'upcase-dwim', 'downcase-dwim', 'capitalize-dwim', 'capitalize-region',
+'replace-string', 'replace-regexp', and 'delimit-columns-region'.
 
 +++
 ** When asked to visit a large file, Emacs now offers visiting it literally.

lisp/simple.el

@@ -9074,7 +9074,7 @@ Otherwise, it calls `capitalize-word', with prefix argument passed to it
 to capitalize ARG words."
   (interactive "*p")
   (if (use-region-p)
-      (capitalize-region (region-beginning) (region-end))
+      (capitalize-region (region-beginning) (region-end) (region-noncontiguous-p))
     (capitalize-word arg)))
 
 ;;; Accessors for `decode-time' values.

src/casefiddle.c

@@ -556,7 +556,7 @@ point and the mark is operated on.  */)
 
   if (!NILP (region_noncontiguous_p))
     {
-      bounds = call1 (Fsymbol_value (intern ("region-extract-function")),
+      bounds = call1 (Fsymbol_value (Qregion_extract_function),
 		      intern ("bounds"));
 
       while (CONSP (bounds))
@@ -571,15 +571,31 @@ point and the mark is operated on.  */)
   return Qnil;
 }
 
-DEFUN ("capitalize-region", Fcapitalize_region, Scapitalize_region, 2, 2, "r",
+DEFUN ("capitalize-region", Fcapitalize_region, Scapitalize_region, 2, 3,
+       "(list (region-beginning) (region-end) (region-noncontiguous-p))",
        doc: /* Convert the region to capitalized form.
 This means that each word's first character is converted to either
 title case or upper case, and the rest to lower case.
 In programs, give two arguments, the starting and ending
 character positions to operate on.  */)
-  (Lisp_Object beg, Lisp_Object end)
+  (Lisp_Object beg, Lisp_Object end, Lisp_Object region_noncontiguous_p)
 {
-  casify_region (CASE_CAPITALIZE, beg, end);
+  Lisp_Object bounds = Qnil;
+
+  if (!NILP (region_noncontiguous_p))
+    {
+      bounds = call1 (Fsymbol_value (Qregion_extract_function),
+		      intern ("bounds"));
+
+      while (CONSP (bounds))
+	{
+	  casify_region (CASE_CAPITALIZE, XCAR (XCAR (bounds)), XCDR (XCAR (bounds)));
+	  bounds = XCDR (bounds);
+	}
+    }
+  else
+    casify_region (CASE_CAPITALIZE, beg, end);
+
   return Qnil;
 }