org-list: move and rename org-list-exchange-items

* lisp/org-list.el (org-list-swap-items): move it to a meaningful
  position in source code (i.e. before any function using it), and
  rename it to an easier name.

lisp/org-list.el

@@ -1093,6 +1093,61 @@ It determines the number of whitespaces to append by looking at
       (string-match "\\S-+\\([ \t]*\\)" bullet)
       (replace-match spaces nil nil bullet 1))))
 
+(defun org-list-swap-items (beg-A beg-B struct)
+  "Swap item starting at BEG-A with item starting at BEG-B in STRUCT.
+Blank lines at the end of items are left in place.  Return the
+new structure after the changes.
+
+Assume BEG-A is lesser than BEG-B and that BEG-A and BEG-B belong
+to the same sub-list.
+
+This function modifies STRUCT."
+  (save-excursion
+    (let* ((end-A-no-blank (org-list-get-item-end-before-blank beg-A struct))
+	   (end-B-no-blank (org-list-get-item-end-before-blank beg-B struct))
+	   (end-A (org-list-get-item-end beg-A struct))
+	   (end-B (org-list-get-item-end beg-B struct))
+	   (size-A (- end-A-no-blank beg-A))
+	   (size-B (- end-B-no-blank beg-B))
+	   (body-A (buffer-substring beg-A end-A-no-blank))
+	   (body-B (buffer-substring beg-B end-B-no-blank))
+	   (between-A-no-blank-and-B (buffer-substring end-A-no-blank beg-B))
+	   (sub-A (cons beg-A (org-list-get-subtree beg-A struct)))
+	   (sub-B (cons beg-B (org-list-get-subtree beg-B struct))))
+      ;; 1. Move effectively items in buffer.
+      (goto-char beg-A)
+      (delete-region beg-A end-B-no-blank)
+      (insert (concat body-B between-A-no-blank-and-B body-A))
+      ;; 2. Now modify struct.  No need to re-read the list, the
+      ;;    transformation is just a shift of positions.  Some special
+      ;;    attention is required for items ending at END-A and END-B
+      ;;    as empty spaces are not moved there.  In others words,
+      ;;    item BEG-A will end with whitespaces that were at the end
+      ;;    of BEG-B and the same applies to BEG-B.
+      (mapc (lambda (e)
+	      (let ((pos (car e)))
+		(cond
+		 ((< pos beg-A))
+		 ((memq pos sub-A)
+		  (let ((end-e (nth 6 e)))
+		    (setcar e (+ pos (- end-B-no-blank end-A-no-blank)))
+		    (setcar (nthcdr 6 e)
+			    (+ end-e (- end-B-no-blank end-A-no-blank)))
+		    (when (= end-e end-A) (setcar (nthcdr 6 e) end-B))))
+		 ((memq pos sub-B)
+		  (let ((end-e (nth 6 e)))
+		    (setcar e (- (+ pos beg-A) beg-B))
+		    (setcar (nthcdr 6 e) (+ end-e (- beg-A beg-B)))
+		    (when (= end-e end-B)
+		      (setcar (nthcdr 6 e)
+			      (+ beg-A size-B (- end-A end-A-no-blank))))))
+		 ((< pos beg-B)
+		  (let ((end-e (nth 6 e)))
+		    (setcar e (+ pos (- size-B size-A)))
+		    (setcar (nthcdr 6 e) (+ end-e (- size-B size-A))))))))
+	    struct)
+      (sort struct (lambda (e1 e2) (< (car e1) (car e2)))))))
+
 (defun org-list-separating-blank-lines-number (pos struct prevs)
   "Return number of blank lines that should separate items in list.
 
@@ -1246,7 +1301,7 @@ This function modifies STRUCT."
       ;; after bullet, counter, checkbox, and label.
       (if beforep
 	  (goto-char item)
-	(setq struct (org-list-exchange-items item (+ item item-size) struct))
+	(setq struct (org-list-swap-items item (+ item item-size) struct))
 	(goto-char (org-list-get-next-item
 		    item struct (org-list-prevs-alist struct))))
       struct)))
@@ -1394,61 +1449,6 @@ This function returns, destructively, the new list structure."
 	(move-marker item nil)))
      (t struct))))
 
-(defun org-list-exchange-items (beg-A beg-B struct)
-  "Swap item starting at BEG-A with item starting at BEG-B in STRUCT.
-Blank lines at the end of items are left in place.  Return the
-new structure after the changes.
-
-Assume BEG-A is lesser than BEG-B and that BEG-A and BEG-B belong
-to the same sub-list.
-
-This function modifies STRUCT."
-  (save-excursion
-    (let* ((end-A-no-blank (org-list-get-item-end-before-blank beg-A struct))
-	   (end-B-no-blank (org-list-get-item-end-before-blank beg-B struct))
-	   (end-A (org-list-get-item-end beg-A struct))
-	   (end-B (org-list-get-item-end beg-B struct))
-	   (size-A (- end-A-no-blank beg-A))
-	   (size-B (- end-B-no-blank beg-B))
-	   (body-A (buffer-substring beg-A end-A-no-blank))
-	   (body-B (buffer-substring beg-B end-B-no-blank))
-	   (between-A-no-blank-and-B (buffer-substring end-A-no-blank beg-B))
-	   (sub-A (cons beg-A (org-list-get-subtree beg-A struct)))
-	   (sub-B (cons beg-B (org-list-get-subtree beg-B struct))))
-      ;; 1. Move effectively items in buffer.
-      (goto-char beg-A)
-      (delete-region beg-A end-B-no-blank)
-      (insert (concat body-B between-A-no-blank-and-B body-A))
-      ;; 2. Now modify struct.  No need to re-read the list, the
-      ;;    transformation is just a shift of positions.  Some special
-      ;;    attention is required for items ending at END-A and END-B
-      ;;    as empty spaces are not moved there.  In others words,
-      ;;    item BEG-A will end with whitespaces that were at the end
-      ;;    of BEG-B and the same applies to BEG-B.
-      (mapc (lambda (e)
-	      (let ((pos (car e)))
-		(cond
-		 ((< pos beg-A))
-		 ((memq pos sub-A)
-		  (let ((end-e (nth 6 e)))
-		    (setcar e (+ pos (- end-B-no-blank end-A-no-blank)))
-		    (setcar (nthcdr 6 e)
-			    (+ end-e (- end-B-no-blank end-A-no-blank)))
-		    (when (= end-e end-A) (setcar (nthcdr 6 e) end-B))))
-		 ((memq pos sub-B)
-		  (let ((end-e (nth 6 e)))
-		    (setcar e (- (+ pos beg-A) beg-B))
-		    (setcar (nthcdr 6 e) (+ end-e (- beg-A beg-B)))
-		    (when (= end-e end-B)
-		      (setcar (nthcdr 6 e)
-			      (+ beg-A size-B (- end-A end-A-no-blank))))))
-		 ((< pos beg-B)
-		  (let ((end-e (nth 6 e)))
-		    (setcar e (+ pos (- size-B size-A)))
-		    (setcar (nthcdr 6 e) (+ end-e (- size-B size-A))))))))
-	    struct)
-      (sort struct (lambda (e1 e2) (< (car e1) (car e2)))))))
-
 (defun org-list-struct-outdent (start end struct parents)
   "Outdent items between positions START and END.
 
@@ -2066,7 +2066,7 @@ the item, so this really moves item trees."
       (error "Cannot move this item further down"))
     (if (not next-item)
 	(setq struct (org-list-send-item item 'begin struct))
-      (setq struct (org-list-exchange-items item next-item struct))
+      (setq struct (org-list-swap-items item next-item struct))
       (goto-char
        (org-list-get-next-item item struct (org-list-prevs-alist struct))))
     (org-list-write-struct struct (org-list-parents-alist struct))
@@ -2087,7 +2087,7 @@ the item, so this really moves item trees."
       (error "Cannot move this item further up"))
     (if (not prev-item)
 	(setq struct (org-list-send-item item 'end struct))
-      (setq struct (org-list-exchange-items prev-item item struct)))
+      (setq struct (org-list-swap-items prev-item item struct)))
     (org-list-write-struct struct (org-list-parents-alist struct))
     (org-move-to-column col)))