Support goal column in multi-line minibuffer

* lisp/simple.el (next-line-or-history-element)
(previous-line-or-history-element): Remember the goal column of
possibly multi-line input, and restore it afterwards.

Fixes: debbugs:19824

2 files changed, 39 insertions, 4 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 97253c8824e..8ddf9ed02ad 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2015-03-12  Juri Linkov  <juri@linkov.net>
+
+        * simple.el (next-line-or-history-element)
+        (previous-line-or-history-element): Remember the goal column of
+        possibly multi-line input, and restore it afterwards.  (Bug#19824)
+
 2015-03-12  Rasmus Pank Roulund  <emacs@pank.eu>
 
         * ido.el (ido-add-virtual-buffers-to-list): Include bookmark-alist
diff --git a/lisp/simple.el b/lisp/simple.el
index 4deb4cfce2e..98188a07b6f 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -1992,7 +1992,14 @@ When point moves over the bottom line of multi-line minibuffer, puts ARGth
 next element of the minibuffer history in the minibuffer."
   (interactive "^p")
   (or arg (setq arg 1))
-  (let ((old-point (point)))
+  (let* ((old-point (point))
+         ;; Remember the original goal column of possibly multi-line input
+         ;; excluding the length of the prompt on the first line.
+         (prompt-end (minibuffer-prompt-end))
+         (old-column (unless (and (eolp) (> (point) prompt-end))
+                       (if (= (line-number-at-pos) 1)
+                           (max (- (current-column) (1- prompt-end)) 0)
+                         (current-column)))))
     (condition-case nil
         (with-no-warnings
           (next-line arg))
@@ -2000,7 +2007,14 @@ next element of the minibuffer history in the minibuffer."
        ;; Restore old position since `line-move-visual' moves point to
        ;; the end of the line when it fails to go to the next line.
        (goto-char old-point)
-       (next-history-element arg)))))
+       (next-history-element arg)
+       ;; Restore the original goal column on the last line
+       ;; of possibly multi-line input.
+       (goto-char (point-max))
+       (when old-column
+         (if (= (line-number-at-pos) 1)
+             (move-to-column (+ old-column (1- (minibuffer-prompt-end))))
+           (move-to-column old-column)))))))
 
 (defun previous-line-or-history-element (&optional arg)
   "Move cursor vertically up ARG lines, or to the previous history element.
@@ -2008,7 +2022,14 @@ When point moves over the top line of multi-line minibuffer, puts ARGth
 previous element of the minibuffer history in the minibuffer."
   (interactive "^p")
   (or arg (setq arg 1))
-  (let ((old-point (point)))
+  (let* ((old-point (point))
+         ;; Remember the original goal column of possibly multi-line input
+         ;; excluding the length of the prompt on the first line.
+         (prompt-end (minibuffer-prompt-end))
+         (old-column (unless (and (eolp) (> (point) prompt-end))
+                       (if (= (line-number-at-pos) 1)
+                           (max (- (current-column) (1- prompt-end)) 0)
+                         (current-column)))))
     (condition-case nil
         (with-no-warnings
           (previous-line arg))
@@ -2016,7 +2037,15 @@ previous element of the minibuffer history in the minibuffer."
        ;; Restore old position since `line-move-visual' moves point to
        ;; the beginning of the line when it fails to go to the previous line.
        (goto-char old-point)
-       (previous-history-element arg)))))
+       (previous-history-element arg)
+       ;; Restore the original goal column on the first line
+       ;; of possibly multi-line input.
+       (goto-char (minibuffer-prompt-end))
+       (if old-column
+           (if (= (line-number-at-pos) 1)
+               (move-to-column (+ old-column (1- (minibuffer-prompt-end))))
+             (move-to-column old-column))
+         (goto-char (line-end-position)))))))
 
 (defun next-complete-history-element (n)
   "Get next history element which completes the minibuffer before the point.