[elpa] externals/undo-tree 1561d8f 099/195: Preserve timestamps when generating diff for visualizer diff view.

[Stefan Monnier]

branch: externals/undo-tree
commit 1561d8f021f3ba054be4403a5549a95621cf9ad2
Author: Toby S. Cubitt <toby-undo-tree@dr-qubit.org>
Commit: Toby S. Cubitt <toby-undo-tree@dr-qubit.org>

    Preserve timestamps when generating diff for visualizer diff view.
    
    Also split out core of undo-tree-undo|redo into internal 
undo-tree-undo|redo-1
    functions, which now accept an additional preserve-timestamps argument.
---
 undo-tree.el | 97 ++++++++++++++++++++++++++++++++++++------------------------
 1 file changed, 59 insertions(+), 38 deletions(-)

diff --git a/undo-tree.el b/undo-tree.el
index 39a78c2..ad2a1a6 100644
--- a/undo-tree.el
+++ b/undo-tree.el
@@ -633,6 +633,10 @@
 ;; * added `called-interactively-p', `registerv-make', `registerv-data',
 ;;   `diff-no-select' and `diff-file-local-copy' compatibility hacks for
 ;;   older Emacsen
+;; * split out core of `undo-tree-undo' and `undo-tree-redo' into internal
+;;   `undo-tree-undo-1' and `undo-tree-redo-1' functions, which now take an
+;;   additional optional argument to preserve timestamps
+;; * preserve timestamps when generating diff for visualizer diff view
 ;;
 ;; Version 0.4
 ;; * implemented persistent history storage: `undo-tree-save-history' and
@@ -2037,7 +2041,7 @@ which is defined in the `warnings' library.\n")
        ;; (recognizable as first node with more than one branch)
        (let ((mark-active nil))
          (while (= (length (undo-tree-node-next node)) 1)
-           (undo-tree-undo)
+           (undo-tree-undo-1)
            (setq fragment node
                  node (undo-tree-current buffer-undo-tree))))
        (when (eq splice node) (setq splice nil))
@@ -2154,7 +2158,7 @@ which is defined in the `warnings' library.\n")
            (let ((mark-active nil))
              (while (not (eq (undo-tree-current buffer-undo-tree)
                              original-current))
-               (undo-tree-redo)))
+               (undo-tree-redo-1)))
            nil)  ; return nil to indicate failure
 
        ;; otherwise...
@@ -2164,9 +2168,9 @@ which is defined in the `warnings' library.\n")
        (let ((mark-active nil)
              (current (undo-tree-current buffer-undo-tree)))
          (while (not (eq (undo-tree-current buffer-undo-tree) node))
-           (undo-tree-undo))
+           (undo-tree-undo-1))
          (while (not (eq (undo-tree-current buffer-undo-tree) current))
-           (undo-tree-redo)))
+           (undo-tree-redo-1)))
 
        (cond
         ;; if there's no remaining fragment, just create undo-in-region node
@@ -2205,7 +2209,7 @@ which is defined in the `warnings' library.\n")
                  (undo-tree-node-previous original-fragment))
            (let ((mark-active nil))
              (while (not (eq (undo-tree-current buffer-undo-tree) splice))
-               (undo-tree-redo nil 'preserve-undo))))
+               (undo-tree-redo-1 nil 'preserve-undo))))
          ;; splice new undo-in-region node into fragment
          (setq node (undo-tree-make-node nil region-changeset))
          (undo-tree-splice-node node splice)
@@ -2576,7 +2580,7 @@ key bindings do not count.)"
 
 
 
-(defun undo-tree-undo (&optional arg preserve-redo)
+(defun undo-tree-undo (&optional arg)
   "Undo changes.
 Repeat this command to undo more changes.
 A numeric ARG serves as a repeat count.
@@ -2584,15 +2588,24 @@ A numeric ARG serves as a repeat count.
 In Transient Mark mode when the mark is active, only undo changes
 within the current region. Similarly, when not in Transient Mark
 mode, just \\[universal-argument] as an argument limits undo to
-changes within the current region.
-
-A non-nil PRESERVE-REDO causes the existing redo record to be
-preserved, rather than replacing it with the new one generated by
-undoing."
+changes within the current region."
   (interactive "*P")
   ;; throw error if undo is disabled in buffer
   (when (eq buffer-undo-list t) (error "No undo information in this buffer"))
-
+  (undo-tree-undo-1 arg)
+  ;; inform user if at branch point
+  (when (> (undo-tree-num-branches) 1) (message "Undo branch point!")))
+
+
+(defun undo-tree-undo-1 (&optional arg preserve-redo preserve-timestamps)
+  ;; Internal undo function. An active mark in `transient-mark-mode', or
+  ;; non-nil ARG otherwise, enables undo-in-region. Non-nil PRESERVE-REDO
+  ;; causes the existing redo record to be preserved, rather than replacing it
+  ;; with the new one generated by undoing. Non-nil PRESERVE-TIMESTAMPS
+  ;; disables updating of timestamps in visited undo-tree nodes. (This latter
+  ;; should *only* be used when temporarily visiting another undo state and
+  ;; immediately returning to the original state afterwards. Otherwise, it
+  ;; could cause history-discarding errors.)
   (let ((undo-in-progress t)
        (undo-in-region (and undo-tree-enable-undo-in-region
                             (or (region-active-p)
@@ -2654,9 +2667,10 @@ undoing."
 
       ;; rewind current node and update timestamp
       (setf (undo-tree-current buffer-undo-tree)
-           (undo-tree-node-previous (undo-tree-current buffer-undo-tree))
-           (undo-tree-node-timestamp (undo-tree-current buffer-undo-tree))
-           (current-time))
+           (undo-tree-node-previous (undo-tree-current buffer-undo-tree)))
+      (unless preserve-timestamps
+       (setf (undo-tree-node-timestamp (undo-tree-current buffer-undo-tree))
+             (current-time)))
 
       ;; if undoing-in-region, record current node, region and direction so we
       ;; can tell if undo-in-region is repeated, and re-activate mark if in
@@ -2671,29 +2685,34 @@ undoing."
        (set-marker pos nil)))
 
     ;; undo deactivates mark unless undoing-in-region
-    (setq deactivate-mark (not undo-in-region))
-    ;; inform user if at branch point
-    (when (and (called-interactively-p 'interactive)
-              (> (undo-tree-num-branches) 1))
-      (message "Undo branch point!"))))
+    (setq deactivate-mark (not undo-in-region))))
 
 
 
-(defun undo-tree-redo (&optional arg preserve-undo)
+(defun undo-tree-redo (&optional arg)
   "Redo changes. A numeric ARG serves as a repeat count.
 
 In Transient Mark mode when the mark is active, only redo changes
 within the current region. Similarly, when not in Transient Mark
 mode, just \\[universal-argument] as an argument limits redo to
-changes within the current region.
-
-A non-nil PRESERVE-UNDO causes the existing undo record to be
-preserved, rather than replacing it with the new one generated by
-redoing."
+changes within the current region."
   (interactive "*P")
   ;; throw error if undo is disabled in buffer
   (when (eq buffer-undo-list t) (error "No undo information in this buffer"))
-
+  (undo-tree-redo-1 arg)
+  ;; inform user if at branch point
+  (when (> (undo-tree-num-branches) 1) (message "Undo branch point!")))
+
+
+(defun undo-tree-redo-1 (&optional arg preserve-undo preserve-timestamps)
+  ;; Internal redo function. An active mark in `transient-mark-mode', or
+  ;; non-nil ARG otherwise, enables undo-in-region. Non-nil PRESERVE-UNDO
+  ;; causes the existing redo record to be preserved, rather than replacing it
+  ;; with the new one generated by undoing. Non-nil PRESERVE-TIMESTAMPS
+  ;; disables updating of timestamps in visited undo-tree nodes. (This latter
+  ;; should *only* be used when temporarily visiting another undo state and
+  ;; immediately returning to the original state afterwards. Otherwise, it
+  ;; could cause history-discarding errors.)
   (let ((undo-in-progress t)
        (redo-in-region (and undo-tree-enable-undo-in-region
                             (or (region-active-p)
@@ -2758,7 +2777,8 @@ redoing."
              (undo-list-byte-size (undo-tree-node-undo current))))
 
       ;; update timestamp
-      (setf (undo-tree-node-timestamp current) (current-time))
+      (unless preserve-timestamps
+       (setf (undo-tree-node-timestamp current) (current-time)))
 
       ;; if redoing-in-region, record current node, region and direction so we
       ;; can tell if redo-in-region is repeated, and re-activate mark if in
@@ -2771,11 +2791,7 @@ redoing."
        (set-marker pos nil)))
 
     ;; redo deactivates the mark unless redoing-in-region
-    (setq deactivate-mark (not redo-in-region))
-    ;; inform user if at branch point
-    (when (and (called-interactively-p 'interactive)
-              (> (undo-tree-num-branches) 1))
-      (message "Undo branch point!"))))
+    (setq deactivate-mark (not redo-in-region))))
 
 
 
@@ -2812,9 +2828,13 @@ using `undo-tree-redo'."
   (message "Switched to branch %d" branch))
 
 
-(defun undo-tree-set (node)
+(defun undo-tree-set (node &optional preserve-timestamps)
   ;; Set buffer to state corresponding to NODE. Returns intersection point
   ;; between path back from current node and path back from selected NODE.
+  ;; Non-nil PRESERVE-TIMESTAMPS disables updating of timestamps in visited
+  ;; undo-tree nodes. (This should *only* be used when temporarily visiting
+  ;; another undo state and immediately returning to the original state
+  ;; afterwards. Otherwise, it could cause history-discarding errors.)
   (let ((path (make-hash-table :test 'eq))
         (n node))
     (puthash (undo-tree-root buffer-undo-tree) t path)
@@ -2834,10 +2854,10 @@ using `undo-tree-redo'."
       (setq n (undo-tree-node-previous n)))
     ;; ascend tree until intersection node
     (while (not (eq (undo-tree-current buffer-undo-tree) n))
-      (undo-tree-undo))
+      (undo-tree-undo-1))
     ;; descend tree until selected node
     (while (not (eq (undo-tree-current buffer-undo-tree) node))
-      (undo-tree-redo))
+      (undo-tree-redo-1))
     n))  ; return intersection node
 
 
@@ -3613,9 +3633,10 @@ at mouse event POS."
     ;; generate diff
     (let ((undo-tree-inhibit-kill-visualizer t)
          (current (undo-tree-current buffer-undo-tree)))
-      (undo-tree-set (or node (undo-tree-node-previous current) current))
+      (undo-tree-set (or node (undo-tree-node-previous current) current)
+                    'preserve-timestamps)
       (setq tmpfile (diff-file-local-copy (current-buffer)))
-      (undo-tree-set current))
+      (undo-tree-set current 'preserve-timestamps))
     (setq buff (diff-no-select
                (current-buffer) tmpfile nil 'noasync
                (get-buffer-create undo-tree-diff-buffer-name)))