[nongnu] elpa/undo-fu cad12914a4 15/82: Add 'undo-fu-allow-undo-in-region' option

[ELPA Syncer]

branch: elpa/undo-fu
commit cad12914a4556faa116aca1701c381c4e85c38e2
Author: Campbell Barton <ideasman42@gmail.com>
Commit: Campbell Barton <ideasman42@gmail.com>

    Add 'undo-fu-allow-undo-in-region' option
---
 readme.rst | 13 ++++++++++++-
 undo-fu.el | 47 +++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/readme.rst b/readme.rst
index 36417f1fe7..1e35085c9a 100644
--- a/readme.rst
+++ b/readme.rst
@@ -74,10 +74,21 @@ Details
   until a new chain of undo/redo events is started.
 
 
+Customization
+-------------
+
+``undo-fu-allow-undo-in-region``
+   This option exists for users who prefer to trade-off undo/redo functionality
+   with the ability to limit undo to a region.
+
+   When this boolean is ``t``, undoing with a selection
+   will use undo within this region.
+
+
 Limitations
 ===========
 
-The feature ``undo-in-region`` is currently unsupported.
+The feature ``undo-in-region`` is disabled by default.
 
 
 Installation
diff --git a/undo-fu.el b/undo-fu.el
index ce4af3270b..83db225c5e 100644
--- a/undo-fu.el
+++ b/undo-fu.el
@@ -43,6 +43,16 @@
 
 ;;; Code:
 
+;; Custom variables.
+
+(defcustom undo-fu-allow-undo-in-region nil
+  "When t, use `undo-in-region' when a selection is present.
+Otherwise `undo-in-region' is never used, since it doesn't support `undo-only',
+causing undo-fu to work with reduced functionality when a selection exists."
+  :group 'undo-fu
+  :type 'boolean)
+
+
 ;; Internal variables.
 
 ;; First undo step in the chain, don't redo past this.
@@ -52,6 +62,9 @@
 ;; Apply undo/redo constraints to stop redo from undoing or
 ;; passing the initial undo checkpoint.
 (defvar-local undo-fu--respect t)
+;; Initiated an undo-in region (don't use `undo-only').
+;; Only use when `undo-fu-allow-undo-in-region' is true.
+(defvar-local undo-fu--in-region nil)
 
 
 ;; Internal functions/macros.
@@ -59,6 +72,7 @@
 (defun undo-fu--checkpoint-disable ()
   "Disable check to prevent crossing the initial boundary when redoing."
   (setq undo-fu--respect nil)
+  (setq undo-fu--in-region nil)
   (setq undo-fu--checkpoint-is-blocking nil)
   (setq undo-fu--checkpoint nil))
 
@@ -152,8 +166,19 @@ Optional argument ARG The number of steps to redo."
     ;; after running non-undo related commands.
     (unless undo-fu--respect
       (unless was-undo-or-redo
+        (when undo-fu-allow-undo-in-region
+          (setq undo-fu--in-region nil))
         (setq undo-fu--respect t)))
 
+    (when (region-active-p)
+      (if undo-fu-allow-undo-in-region
+        (progn
+          (message "Undo in region in use. Undo end-point ignored!")
+          (undo-fu--checkpoint-disable)
+          (setq undo-fu--in-region t))
+        ;; Default behavior, just remove selection.
+        (deactivate-mark)))
+
     ;; Allow crossing the boundary, if we press [keyboard-quit].
     ;; This allows explicitly over-stepping the boundary, in cases where it's 
needed.
     (when undo-fu--respect
@@ -197,9 +222,6 @@ Optional argument ARG The number of steps to redo."
         (success
           (condition-case err
             (progn
-              ;; 'undo-in-region' unsupported.
-              (when transient-mark-mode
-                (deactivate-mark))
               (undo-fu--with-message-suffix
                 (if undo-fu--respect
                   ""
@@ -233,11 +255,22 @@ Optional argument ARG the number of steps to undo."
     ;; after running non-undo related commands.
     (unless undo-fu--respect
       (unless was-undo-or-redo
+        (when undo-fu-allow-undo-in-region
+          (setq undo-fu--in-region nil))
         (setq undo-fu--respect t)))
 
     (when (or undo-fu--checkpoint-is-blocking (not was-undo-or-redo))
       (setq undo-fu--checkpoint (cdr buffer-undo-list)))
 
+    (when (region-active-p)
+      (if undo-fu-allow-undo-in-region
+        (progn
+          (message "Undo in region in use. Undo end-point ignored!")
+          (undo-fu--checkpoint-disable)
+          (setq undo-fu--in-region t))
+        ;; Default behavior, just remove selection.
+        (deactivate-mark)))
+
     ;; Allow crossing the boundary, if we press [keyboard-quit].
     ;; This allows explicitly over-stepping the boundary, in cases where it's 
needed.
     (when undo-fu--respect
@@ -261,15 +294,13 @@ Optional argument ARG the number of steps to undo."
         (success
           (condition-case err
             (progn
-              ;; 'undo-in-region' unsupported.
-              (when transient-mark-mode
-                (deactivate-mark))
-
               (undo-fu--with-message-suffix
                 (if undo-fu--respect
                   ""
                   " (unconstrained)")
-                (undo-only steps))
+                (if undo-fu--in-region
+                  (undo steps)
+                  (undo-only steps)))
               t)
             (error (message "%s" (error-message-string err))))))
       (when success