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Map redo records for undo in region to 'undo-in-region

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* lisp/simple.el (undo-equiv-table): Add explaination for
undo-in-region, undo to the beginning of undo list and null undo.
(undo): If equiv is 'undo-in-region, empty or t, set pending-undo-list
to t.  If the redo is undo-in-region, map buffer-undo-list to
'undo-in-region instead of t, if it is an identity mapping, map to
'empty.
(undo-make-selective-list): Only continue when ulist is a proper list.
* test/lisp/simple-tests.el (simple-tests--undo): Add test for
undo-only in region.
(simple-tests--sans-leading-nil): New helper function.
(simple-tests--undo-equiv-table): New test for 'undo-equiv-table'.
This commit is contained in:
Yuan Fu 2021-03-03 09:50:15 -05:00 • committed by Stefan Monnier
parent d9c94e93b7
commit 71ef0122ab
2 changed files with 155 additions and 11 deletions
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55
lisp/simple.el
View file

@ -2824,8 +2824,35 @@ the minibuffer contents."
(defconst undo-equiv-table (make-hash-table :test 'eq :weakness t)
"Table mapping redo records to the corresponding undo one.
A redo record for undo-in-region maps to t.
A redo record for ordinary undo maps to the following (earlier) undo.")
A redo record for an undo in region maps to 'undo-in-region.
A redo record for ordinary undo maps to the following (earlier) undo.
A redo record that undoes to the beginning of the undo list maps to t.
In the rare case where there are (erroneously) consecutive nil's in
`buffer-undo-list', `undo' maps the previous valid undo record to
'empty, if the previous record is a redo record, `undo' doesn't change
its mapping.
To be clear, a redo record is just an undo record, the only difference
is that it is created by an undo command (instead of an ordinary buffer
edit). Since a record used to undo ordinary change is called undo
record, a record used to undo an undo is called redo record.
`undo' uses this table to make sure the previous command is `undo'.
`undo-redo' uses this table to set the correct `pending-undo-list'.
When you undo, `pending-undo-list' shrinks and `buffer-undo-list'
grows, and Emacs maps the tip of `buffer-undo-list' to the tip of
`pending-undo-list' in this table.
For example, consider this undo list where each node represents an
undo record: if we undo from 4, `pending-undo-list' will be at 3,
`buffer-undo-list' at 5, and 5 will map to 3.
|
3 5
| /
|/
4")
(defvar undo-in-region nil
"Non-nil if `pending-undo-list' is not just a tail of `buffer-undo-list'.")
@ -2872,7 +2899,9 @@ as an argument limits undo to changes within the current region."
;; the next command should not be a "consecutive undo".
;; So set `this-command' to something other than `undo'.
(setq this-command 'undo-start)
;; Here we decide whether to break the undo chain. If the
;; previous command is `undo', we don't call `undo-start', i.e.,
;; don't break the undo chain.
(unless (and (eq last-command 'undo)
(or (eq pending-undo-list t)
;; If something (a timer or filter?) changed the buffer
@ -2901,7 +2930,7 @@ as an argument limits undo to changes within the current region."
;; undo-redo-undo-redo-... so skip to the very last equiv.
(while (let ((next (gethash equiv undo-equiv-table)))
(if next (setq equiv next))))
(setq pending-undo-list equiv)))
(setq pending-undo-list (if (consp equiv) equiv t))))
(undo-more
(if (numberp arg)
(prefix-numeric-value arg)
@ -2917,11 +2946,17 @@ as an argument limits undo to changes within the current region."
(while (eq (car list) nil)
(setq list (cdr list)))
(puthash list
;; Prevent identity mapping. This can happen if
;; consecutive nils are erroneously in undo list.
(if (or undo-in-region (eq list pending-undo-list))
t
pending-undo-list)
(cond
(undo-in-region 'undo-in-region)
;; Prevent identity mapping. This can happen if
;; consecutive nils are erroneously in undo list. It
;; has to map to _something_ so that the next `undo'
;; command recognizes that the previous command is
;; `undo' and doesn't break the undo chain.
((eq list pending-undo-list)
(or (gethash list undo-equiv-table)
'empty))
(t pending-undo-list))
undo-equiv-table))
;; Don't specify a position in the undo record for the undo command.
;; Instead, undoing this should move point to where the change is.
@ -3234,7 +3269,7 @@ list can be applied to the current buffer."
undo-elt)
(while ulist
(when undo-no-redo
(while (gethash ulist undo-equiv-table)
(while (consp (gethash ulist undo-equiv-table))
(setq ulist (gethash ulist undo-equiv-table))))
(setq undo-elt (car ulist))
(cond

111
test/lisp/simple-tests.el
View file

@ -465,8 +465,117 @@ See bug#35036."
(simple-tests--exec '(backward-char undo-redo undo-redo))
(should (equal (buffer-string) "abc"))
(simple-tests--exec '(backward-char undo-redo undo-redo))
(should (equal (buffer-string) "abcde")))
;; Test undo/redo in region.
(with-temp-buffer
(buffer-enable-undo)
(dolist (x '("a" "b" "c" "d" "e"))
(insert x)
(undo-boundary))
(should (equal (buffer-string) "abcde"))
))
;; The test does this: activate region, `undo', break the undo
;; chain (by deactivating and reactivating the region), then
;; `undo-only'. There used to be a bug in
;; `undo-make-selective-list' that makes `undo-only' error out in
;; that case, which is fixed by in the same commit as this change.
(simple-tests--exec '(move-beginning-of-line
push-mark-command
forward-char
forward-char
undo))
(should (equal (buffer-string) "acde"))
(simple-tests--exec '(move-beginning-of-line
push-mark-command
forward-char
forward-char
undo-only))
(should (equal (buffer-string) "abcde"))
;; Rest are simple redo in region tests.
(simple-tests--exec '(undo-redo))
(should (equal (buffer-string) "acde"))
(simple-tests--exec '(undo-redo))
(should (equal (buffer-string) "abcde"))))
(defun simple-tests--sans-leading-nil (lst)
"Return LST sans the leading nils."
(while (and (consp lst) (null (car lst)))
(setq lst (cdr lst)))
lst)
(ert-deftest simple-tests--undo-equiv-table ()
(with-temp-buffer
(buffer-enable-undo)
(let ((ul-hash-table (make-hash-table :test #'equal)))
(dolist (x '("a" "b" "c"))
(insert x)
(puthash x (simple-tests--sans-leading-nil buffer-undo-list)
ul-hash-table)
(undo-boundary))
(should (equal (buffer-string) "abc"))
;; Tests mappings in `undo-equiv-table'.
(simple-tests--exec '(undo))
(should (equal (buffer-string) "ab"))
(should (eq (gethash (simple-tests--sans-leading-nil
buffer-undo-list)
undo-equiv-table)
(gethash "b" ul-hash-table)))
(simple-tests--exec '(backward-char undo))
(should (equal (buffer-string) "abc"))
(should (eq (gethash (simple-tests--sans-leading-nil
buffer-undo-list)
undo-equiv-table)
(gethash "c" ul-hash-table)))
;; Undo in region should map to 'undo-in-region.
(simple-tests--exec '(backward-char
push-mark-command
move-end-of-line
undo))
(should (equal (buffer-string) "ab"))
(should (eq (gethash (simple-tests--sans-leading-nil
buffer-undo-list)
undo-equiv-table)
'undo-in-region))
;; The undo that undoes to the beginning should map to t.
(deactivate-mark 'force)
(simple-tests--exec '(backward-char
undo undo undo
undo undo undo))
(should (equal (buffer-string) ""))
(should (eq (gethash (simple-tests--sans-leading-nil
buffer-undo-list)
undo-equiv-table)
t))
;; Erroneous nil undo should map to 'empty.
(insert "a")
(undo-boundary)
(push nil buffer-undo-list)
(simple-tests--exec '(backward-char undo))
(should (equal (buffer-string) "a"))
(should (eq (gethash (simple-tests--sans-leading-nil
buffer-undo-list)
undo-equiv-table)
'empty))
;; But if the previous record is a redo record, its mapping
;; shouldn't change.
(insert "e")
(undo-boundary)
(should (equal (buffer-string) "ea"))
(puthash "e" (simple-tests--sans-leading-nil buffer-undo-list)
ul-hash-table)
(insert "a")
(undo-boundary)
(simple-tests--exec '(backward-char undo))
(should (equal (buffer-string) "ea"))
(push nil buffer-undo-list)
(simple-tests--exec '(forward-char undo))
;; Buffer content should change since we just undid a nil
;; record.
(should (equal (buffer-string) "ea"))
;; The previous redo record shouldn't map to empty.
(should (equal (gethash (simple-tests--sans-leading-nil
buffer-undo-list)
undo-equiv-table)
(gethash "e" ul-hash-table))))))
;;; undo auto-boundary tests
(ert-deftest undo-auto-boundary-timer ()