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diff --git a/runtime/doc/usr_32.txt b/runtime/doc/usr_32.txt new file mode 100644 index 0000000..7c043a1 --- /dev/null +++ b/runtime/doc/usr_32.txt @@ -0,0 +1,180 @@ +*usr_32.txt* For Vim version 8.1. Last change: 2010 Jul 20 + + VIM USER MANUAL - by Bram Moolenaar + + The undo tree + + +Vim provides multi-level undo. If you undo a few changes and then make a new +change you create a branch in the undo tree. This text is about moving +through the branches. + +|32.1| Undo up to a file write +|32.2| Numbering changes +|32.3| Jumping around the tree +|32.4| Time travelling + + Next chapter: |usr_40.txt| Make new commands + Previous chapter: |usr_31.txt| Exploiting the GUI +Table of contents: |usr_toc.txt| + +============================================================================== +*32.1* Undo up to a file write + +Sometimes you make several changes, and then discover you want to go back to +when you have last written the file. You can do that with this command: > + + :earlier 1f + +The "f" stands for "file" here. + +You can repeat this command to go further back in the past. Or use a count +different from 1 to go back faster. + +If you go back too far, go forward again with: > + + :later 1f + +Note that these commands really work in time sequence. This matters if you +made changes after undoing some changes. It's explained in the next section. + +Also note that we are talking about text writes here. For writing the undo +information in a file see |undo-persistence|. + +============================================================================== +*32.2* Numbering changes + +In section |02.5| we only discussed one line of undo/redo. But it is also +possible to branch off. This happens when you undo a few changes and then +make a new change. The new changes become a branch in the undo tree. + +Let's start with the text "one". The first change to make is to append +" too". And then move to the first 'o' and change it into 'w'. We then have +two changes, numbered 1 and 2, and three states of the text: + + one ~ + | + change 1 + | + one too ~ + | + change 2 + | + one two ~ + +If we now undo one change, back to "one too", and change "one" to "me" we +create a branch in the undo tree: + + one ~ + | + change 1 + | + one too ~ + / \ + change 2 change 3 + | | + one two me too ~ + +You can now use the |u| command to undo. If you do this twice you get to +"one". Use |CTRL-R| to redo, and you will go to "one too". One more |CTRL-R| +takes you to "me too". Thus undo and redo go up and down in the tree, using +the branch that was last used. + +What matters here is the order in which the changes are made. Undo and redo +are not considered changes in this context. After each change you have a new +state of the text. + +Note that only the changes are numbered, the text shown in the tree above has +no identifier. They are mostly referred to by the number of the change above +it. But sometimes by the number of one of the changes below it, especially +when moving up in the tree, so that you know which change was just undone. + +============================================================================== +*32.3* Jumping around the tree + +So how do you get to "one two" now? You can use this command: > + + :undo 2 + +The text is now "one two", you are below change 2. You can use the |:undo| +command to jump to below any change in the tree. + +Now make another change: change "one" to "not": + + one ~ + | + change 1 + | + one too ~ + / \ + change 2 change 3 + | | + one two me too ~ + | + change 4 + | + not two ~ + +Now you change your mind and want to go back to "me too". Use the |g-| +command. This moves back in time. Thus it doesn't walk the tree upwards or +downwards, but goes to the change made before. + +You can repeat |g-| and you will see the text change: + me too ~ + one two ~ + one too ~ + one ~ + +Use |g+| to move forward in time: + one ~ + one too ~ + one two ~ + me too ~ + not two ~ + +Using |:undo| is useful if you know what change you want to jump to. |g-| and +|g+| are useful if you don't know exactly what the change number is. + +You can type a count before |g-| and |g+| to repeat them. + +============================================================================== +*32.4* Time travelling + +When you have been working on text for a while the tree grows to become big. +Then you may want to go to the text of some minutes ago. + +To see what branches there are in the undo tree use this command: > + + :undolist +< number changes time ~ + 3 2 16 seconds ago + 4 3 5 seconds ago + +Here you can see the number of the leaves in each branch and when the change +was made. Assuming we are below change 4, at "not two", you can go back ten +seconds with this command: > + + :earlier 10s + +Depending on how much time you took for the changes you end up at a certain +position in the tree. The |:earlier| command argument can be "m" for minutes, +"h" for hours and "d" for days. To go all the way back use a big number: > + + :earlier 100d + +To travel forward in time again use the |:later| command: > + + :later 1m + +The arguments are "s", "m" and "h", just like with |:earlier|. + +If you want even more details, or want to manipulate the information, you can +use the |undotree()| function. To see what it returns: > + + :echo undotree() + +============================================================================== + +Next chapter: |usr_40.txt| Make new commands + +Copyright: see |manual-copyright| vim:tw=78:ts=8:noet:ft=help:norl: |