| *usr_32.txt* For Vim version 7.4. Last change: 2010 Jul 20 |
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| VIM USER MANUAL - by Bram Moolenaar |
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| The undo tree |
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| 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. |
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| |32.1| Undo up to a file write |
| |32.2| Numbering changes |
| |32.3| Jumping around the tree |
| |32.4| Time travelling |
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| Next chapter: |usr_40.txt| Make new commands |
| Previous chapter: |usr_31.txt| Exploiting the GUI |
| Table of contents: |usr_toc.txt| |
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| ============================================================================== |
| *32.1* Undo up to a file write |
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| 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: > |
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| :earlier 1f |
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| The "f" stands for "file" here. |
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| You can repeat this command to go further back in the past. Or use a count |
| different from 1 to go back faster. |
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| If you go back too far, go forward again with: > |
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| :later 1f |
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| 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. |
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| Also note that we are talking about text writes here. For writing the undo |
| information in a file see |undo-persistence|. |
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| ============================================================================== |
| *32.2* Numbering changes |
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| 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. |
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| 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: |
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| one ~ |
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| change 1 |
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| one too ~ |
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| change 2 |
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| one two ~ |
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| If we now undo one change, back to "one too", and change "one" to "me" we |
| create a branch in the undo tree: |
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| one ~ |
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| change 1 |
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| one too ~ |
| / \ |
| change 2 change 3 |
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| one two me too ~ |
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| 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. |
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| 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. |
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| 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. |
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| ============================================================================== |
| *32.3* Jumping around the tree |
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| So how do you get to "one two" now? You can use this command: > |
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| :undo 2 |
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| 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. |
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| Now make another change: change "one" to "not": |
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| one ~ |
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| change 1 |
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| one too ~ |
| / \ |
| change 2 change 3 |
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| one two me too ~ |
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| change 4 |
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| not two ~ |
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| 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. |
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| You can repeat |g-| and you will see the text change: |
| me too ~ |
| one two ~ |
| one too ~ |
| one ~ |
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| Use |g+| to move forward in time: |
| one ~ |
| one too ~ |
| one two ~ |
| me too ~ |
| not two ~ |
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| 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. |
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| You can type a count before |g-| and |g+| to repeat them. |
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| ============================================================================== |
| *32.4* Time travelling |
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| 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. |
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| To see what branches there are in the undo tree use this command: > |
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| :undolist |
| < number changes time ~ |
| 3 2 16 seconds ago |
| 4 3 5 seconds ago |
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| 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: > |
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| :earlier 10s |
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| 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: > |
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| :earlier 100d |
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| To travel forward in time again use the |:later| command: > |
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| :later 1m |
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| The arguments are "s", "m" and "h", just like with |:earlier|. |
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| If you want even more details, or want to manipulate the information, you can |
| use the |undotree()| function. To see what it returns: > |
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| :echo undotree() |
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| ============================================================================== |
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| Next chapter: |usr_40.txt| Make new commands |
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| Copyright: see |manual-copyright| vim:tw=78:ts=8:ft=help:norl: |