Mercurial > vim
annotate runtime/doc/undo.txt @ 2231:aa6412cab544 vim73
Various improvements to undo file code to make it more robust.
| author | Bram Moolenaar <bram@vim.org> |
|---|---|
| date | Sat, 29 May 2010 20:33:07 +0200 |
| parents | 81b83a19e127 |
| children | dc2e5ec0500d |
| rev | line source |
|---|---|
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1 *undo.txt* For Vim version 7.3a. Last change: 2009 Apr 12 |
| 7 | 2 |
| 3 | |
| 4 VIM REFERENCE MANUAL by Bram Moolenaar | |
| 5 | |
| 6 | |
| 7 Undo and redo *undo-redo* | |
| 8 | |
| 9 The basics are explained in section |02.5| of the user manual. | |
| 10 | |
| 11 1. Undo and redo commands |undo-commands| | |
| 12 2. Two ways of undo |undo-two-ways| | |
| 697 | 13 3. Undo blocks |undo-blocks| |
| 758 | 14 4. Undo branches |undo-branches| |
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15 5. Undo persistence |undo-persistence| |
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16 6. Remarks about undo |undo-remarks| |
| 7 | 17 |
| 18 ============================================================================== | |
| 19 1. Undo and redo commands *undo-commands* | |
| 20 | |
| 21 <Undo> or *undo* *<Undo>* *u* | |
| 22 u Undo [count] changes. {Vi: only one level} | |
| 23 | |
| 24 *:u* *:un* *:undo* | |
| 25 :u[ndo] Undo one change. {Vi: only one level} | |
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26 *E830* |
| 772 | 27 :u[ndo] {N} Jump to after change number {N}. See |undo-branches| |
| 28 for the meaning of {N}. {not in Vi} | |
| 29 | |
| 7 | 30 *CTRL-R* |
| 31 CTRL-R Redo [count] changes which were undone. {Vi: redraw | |
| 32 screen} | |
| 33 | |
| 34 *:red* *:redo* *redo* | |
| 35 :red[o] Redo one change which was undone. {Vi: no redo} | |
| 36 | |
| 37 *U* | |
| 38 U Undo all latest changes on one line. {Vi: while not | |
| 39 moved off of it} | |
| 40 | |
| 41 The last changes are remembered. You can use the undo and redo commands above | |
| 42 to revert the text to how it was before each change. You can also apply the | |
| 43 changes again, getting back the text before the undo. | |
| 44 | |
| 45 The "U" command is treated by undo/redo just like any other command. Thus a | |
| 46 "u" command undoes a "U" command and a 'CTRL-R' command redoes it again. When | |
| 47 mixing "U", "u" and 'CTRL-R' you will notice that the "U" command will | |
| 48 restore the situation of a line to before the previous "U" command. This may | |
| 49 be confusing. Try it out to get used to it. | |
| 50 The "U" command will always mark the buffer as changed. When "U" changes the | |
| 51 buffer back to how it was without changes, it is still considered changed. | |
| 52 Use "u" to undo changes until the buffer becomes unchanged. | |
| 53 | |
| 54 ============================================================================== | |
| 55 2. Two ways of undo *undo-two-ways* | |
| 56 | |
| 57 How undo and redo commands work depends on the 'u' flag in 'cpoptions'. | |
| 58 There is the Vim way ('u' excluded) and the vi-compatible way ('u' included). | |
| 59 In the Vim way, "uu" undoes two changes. In the Vi-compatible way, "uu" does | |
| 60 nothing (undoes an undo). | |
| 61 | |
| 62 'u' excluded, the Vim way: | |
| 63 You can go back in time with the undo command. You can then go forward again | |
| 64 with the redo command. If you make a new change after the undo command, | |
| 65 the redo will not be possible anymore. | |
| 66 | |
| 67 'u' included, the Vi-compatible way: | |
| 68 The undo command undoes the previous change, and also the previous undo command. | |
| 69 The redo command repeats the previous undo command. It does NOT repeat a | |
| 70 change command, use "." for that. | |
| 71 | |
| 72 Examples Vim way Vi-compatible way ~ | |
| 73 "uu" two times undo no-op | |
| 74 "u CTRL-R" no-op two times undo | |
| 75 | |
| 76 Rationale: Nvi uses the "." command instead of CTRL-R. Unfortunately, this | |
| 77 is not Vi compatible. For example "dwdwu." in Vi deletes two | |
| 78 words, in Nvi it does nothing. | |
| 79 | |
| 80 ============================================================================== | |
| 697 | 81 3. Undo blocks *undo-blocks* |
| 82 | |
| 83 One undo command normally undoes a typed command, no matter how many changes | |
| 84 that command makes. This sequence of undo-able changes forms an undo block. | |
| 85 Thus if the typed key(s) call a function, all the commands in the function are | |
| 86 undone together. | |
| 87 | |
| 88 If you want to write a function or script that doesn't create a new undoable | |
| 89 change but joins in with the previous change use this command: | |
| 90 | |
| 839 | 91 *:undoj* *:undojoin* *E790* |
| 697 | 92 :undoj[oin] Join further changes with the previous undo block. |
| 93 Warning: Use with care, it may prevent the user from | |
| 839 | 94 properly undoing changes. Don't use this after undo |
| 95 or redo. | |
| 697 | 96 {not in Vi} |
| 97 | |
| 98 This is most useful when you need to prompt the user halfway a change. For | |
| 99 example in a function that calls |getchar()|. Do make sure that there was a | |
| 100 related change before this that you must join with. | |
| 101 | |
| 102 This doesn't work by itself, because the next key press will start a new | |
| 103 change again. But you can do something like this: > | |
| 104 | |
| 105 :undojoin | delete | |
| 106 | |
| 107 After this an "u" command will undo the delete command and the previous | |
| 108 change. | |
| 109 | |
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110 To do the opposite, break a change into two undo blocks, in Insert mode use |
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111 CTRL-G u. This is useful if you want an insert command to be undoable in |
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112 parts. E.g., for each sentence. |i_CTRL-G_u| |
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113 Setting the value of 'undolevels' also breaks undo. Even when the new value |
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114 is equal to the old value. |
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115 |
| 697 | 116 ============================================================================== |
| 827 | 117 4. Undo branches *undo-branches* *undo-tree* |
| 758 | 118 |
| 793 | 119 Above we only discussed one line of undo/redo. But it is also possible to |
| 120 branch off. This happens when you undo a few changes and then make a new | |
| 121 change. The undone changes become a branch. You can go to that branch with | |
| 122 the following commands. | |
| 758 | 123 |
| 799 | 124 This is explained in the user manual: |usr_32.txt|. |
| 758 | 125 |
| 772 | 126 *:undol* *:undolist* |
| 127 :undol[ist] List the leafs in the tree of changes. Example: | |
| 128 number changes time ~ | |
| 856 | 129 4 10 10:34:11 |
| 130 18 4 11:01:46 | |
| 772 | 131 |
| 132 The "number" column is the change number. This number | |
| 133 continuously increases and can be used to identify a | |
| 134 specific undo-able change, see |:undo|. | |
| 135 The "changes" column is the number of changes to this | |
| 136 leaf from the root of the tree. | |
| 137 The "time" column is the time this change was made. | |
| 138 | |
| 758 | 139 *g-* |
| 140 g- Go to older text state. With a count repeat that many | |
| 141 times. {not in Vi} | |
| 142 *:ea* *:earlier* | |
| 143 :earlier {count} Go to older text state {count} times. | |
| 144 :earlier {N}s Go to older text state about {N} seconds before. | |
| 145 :earlier {N}m Go to older text state about {N} minutes before. | |
| 146 :earlier {N}h Go to older text state about {N} hours before. | |
| 147 | |
| 148 *g+* | |
| 149 g+ Go to newer text state. With a count repeat that many | |
| 150 times. {not in Vi} | |
| 151 *:lat* *:later* | |
| 152 :later {count} Go to newer text state {count} times. | |
| 153 :later {N}s Go to newer text state about {N} seconds later. | |
| 154 :later {N}m Go to newer text state about {N} minutes later. | |
| 155 :later {N}h Go to newer text state about {N} hours later. | |
| 156 | |
| 772 | 157 |
| 758 | 158 Note that text states will become unreachable when undo information is cleared |
| 159 for 'undolevels'. | |
| 160 | |
| 161 Don't be surprised when moving through time shows multiple changes to take | |
| 162 place at a time. This happens when moving through the undo tree and then | |
| 163 making a new change. | |
| 164 | |
| 165 EXAMPLE | |
| 166 | |
| 167 Start with this text: | |
| 168 one two three ~ | |
| 169 | |
| 170 Delete the first word by pressing "x" three times: | |
| 171 ne two three ~ | |
| 172 e two three ~ | |
| 173 two three ~ | |
| 174 | |
| 175 Now undo that by pressing "u" three times: | |
| 176 e two three ~ | |
| 177 ne two three ~ | |
| 178 one two three ~ | |
| 179 | |
| 180 Delete the second word by pressing "x" three times: | |
| 181 one wo three ~ | |
| 182 one o three ~ | |
| 183 one three ~ | |
| 184 | |
| 185 Now undo that by using "g-" three times: | |
| 186 one o three ~ | |
| 187 one wo three ~ | |
| 188 two three ~ | |
| 189 | |
| 190 You are now back in the first undo branch, after deleting "one". Repeating | |
| 191 "g-" will now bring you back to the original text: | |
| 192 e two three ~ | |
| 193 ne two three ~ | |
| 194 one two three ~ | |
| 195 | |
| 196 Jump to the last change with ":later 1h": | |
| 197 one three ~ | |
| 198 | |
| 199 And back to the start again with ":earlier 1h": | |
| 200 one two three ~ | |
| 201 | |
| 202 | |
| 203 Note that using "u" and CTRL-R will not get you to all possible text states | |
| 204 while repeating "g-" and "g+" does. | |
| 205 | |
| 206 ============================================================================== | |
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207 5. Undo persistence *undo-persistence* *persistent-undo* |
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208 |
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209 When unloading a buffer Vim normally destroys the tree of undos created for |
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210 that buffer. By setting the 'undofile' option, Vim will automatically save |
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211 your undo history when you write a file and restore undo history when you edit |
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212 the file again. |
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213 |
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214 The 'undofile' option is checked after writing a file, before the BufWritePost |
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215 autocommands. If you want to control what files to write undo information |
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216 for, you can use a BufWritePre autocommand: > |
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217 au BufWritePre /tmp/* setlocal noundofile |
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218 |
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219 Vim saves undo trees in a separate undo file, one for each edited file, using |
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220 a simple scheme that maps filesystem paths directly to undo files. Vim will |
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221 detect if an undo file is no longer synchronized with the file it was written |
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222 for (with a hash of the file contents) and ignore it when the file was changed |
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223 after the undo file was written, to prevent corruption. |
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224 |
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225 Undo files are normally saved in the same directory as the file. This can be |
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226 changed with the 'undodir' option. |
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227 |
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228 You can also save and restore undo histories by using ":wundo" and ":rundo" |
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229 respectively: |
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230 *:wundo* *:rundo* |
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231 :wundo[!] {file} |
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232 Write undo history to {file}. |
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233 When {file} exists and it does not look like an undo file |
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234 (the magic number at the start of the file is wrong), then |
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235 this fails, unless the ! was added. |
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236 If it exists and does look like an undo file it is |
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237 overwritten. |
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238 {not in Vi} |
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239 |
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240 :rundo {file} Read undo history from {file}. |
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241 {not in Vi} |
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242 |
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243 You can use these in autocommands to explicitly specify the name of the |
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244 history file. E.g.: > |
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245 |
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246 au BufReadPost * rundo %:h/UNDO/%:t |
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247 au BufWritePost * wundo %:h/UNDO/%:t |
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248 |
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249 You should keep 'undofile' off, otherwise you end up with two undo files for |
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250 every write. |
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251 Note: I did not verify this always works! |
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252 |
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253 Note that while reading/writing files and 'undofile' is set most errors will |
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254 be silent, unless 'verbose' is set. With :wundo and :rundo you will get more |
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255 error messages, e.g., when the file cannot be read or written. |
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256 |
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257 NOTE: undo files are never deleted by Vim. You need to delete them yourself. |
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258 |
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259 Reading an existing undo file may fail for several reasons: |
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260 *E822* It cannot be opened, because the file permissions don't allow it. |
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261 *E823* The magic number at the start of the file doesn't match. This usually |
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262 means it is not an undo file. |
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263 *E824* The version number of the undo file indicates that it's written by a |
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264 newer version of Vim. You need that newer version to open it. Don't |
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265 write the buffer if you want to keep the undo info in the file. |
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266 "File contents changed, cannot use undo info" |
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267 The file text differs from when the undo file was written. This means |
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268 the undo file cannot be used, it would corrupt the text. This also |
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269 happens when 'encoding' differs from when the undo file was written. |
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270 *E825* The undo file does not contain valid contents and cannot be used. |
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271 |
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272 Writing an undo file may fail for these reasons: |
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273 *E828* The file to be written cannot be created. Perhaps you do not have |
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274 write permissions in the directory. |
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275 "Will not overwrite with undo file, cannot read" |
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276 A file exists with the name of the undo file to be written, but it |
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277 cannot be read. You may want to delete this file or rename it. |
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278 "Will not overwrite, this is not an undo file" |
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279 A file exists with the name of the undo file to be written, but it |
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280 does not start with the right magic number. You may want to delete |
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281 this file or rename it. |
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282 *E829* An error occurred while writing the undo file. You may want to try |
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283 again. |
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284 |
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285 ============================================================================== |
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286 6. Remarks about undo *undo-remarks* |
| 7 | 287 |
| 288 The number of changes that are remembered is set with the 'undolevels' option. | |
| 289 If it is zero, the Vi-compatible way is always used. If it is negative no | |
| 290 undo is possible. Use this if you are running out of memory. | |
| 291 | |
| 292 Marks for the buffer ('a to 'z) are also saved and restored, together with the | |
| 293 text. {Vi does this a little bit different} | |
| 294 | |
| 295 When all changes have been undone, the buffer is not considered to be changed. | |
| 296 It is then possible to exit Vim with ":q" instead of ":q!" {not in Vi}. Note | |
| 297 that this is relative to the last write of the file. Typing "u" after ":w" | |
| 298 actually changes the buffer, compared to what was written, so the buffer is | |
| 299 considered changed then. | |
| 300 | |
| 301 When manual |folding| is being used, the folds are not saved and restored. | |
| 302 Only changes completely within a fold will keep the fold as it was, because | |
| 303 the first and last line of the fold don't change. | |
| 304 | |
| 305 The numbered registers can also be used for undoing deletes. Each time you | |
| 306 delete text, it is put into register "1. The contents of register "1 are | |
| 307 shifted to "2, etc. The contents of register "9 are lost. You can now get | |
| 308 back the most recent deleted text with the put command: '"1P'. (also, if the | |
| 309 deleted text was the result of the last delete or copy operation, 'P' or 'p' | |
| 310 also works as this puts the contents of the unnamed register). You can get | |
| 311 back the text of three deletes ago with '"3P'. | |
| 312 | |
| 313 *redo-register* | |
| 314 If you want to get back more than one part of deleted text, you can use a | |
| 315 special feature of the repeat command ".". It will increase the number of the | |
| 316 register used. So if you first do ""1P", the following "." will result in a | |
| 317 '"2P'. Repeating this will result in all numbered registers being inserted. | |
| 318 | |
| 319 Example: If you deleted text with 'dd....' it can be restored with | |
| 320 '"1P....'. | |
| 321 | |
| 322 If you don't know in which register the deleted text is, you can use the | |
| 323 :display command. An alternative is to try the first register with '"1P', and | |
| 324 if it is not what you want do 'u.'. This will remove the contents of the | |
| 325 first put, and repeat the put command for the second register. Repeat the | |
| 326 'u.' until you got what you want. | |
| 327 | |
| 328 vim:tw=78:ts=8:ft=help:norl: |