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diff --git a/runtime/doc/diff.txt b/runtime/doc/diff.txt new file mode 100644 index 0000000..216922a --- /dev/null +++ b/runtime/doc/diff.txt @@ -0,0 +1,478 @@ +*diff.txt* For Vim version 9.0. Last change: 2023 Jan 21 + + + VIM REFERENCE MANUAL by Bram Moolenaar + + + *diff* *vimdiff* *gvimdiff* *diff-mode* +This file describes the |+diff| feature: Showing differences between two to +eight versions of the same file. + +The basics are explained in section |08.7| of the user manual. + +1. Starting diff mode |start-vimdiff| +2. Viewing diffs |view-diffs| +3. Jumping to diffs |jumpto-diffs| +4. Copying diffs |copy-diffs| +5. Diff options |diff-options| + +============================================================================== +1. Starting diff mode *start-vimdiff* + +The easiest way to start editing in diff mode is with the "vimdiff" command. +This starts Vim as usual, and additionally sets up for viewing the differences +between the arguments. > + + vimdiff file1 file2 [file3 [file4]] + +This is equivalent to: > + + vim -d file1 file2 [file3 [file4]] + +You may also use "gvimdiff" or "vim -d -g". The GUI is started then. +You may also use "viewdiff" or "gviewdiff". Vim starts in readonly mode then. +"r" may be prepended for restricted mode (see |-Z|). + +The second and following arguments may also be a directory name. Vim will +then append the file name of the first argument to the directory name to find +the file. + +By default an internal diff library will be used. When 'diffopt' or +'diffexpr' has been set an external "diff" command will be used. This only +works when such a diff program is available. + +Diffs are local to the current tab page |tab-page|. You can't see diffs with +a window in another tab page. This does make it possible to have several +diffs at the same time, each in their own tab page. + +What happens is that Vim opens a window for each of the files. This is like +using the |-O| argument. This uses vertical splits. If you prefer horizontal +splits add the |-o| argument: > + + vimdiff -o file1 file2 [file3 [file4]] + +If you always prefer horizontal splits include "horizontal" in 'diffopt'. + +In each of the edited files these options are set: + + 'diff' on + 'scrollbind' on + 'cursorbind' on + 'scrollopt' includes "hor" + 'wrap' off, or leave as-is if 'diffopt' includes "followwrap" + 'foldmethod' "diff" + 'foldcolumn' value from 'diffopt', default is 2 + +These options are set local to the window. When editing another file they are +reset to the global value. +The options can still be overruled from a modeline when re-editing the file. +However, 'foldmethod' and 'wrap' won't be set from a modeline when 'diff' is +set. +See `:diffoff` for an easy way to revert the options. + +The differences shown are actually the differences in the buffer. Thus if you +make changes after loading a file, these will be included in the displayed +diffs. You might have to do ":diffupdate" now and then, not all changes are +immediately taken into account, especially when using an external diff command. + +In your .vimrc file you could do something special when Vim was started in +diff mode. You could use a construct like this: > + + if &diff + setup for diff mode + else + setup for non-diff mode + endif + +While already in Vim you can start diff mode in three ways. + + *E98* +:diffs[plit] {filename} *:diffs* *:diffsplit* + Open a new window on the file {filename}. The options are set + as for "vimdiff" for the current and the newly opened window. + Also see 'diffexpr'. + + *:difft* *:diffthis* +:difft[his] Make the current window part of the diff windows. This sets + the options like for "vimdiff". + +:diffp[atch] {patchfile} *E816* *:diffp* *:diffpatch* + Use the current buffer, patch it with the diff found in + {patchfile} and open a buffer on the result. The options are + set as for "vimdiff". + {patchfile} can be in any format that the "patch" program + understands or 'patchexpr' can handle. + Note that {patchfile} should only contain a diff for one file, + the current file. If {patchfile} contains diffs for other + files as well, the results are unpredictable. Vim changes + directory to /tmp to avoid files in the current directory + accidentally being patched. But it may still result in + various ".rej" files to be created. And when absolute path + names are present these files may get patched anyway. + +To make these commands use a vertical split, prepend |:vertical|. Examples: > + + :vert diffsplit main.c~ + :vert diffpatch /tmp/diff + +If you always prefer a vertical split include "vertical" in 'diffopt'. + + *E96* +There can be up to eight buffers with 'diff' set. + +Since the option values are remembered with the buffer, you can edit another +file for a moment and come back to the same file and be in diff mode again. + + *:diffo* *:diffoff* +:diffo[ff] Switch off diff mode for the current window. Resets related + options also when 'diff' was not set. + +:diffo[ff]! Switch off diff mode for the current window and in all windows + in the current tab page where 'diff' is set. Resetting + related options only happens in a window that has 'diff' set, + if the current window does not have 'diff' set then no options + in it are changed. + Hidden buffers are also removed from the list of diff'ed + buffers. + +The `:diffoff` command resets the relevant options to the values they had when +using `:diffsplit`, `:diffpatch`, `:diffthis`. or starting Vim in diff mode. +When using `:diffoff` twice the last saved values are restored. +Otherwise they are set to their default value: + + 'diff' off + 'scrollbind' off + 'cursorbind' off + 'scrollopt' without "hor" + 'wrap' on, or leave as-is if 'diffopt' includes "followwrap" + 'foldmethod' "manual" + 'foldcolumn' 0 + +'foldenable' will most-likely be reset to off. That is when 'foldmethod' is +is restored to "manual". The folds themselves are not cleared but they should +not show up, resetting 'foldenable' is the best way to do that. + +============================================================================== +2. Viewing diffs *view-diffs* + +The effect is that the diff windows show the same text, with the differences +highlighted. When scrolling the text, the 'scrollbind' option will make the +text in other windows to be scrolled as well. With vertical splits the text +should be aligned properly. + +The alignment of text will go wrong when: +- 'wrap' is on, some lines will be wrapped and occupy two or more screen + lines +- folds are open in one window but not another +- 'scrollbind' is off +- changes have been made to the text +- "filler" is not present in 'diffopt', deleted/inserted lines makes the + alignment go wrong + +All the buffers edited in a window where the 'diff' option is set will join in +the diff. This is also possible for hidden buffers. They must have been +edited in a window first for this to be possible. To get rid of the hidden +buffers use `:diffoff!`. + + *:DiffOrig* *diff-original-file* +Since 'diff' is a window-local option, it's possible to view the same buffer +in diff mode in one window and "normal" in another window. It is also +possible to view the changes you have made to a buffer since the file was +loaded. Since Vim doesn't allow having two buffers for the same file, you +need another buffer. This command is useful: > + command DiffOrig vert new | set bt=nofile | r ++edit # | 0d_ + \ | diffthis | wincmd p | diffthis +(this is in |defaults.vim|). Use ":DiffOrig" to see the differences between +the current buffer and the file it was loaded from. + +A buffer that is unloaded cannot be used for the diff. But it does work for +hidden buffers. You can use ":hide" to close a window without unloading the +buffer. If you don't want a buffer to remain used for the diff do ":set +nodiff" before hiding it. + + *:dif* *:diff* *:diffupdate* +:dif[fupdate][!] Update the diff highlighting and folds. + +Vim attempts to keep the differences updated when you make changes to the +text. This mostly takes care of inserted and deleted lines. Changes within a +line and more complicated changes do not cause the differences to be updated. +To force the differences to be updated use: > + + :diffupdate + +If the ! is included Vim will check if the file was changed externally and +needs to be reloaded. It will prompt for each changed file, like `:checktime` +was used. + +Vim will show filler lines for lines that are missing in one window but are +present in another. These lines were inserted in another file or deleted in +this file. Removing "filler" from the 'diffopt' option will make Vim not +display these filler lines. + + +Folds are used to hide the text that wasn't changed. See |folding| for all +the commands that can be used with folds. + +The context of lines above a difference that are not included in the fold can +be set with the 'diffopt' option. For example, to set the context to three +lines: > + + :set diffopt=filler,context:3 + + +The diffs are highlighted with these groups: + +|hl-DiffAdd| DiffAdd Added (inserted) lines. These lines exist in + this buffer but not in another. +|hl-DiffChange| DiffChange Changed lines. +|hl-DiffText| DiffText Changed text inside a Changed line. Vim + finds the first character that is different, + and the last character that is different + (searching from the end of the line). The + text in between is highlighted. This means + that parts in the middle that are still the + same are highlighted anyway. The 'diffopt' + flags "iwhite" and "icase" are used here. +|hl-DiffDelete| DiffDelete Deleted lines. Also called filler lines, + because they don't really exist in this + buffer. + +============================================================================== +3. Jumping to diffs *jumpto-diffs* + +Two commands can be used to jump to diffs: + *[c* + [c Jump backwards to the previous start of a change. + When a count is used, do it that many times. + *]c* + ]c Jump forwards to the next start of a change. + When a count is used, do it that many times. + +It is an error if there is no change for the cursor to move to. + +============================================================================== +4. Diff copying *copy-diffs* *E99* *E100* *E101* *E102* *E103* + *merge* +There are two commands to copy text from one buffer to another. The result is +that the buffers will be equal within the specified range. + + *:diffg* *:diffget* +:[range]diffg[et] [bufspec] + Modify the current buffer to undo difference with another + buffer. If [bufspec] is given, that buffer is used. If + [bufspec] refers to the current buffer then nothing happens. + Otherwise this only works if there is one other buffer in diff + mode. + See below for [range]. + + *:diffpu* *:diffput* *E793* +:[range]diffpu[t] [bufspec] + Modify another buffer to undo difference with the current + buffer. Just like ":diffget" but the other buffer is modified + instead of the current one. + When [bufspec] is omitted and there is more than one other + buffer in diff mode where 'modifiable' is set this fails. + See below for [range]. + + *do* +[count]do Same as ":diffget" without range. The "o" stands for "obtain" + ("dg" can't be used, it could be the start of "dgg"!). Note: + this doesn't work in Visual mode. + If you give a [count], it is used as the [bufspec] argument + for ":diffget". + + *dp* +[count]dp Same as ":diffput" without range. Note: this doesn't work in + Visual mode. + If you give a [count], it is used as the [bufspec] argument + for ":diffput". + + +When no [range] is given, the diff at the cursor position or just above it is +affected. When [range] is used, Vim tries to only put or get the specified +lines. When there are deleted lines, this may not always be possible. + +There can be deleted lines below the last line of the buffer. When the cursor +is on the last line in the buffer and there is no diff above this line, the +":diffget" and "do" commands will obtain lines from the other buffer. + +To be able to get those lines from another buffer in a [range] it's allowed to +use the last line number plus one. This command gets all diffs from the other +buffer: > + + :1,$+1diffget + +Note that deleted lines are displayed, but not counted as text lines. You +can't move the cursor into them. To fill the deleted lines with the lines +from another buffer use ":diffget" on the line below them. + *E787* +When the buffer that is about to be modified is read-only and the autocommand +that is triggered by |FileChangedRO| changes buffers the command will fail. +The autocommand must not change buffers. + +The [bufspec] argument above can be a buffer number, a pattern for a buffer +name or a part of a buffer name. Examples: + + :diffget Use the other buffer which is in diff mode + :diffget 3 Use buffer 3 + :diffget v2 Use the buffer which matches "v2" and is in + diff mode (e.g., "file.c.v2") + +============================================================================== +5. Diff options *diff-options* + +Also see |'diffopt'| and the "diff" item of |'fillchars'|. + + *diff-slow* *diff_translations* +For very long lines, the diff syntax highlighting might be slow, especially +since it tries to match all different kind of localisations. To disable +localisations and speed up the syntax highlighting, set the global variable +g:diff_translations to zero: > + + let g:diff_translations = 0 +< +After setting this variable, reload the syntax script: > + + set syntax=diff +< + + +FINDING THE DIFFERENCES *diff-diffexpr* + +The 'diffexpr' option can be set to use something else than the internal diff +support or the standard "diff" program to compare two files and find the +differences. *E959* + +When 'diffexpr' is empty, Vim uses this command to find the differences +between file1 and file2: > + + diff file1 file2 > outfile + +The ">" is replaced with the value of 'shellredir'. + +The output of "diff" must be a normal "ed" style diff or a unified diff. A +context diff will NOT work. For a unified diff no context lines can be used. +Using "diff -u" will NOT work, use "diff -U0". + +This example explains the format that Vim expects for the "ed" style diff: > + + 1a2 + > bbb + 4d4 + < 111 + 7c7 + < GGG + --- + > ggg + +The "1a2" item appends the line "bbb". +The "4d4" item deletes the line "111". +The "7c7" item replaces the line "GGG" with "ggg". + +When 'diffexpr' is not empty, Vim evaluates it to obtain a diff file in the +format mentioned. These variables are set to the file names used: + + v:fname_in original file + v:fname_new new version of the same file + v:fname_out where to write the resulting diff file + +Additionally, 'diffexpr' should take care of "icase" and "iwhite" in the +'diffopt' option. 'diffexpr' cannot change the value of 'lines' and +'columns'. + +The advantage of using a function call without arguments is that it is faster, +see |expr-option-function|. + +Example (this does almost the same as 'diffexpr' being empty): > + + set diffexpr=MyDiff() + function MyDiff() + let opt = "" + if &diffopt =~ "icase" + let opt = opt .. "-i " + endif + if &diffopt =~ "iwhite" + let opt = opt .. "-b " + endif + silent execute "!diff -a --binary " .. opt .. v:fname_in .. " " .. v:fname_new .. + \ " > " .. v:fname_out + redraw! + endfunction + +The "-a" argument is used to force comparing the files as text, comparing as +binaries isn't useful. The "--binary" argument makes the files read in binary +mode, so that a CTRL-Z doesn't end the text on DOS. + +The `redraw!` command may not be needed, depending on whether executing a +shell command shows something on the display or not. + +If the 'diffexpr' expression starts with s: or |<SID>|, then it is replaced +with the script ID (|local-function|). Example: > + set diffexpr=s:MyDiffExpr() + set diffexpr=<SID>SomeDiffExpr() +Otherwise, the expression is evaluated in the context of the script where the +option was set, thus script-local items are available. + + *E810* *E97* +Vim will do a test if the diff output looks alright. If it doesn't, you will +get an error message. Possible causes: +- The "diff" program cannot be executed. +- The "diff" program doesn't produce normal "ed" style diffs (see above). +- The 'shell' and associated options are not set correctly. Try if filtering + works with a command like ":!sort". +- You are using 'diffexpr' and it doesn't work. +If it's not clear what the problem is set the 'verbose' option to one or more +to see more messages. + +The self-installing Vim for MS-Windows includes a diff program. If you don't +have it you might want to download a diff.exe. For example from +http://gnuwin32.sourceforge.net/packages/diffutils.htm. + + +USING PATCHES *diff-patchexpr* + +The 'patchexpr' option can be set to use something else than the standard +"patch" program. + +When 'patchexpr' is empty, Vim will call the "patch" program like this: > + + patch -o outfile origfile < patchfile + +This should work fine with most versions of the "patch" program. Note that a +CR in the middle of a line may cause problems, it is seen as a line break. + +If the default doesn't work for you, set the 'patchexpr' to an expression that +will have the same effect. These variables are set to the file names used: + + v:fname_in original file + v:fname_diff patch file + v:fname_out resulting patched file + +The advantage of using a function call without arguments is that it is faster, +see |expr-option-function|. + +Example (this does the same as 'patchexpr' being empty): > + + set patchexpr=MyPatch() + function MyPatch() + :call system("patch -o " .. v:fname_out .. " " .. v:fname_in .. + \ " < " .. v:fname_diff) + endfunction + +Make sure that using the "patch" program doesn't have unwanted side effects. +For example, watch out for additionally generated files, which should be +deleted. It should just patch the file and nothing else. + Vim will change directory to "/tmp" or another temp directory before +evaluating 'patchexpr'. This hopefully avoids that files in the current +directory are accidentally patched. Vim will also delete files starting with +v:fname_in and ending in ".rej" and ".orig". + +If the 'patchexpr' expression starts with s: or |<SID>|, then it is replaced +with the script ID (|local-function|). Example: > + set patchexpr=s:MyPatchExpr() + set patchexpr=<SID>SomePatchExpr() +Otherwise, the expression is evaluated in the context of the script where the +option was set, thus script-local items are available. + + + vim:tw=78:ts=8:noet:ft=help:norl: |