by Alexey Radkov and Dmitry Hrabrov a.k.a. DeXPeriX

• About
• Features
• Setup
• Configuration
  • Basic configuration
  • Keymap assistance in Normal mode
  • Default layouts
  • Disable for specific filetypes
  • Enable in runtime
• Custom keyboard layout switching rules
• Troubleshooting

If you speak and write in two or more languages, you may know how it's frustrating to constantly switch keyboard layouts manually, because vim in command mode can understand only English letters. So you need constantly change keyboard layout into English if you need perform some command and if you are writing texts, for example, in Russian, German or Chinese at the same time.

Vim plugin XkbSwitch can be used to easily switch current keyboard layout back and forth when entering and leaving Insert mode. Say, you are typing some document in Russian and have to leave Insert mode: when you press <Esc> your keyboard layout switches to US/English automatically. When you further enter Insert mode once again the Russian keyboard layout will be automatically switched back!

XkbSwitch requires an OS dependent keyboard layout switcher. Below is the list of compatible switchers.

• UNIX / Linux / X Server: xkb-switch.

• Windows: xkb-switch-win.

• Mac OS X: xkbswitch-macosx or Input Source Switcher. In the latter case, put line

  let g:XkbSwitchLib = '/usr/local/lib/libInputSourceSwitcher.dylib'

  into your .vimrc settings.

• Gnome 3 and 4x: g3kb-switch. The plugin can be loaded with

  let g:XkbSwitchLib = '/usr/local/lib/libg3kbswitch.so'

• i3wm: xkb-switch-i3.

• Supported OS: UNIX / X Server, Windows, Mac OS X.

• Switches keyboard layout when entering / leaving Insert and Select modes as well as the command line when searching patterns.

• Dynamic keymap assistance in commands like r and f in Normal mode.

• Keyboard layouts are stored separately for each buffer.

• Keyboard layouts are kept intact while navigating between windows or tabs without leaving Insert mode.

• Automatic loading of language-friendly Insert mode mappings duplicates. For example, when Russian mappings have loaded then if there was a mapping

  <C-G>S        <Plug>ISurround

  a new mapping

  <C-G>Ы        <Plug>ISurround

  will be loaded. Insert mode mappings duplicates make it easy to apply existing maps in Insert mode without switching current keyboard layout.

• Fast and easy building of custom syntax based keyboard layout switching rules in Insert mode.

Before installation of the plugin the OS dependent keyboard layout switcher must be installed (see About). The plugin itself is installed by extracting of the distribution in your vim runtime directory.

Basic configuration requires only 1 line in your .vimrc:

let g:XkbSwitchEnabled = 1

Additionally path to the backend switcher library can be defined:

let g:XkbSwitchLib = '/usr/local/lib/libxkbswitch.so'

However normally it is not necessary as far as the plugin is able to find it automatically. To enable Insert mode mappings duplicates user may want to add

let g:XkbSwitchIMappings = ['ru']

Here Insert mappings duplicates for Russian winkeys layout will be generated whenever Insert mode is started. It is possible to define a list of different layouts, for example

let g:XkbSwitchIMappings = ['ru', 'de']

but currently only Russian winkeys ('ru') and Ukrainian ('uk') layout translation maps are supported out of the box. There are 2 ways how a user can provide extra definitions of keyboard layout translation maps (or alter/remove existing default 'ru' and 'uk' maps):

• Define variable g:XkbSwitchIMappingsTr:

  let g:XkbSwitchIMappingsTr = {
            \ 'ru':
            \ {'<': 'qwertyuiop[]asdfghjkl;''zxcvbnm,.`/'.
            \       'QWERTYUIOP{}ASDFGHJKL:"ZXCVBNM<>?~@#$^&|',
            \  '>': 'йцукенгшщзхъфывапролджэячсмитьбюё.'.
            \       'ЙЦУКЕНГШЩЗХЪФЫВАПРОЛДЖЭЯЧСМИТЬБЮ,Ё"№;:?/'},
            \ 'de':
            \ {'<': 'yz-[];''/YZ{}:"<>?~@#^&*_\',
            \  '>': 'zyßü+öä-ZYÜ*ÖÄ;:_°"§&/(?#'},
            \ }

• Create a file with layout translation maps and put its path into variable g:XkbSwitchIMappingsTrData, for example:

  let g:XkbSwitchIMappingsTrData = $HOME.'/opt/xkbswitch.tr'

  File with maps must follow this format:

  ru  Russian winkeys layout
  < qwertyuiop[]asdfghjkl;'zxcvbnm,.`/QWERTYUIOP{}ASDFGHJKL:"ZXCVBNM<>?~@#$^&|
  > йцукенгшщзхъфывапролджэячсмитьбюё.ЙЦУКЕНГШЩЗХЪФЫВАПРОЛДЖЭЯЧСМИТЬБЮ,Ё"№;:?/
  
  de
  < yz-[];'/YZ{}:"<>?~@#^&*(_\
  > zyßü+öä-ZYÜ*ÖÄ;:_°"§&/()?#
  

  Sample file xkbswitch.tr with exactly this content is shipped with this plugin distribution. It is encoded in UTF-8 and it is important as far as its content is read using readfile()! If your locale is not UTF-8 and you want to use this sample file then it seems that you will have to re-encode it in your locale standard encoding

Be very careful with mapping duplicates! They won't replace existing Insert mode mappings but may define extra mappings that will change normal Insert mode user experience. For example, plugin echofunc defines Insert mode mappings for '(' and ')', therefore assuming that in Deutsch translation map there could be ')' to '=' translation, we would get '=' unusable in any keyboard layout (as far as echofunc treats ')' in a very specific way). That is why this translation is missing in example above and in file xkbswitch.tr content.

There are multiple examples of similar issues. For instance Russian winkeys translate '.' into 'ю' and when you are editing a C/C++ source file with enabled omnicompletion plugin character 'ю' (which you can use in comments) will always be replaced by '.'. To address these issues starting from version 0.10 a new variable g:XkbSwitchSkipIMappings was introduced. It defines which original Insert mode mappings should not be translated for specific filetypes. Add into your .vimrc lines

let g:XkbSwitchSkipIMappings =
        \ {'c'   : ['.', '>', ':', '{<CR>', '/*', '/*<CR>'],
        \  'cpp' : ['.', '>', ':', '{<CR>', '/*', '/*<CR>']}

and now you will be able to print 'ю' in C and C++ source files. In this example six Insert mode mappings were prohibited for translation in two filetypes: C and C++. The first three correspond to omnicompletion plugin and the last three address plugin c.vim. Why mappings duplicates starting from '/' were added: Russian winkeys translate '/' into '.' and this makes vim wait for a while until the next character after '.' has been inserted which makes omnicompletion plugin almost unusable. If you want to skip specific Insert mode mappings for all filetypes then you can use '*' as the filetype key in g:XkbSwitchSkipIMappings.

Beware: variable g:XkbSwitchSkipIMappings is not parameterized by keyboard layouts but only by filetypes.

Besides natural Insert mode mappings, register insertion translations are also supported. For example, being in Insert mode and having Russian winkeys layout on, you can insert content of register 'a' just printing <C-R>ф without switching current keyboard layout. To disable translation of register names in Insert mode put line

let g:XkbSwitchLoadRIMappings = 0

into your .vimrc.

XkbSwitch is unable to guess keyboard layout when using Normal mode commands r and f and, in the past, searching patterns with / and ?. Fortunately, it can assist keymap in this by setting

let g:XkbSwitchAssistNKeymap = 1    " for commands r and f
let g:XkbSwitchAssistSKeymap = 1    " for search lines

given that keymap is set to some value, for example

set keymap=russian-jcukenwin
set iminsert=0
set imsearch=0

(Note that setting of g:XkbSwitchAssistSKeymap is deprecated because tracking of entering / leaving command line for searching patterns is fully supported after CmdlineEnter and CmdlineLeave events have been introduced in vim.)

Now when you leave Insert mode, the keyboard layout is switched back to the usual Normal mode value, but values of iminsert and imsearch are set depending on the last Insert mode keyboard layout: if it was equal to the value of b:keymap_name that is normally defined in keymap files then they are set to 1, otherwise to 0. If keymap names do not match system keyboard layout names then you can remap them using variable g:XkbSwitchKeymapNames.

let g:XkbSwitchKeymapNames = {'ru' : 'ru_keymap', 'uk' : 'uk_keymap'}

Here ru and uk are system keyboard layout names whereas ru_keymap and uk_keymap are values of b:keymap_name.

When more than two keyboard layouts are used it probably makes sense to set keymaps dynamically in runtime. XkbSwitch can do it for you! You only need to define a new variable

let g:XkbSwitchDynamicKeymap = 1

and map g:XkbSwitchKeymapNames to keymap names instead of values of b:keymap_name. For example

let g:XkbSwitchKeymapNames =
            \ {'ru' : 'russian-jcukenwin', 'uk' : 'ukrainian-jcuken'}

Now keymap will automatically switch to the last keyboard layout when you leave Insert mode.

To toggle keymap layout in Normal mode for using in commands r and f, you may need to set a dedicated key:

let g:XkbSwitchIminsertToggleKey = '<C-^>'

By default pressing the key will be echoed in the command-line which is sometimes superfluous: modern status-line plugins such as airline normally provide support for showing iminsert indicators.

To disable echo messages when toggling keymap layout add line

let g:XkbSwitchIminsertToggleEcho = 0

into your .vimrc.

To enable the iminsert indicator in airline add line

let g:airline_detect_iminsert = 1

Notice that toggling keymap layout when typing a pattern for a search command can be done with the builtin key Ctrl-^.

By default last Normal mode keyboard layout is restored when leaving Insert mode, but you can specify to use particular layout for that:

let g:XkbSwitchNLayout = 'us'

Also you can specify original Insert mode keyboard layout:

let g:XkbSwitchILayout = 'us'

Or unconditional Insert mode keyboard layout using buffer variable with the same name:

let b:XkbSwitchILayout = 'us'

If b:XkbSwitchILayout is set to the empty value then the keyboard layout is not changed when entering Insert mode. Be aware that momental switching from-and-to Insert mode (e.g. with Insert mode command <C-O> and all types of selections) will turn current keyboard layout to the value of b:XkbSwitchILayout. If you want to use unconditional Insert mode keyboard layout by default then put line

autocmd BufEnter * let b:XkbSwitchILayout = 'us'

into your .vimrc (change us to desired value if needed).

It makes sense to disable XkbSwitch for buffers with specific filetypes, for example various file system or tag navigators. For example, to disable XkbSwitch for NerdTree add in your .vimrc line

let g:XkbSwitchSkipFt = ['nerdtree']

By default (e.g. when g:XkbSwitchSkipFt is not defined in .vimrc) following filetypes are skipped: tagbar, gundo, nerdtree and fuf (FuzzyFinder).

You can enable XkbSwitch in runtime (e.g. when g:XkbSwitchEnabled is not set in your .vimrc) by issuing command

:EnableXkbSwitch

This command will respect current settings of g:XkbSwitchIMappings etc. Be aware that there is no way to disable XkbSwitch after it has been enabled.

Imagine that you are editing a simple dictionary with 2 columns delimited by vertical bars. In the first column you are writing down a German word and in the second column - its Russian translation. For example:

| Wort         | Übersetzung |
|--------------|-------------|
| der Mond     | луна        |
| humpeln      | хромать     |
| stark        | сильный     |

You want the keyboard layout to be automatically switched to the corresponding language when you are moving between the columns in Insert mode. It is feasible! When you start editing switch layouts in the both columns manually just once: after that XkbSwitch will learn how to switch them further. It will restore layouts after leaving Insert mode and entering it once again.

In this section it will be shown how to achieve this. First of all there should exist criteria upon which XkbSwitch will decide when it must switch layouts. The simplest criteria are syntactic rules. So the content of the columns must be syntactically distinguishable. It means that we need a file with syntax rules and some new filetype defined, say mdict. For the sake of simplicity let it be not an absolutely new filetype but rather a subclass of an existing one, for example vimwiki. Then we should create a new file after/syntax/vimwiki.vim:

if match(bufname('%'), '\.mdict$') == -1
    finish
endif

let s:colors = {'original':   [189, '#d7d7ff'],
              \ 'translated': [194, '#d7ffd7'],
              \ 'extra':      [191, '#d7ff5f']}

function! s:set_colors()
    let colors = deepcopy(s:colors)
    if exists('g:colors_name') && g:colors_name == 'lucius' &&
                \ g:lucius_style == 'light'
        let colors['original']   = [26,  '#005fd7']
        let colors['translated'] = [22,  '#005f00']
        let colors['extra']      = [167, '#d75f5f']
    endif
    exe 'hi mdictOriginalHl term=standout ctermfg='.colors['original'][0].
                \ ' guifg='.colors['original'][1]
    exe 'hi mdictTranslatedHl term=standout ctermfg='.colors['translated'][0].
                \ ' guifg='.colors['translated'][1]
    exe 'hi mdictExtraHl term=standout ctermfg='.colors['extra'][0].
                \ ' guifg='.colors['extra'][1]
endfunction

syntax match mdictCell '|[^|]*\ze|' containedin=VimwikiTableRow contained
            \ contains=VimwikiCellSeparator,mdictOriginal,mdictTranslated
syntax match mdictOriginal '[^|]\+\ze|\s*\S*.*$' contained contains=mdictExtra
syntax match mdictTranslated '[^|]\+\ze|\s*$' contained contains=mdictExtra
syntax match mdictExtra '([^()]*)' contained

call s:set_colors()
autocmd ColorScheme * call s:set_colors()

hi link mdictOriginal   mdictOriginalHl
hi link mdictTranslated mdictTranslatedHl
hi link mdictExtra      mdictExtraHl

Here the syntactic criteria have been defined: content of the first column will have syntax id mdictOriginal and content of the second column - mdictTranslated.

In .vimrc following lines must be added:

let g:mdict_synroles = ['mdictOriginal', 'mdictTranslated']

fun! MdictCheckLang(force)
    if !filereadable(g:XkbSwitchLib)
        return
    endif

    let cur_synid  = synIDattr(synID(line("."), col("."), 1), "name")

    if !exists('b:saved_cur_synid')
        let b:saved_cur_synid = cur_synid
    endif
    if !exists('b:saved_cur_layout')
        let b:saved_cur_layout = {}
    endif

    if cur_synid != b:saved_cur_synid || a:force
        let cur_layout = ''
        for role in g:mdict_synroles
            if b:saved_cur_synid == role
                let cur_layout =
                    \ libcall(g:XkbSwitchLib, 'Xkb_Switch_getXkbLayout', '')
                let b:saved_cur_layout[role] = cur_layout
                break
            endif
        endfor
        for role in g:mdict_synroles
            if cur_synid == role
                if exists('b:saved_cur_layout[role]')
                    call libcall(g:XkbSwitchLib, 'Xkb_Switch_setXkbLayout',
                                \ b:saved_cur_layout[role])
                else
                    let b:saved_cur_layout[role] = empty(cur_layout) ?
                                \ libcall(g:XkbSwitchLib,
                                \ 'Xkb_Switch_getXkbLayout', '') : cur_layout
                endif
                break
            endif
        endfor
        let b:saved_cur_synid = cur_synid
    endif
endfun

autocmd BufNewFile,BufRead *.mdict setlocal filetype=vimwiki |
           \ EnableXkbSwitch
autocmd BufNewFile         *.mdict VimwikiTable 2 2
autocmd BufNewFile         *.mdict exe "normal dd" | startinsert
autocmd CursorMovedI       *.mdict call MdictCheckLang(0)

let g:XkbSwitchPostIEnterAuto = [
            \ [{'pat': '*.mdict', 'cmd': 'call MdictCheckLang(1)'}, 0] ]

Function MdictCheckLang() does all the custom layout switching and can be regarded as a plugin to the XkbSwitch. The first autocommand states that if file has extension .mdict then its filetype must be vimwiki and turns on XkbSwitch. The next two autocommands are optional and only make editing mdict files more comfortable. The last autocommand (for CursorMovedI events) calls MdictCheckLang() when cursor moves into different columns in Insert mode. The next definition

let g:XkbSwitchPostIEnterAuto = [
            \ [{'pat': '*.mdict', 'cmd': 'call MdictCheckLang(1)'}, 0] ]

registers an InsertEnter autocommand in augroup XkbSwitch. If we had instead defined an InsertEnter autocommand here then the command would have been put before the standard InsertEnter autocommand in augroup XkbSwitch. Using variable g:XkbSwitchPostIEnterAuto ensures that the new command will run after the standard InsertEnter autocommand. The second element in an item inside g:XkbSwitchPostIEnterAuto can be 0 or 1. If it is 1 then XkbSwitch won't switch layout itself when entering Insert mode. In our case it should be 0 because MdictCheckLang() requires preliminary switching keyboard layout from XkbSwitch when entering Insert mode.

Starting from version 0.9 a generic helper for building custom syntax based keyboard layout switching rules was implemented inside the plugin code. Now building syntax rules is as simple as defining variable g:XkbSwitchSyntaxRules in .vimrc. For example

let g:XkbSwitchSyntaxRules = [
            \ {'pat': '*.mdict', 'in': ['mdictOriginal', 'mdictTranslated']},
            \ {'ft': 'c,cpp', 'inout': ['cComment', 'cCommentL']} ]

registers syntax rules for files with extension .mdict (the first element in g:XkbSwitchSyntaxRules: it replaces our old definitions of g:mdict_synroles, MdictCheckLang(), autocmd CursorMovedI and g:XkbSwitchPostIEnterAuto) and comments rules for C and C++ files (the second element in g:XkbSwitchSyntaxRules). The comments rules define that comments areas may have their own keyboard layouts in Insert mode and when cursor enters or leaves them the corresponding layouts must be restored. It may be useful if a user wants to make comments in a language that uses not standard keyboard layout without switching layouts back and forth. Notice that the second rule lists syntax groups in element inout whereas the first rule uses element in. The difference is that in the case of the comments rule we want to restore basic keyboard layout (i.e. layout for code areas) when leaving comments areas, but in the mdict rule we do not care about leaving areas mdictOriginal and mdictTranslated and only care about entering them.

• To test if the switcher library is well configured, run commands

  :echo libcall(g:XkbSwitchLib, 'Xkb_Switch_getXkbLayout', '')

  and

  :call libcall(g:XkbSwitchLib, 'Xkb_Switch_setXkbLayout', 'ru')

  which get and set the keyboard layout.

• Some characters from alternative keyboard layouts may fail to enter or behave in strange ways for certain filetypes. For example in Russian winkeys layout characters 'б', 'ю', 'ж' and 'э' may fail to enter in C++ source files. The reason of that is layout translation maps specified in variable g:XkbSwitchIMappings. You may work this around by simply not setting this variable, or better by specifying characters from the main keyboard layout whose translation should be skipped using variable g:XkbSwitchSkipIMappings. See details in section Basic configuration.

• There is a known issue when vim-latex package is installed. In this case entering Russian symbols in Insert mode when editing tex files becomes impossible. The issue arises from clashing XkbSwitch Insert mappings duplicates with mappings defined in vim-latex. To work this issue around you can disable XkbSwitch Insert mode mappings duplicates for filetype tex:

  let g:XkbSwitchIMappingsSkipFt = ['tex']

• When leaving Insert mode after using an alternative keyboard layout (say Russian), there could be a time lag (of length 1 sec if the value of timeoutlen was not altered) before typing commands in Normal mode gets back to produce any effect. To cope with this issue, the value of ttimeoutlen (notice the double-t in the beginning of its name!) must be set to some small value, say

  set ttimeoutlen=50

• Related to X Server only. When editing files on a remote host via ssh the ssh -X option must be supplied:

  ssh -X remote.host

  This option will make ssh forward X Server protocol messages between the local host and the remote host thus making it possible to switch the local host keyboard layouts.

• Related to GTK based gvim only. In bare X terminals keycodes for <C-S> and <C-Ы> are the same which makes it possible to leave sequences with control keys in Insert mode mappings duplicates as they are. But this is not the case in GTK based gvim. The issue is still investigated.