vim-airline/doc/airline.txt

*airline.txt*  Lean and mean statusline that's light as air
                   _                       _      _ _                        ~
            __   _(_)_ __ ___         __ _(_)_ __| (_)_ __   ___             ~
            \ \ / / | '_ ` _ \ _____ / _` | | '__| | | '_ \ / _ \            ~
             \ V /| | | | | | |_____| (_| | | |  | | | | | |  __/            ~
              \_/ |_|_| |_| |_|      \__,_|_|_|  |_|_|_| |_|\___|            ~
                                                                             ~
==============================================================================
INTRODUCTION                                                       *airline*

vim-airline is a fast and lightweight alternative to powerline, written
in 100% vimscript with no outside dependencies.

==============================================================================
FEATURES                                                  *airline-features*

*  tiny core written with extensibility in mind.
*  integrates with many popular plugins.
*  looks good with regular fonts, and provides configuration points so you
   can use unicode or powerline symbols.
*  optimized for speed; it loads in under a millisecond.
*  fully customizable; if you know a little |statusline| syntax you can
   tweak it to your needs.
*  extremely easy to write themes.

==============================================================================
NAME                                                          *airline-name*

Where did the name come from?

I wrote this on an airplane, and since it's light as air it turned out to be a
good name :-)

==============================================================================
CONFIGURATION                                        *airline-configuration*

There are a couple configuration values available (shown with their default
values):

* the separator used on the left side >
  let g:airline_left_sep='>'
<
* the separator used on the right side >
  let g:airline_right_sep='<'
<
* enable modified detection >
  let g:airline_detect_modified=1

* enable paste detection >
  let g:airline_detect_paste=1
<
* enable iminsert detection >
  let g:airline_detect_iminsert=1
<
* determine whether inactive windows should have the left section collapsed to
  only the filename of that buffer.  >
  let g:airline_inactive_collapse=1
<
* themes are automatically selected based on the matching colorscheme. this
  can be overridden by defining a value. >
  let g:airline_theme=
<
* enable/disable usage of patched powerline font symbols >
  let g:airline_powerline_fonts=0
<
* define the set of text to display for each mode.  >
  let g:airline_mode_map = {} " see source for the defaults

  " or copy paste the following into your vimrc for shortform text
  let g:airline_mode_map = {
      \ '__' : '-',
      \ 'n'  : 'N',
      \ 'i'  : 'I',
      \ 'R'  : 'R',
      \ 'c'  : 'C',
      \ 'v'  : 'V',
      \ 'V'  : 'V',
      \ '' : 'V',
      \ 's'  : 'S',
      \ 'S'  : 'S',
      \ '' : 'S',
      \ }
<
* define the set of filename match queries which excludes a window from having
  its statusline modified >
  let g:airline_exclude_filenames = [] " see source for current list
<
* define the set of filetypes which are excluded from having its window
  statusline modified >
  let g:airline_exclude_filetypes = [] " see source for current list
<
* defines whether the preview window should be excluded from have its window
  statusline modified (may help with plugins which use the preview window
  heavily) >
  let g:airline_exclude_preview = 0
<
==============================================================================
COMMANDS                                                  *airline-commands*

:AirlineTheme {theme-name}                                   *:AirlineTheme*
  Displays or changes the current theme.

:AirlineToggleWhitespace                          *:AirlineToggleWhitespace*
  Toggles whitespace detection.

:AirlineToggle                                              *:AirlineToggle*
  Toggle this plugin (e.g. the nice statusline)

==============================================================================
CUSTOMIZATION                                        *airline-customization*

The following are some unicode symbols for customizing the left/right
separators, as well as the powerline font glyths.
>
  " unicode symbols
  let g:airline_left_sep = '»'
  let g:airline_left_sep = '▶'
  let g:airline_right_sep = '«'
  let g:airline_right_sep = '◀'
  let g:airline_linecolumn_prefix = '␊ '
  let g:airline_linecolumn_prefix = '␤ '
  let g:airline_linecolumn_prefix = '¶ '
  let g:airline#extensions#branch#symbol = '⎇ '
  let g:airline_paste_symbol = 'ρ'
  let g:airline_paste_symbol = 'Þ'
  let g:airline_paste_symbol = '∥'
  let g:airline#extensions#whitespace#symbol = 'Ξ'

  " powerline symbols
  let g:airline_left_sep = ''
  let g:airline_left_alt_sep = ''
  let g:airline_right_sep = ''
  let g:airline_right_alt_sep = ''
  let g:airline#extensions#branch#symbol = ' '
  let g:airline_readonly_symbol = ''
  let g:airline_linecolumn_prefix = ' '

  " old vim-powerline symbols
  let g:airline_left_sep = '⮀'
  let g:airline_left_alt_sep = '⮁'
  let g:airline_right_sep = '⮂'
  let g:airline_right_alt_sep = '⮃'
  let g:airline#extensions#branch#symbol = '⭠'
  let g:airline_readonly_symbol = '⭤'
  let g:airline_linecolumn_prefix = '⭡'
<

For more intricate customizations, you can replace the predefined sections
with the usual statusline syntax. Note that many of these settings can also be
controlled with |airline-configuration| variables, which is useful for
sections which by default host more than one extension.
>
  variable names                default contents
  ----------------------------------------------------------------------------
  let g:airline_section_a       (the mode/paste indicator)
  let g:airline_section_b       (the fugitive/lawrencium branch indicator)
  let g:airline_section_c       (bufferline or filename)
  let g:airline_section_gutter  (csv)
  let g:airline_section_x       (tagbar, filetype)
  let g:airline_section_y       (fileencoding, fileformat)
  let g:airline_section_z       (percentage, line number, column number)
  let g:airline_section_warning (syntastic, whitespace)

  " here is an example of how you could replace the branch indicator with
  " the current working directory, followed by the filename.
  let g:airline_section_b = '%{getcwd()}'
  let g:airline_section_c = '%t'
<
==============================================================================
EXTENSIONS                                              *airline-extensions*

                                                            *airline-branch*
fugitive.vim <https://github.com/tpope/vim-fugitive>
lawrencium   <https://bitbucket.org/ludovicchabant/vim-lawrencium>

* enable/disable fugitive/lawrencium integration >
  let g:airline#extensions#branch#enabled = 1
<
* change the text for when no branch is detected >
  let g:airline#extensions#branch#empty_message = ''
<
                                                         *airline-syntastic*
syntastic <https://github.com/scrooloose/syntastic>

* enable/disable syntastic integration >
  let g:airline#extensions#syntastic#enabled = 1
<
                                                            *airline-tagbar*
tagbar <https://github.com/majutsushi/>

* enable/disable tagbar integration >
  let g:airline#extensions#tagbar#enabled = 1
<
                                                               *airline-csv*
csv.vim <https://github.com/chrisbra/csv.vim>

* enable/disable csv integration for displaying the current column. >
  let g:airline#extensions#csv#enabled = 1
<
* change how columns are displayed. >
  let g:airline#extensions#csv#column_display = 'Number' (default)
  let g:airline#extensions#csv#column_display = 'Name'
<
                                                             *airline-hunks*
vim-gitgutter <https://github.com/airblade/vim-gitgutter>

* enable/disable detecting changed hunks under source control. >
  let g:airline#extensions#hunks#enabled = 1
<
* enable/disable showing only non-zero hunks. >
  let g:airline#extensions#hunks#non_zero_only = 0
<
* set hunk count symbols. >
  let g:airline#extensions#hunks#hunk_symbols = ['+', '~', '-']
<
                                                        *airline-whitespace*
* enable/disable detection of whitespace errors. >
  let g:airline#extensions#whitespace#enabled = 1
<
* customize the whitespace symbol. >
  let g:airline#extensions#whitespace#symbol = '!'
<
* configure which whitespace checks to enable. >
  let g:airline#extensions#whitespace#checks = [ 'indent', 'trailing' ]
<
* configure whether a message should be displayed. >
  let g:airline#extensions#whitespace#show_message = 1
<

==============================================================================
FUNCREFS                                                  *airline-funcrefs*

vim-airline internally uses funcrefs to integrate with third party plugins,
and you can tap into this functionality to extend it for you needs.

                                             *g:airline_statusline_funcrefs*
The g:airline_statusline_funcrefs variable is an array of funcrefs that get
invoked before the statusline gets overwritten for each window.  The following
is an example of how you can extend vim-airline to support a new plugin.
>
  function! MyPlugin()
    if &filetype == 'MyPluginFileType'
      let w:airline_section_a = 'MyPlugin'
      let w:airline_section_b = '%f'
      let w:airline_section_c = '%{MyPlugin#function()}'
      let g:airline_variable_referenced_in_statusline = 'foo'
    endif
  endfunction
  call add(g:airline_statusline_funcrefs, function('MyPlugin'))
<
                                                *g:airline_exclude_funcrefs*
The g:airline_exclude_funcrefs variable is an array that's returns 1 or 0 to
determine whether that particular window should be excluded from having its
statusline modified.  Here is an example:
>
  function! ExcludeFoo()
    return &filetype == 'FooType'
  endfunction
  call add(g:airline_exclude_funcrefs, function('ExcludeFoo'))
<

==============================================================================
WRITING EXTENSIONS                              *airline-writing-extensions*

The basic idea is that the statusline is rendered with a series of overrides.
For each section that the algorithm encounters, it will first check to see if
there is a window-local variable of the section.  If it exists, the value will
be used, otherwise, the global variable of the section will be used.  This
means it is possible to override only one or two sections of the statusline.
See |g:airline_statusline_funcrefs| for an example of a simple extension.

For contributions into the plugin, here are the following guidelines:

1.  For simple |&filetype| checks, they can be added directly into the
`extensions.vim` file.

2.  Pretty much everything else should live as a separate file under the
`extensions/` directory.

  a.  Inside `extensions.vim`, add a check for some variable or command that
      is always available (these must be defined in `plugin`, and _not_
      `autoload` of the other plugin).  If it exists, then initialize the
      extension. This ensures that the extension is loaded if and only if the
      user has the other plugin installed.

  b.  Extension specific variables should be defined in the extension, e.g.
      `g:airline#extensions#foo_plugin#bar_variable`.  Unfortunately, the
      branch extension does not follow this convention, but for legacy reasons
      those variables are kept as is.

See the source of |example.vim| for a working extension.

==============================================================================
WRITING THEMES                                              *airline-themes*

Themes are written "close to the metal" -- you will need to know some basic
VimL syntax to write a theme, but if you've written in any programming
language before it will be easy to pick up.

The |dark.vim| theme fully documents this procedure and will guide you through
the process.  The |jellybeans.vim| theme is another example of how to write a
theme, but instead of manually declaring colors, it extracts the values from
highlight groups.

==============================================================================
TROUBLESHOOTING                                    *airline-troubleshooting*

Q. There are no colors.
A. You need to set up your terminal correctly.  For more details, see
   <http://vim.wikia.com/wiki/256_colors_in_vim>.  Alternatively, if you want
   to bypass the automatic detection of terminal colors, you can force Vim
   into 256 color mode with this: >
  set t_Co=256
<
Q. The statusline does not appear until I create a split.
A. This is the default setting of |laststatus|.  If you want it to appear all
   the time, add the following to your vimrc: >
  set laststatus=2
<
Q. Powerline symbols are not showing up.
A. First, you must install patched powerline fonts. Second, you must enable
   unicode in vim.  >
  set encoding=utf-8
<
Q. There is a pause when leaving insert mode.
A. Add the following to your vimrc.  >
  set ttimeoutlen=50
<
Q. The colors look a little off for some themes.
A. Certain themes are derived from the active colorscheme by extracting colors
   from predefined highlight groups.  These airline themes will look good for
   their intended matching colorschemes, but will be hit or miss when loaded
   with other colorschemes.


Solutions to other common problems can be found in the Wiki:
<https://github.com/bling/vim-airline/wiki/FAQ>

==============================================================================
CONTRIBUTIONS                                        *airline-contributions*

Contributions and pull requests are welcome.

==============================================================================
LICENSE                                                    *airline-license*

MIT License.  Copyright © 2013 Bailey Ling.


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