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 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=
<
* if you want to patch the airline theme before it gets applied, you can
  supply the name of a function where you can modify the palette. >
  let g:airline_theme_patch_func = 'AirlineThemePatch'
  function! AirlineThemePatch(palette)
    if g:airline_theme == 'badwolf'
      for colors in values(a:palette.inactive)
        let colors[3] = 245
      endfor
    endif
  endfunction
<
* 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*
  Toggles between the standard `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#fragments#symbols.paste = 'ρ'
  let g:airline#fragments#symbols.paste = 'Þ'
  let g:airline#fragments#symbols.paste = '∥'
  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#extensions#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#extensions#readonly#symbol = '⭤'
  let g:airline_linecolumn_prefix = '⭡'
<

For more intricate customizations, you can replace the predefined sections
with the usual statusline syntax.

Note: 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  (readonly, csv)
  let g:airline_section_x       (tagbar, virtualenv, 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*

Most extensions are enabled by default and lazily loaded when the
corresponding plugin (if any) is detected.

                                                           *airline-default*
The default extension understands all of the `g:` variables in the
|airline-configuration| section, however it also has some more fine-tuned
configuration values that you can use.

* control which sections get truncated and at what width. >
  let g:airline#extensions#default#section_truncate_width = {
      \ 'b': 90,
      \ 'y': 90,
      \ })
<
                                                            *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>
vim-signify <https://github.com/mhinz/vim-signify>

* enable/disable showing a summary of 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
<
* configure the formatting of the warning messages. >
  let g:airline#extensions#whitespace#trailing_format = 'trailing[%s]'
  let g:airline#extensions#whitespace#mixed_indent_format = 'mixed-indent[%s]'
<
                                                             *airline-ctrlp*
ctrlp <https://github.com/kien/ctrlp.vim>

* configure which mode colors should ctrlp window use (takes effect
  only if the active airline theme doesn't define ctrlp colors) >
  let g:airline#extensions#ctrlp#color_template = 'insert' (default)
  let g:airline#extensions#ctrlp#color_template = 'normal'
  let g:airline#extensions#ctrlp#color_template = 'visual'
  let g:airline#extensions#ctrlp#color_template = 'replace'
<
                                                        *airline-virtualenv*

virtualenv <https://github.com/jmcantrell/vim-virtualenv>

* enable/disable virtualenv integration >
  let g:airline#extensions#virtualenv#enabled = 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.

                                                       *add_statusline_func*
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 airline#add_statusline_func('MyPlugin')
<
                                                    *remove_statusline_func*
You can also remove a function as well, which is useful for when you want a
temporary override. >
  call airline#remove_statusline_func('MyPlugin')
<

==============================================================================
PIPELINE                                                  *airline-pipeline*

Sometimes you want to do more than just use overrides.  The statusline funcref
is invoked and passed a bunch of arguments.  The first of these arguments is
the statusline builder.  You can use this to build completely custom
statuslines to your liking.  Here is an example: >
>
  function! MyPlugin(...)
    " first variable is the statusline builder
    let builder = a:1

    " build and set the statusline
    " WARNING: the API for the builder is not finalized and may change
    call builder.add_section('Normal', '%f')
    call builder.add_section('WarningMsg', '%{getcwd()}')
    call setwinvar(winnr(), '&statusline', builder.build())

    return -1
  endfunction
<
The second variable is the context, which is a dictionary containing various
values such as whether the statusline is active or not, and the window number.
>
  context = {
    'winnr': 'the window number for the statusline',
    'active': 'whether the window is active or not',
  }
<

                                             *airline-pipeline-return-codes*
The pipeline accepts various return codes and can be used to determine the
next action.  The following are the supported codes: >
   0   the default, continue on with the next funcref
  -1   do not modify the statusline
   1   modify the statusline with the current contents of the builder
<
Note: Any value other than 0 will halt the pipeline and prevent the next
funcref from executing.

==============================================================================
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 |add_statusline_func| 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.  Also, a check to
      `airline#extensions#foo_plugin#enabled` should be performed to allow the
      user to disable it.

  b.  Configuration variables for the extension should reside in the
      extension, e.g. `g:airline#extensions#foo_plugin#bar_variable`.

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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