Kakoune
=======

Introduction:
-------------

Kakoune is a code editor heavily inspired by vim, as such most of it's
commands are similar to vi's ones.

Kakoune can operate in two modes, normal and insertion. In insertion mode,
keys are directly inserted into the current buffer. In normal mode, keys
are used to manipulate the current selection and to enter insertion mode.

There is no concept of cursor in kakoune, only selections, a single character
selection can be seen as a cursor but there is no difference internally.

Building
--------

Kakoune dependencies are:

 * GCC >= 4.7
 * boost
 * ncurses

To build, just type *make* in the src directory

Basic Movement
--------------

 * _space_: select the character under selection end

 * _h_: select the character on the right of selection end
 * _j_: select the character below the selection end
 * _k_: select the character above the selection end
 * _l_: select the character on the left of selection end

 * _w_: select the word and following whitespaces  on the right of selection end
 * _b_: select preceding whitespaces and the word on the left of selection end
 * _e_: select preceding whitespaces and the word on the right of selection end

 * _x_: select line on which selection end lies (or next line when end lies on
        an end-of-line)
 * _alt-x_: expand selections to contain full lines (including end-of-lines)

 * _%_: select whole buffer

 * _gh_, _alt-H_: select to line begin
 * _gl_, _alt-L_: select to line end

 * _gg_, _gt_: go to the first line
 * _gb_: go to the last line

Appending
---------

for most selection commands, using shift permits to add to current selection
instead of replacing it. for example, _wWW_ selects 3 consecutive words

Using Counts
------------

Most selection commands also support counts, which are entered before the
command itself.

for example, _3W_ selects 3 consecutive words and _3w_ select the third word on
the right of selection end.

 * _space_: when used with count, keep only the counth selection
 * _alt-space_: when used with count, remove the counth selection

Changes
-------

 * _i_: insert before current selection
 * _a_: insert after current selection
 * _d_: yank and delete current selection
 * _c_: yank and delete current selection and insert

 * _I_: insert at current selection begin line start
 * _A_: insert at current selection end line end
 * _o_: insert in a new line below current selection end
 * _O_: insert in a new line above current selection begin

 * _p_: paste after current selection end
 * _P_: paste before current selection begin

 * _alt-j_: join selected lines

 * _|_: pipe each selections through the given external filter program
        and replace with it's output.

Multi Selection
---------------

Kak was designed from the start to handle multiple selections.
On way to get a multiselection is via the _s_ key.

For example, to change all occurences of word 'roger' to word 'marcel'
in a paragraph, here is what can be done:

select the paragraph with enough _x_. press _s_ and enter roger then enter.
now paragraph selection was replaced with multiselection of each roger in
the paragraph. press _c_ and marcel<esc> to replace rogers with marcels.

A multiselection can also be obtained with _Alt-s_, which splits the current
selection according to the regex entered. To split a comma separated list,
use _alt-s_ then ', *'

To clear multiple selections, use _space_. To keep only the nth selection
use _n_ followed by _space_.

Object Selection
----------------

Using alt-i and alt-a, you can select some text object, the starting
point is always the last character of the selection.

 * _b_, _(_ or _)_: select the enclosing parenthesis
 * _B_, _{_ or _}_: select the enclosing {} block
 * _[_ or _]_: select the enclosing [] block
 * _<_ or _>_: select the enclosing <> block
 * w: select the whole word
 * W: select the whole WORD

When it makes sense, _alt-i_ selects the inner object and alt-a the whole
object. For example _alt-i_ ( will only select the inside of the parenthesis,
for words, the difference between _alt-i_ and _alt-a_ is that _alt-a_ also
selects the following blanks.

Registers
---------

registers are named list of text. They are used for various purpose, like
storing the last yanked test, or the captures groups associated with the
last selection.

While in insert mode, ctrl-r followed by a register name (one character)
inserts it.

For example, ctrl-r followed by " will insert the currently yanked text.
ctrl-r followed by 2 will insert the second capture group from the last regex
selection.

Registers are lists, instead of simply text in order to interact well with
multiselection. Each selection have it's own captures, or yank buffer.

Basic Commands
--------------

Commands are entered using *:*.

 * e[dit] <filename> [<line> [<column>]]: open buffer on file, go to given
     line and column. If file is already opened, just switch to this file.
     use edit! to force reloading.
 * w[rite] [<filename>]: write buffer to <filename> or use it's name if
      filename is not given.
 * q[uit]: exit Kakoune, use quit! to force quitting even if there is some
      unsaved buffers remaining.
 * wq: write current buffer and quit
 * b[uffer] <name>: switch to buffer <name>
 * d[el]b[uf] [<name>]: delete the buffer <name>
 * source <filename>: execute commands in <filename>
 * runtime <filename>: execute commands in <filename>, <filename>
      is relative to kak executable path.
 * exec <keys>: execute <keys> as if pressed in normal mode.
 * echo <text>: show <text> in status line
 * set[bwg] <option> <value>: set <option> to <value> in *b*uffer, *w*indow
      or *g*lobal scope.

String syntax
-------------

When entering a command, parameters are separated by whitespace (shell like),
if you want to give parameters with spaces, you should quote them.

Kakoune support three string syntax:

 * "strings" and 'strings': classic strings, use \' or \" to escape the
                            separator.

 * %{strings}: these strings are very usefull when entering commands, first the '{' and '}'
               delimiter is configurable: you can use any non alphanumeric character.
               like %[string], %<string>, %(string), %~string~ or %!string!...
               if the character following the % is one of {[(<, then the closing one is
               the matching }])>, and these delimiters in the string need not to be
               escaped if the contained delimiters are balanced.
               for example %{ roger {}; } is a valid string.

Highlighters
------------

Manipulation of the displayed text is done through highlighters, which can be added
or removed with the command :addhl <highlighter_name> <highlighter_parameters...>
and :rmhl <highlighter_id>

existing highlighters are:

 * *highlight_selections*: used to make current selection visible
 * *expand_tabs*: expand tabs to next 8 multiple column (to make configurable)
 * *number_lines*: show line numbers
 * *group*: highlighter group, containing other highlighters. takes one
            parameter, <group_name>. useful when multiple highlighters work
            together and need to be removed as one. Adding and removing from
            a group can be done using
            :addhl -group <group> <highlighter_name> <highlighter_parameters...>
            :rmhl  -group <group> <highlighter_name>
 * *regex*: highlight a regex, takes the regex as first parameter, followed by
            any number of color spec parameters.
            color spec format is: <capture_id>:<fg_color>[,<bg_color>]
            For example:
            :addhl regex //(\h+TODO:)?[^\n]+ 0:cyan 1:yellow,red
            will highlight C++ style comments in cyan, with an eventual
            'TODO:' in yellow on red background.

Filters
-------

Filters can be installed to interact with buffer modifications. They can be
added or removed with :addfilter <filter_name> <filter_parameters...> and
:rmfilter <filter_id>

exisiting filters are:

 * *preserve_indent*: insert previous line indent when inserting a newline
 * *cleanup_whitespaces*: remove trailing whitespaces on the previous line
                          when inserting an end-of-line.
 * *expand_tabulations*: insert spaces instead of tab characters
 * *group*: same as highlighters group

Hooks
-----

commands can be registred to be executed when certain events arise.
to register a hook, use the hook command.

:hook <scope> <hook_name> <filtering_regex> <commands>

<scope> can be either global, buffer or window, the scope are hierarchical,
meaning that a Window calling a hook will execute it's own, the buffer ones
and the global ones.

<command> is a string containing the commands to execute when the hook is
called.

for example, to automatically use line numbering with .cc files,
use the following command:

:hook global WinCreate .*\.cc %{ addhl number_lines }

Shell expansion
---------------

A special string syntax is supported which replace it's content with the
output of the shell commands in it, it is similar to the shell $(...)
syntax and is evaluated only when needed.
for example: %sh{ ls } is replaced with the output of the ls command.

Some of kakoune state is available through environment variables:

 * *kak_selection*: content of the last selection
 * *kak_bufname*: name of the current buffer
 * *kak_runtime*: directory containing the kak binary
 * *kak_opt_name*: value of option name
 * *kak_reg_x*: value of register x

for example you can print informations on the current file in the status
line using:
:echo %sh{ ls -l $kak_bufname }

Register and Option expansion
-----------------------------

Similar to shell expansion, register contents and options values can be
accessed through %reg{<register>} and %opt{<option>} syntax.

for example you can display last search pattern with
:echo %reg{/}

Defining Commands
-----------------

new commands can be defined using the *def* command.

:def <command_name> <commands>

<commands> is a string containing the commands to execute

def can also takes some flags:
 * *-env-params*: pass parameters given to commands in the environement as
                  kak_paramN with N the parameter number
 * *-shell-params*: pass parameters given to commands as positional parameters
                    to any shell expansions used in the command.
 * *-shell-completion*: following string is a shell command which takes
                        parameters as positional params and output one
                        completion candidate per line.
 * *-allow-override*: allow the new command to replace an exisiting one
                      with the same name.

Using shell expansion permits to define complex commands or to access
kakoune state:

:def print_selection %{ echo %sh{ ${kak_selection} } }

Some helper commands can be used to define composite commands:

 * menu <label1> <commands1> <label2> <commands2>...: display a menu using
     labels, the selected label's commands are executed.
 * try <commands> catch <on_error_commands>: prevent an error in <commands>
     from aborting the whole commands execution, execute <on_error_commands>
     instead.

Note that these commands are available in interactive command mode, but are
not that useful in this context.

FIFO Buffer
-----------

the *edit* command can take a -fifo parameter:
:edit -fifo <filename> <buffername>
in this case, a buffer named <buffername> is created which reads its content
from <filename>. When filename is appended to, the buffer is automatically
updated.
This is very useful for running some commands asynchronously while displaying
their result in a buffer. See rc/make.kak and rc/grep.kak for examples.