kakoune/doc/manpages/highlighters.asciidoc

KAKOUNE(1)
==========

NAME
----
highlighters - a

Description
-----------

Manipulation of the displayed text is done through highlighters, which can be added or removed with the following
commands:

-------------------------------------------------------
addhl <highlighter_name> <highlighter_parameters> ...
-------------------------------------------------------

and

-----------------------
*rmhl* <highlighter_id>
-----------------------

*highlighter_id* is a name generated by the highlighter specified with *highlighter_name*, possibly dependent on
the parameters. Use command completion in a prompt on the *rmhl* command to see the existing highlighters ids.

General highlighters
--------------------
*regex* <ex> <capture_id>:<face> ...::
	highlight a regex, takes the regex as first parameter, followed by any number of face parameters. For example:

		addhl regex //(\hTODO:)?[^\n] 0:cyan 1:yellow,red

	will highlight C++ style comments in cyan, with an eventual 'TODO:' in yellow on red background

*dynregex*::
	Similar to regex, but expand (like a command paramater would) the given expression before building a regex from the result

*flag_lines* <flag> <option_name>::
	add a column in front of text, and display the given flag in it for everly line contained in the int-list option named <option_name>

*show_matching*::
	highlight matching char of the character under the selections cursor using MatchingChar face

*number_lines* [options]::
	show line numbers, with the following *options*:

	*-relative*:::
		show line numbers relative to the main cursor line

	*-hlcursor*:::
		highlight the cursor line with a separate face

	*-separator* <separator text>:::
		specify a string to separate the line numbers column with the rest of the buffer (default is '|')

*fill* <face>::
	fill using the given *face*, mostly useful with regions highlighters

Highlighting Groups
-------------------

The group highlighter is a container for other highlighters. You can add a group to the current window using

--------------------
addhl group <name>
--------------------

The *-group* switch of the *addhl* command provides a mean to add highlighters inside this group:

----------------------------------------
addhl -group <name> <type> <params>...
----------------------------------------

Groups can contain other groups, the *-group* switch can be used to define a path as follows:

--------------------------------------------------
addhl -group <name> group <subname>
addhl -group <name>/<subname> <type> <params>...
--------------------------------------------------

Regions highlighters
--------------------

A special highlighter provides a way to segment the buffer into regions, which are to be highlighted differently.

*name*::
	user defined, used to identify the region
*opening*::
	regex that defines the region start text
*closing*::
	regex that defines the region end text
*recurse*::
	regex that defines the text that matches recursively an end token into the region

The *recurse* option is useful for regions that can be nested, for example the following contruct:

----------
%sh{ ... }
----------

accepts nested braces scopes ('{ ... }') so the following string is valid:

----------------------
%sh{ ... { ... } ... }
----------------------

This region can be defined with:

------------------------
shell_expand %sh\{ \} \{
------------------------

Regions are used in the regions highlighter which can take any number of regions.

The following command:

-----------------------------------------------------------------------
addhl regions <name> <region_name1> <opening1> <closing1> <recurse1>
				<region_name2> <opening2> <closing2> <recurse2>...
-----------------------------------------------------------------------

defines multiple regions in which other highlighters can be added as follows:

---------------------------------------
addhl -group <name>/<region_name> ...
---------------------------------------

Regions are matched using the left-most rule: the left-most region opening starts a new region. When a region closes, the closest next opening start another region.

That matches the rule governing most programming language parsing.

Regions also supports a *-default <default_region>* switch to define the default region, when no other region matches the current buffer range.

Most programming languages can then be properly highlighted using a regions highlighter as root:

-----------------------------------------------------------------
addhl regions -default code <lang> \
	string <str_opening> <str_closing> <str_recurse> \
	comment <comment_opening> <comment_closing> <comment_recurse>

addhl -group <lang>/code ...
addhl -group <lang>/string ...
addhl -group <lang>/comment ...
-----------------------------------------------------------------

Shared Highlighters
-------------------

Highlighters are often defined for a specific filetype, and it makes then sense to share the highlighters between all the windows on the same filetypes.

A shared highlighter can be defined with the following command:

--------------------------------
addhl -group /<group_name> ...
--------------------------------

When the group switch values starts with a '/', it references a group in the shared highlighters, rather than the window highlighters.

The common case would be to create a named shared group, and then fill it with highlighters:

------------------------------
addhl -group / group <name>
addhl -group /name regex ...
------------------------------

It can then be referenced in a window using the ref highlighter.

------------------
addhl ref <name>
------------------

The ref can reference any named highlighter in the shared namespace.