= Structural selections for Kakoune

kak-tree is a plugin for Kakoune which enables selection of syntax tree nodes. Parsing is performed with https://github.com/tree-sitter/tree-sitter[tree-sitter].

Status: proof of concept, interface and overall development direction could change drastically based on feedback.

== Installation

Replace `"rust javascript"` with a list of languages you need. Or use `all` to build all supported
languages. Note that `all` build takes a long time, and resulting binary is quite fat which could
have a negative impact on responsiveness.

----
git clone --recurse-submodules
cargo install --path . --force --features "rust javascript"
cp rc/tree.kak ~/.config/kak/autoload/
----

Look at `Cargo.toml` for a full list of supported languages.

It is possible to check programmaticaly if kak-tree was built with support for a given filetype:

----
kak-tree --do-you-understand rust
----

If language is supported then exit code is 0 otherwise it's non-zero (1 at the moment, but it is not
guaranteed in future).

== Usage

Tree-sitter parsers produce very detailed syntax tree, many elements of which are not interesting
for day-to-day selection purposes. kak-tree introduces the concept of a _visible_ node. Node is
_visible_ when:

. Node is named in the tree-sitter grammar for the given language (as opposed to anonymous nodes,
http://tree-sitter.github.io/tree-sitter/using-parsers#named-vs-anonymous-nodes[more]).
. Either there is no white/blacklist for the given filetype or node kind is whitelisted or not
blacklisted. See <<Configuration>> for details about white/blacklisting.

Most of the kak-tree commands operate on _visible_ nodes and skip not _visible_ ones.

[cols=2*]
|===

| tree-select-parent-node [<KIND>]
| Select the closest visible ancestor or ancestor of KIND when provided.

| tree-select-next-node [<KIND>]
| Select the closest visible next sibling or next sibling of KIND when provided.

| tree-select-previous-node [<KIND>]
| Select the closest visible previous sibling or previous sibling of KIND when provided.

| tree-select-children [<KIND>]
| Select all immediate visible children or all descendants matching KIND when provided.

| tree-select-first-child [<KIND>]
| Select the first immediate visible children or the first descendant matching KIND when provided.

| tree-node-sexp
| Show info box with a syntax tree of the main selection parent.
|===

== Configuration

kak-tree supports configuration via a configuration file. As for now there is no default path to
load the configuration file, and it must be given using CLI option `--config` or `-c` for short:

----
set global tree_cmd 'kak-tree -c /path/to/kak-tree.toml'
----

=== Filetype configuration

Configuration for specific filetypes should be provided like this:

----
[filetype.rust]
blacklist = ["identifier", "scoped_identifier", "string_literal"]
whitelist = ["function_item"]
group.identifier = ["identifier", "scoped_identifier"]
group.fn = ["function_item"]

[filetype.javascript]
group.fn = ["function", "arrow_function"]
----

Configuration under the `[filetype.default]` key will be used for all filetypes without
configuration. Specific filetype configuration _doesn't_ extend default configuration but rather
overwrites it.

==== White/blacklisting

If `whitelist` array is provided then kak-tree selection will skip nodes which kinds are not whitelisted.
If `blacklist` array is provided then kak-tree selection will skip nodes which kinds are blacklisted.

NOTE: `whitelist` takes precedence over `blacklist`. In the Rust example above kak-tree would expand
selection up to the function definition, ignoring other node kinds.

NOTE: `tree-node-sexp` command is useful for exploring node kinds which appear in the specific code.

Whitelisting or blacklisting node kinds could be tedious as tree-sitter parsers define many of them,
but it also could be rewarding as you will be able to quickly modify selection in scopes which
matter for you with fewer keystrokes.

==== Kind groups

Groups of node kinds serve a two-fold purpose:

. Groups allow matching functionally similar node kinds (i.e. `identifier` and `scoped_identifier`
in Rust) by a single query.

. Groups allow matching functionally similar nodes across filetypes (i.e. `function_item` in Rust
and `function` in JavaScript) as tree-sitter parsers don't use uniform node kind names.

NOTE: `whitelist` and `blacklist` options doesn't expand groups yet.

== License

For kak-tree see UNLICENSE file. For tree-sitter and its parsers look at their repositories.