doomemacs/modules/tools/tree-sitter/README.org

#+TITLE:   tools/tree-sitter
#+DATE:    August 17, 2021
#+SINCE:   3.0.0
#+STARTUP: inlineimages nofold

* Table of Contents :TOC_3:noexport:
- [[#description][Description]]
  - [[#maintainers][Maintainers]]
  - [[#module-flags][Module Flags]]
  - [[#plugins][Plugins]]
- [[#prerequisites][Prerequisites]]
- [[#features][Features]]
  - [[#language-support][Language support]]
  - [[#text-objects][Text Objects]]
  - [[#goto-certain-nodes][Goto certain nodes]]
- [[#configuration][Configuration]]
  - [[#rebinding-text-objects][Rebinding text objects]]
  - [[#adding-your-own-text-objects][Adding your own text objects]]
  - [[#disabling-highlighting-for-certain-modes][Disabling highlighting for certain modes]]
- [[#troubleshooting][Troubleshooting]]
  - [[#error-bad-bounding-indices-0-1][=(error "Bad bounding indices: 0, 1")=]]

* Description

This module adds [[https://tree-sitter.github.io/tree-sitter/][tree-sitter]] support to Doom:

#+begin_quote
Tree sitter is a parser generator tool and an incremental parsing library. It
can build a concrete syntax tree for a source file and efficiently update the
syntax tree as the source file is edited. This allows for features of the editor
to become syntax aware.
#+end_quote

It includes:

+ Better syntax highlighting of supported languages.
+ Structural text objects to manipulate functions statements and other code
  structures like any other text object.

** Maintainers

+ @jeetelongname

** Module Flags

This module provides no flags.

** Plugins

+ [[https://github.com/emacs-tree-sitter/elisp-tree-sitter][tree-sitter]]
+ [[https://github.com/emacs-tree-sitter/tree-sitter-langs][tree-sitter-langs]]
+ [[https://github.com/meain/evil-textobj-tree-sitter][evil-textobj-tree-sitter]]* (=:editor evil +everywhere=)

* Prerequisites

This module has no prerequisites. 

* Features
** Language support

Currently Emacs tree sitter has [[https://github.com/emacs-tree-sitter/tree-sitter-langs/tree/master/repos][parsers for these languages]], and syntax
highlighting support for [[https://github.com/emacs-tree-sitter/tree-sitter-langs/tree/master/queries][these languages]] as well as ~typescript-tsx-mode~.

To enable tree sitter for individual languages, add the =+tree-sitter= flag. Check
the module readme of your language for support.

** Text Objects

Not all languages support all text objects (yet). [[https://github.com/nvim-treesitter/nvim-treesitter-textobjects#built-in-textobjects][Here is a table of the text
object languages support]].

Note: Only languages with parsers in Emacs have text object support currently.
Currently text objects are bound to:

| key | text object         |
|-----+---------------------|
| =A=   | parameter list      |
| =f=   | function definition |
| =F=   | function call       |
| =C=   | class               |
| =c=   | comment             |
| =v=   | conditional         |
| =l=   | loop                |

They are used in a container context (not =vf= but =vaf= or =vif=)

** Goto certain nodes

You can also jump to the next / previous node type in a buffer by using =[g= or =]g=
respectfully, the following key will correspond to the text object you want to
jump to.

Currently keys are bound to:

| key | text object    |
|-----+----------------|
| =a=   | parameter list |
| =f=   | function       |
| =F=   | function call  |
| =c=   | comment        |
| =C=   | class          |
| =v=   | conditional    |
| =l=   | loop           |

* Configuration
** Rebinding text objects

Rebinding keys is the same as any other key, but do note that they need to be
bound to the keymaps ~+tree-sitter-inner-text-object-map~ or
~+tree-sitter-outer-text-object-map~.

#+begin_src emacs-lisp
(map! (:map +tree-sitter-outer-text-objects-map
       "f" nil
       "f" (evil-textobj-tree-sitter-get-textobj "call.inner")
       "F" nil
       "F" (evil-textobj-tree-sitter-get-textobj "function.inner"))
      (:map +tree-sitter-inner-text-objects-map
       "f" nil
       "f" (evil-textobj-tree-sitter-get-textobj "call.inner")
       "F" nil
       "F" (evil-textobj-tree-sitter-get-textobj "function.inner")))
#+end_src

** Adding your own text objects
If you wish to [[https://github.com/meain/evil-textobj-tree-sitter#custom-textobjects][add your own custom text objects]] then you need to bind them to
~+tree-sitter-{inner, outer}-text-objects-map~. For example:

#+begin_src emacs-lisp
(map! (:map +tree-sitter-outer-text-objects-map
       "m" (evil-textobj-tree-sitter-get-textobj "import"
             '((python-mode . [(import_statement) @import])
               (rust-mode . [(use_declaration) @import])))))
#+end_src

** Disabling highlighting for certain modes

If you want to disable highlighting by default you can do:

#+begin_src emacs-lisp
(after! MODE-PACKAGE
  (tree-sitter-hl-mode -1))
#+end_src

If you only want it for certain modes, then:

#+begin_src emacs-lisp
(remove-hook 'tree-sitter-after-on-hook #'tree-sitter-hl-mode)

(add-hook 'MAJOR-MODE-HOOK #'tree-sitter-hl-mode)
#+end_src

* Troubleshooting
** =(error "Bad bounding indices: 0, 1")=

This means that the text object does not have the underlying query needed. This
can be fixed by either adding in a custom query (which would override the
current key bound) or [[https://github.com/nvim-treesitter/nvim-treesitter-textobjects/][contributing upstream!]]