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]]
  - [[#disable-text-objects-for-certain-modes][Disable text objects for certain modes]]
  - [[#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")=]]
  - [[#no-textobj-text-object-found][=No 'TEXTOBJ' text object found=]]

* 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 got [[https://github.com/emacs-tree-sitter/tree-sitter-langs/tree/master/repos][parsers for these languages]] with syntax
highlighting support for [[https://emacs-tree-sitter.github.io/syntax-highlighting/][these languages]] as well as ~typescript-tsx-mode~

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

* Configuration
** Disable text objects for certain modes
If you wish to disable tree sitter text objects then you can just remove
=+tree-sitter-keys-mode= from the language mode hook, for example if we did not
want it for ruby we would use this snippet
#+begin_src emacs-lisp
(remove-hook! 'ruby-mode-hook #'+tree-sitter-keys-mode)
#+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 and
add them to the ~+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 add a 
#+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!]]

** =No 'TEXTOBJ' text object found=
the main reason for this is the underlying text object using the =#make-range!=
predicate, which at the moment [[https://github.com/emacs-tree-sitter/elisp-tree-sitter/issues/180][is not implemented in emacs tree sitter]] (see this
issue on [[https://github.com/meain/evil-textobj-tree-sitter/issues/33][evil-textobj-tree-sitter]]).

the only way around it is to rewrite the query to not use =#make-range!= or to
implement that predicate the elisp tree sitter core