evil-textobj-tree-sitter

Tree-sitter powered textobjects for evil mode in Emacs.

This is an Emacs port of nvim-treesitter/nvim-treesitter-textobjects.

This package will let you create evil textobjects using tree-sitter grammars. You can easily create function,class,comment etc textobjects in multiple languages.

Installation & Usage

You can install evil-textobj-tree-sitter from melpa. Here is how you would do it using use-package and package.el:

(use-package evil-textobj-tree-sitter :ensure t)

Or you can use straight.el:

(use-package evil-textobj-tree-sitter :straight t)

Or using straight.el and el-get to pull from source:

(use-package evil-textobj-tree-sitter
  :straight (evil-textobj-tree-sitter :type git
                      :host github
                      :repo "meain/evil-textobj-tree-sitter"
                      :files (:defaults "queries")))

You will also have to setup tree-sitter.

Mapping textobjects

By default, the library does not provide any keybindings, but it should be relatively easy to add them.

;; bind `function.outer`(entire function block) to `f` for use in things like `vaf`, `yaf`
(define-key evil-outer-text-objects-map "f" (evil-textobj-tree-sitter-get-textobj "function.outer"))
;; bind `function.inner`(function block without name and args) to `f` for use in things like `vif`, `yif`
(define-key evil-inner-text-objects-map "f" (evil-textobj-tree-sitter-get-textobj "function.inner"))

;; You can also bind multiple items and we will match the first one we can find
(define-key evil-outer-text-objects-map "a" (evil-textobj-tree-sitter-get-textobj ("conditional.outer" "loop.outer")))

We support quite a few textobjects. You can find a list of available textobjects at nvim-treesitter/nvim-treesitter-textobjects. We might not have support for all of them as emacs-tree-sitter does not yet support all the languages as of now. As for the list of languages that we support you can check the value of evil-textobj-tree-sitter-major-mode-language-alist.

Custom textobjects

If you are not able to find the text object that you are looking for in the builtin list, you can create custom text objects by passing the a custom query with captures.

For example if you want to create text object to select import statements, you can write something like below. You will have to provide the tree-sitter queries for all the languages that you want it to work for

;; The first arguemnt to `evil-textobj-tree-sitter-get-textobj' will be the capture group to use
;; and the second arg will be an alist mapping major-mode to the corresponding query to use.
(define-key evil-outer-text-objects-map "m" (evil-textobj-tree-sitter-get-textobj "import"
                                              '((python-mode . [(import_statement) @import])
                                                (rust-mode . [(use_declaration) @import]))))

Goto

We have also added support for for a fancier version of goto-char. You can use this to go to the next function, previous class or do any motions like that.

You can use the evil-textobj-tree-sitter-goto-textobj function to invoke goto. You can either use this in other function or just bound to a key. The first argument is the textobj that you want to use, the second one specifies if you want to search forward or backward and the last one is for specifying wheather to go to the start or end of the textobj.

Below are some sample binding that you can do. You can use any textobj that is available here.

;; Goto start of next function
(define-key evil-normal-state-map (kbd "]f") (lambda ()
                                                  (interactive)
                                                  (evil-textobj-tree-sitter-goto-textobj "function.outer")))
;; Goto start of previous function
(define-key evil-normal-state-map (kbd "[f") (lambda ()
                                                  (interactive)
                                                  (evil-textobj-tree-sitter-goto-textobj "function.outer" t)))
;; Goto end of next function
(define-key evil-normal-state-map (kbd "]F") (lambda ()
                                                  (interactive)
                                                  (evil-textobj-tree-sitter-goto-textobj "function.outer" nil t)))
;; Goto end of previous function
(define-key evil-normal-state-map (kbd "[F") (lambda ()
                                                  (interactive)
                                                  (evil-textobj-tree-sitter-goto-textobj "function.outer" t t)))

Contributing new textobjects

As I have already mentioned, I pull the text objects from nvim-treesitter/nvim-treesitter-textobjects project. This right now automatically happens every friday using a Github Action which will create a new PR on the repo. So if you would like to update/add the builtin tree-sitter objects, feel free to update them in the neovim project repository. Unless there is something Emacs specific I recommend everyone to just submit the new queries to that project.

If you are adding a completely new language, there is two other things that you will have to do to make sure everything will work well.

1. Make sure the lang is available in emacs-tree-sitter/tree-sitter-langs
2. Make sure we have a major-mode mapping in evil-textobj-tree-sitter-major-mode-language-alist

License

The primary codebase is licensed under Apache-2.0. The queries have be taken from nvim-treesitter/nvim-treesitter-textobjects which is also licensed under the same license.