# Tree-sitter Grammar for Emacs Lisp crates.io npm A tree-sitter grammar for elisp. Syntax supported: * Atoms (integers, floats, strings, characters, symbols) * Lists (normal syntax `(a b)` and dotted `(a . b)`) * Vectors * Quoting and unquoting (`'`, `#'`, `` ` ``, `,`, `,@`) * Some special read syntax (`$#`, `##`, `#("foo" 1 2 x)`) * Bytecode literals (`#[1 2 3 4]`) * Special forms (`let` etc) * Comments Limitations: * Autoload cookies are treated as plain comments ## Limitations Elisp is a lisp-2 with user-defined macros. A simple parser cannot detect if e.g. `(foo (let ...))` is a function call with a `let` expression argument, or a macro call where `let` means something else. Currently tree-sitter-elisp treats everything as an s-expression. This is accurate, but makes this package less useful for generating a summary of file contents, or for syntax highlighting. Emacs itself has more information that it can use. Emacs will highlight macro calls based on which macros are defined in the current instance. Some elisp packages also offer custom highlighting logic, such as `dash-fontify-mode` in [dash.el](https://github.com/magnars/dash.el). ## Developing Check out the repo, then use `npm` to install dependencies. ``` $ npm install ``` You can then parse your favourite elisp files. ``` $ npm run parse ~/.emacs.d/init.el ``` The grammar itself is in [grammar.js](https://github.com/Wilfred/tree-sitter-elisp/blob/main/grammar.js). You'll need to regenerate the code after editing the grammar. ``` $ npm run generate ``` This project also contains a few tests. ``` $ npm test ``` You can also run this parser against your `.emacs.d` to confirm it can parse everything. ``` $ npm run parse -- '/home/wilfred/.emacs.d/**/*.el' --quiet --stat ``` ## Why? The best place to read and write elisp is of course Emacs. However, there is a growing ecosystem of tools built on top of tree-sitter, such as GitHub. This project should allow them to support emacs lisp too. ## Related Projects [tree-sitter-clojure](https://github.com/sogaiu/tree-sitter-clojure) is another tree-sitter package for the lisp family. It's a useful project to compare with, and [has notes discussing lisp-specific challenges](https://github.com/sogaiu/tree-sitter-clojure/blob/master/doc/scope.md). [language-emacs-lisp](https://github.com/Alhadis/language-emacs-lisp) is a textmate grammar for elisp that's used for Atom and GitHub.