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| | ;;; json-ts-mode.el --- tree sitter support for JSON -*- lexical-binding: t; -*-
;; Copyright (C) 2022 Free Software Foundation, Inc.
;; Author : Theodor Thornhill <theo@thornhill.no>
;; Maintainer : Theodor Thornhill <theo@thornhill.no>
;; Created : November 2022
;; Keywords : json languages tree-sitter
;; This file is part of GNU Emacs.
;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;;; Code:
(require 'treesit)
(require 'rx)
(defcustom json-ts-mode-indent-offset 2
"Number of spaces for each indentation step in `json-ts-mode'."
:type 'integer
:safe 'integerp
:group 'json)
(defvar json-ts-mode--syntax-table
(let ((table (make-syntax-table)))
;; Taken from the cc-langs version
(modify-syntax-entry ?_ "_" table)
(modify-syntax-entry ?$ "_" table)
(modify-syntax-entry ?\\ "\\" table)
(modify-syntax-entry ?+ "." table)
(modify-syntax-entry ?- "." table)
(modify-syntax-entry ?= "." table)
(modify-syntax-entry ?% "." table)
(modify-syntax-entry ?< "." table)
(modify-syntax-entry ?> "." table)
(modify-syntax-entry ?& "." table)
(modify-syntax-entry ?| "." table)
(modify-syntax-entry ?` "\"" table)
(modify-syntax-entry ?\240 "." table)
table)
"Syntax table for `json-ts-mode'.")
(defvar json-ts--indent-rules
`((json
((node-is "}") parent-bol 0)
((node-is ")") parent-bol 0)
((node-is "]") parent-bol 0)
((parent-is "object") parent-bol json-ts-mode-indent-offset))))
(defvar json-ts-mode--font-lock-settings
(treesit-font-lock-rules
:language 'json
:feature 'minimal
:override t
`((pair
key: (_) @font-lock-string-face)
(string) @font-lock-string-face
(number) @font-lock-constant-face
[(null) (true) (false)] @font-lock-constant-face
(escape_sequence) @font-lock-constant-face
(comment) @font-lock-comment-face))
"Font-lock settings for JSON.")
(defun json-ts-mode--imenu-1 (node)
"Helper for `json-ts-mode--imenu'.
Find string representation for NODE and set marker, then recurse
the subtrees."
(let* ((ts-node (car node))
(subtrees (mapcan #'json-ts-mode--imenu-1 (cdr node)))
(name (when ts-node
(treesit-node-text
(treesit-node-child-by-field-name
ts-node "key")
t)))
(marker (when ts-node
(set-marker (make-marker)
(treesit-node-start ts-node)))))
(cond
((null ts-node) subtrees)
(subtrees
`((,name ,(cons name marker) ,@subtrees)))
(t
`((,name . ,marker))))))
(defun json-ts-mode--imenu ()
"Return Imenu alist for the current buffer."
(let* ((node (treesit-buffer-root-node))
(tree (treesit-induce-sparse-tree
node "pair")))
(json-ts-mode--imenu-1 tree)))
;;;###autoload
(define-derived-mode json-ts-mode prog-mode "JSON"
"Major mode for editing JSON, powered by Tree Sitter."
:group 'json
:syntax-table json-ts-mode--syntax-table
(unless (treesit-ready-p nil 'json)
(error "Tree Sitter for JSON isn't available"))
(treesit-parser-create 'json)
;; Comments.
(setq-local comment-start "// ")
(setq-local comment-start-skip "\\(?://+\\|/\\*+\\)\\s *")
(setq-local comment-end "")
;; Indent.
(setq-local treesit-simple-indent-rules json-ts--indent-rules)
;; Navigation.
(setq-local treesit-defun-type-regexp
(rx (or "pair" "object")))
;; Font-lock.
(setq-local treesit-font-lock-settings json-ts-mode--font-lock-settings)
(setq-local treesit-font-lock-feature-list
'((minimal) () ()))
;; Imenu.
(setq-local imenu-create-index-function #'json-ts-mode--imenu)
(setq-local which-func-functions nil) ;; Piggyback on imenu
(treesit-major-mode-setup))
(provide 'json-ts-mode)
;;; json-ts-mode.el ends here
|