--- /dev/null
+;;; lua-ts-mode.el --- Major mode for editing Lua files -*- lexical-binding: t -*-
+
+;; Copyright (C) 2023 Free Software Foundation, Inc.
+
+;; Author: John Muhl <jm@pub.pink>
+;; Created: June 27, 2023
+;; Keywords: lua languages tree-sitter
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs 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.
+;;
+;; GNU Emacs 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 GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This package provides `lua-ts-mode' which is a major mode for Lua
+;; files that uses Tree Sitter to parse the language.
+;;
+;; This package is compatible with and tested against the grammar
+;; for Lua found at https://github.com/MunifTanjim/tree-sitter-lua
+
+;;; Code:
+
+(require 'comint)
+(require 'treesit)
+
+(eval-when-compile
+ (require 'cl-lib)
+ (require 'rx))
+
+(declare-function treesit-node-child-by-field-name "treesit.c")
+(declare-function treesit-node-type "treesit.c")
+(declare-function treesit-parser-create "treesit.c")
+(declare-function treesit-search-subtree "treesit.c")
+
+(defgroup lua-ts nil
+ "Major mode for editing Lua files."
+ :prefix "lua-ts-"
+ :group 'languages)
+
+(defcustom lua-ts-indent-offset 4
+ "Number of spaces for each indentation step in `lua-ts-mode'."
+ :type 'natnum
+ :safe 'natnump
+ :group 'lua-ts
+ :version "30.1")
+
+(defcustom lua-ts-luacheck-program "luacheck"
+ "Location of the Luacheck program."
+ :type '(choice (const nil) string)
+ :group 'lua-ts
+ :version "30.1")
+
+(defcustom lua-ts-inferior-buffer "*Lua*"
+ "Name of the inferior Lua buffer."
+ :type 'string
+ :safe 'stringp
+ :group 'lua-ts
+ :version "30.1")
+
+(defcustom lua-ts-inferior-program "lua"
+ "Program to run in the inferior Lua process."
+ :type '(choice (const nil) string)
+ :group 'lua-ts
+ :version "30.1")
+
+(defcustom lua-ts-inferior-options '("-i")
+ "Command line options for the inferior Lua process."
+ :type '(repeat string)
+ :group 'lua-ts
+ :version "30.1")
+
+(defcustom lua-ts-inferior-startfile nil
+ "File to load into the inferior Lua process at startup."
+ :type '(choice (const nil) (file :must-match t))
+ :group 'lua-ts
+ :version "30.1")
+
+(defcustom lua-ts-inferior-prompt-regexp "^>>?[[:blank:]]"
+ "Regular expression matching the prompt of the inferior Lua process."
+ :type 'regexp
+ :group 'lua-ts
+ :version "30.1")
+
+(defvar lua-ts--builtins
+ '("assert" "bit32" "collectgarbage" "coroutine" "debug" "dofile"
+ "error" "getmetatable" "io" "ipairs" "load" "loadfile"
+ "math" "next" "os" "package" "pairs" "pcall" "print"
+ "rawequal" "rawget" "rawlen" "rawset" "require" "select"
+ "setmetatable" "string" "table" "tonumber" "tostring"
+ "type" "utf8" "warn" "xpcall" "_G" "_VERSION"
+ ;; methods for file handlers
+ "close" "flush" "lines" "read" "seek" "setvbuf" "write")
+ "Lua built-in functions for tree-sitter font-locking.")
+
+(defvar lua-ts--font-lock-settings
+ (treesit-font-lock-rules
+ :language 'lua
+ :feature 'bracket
+ '(["(" ")" "[" "]" "{" "}"] @font-lock-bracket-face)
+
+ :language 'lua
+ :feature 'delimiter
+ '(["," ";"] @font-lock-delimiter-face)
+
+ :language 'lua
+ :feature 'escape
+ '((escape_sequence) @font-lock-escape-face)
+
+ :language 'lua
+ :feature 'constant
+ '((variable_list
+ attribute: (attribute (["<" ">"] (identifier))))
+ @font-lock-constant-face)
+
+ :language 'lua
+ :feature 'operator
+ '(["and" "not" "or" "+" "-" "*" "/" "%" "^"
+ "#" "==" "~=" "<=" ">=" "<" ">" "=" "&"
+ "~" "|" "<<" ">>" "//" ".."]
+ @font-lock-operator-face
+ (vararg_expression) @font-lock-operator-face)
+
+ :language 'lua
+ :feature 'property
+ '((field name: (identifier) @font-lock-property-name-face)
+ (dot_index_expression
+ field: (identifier) @font-lock-property-use-face))
+
+ :language 'lua
+ :feature 'builtin
+ `(((identifier) @font-lock-builtin-face
+ (:match ,(regexp-opt lua-ts--builtins 'symbols)
+ @font-lock-builtin-face)))
+
+ :language 'lua
+ :feature 'function
+ '((function_call name: (identifier) @font-lock-function-call-face)
+ (function_call
+ name: (method_index_expression
+ method: (identifier) @font-lock-function-call-face))
+ (function_call
+ name: (dot_index_expression
+ table: (identifier) @font-lock-function-call-face)))
+
+ :language 'lua
+ :feature 'punctuation
+ '(["." ":"] @font-lock-punctuation-face)
+
+ :language 'lua
+ :feature 'variable
+ '((function_call
+ arguments: (arguments (identifier))
+ @font-lock-variable-use-face)
+ (function_call
+ name: (method_index_expression
+ table: (identifier) @font-lock-variable-use-face))
+ (goto_statement (identifier) @font-lock-variable-use-face))
+
+ :language 'lua
+ :feature 'assignment
+ '((variable_list (identifier) @font-lock-variable-name-face))
+
+ :language 'lua
+ :feature 'number
+ '((number) @font-lock-number-face)
+
+ :language 'lua
+ :feature 'keyword
+ '((break_statement) @font-lock-keyword-face
+ (true) @font-lock-constant-face
+ (false) @font-lock-constant-face
+ (nil) @font-lock-constant-face
+ ["and" "do" "else" "elseif" "end" "for" "function"
+ "goto" "if" "in" "local" "not" "or" "repeat"
+ "return" "then" "until" "while"]
+ @font-lock-keyword-face)
+
+ :language 'lua
+ :feature 'string
+ '((string) @font-lock-string-face)
+
+ :language 'lua
+ :feature 'comment
+ '((comment) @font-lock-comment-face
+ (hash_bang_line) @font-lock-comment-face)
+
+ :language 'lua
+ :feature 'definition
+ '((function_declaration
+ name: (identifier) @font-lock-function-name-face)
+ (parameters
+ name: (identifier) @font-lock-variable-name-face)
+ (label_statement) @font-lock-variable-name-face)
+
+ :language 'lua
+ :feature 'error
+ :override t
+ '((ERROR) @font-lock-warning-face))
+ "Tree-sitter font-lock settings for `lua-ts-mode'.")
+
+(defvar lua-ts--simple-indent-rules
+ `((lua
+ ((parent-is "chunk") column-0 0)
+ ((node-is "comment_end") column-0 0)
+ ((parent-is "block") parent-bol 0)
+ ((node-is "}") parent-bol 0)
+ ((node-is ")") parent-bol 0)
+ ((node-is "else_statement") parent-bol 0)
+ ((node-is "elseif_statement") parent-bol 0)
+ ((node-is "end") parent-bol 0)
+ ((node-is "until") parent-bol 0)
+ ((parent-is "for_statement") parent-bol lua-ts-indent-offset)
+ ((parent-is "function_declaration") parent-bol lua-ts-indent-offset)
+ ((parent-is "function_definition") parent-bol lua-ts-indent-offset)
+ ((parent-is "if_statement") parent-bol lua-ts-indent-offset)
+ ((parent-is "else_statement") parent-bol lua-ts-indent-offset)
+ ((parent-is "repeat_statement") parent-bol lua-ts-indent-offset)
+ ((parent-is "while_statement") parent-bol lua-ts-indent-offset)
+ ((parent-is "table_constructor") parent-bol lua-ts-indent-offset)
+ ((parent-is "arguments") parent-bol lua-ts-indent-offset)
+ ((parent-is "parameters") parent-bol lua-ts-indent-offset)
+ ((parent-is "ERROR") no-indent 0))))
+
+(defvar lua-ts--syntax-table
+ (let ((table (make-syntax-table)))
+ (modify-syntax-entry ?+ "." table)
+ (modify-syntax-entry ?- ". 12" 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 ?\n ">" table)
+ (modify-syntax-entry ?\' "\"" table)
+ (modify-syntax-entry ?\" "\"" table)
+ table)
+ "Syntax table for `lua-ts-mode'.")
+
+(defun lua-ts--defun-name-function (node)
+ "Return the defun name of NODE.
+Return nil if there is no name or if NODE is not a defun node."
+ (let ((child (treesit-node-child-by-field-name node "name")))
+ (pcase (treesit-node-type node)
+ ((or "function_declaration" "function_definition")
+ (treesit-node-text child t))
+ ("variable_declaration"
+ (if child
+ (treesit-node-text child t)
+ (treesit-node-text
+ (treesit-node-child-by-field-name
+ (treesit-search-subtree node "assignment_statement" nil nil 1)
+ "name"))))
+ ("field"
+ (and (treesit-search-subtree node "function_definition" nil nil 1)
+ (treesit-node-text child t))))))
+
+(defvar-local lua-ts--flymake-process nil)
+
+(defun lua-ts-flymake-luacheck (report-fn &rest _args)
+ "Luacheck backend for Flymake.
+Calls REPORT-FN directly."
+ (when (process-live-p lua-ts--flymake-process)
+ (kill-process lua-ts--flymake-process))
+ (let ((source (current-buffer)))
+ (save-restriction
+ (widen)
+ (setq lua-ts--flymake-process
+ (make-process
+ :name "lua-ts-flymake-luacheck"
+ :noquery t
+ :connection-type 'pipe
+ :buffer (generate-new-buffer " *lua-ts-flymake-luacheck*")
+ :command `(,lua-ts-luacheck-program
+ "--codes" "--ranges" "--formatter" "plain" "-")
+ :sentinel
+ (lambda (proc _event)
+ (when (eq 'exit (process-status proc))
+ (unwind-protect
+ (if (with-current-buffer source
+ (eq proc lua-ts--flymake-process))
+ (with-current-buffer (process-buffer proc)
+ (goto-char (point-min))
+ (cl-loop
+ while (search-forward-regexp
+ (rx (seq bol
+ (0+ alnum) ":"
+ (group (1+ digit)) ":"
+ (group (1+ digit)) "-"
+ (group (1+ digit)) ": "
+ (group (0+ nonl))
+ eol))
+ nil t)
+ for line = (string-to-number (match-string 1))
+ for beg = (string-to-number (match-string 2))
+ for end = (string-to-number (match-string 3))
+ for msg = (match-string 4)
+ for type = (if (string-match "^(W" msg)
+ :warning
+ :error)
+ when (and beg end)
+ collect (flymake-make-diagnostic source
+ (cons line beg)
+ (cons line (1+ end))
+ type
+ msg)
+ into diags
+ finally (funcall report-fn diags)))
+ (flymake-log :warning "Canceling obsolete check %s" proc))
+ (kill-buffer (process-buffer proc)))))))
+ (process-send-region lua-ts--flymake-process (point-min) (point-max))
+ (process-send-eof lua-ts--flymake-process))))
+
+;;;###autoload
+(defun lua-ts-inferior-lua ()
+ "Run a Lua interpreter in an inferior process."
+ (interactive)
+ (let* ((buffer lua-ts-inferior-buffer)
+ (name (string-replace "*" "" buffer))
+ (program lua-ts-inferior-program)
+ (prompt-regexp lua-ts-inferior-prompt-regexp)
+ (switches lua-ts-inferior-options)
+ (startfile lua-ts-inferior-startfile))
+ (unless (comint-check-proc buffer)
+ (set-buffer (apply (function make-comint) name program startfile switches))
+ (setq-local comint-input-ignoredups t
+ comint-prompt-read-only t
+ comint-prompt-regexp prompt-regexp
+ comint-use-prompt-regexp t))
+ (select-window (display-buffer buffer '((display-buffer-reuse-window
+ display-buffer-pop-up-frame)
+ (reusable-frames . t))))))
+
+;;;###autoload
+(define-derived-mode lua-ts-mode prog-mode "Lua"
+ "Major mode for editing Lua files, powered by tree-sitter."
+ :syntax-table lua-ts--syntax-table
+
+ (when (treesit-ready-p 'lua)
+ (treesit-parser-create 'lua)
+
+ ;; Comments.
+ (setq-local comment-start "--")
+ (setq-local comment-start-skip "--\\s-*")
+ (setq-local comment-end "")
+
+ ;; Font-lock.
+ (setq-local treesit-font-lock-settings lua-ts--font-lock-settings)
+ (setq-local treesit-font-lock-feature-list
+ '((comment definition)
+ (keyword property string)
+ (assignment builtin constant number)
+ (bracket
+ delimiter
+ escape
+ function
+ operator
+ punctuation
+ variable)))
+
+ ;; Indent.
+ (setq-local treesit-simple-indent-rules lua-ts--simple-indent-rules)
+
+ ;; Navigation.
+ (setq-local treesit-defun-name-function #'lua-ts--defun-name-function)
+ (setq-local treesit-defun-type-regexp
+ (rx (or "function_declaration" "function_definition")))
+ (setq-local treesit-thing-settings
+ `((lua
+ (sentence ,(rx (or "do_statement"
+ "field"
+ "for_statement"
+ "function_call"
+ "if_statement"
+ "repeat_statement"
+ "return_statement"
+ "variable_declaration"
+ "while_statement")))
+ (sexp ,(rx (or "arguments"
+ "block"
+ "parameters"
+ "string"
+ "table_constructor")))
+ (text "comment"))))
+
+ ;; Imenu.
+ (setq-local treesit-simple-imenu-settings
+ `(("Variable" ,(rx bos "variable_declaration" eos) nil nil)
+ ("Function" ,(rx bos
+ (or "function_declaration"
+ "function_definition"
+ "field")
+ eos)
+ nil nil)))
+
+ ;; Which-function.
+ (setq-local which-func-functions (treesit-defun-at-point))
+
+ ;; Outline.
+ (setq-local outline-regexp
+ (rx (seq (0+ space)
+ (or (seq "--[[" (0+ space) eol)
+ (seq symbol-start
+ (or "do" "for" "if" "repeat" "while"
+ (seq (? (seq "local" (1+ space)))
+ "function"))
+ symbol-end)))))
+
+ (treesit-major-mode-setup))
+
+ (add-hook 'flymake-diagnostic-functions #'lua-ts-flymake-luacheck nil 'local))
+
+(when (treesit-ready-p 'lua)
+ (add-to-list 'auto-mode-alist '("\\.lua\\'" . lua-ts-mode)))
+
+(provide 'lua-ts-mode)
+
+;;; lua-ts-mode.el ends here
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