Add TypeScript support with tree-sitter

* lisp/progmodes/ts-mode.el (ts-mode): New major mode for TypeScript
with support for tree-sitter.  It uses the TSX parser, so that we get
support for TSX as well as TypeScript.  If we cannot find tree-sitter,
we default to using js-mode.

2 files changed, 371 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 88b1431d6a6..c5a142b500f 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2775,6 +2775,13 @@ This is a lightweight variant of 'js-mode' that is used by default
 when visiting JSON files.
 
 
+** New mode ts-mode'.
+Support is added for TypeScript, based on the new integration with
+Tree-Sitter. There's support for font-locking, indentation and
+navigation.  Tree-Sitter is required for this mode to function, but if
+it is not available, we will default to use 'js-mode'.
+
+
 * Incompatible Lisp Changes in Emacs 29.1
 
 +++
diff --git a/lisp/progmodes/ts-mode.el b/lisp/progmodes/ts-mode.el
new file mode 100644
index 00000000000..99ffe0c0f63
--- /dev/null
+++ b/lisp/progmodes/ts-mode.el
@@ -0,0 +1,364 @@
+;;; ts-mode.el --- tree sitter support for TypeScript  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2022 Free Software Foundation, Inc.
+
+;; Author     : Theodor Thornhill <theo@thornhill.no>
+;; Maintainer : Theodor Thornhill <theo@thornhill.no>
+;; Created    : October 2022
+;; Keywords   : typescript tsx 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/>.
+
+(require 'treesit)
+(require 'rx)
+(require 'js)
+
+(defcustom ts-mode-indent-offset 2
+  "Number of spaces for each indentation step in `ts-mode'."
+  :type 'integer
+  :safe 'integerp
+  :group 'typescript)
+
+(defvar 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 `ts-mode'.")
+
+(defvar ts-mode--indent-rules
+  `((tsx
+     ((node-is "}") parent-bol 0)
+     ((node-is ")") parent-bol 0)
+     ((node-is "]") parent-bol 0)
+     ((node-is ">") parent-bol 0)
+     ((node-is ".")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "ternary_expression")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "named_imports")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "statement_block")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "type_arguments")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "variable_declarator")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "arguments")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "array")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "formal_parameters")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "template_substitution")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "object_pattern")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "object")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "object_type")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "enum_body")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "arrow_function")
+      parent-bol ,ts-mode-indent-offset)
+     ((parent-is "parenthesized_expression")
+      parent-bol ,ts-mode-indent-offset)
+
+     ;; TSX
+     ((parent-is "jsx_opening_element")
+      parent ,ts-mode-indent-offset)
+     ((node-is "jsx_closing_element") parent 0)
+     ((parent-is "jsx_element")
+      parent ,ts-mode-indent-offset)
+     ((node-is "/") parent 0)
+     ((parent-is "jsx_self_closing_element")
+      parent ,ts-mode-indent-offset)
+     (no-node parent-bol 0))))
+
+(defvar ts-mode--settings
+  (treesit-font-lock-rules
+   :language 'tsx
+   :override t
+   '(
+     (template_string) @font-lock-string-face
+
+     ((identifier) @font-lock-constant-face
+      (:match "^[A-Z_][A-Z_\\d]*$" @font-lock-constant-face))
+
+     (nested_type_identifier
+      module: (identifier) @font-lock-type-face)
+     (type_identifier) @font-lock-type-face
+     (predefined_type) @font-lock-type-face
+
+     (new_expression
+      constructor: (identifier) @font-lock-type-face)
+
+     (function
+      name: (identifier) @font-lock-function-name-face)
+
+     (function_declaration
+      name: (identifier) @font-lock-function-name-face)
+
+     (method_definition
+      name: (property_identifier) @font-lock-function-name-face)
+
+     (variable_declarator
+      name: (identifier) @font-lock-function-name-face
+      value: [(function) (arrow_function)])
+
+     (variable_declarator
+      name: (array_pattern
+             (identifier)
+             (identifier) @font-lock-function-name-face)
+      value: (array (number) (function)))
+
+     (assignment_expression
+      left: [(identifier) @font-lock-function-name-face
+             (member_expression
+              property: (property_identifier) @font-lock-function-name-face)]
+      right: [(function) (arrow_function)])
+
+     (call_expression
+      function:
+      [(identifier) @font-lock-function-name-face
+       (member_expression
+        property: (property_identifier) @font-lock-function-name-face)])
+
+     (variable_declarator
+      name: (identifier) @font-lock-variable-name-face)
+
+     (enum_declaration (identifier) @font-lock-type-face)
+
+     (enum_body (property_identifier) @font-lock-type-face)
+
+     (enum_assignment name: (property_identifier) @font-lock-type-face)
+
+     (assignment_expression
+      left: [(identifier) @font-lock-variable-name-face
+             (member_expression
+              property: (property_identifier) @font-lock-variable-name-face)])
+
+     (for_in_statement
+      left: (identifier) @font-lock-variable-name-face)
+
+     (arrow_function
+      parameter: (identifier) @font-lock-variable-name-face)
+
+     (arrow_function
+      parameters:
+      [(_ (identifier) @font-lock-variable-name-face)
+       (_ (_ (identifier) @font-lock-variable-name-face))
+       (_ (_ (_ (identifier) @font-lock-variable-name-face)))])
+
+
+     (pair key: (property_identifier) @font-lock-variable-name-face)
+
+     (pair value: (identifier) @font-lock-variable-name-face)
+
+     (pair
+      key: (property_identifier) @font-lock-function-name-face
+      value: [(function) (arrow_function)])
+
+     (property_signature
+      name: (property_identifier) @font-lock-variable-name-face)
+
+     ((shorthand_property_identifier) @font-lock-variable-name-face)
+
+     (pair_pattern
+      key: (property_identifier) @font-lock-variable-name-face)
+
+     ((shorthand_property_identifier_pattern)
+      @font-lock-variable-name-face)
+
+     (array_pattern (identifier) @font-lock-variable-name-face)
+
+     (jsx_opening_element
+      [(nested_identifier (identifier)) (identifier)]
+      @font-lock-function-name-face)
+
+     (jsx_closing_element
+      [(nested_identifier (identifier)) (identifier)]
+      @font-lock-function-name-face)
+
+     (jsx_self_closing_element
+      [(nested_identifier (identifier)) (identifier)]
+      @font-lock-function-name-face)
+
+     (jsx_attribute (property_identifier) @font-lock-constant-face)
+
+     [(this) (super)] @font-lock-keyword-face
+
+     [(true) (false) (null)] @font-lock-constant-face
+     (regex pattern: (regex_pattern)) @font-lock-string-face
+     (number) @font-lock-constant-face
+
+     (string) @font-lock-string-face
+     (template_string) @font-lock-string-face
+
+     (template_substitution
+      ["${" "}"] @font-lock-constant-face)
+
+     ["!"
+      "abstract"
+      "as"
+      "async"
+      "await"
+      "break"
+      "case"
+      "catch"
+      "class"
+      "const"
+      "continue"
+      "debugger"
+      "declare"
+      "default"
+      "delete"
+      "do"
+      "else"
+      "enum"
+      "export"
+      "extends"
+      "finally"
+      "for"
+      "from"
+      "function"
+      "get"
+      "if"
+      "implements"
+      "import"
+      "in"
+      "instanceof"
+      "interface"
+      "keyof"
+      "let"
+      "namespace"
+      "new"
+      "of"
+      "private"
+      "protected"
+      "public"
+      "readonly"
+      "return"
+      "set"
+      "static"
+      "switch"
+      "target"
+      "throw"
+      "try"
+      "type"
+      "typeof"
+      "var"
+      "void"
+      "while"
+      "with"
+      "yield"
+      ] @font-lock-keyword-face
+
+     (comment) @font-lock-comment-face
+     )))
+
+(defvar ts-mode--defun-type-regexp
+  (rx (or "class_declaration"
+          "method_definition"
+          "function_declaration"
+          "lexical_declaration"))
+  "Regular expression that matches type of defun nodes.
+Used in `ts-mode--beginning-of-defun' and friends.")
+
+(defun ts-mode--beginning-of-defun (&optional arg)
+  "Tree-sitter `beginning-of-defun' function.
+ARG is the same as in `beginning-of-defun."
+  (let ((arg (or arg 1)))
+    (if (> arg 0)
+        ;; Go backward.
+        (while (and (> arg 0)
+                    (treesit-search-forward-goto
+                     ts-mode--defun-type-regexp 'start nil t))
+          (setq arg (1- arg)))
+      ;; Go forward.
+      (while (and (< arg 0)
+                  (treesit-search-forward-goto
+                   ts-mode--defun-type-regexp 'start))
+        (setq arg (1+ arg))))))
+
+(defun ts-mode--end-of-defun (&optional arg)
+  "Tree-sitter `end-of-defun' function.
+ARG is the same as in `end-of-defun."
+  (let ((arg (or arg 1)))
+    (if (< arg 0)
+        ;; Go backward.
+        (while (and (< arg 0)
+                    (treesit-search-forward-goto
+                     ts-mode--defun-type-regexp 'end nil t))
+          (setq arg (1+ arg)))
+      ;; Go forward.
+      (while (and (> arg 0)
+                  (treesit-search-forward-goto
+                   ts-mode--defun-type-regexp 'end))
+        (setq arg (1- arg))))))
+
+;;;###autoload
+(add-to-list 'auto-mode-alist '("\\.ts\\'" . ts-mode))
+
+;;;###autoload
+(add-to-list 'auto-mode-alist '("\\.tsx\\'" . ts-mode))
+
+;;;###autoload
+(define-derived-mode ts-mode prog-mode "TypeScript"
+  "Major mode for editing TypeScript."
+  :group 'typescript
+  :syntax-table ts-mode--syntax-table
+
+  (cond
+   ((and (treesit-can-enable-p)
+         (treesit-language-available-p 'tsx))
+    ;; Comments
+    (setq-local comment-start "// ")
+    (setq-local comment-start-skip "\\(?://+\\|/\\*+\\)\\s *")
+    (setq-local comment-end "")
+
+    (setq-local treesit-simple-indent-rules ts-mode--indent-rules)
+    (setq-local indent-line-function #'treesit-indent)
+
+    (setq-local beginning-of-defun-function #'ts-mode--beginning-of-defun)
+    (setq-local end-of-defun-function #'ts-mode--end-of-defun)
+
+    (unless font-lock-defaults
+      (setq font-lock-defaults '(nil t)))
+
+    (setq-local treesit-font-lock-settings ts-mode--settings)
+
+    (treesit-font-lock-enable))
+   (t
+    (message "Tree sitter for TypeScript isn't available, defaulting to js-mode")
+    (js-mode))))
+
+(provide 'ts-mode)
+
+;;; ts-mode.el ends here