Tree sitter support for csharp mode

README.org

@@ -4,8 +4,7 @@
 
 * csharp-mode
 
-This is a mode for editing C# in emacs. It's based on cc-mode, v5.30.3 and above.
-
+This is a mode for editing C# in emacs. It's using [[https://github.com/ubolonton/emacs-tree-sitter][tree-sitter]] for highlighting and indentation.
 ** Main features
 
 - font-lock and indent of C# syntax including:
@@ -17,11 +16,26 @@ This is a mode for editing C# in emacs. It's based on cc-mode, v5.30.3 and above
   - anonymous functions and methods
   - verbatim literal strings (those that begin with @)
   - generics 
-- automagic code-doc generation when you type three slashes.
 - intelligent insertion of matched pairs of curly braces.
-- imenu indexing of C# source, for easy menu-based navigation. 
 - compilation-mode support for msbuild, devenv and xbuild.
 
+** tree-sitter support
+You can enable experimental tree sitter support for indentation and highlighting using
+#+begin_src elisp
+  (use-package tree-sitter)
+  (use-package tree-sitter-langs)
+
+  (use-package csharp-mode
+    :straight
+    (csharp-mode :type git
+                 :host github
+                 :repo "emacs-csharp/csharp-mode"
+                 :branch "tree-sitter")
+    :config
+    (add-to-list 'auto-mode-alist '("\\.cs\\'" . csharp-tree-sitter-mode)))
+#+end_src
+If you are using this, clearly state so if you find any issues.
+
 ** Usage
 
 This package is currently available on MELPA. Install using ~M-x
@@ -44,10 +58,10 @@ To do so, add the following to your .emacs-file:
   (add-hook 'csharp-mode-hook 'my-csharp-mode-hook)
 #+END_SRC
 
-For further mode-specific customization, ~M-x customize-group RET csharp RET~ will show available settings with documentation. For configuring ~cc-mode~ settings (which csharp-mode derives from) see the [[https://www.gnu.org/software/emacs/manual/html_mono/ccmode.html][cc-mode manual]].
+For further mode-specific customization, ~M-x customize-group RET csharp RET~ will show available settings with documentation.
 
 For more advanced and IDE-like functionality we recommend using csharp-mode together
-with [[https://github.com/OmniSharp/omnisharp-emacs][Omnisharp-Emacs]].
+with [[https://github.com/emacs-lsp/lsp-mode][lsp-mode]] or [[https://github.com/joaotavora/eglot][eglot]]
 
 * Attribution
 

csharp-tree-sitter.el

@@ -0,0 +1,291 @@
+;;; csharp-tree-sitter.el --- tree sitter support for C#  -*- lexical-binding: t; -*-
+
+;; Author     : Theodor Thornhill <theo@thornhill.no>
+;; Maintainer : Jostein Kjønigsen <jostein@gmail.com>
+;;            : Theodor Thornhill <theo@thornhill.no>
+;; Created    : September 2020
+;; Modified   : 2020
+;; Version    : 0.10.0
+;; Keywords   : c# languages oop mode
+;; X-URL      : https://github.com/emacs-csharp/csharp-mode
+;; Package-Requires: ((emacs "26.1") (tree-sitter "0.12.1") (tree-sitter-indent "0.1"))
+
+;; 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/>.
+
+
+;;; Code:
+(require 'cl-lib)
+(require 'seq)
+(require 'tree-sitter)
+(require 'tree-sitter-hl)
+(require 'tree-sitter-indent)
+
+;;; Tree-sitter
+
+(defvar-local csharp-mode-tree-sitter-patterns
+  [ ;; Various constructs
+   (comment) @comment
+   (modifier) @keyword
+   (this_expression) @keyword
+
+   ;; Literals
+   [(real_literal) (integer_literal)] @number
+   (null_literal) @constant
+   (boolean_literal) @constant
+   (character_literal) @string
+
+   ;; Keywords
+   ["using" "namespace" "class" "if" "else" "throw" "new" "for"
+    "return" "await" "struct" "enum" "switch" "case"
+    "default" "typeof" "try" "catch" "finally" "break"
+    "foreach" "in" "yield" "get" "set" "when" "as" "out"
+    "is" "while" "continue" "this" "ref" "goto" "interface"
+    "from" "where" "select"
+    ] @keyword
+
+   ;; Linq
+   (from_clause (identifier) @variable)
+   (group_clause)
+   (order_by_clause)
+   (select_clause (identifier) @variable)
+   (query_continuation (identifier) @variable) @keyword
+
+   ;; String
+   (interpolation (identifier) (interpolation_format_clause) @variable)
+   (interpolation (identifier)* @variable)
+   [(string_literal) (verbatim_string_literal) (interpolated_string_expression)] @string
+
+   ;; Enum
+   (enum_member_declaration (identifier) @variable)
+   (enum_declaration (identifier) @type)
+
+   ;; Interface
+   (interface_declaration
+    name: (identifier) @type)
+
+   ;; Struct
+   (struct_declaration (identifier) @type)
+
+   ;; Namespace
+   (namespace_declaration
+    name: (identifier) @type)
+
+   ;; Class
+   (base_list (identifier) @type)
+   (property_declaration
+    type: (nullable_type) @type
+    name: (identifier) @variable)
+   (property_declaration
+    type: (predefined_type) @type
+    name: (identifier) @variable)
+   (property_declaration
+    type: (identifier) @type
+    name: (identifier) @variable)
+   (class_declaration
+    name: (identifier) @type)
+   (constructor_declaration (identifier) @type)
+
+   ;; Method
+   (method_declaration (identifier) @type (identifier) @function)
+   (method_declaration (predefined_type) @type (identifier) @function)
+   (method_declaration (nullable_type) @type (identifier) @function)
+   (method_declaration (void_keyword) @type (identifier) @function)
+   (method_declaration (generic_name) (identifier) @function)
+
+   ;; Function
+   (local_function_statement (identifier) @type (identifier) @function)
+   (local_function_statement (predefined_type) @type (identifier) @function)
+   (local_function_statement (nullable_type) @type (identifier) @function)
+   (local_function_statement (void_keyword) @type (identifier) @function)
+   (local_function_statement (generic_name) (identifier) @function)
+
+   ;; Parameter
+   (parameter
+    type: (identifier) @type
+    name: (identifier) @variable)
+   (parameter (identifier) @variable)
+
+   ;; Array
+   (array_rank_specifier (identifier) @variable) 
+   (array_type (identifier) @type)
+   (array_creation_expression)
+
+   ;; Attribute
+   (attribute (identifier) @variable (attribute_argument_list))
+   (attribute (identifier) @variable)
+
+   ;; Object init
+   (anonymous_object_creation_expression)
+   (object_creation_expression (identifier) @type)
+   (initializer_expression (identifier) @variable)
+
+   ;; Variable
+   (variable_declaration (identifier) @type)
+   (variable_declarator (identifier) @variable)
+
+   ;; Equals value
+   (equals_value_clause (identifier) @variable)
+
+   ;; Return
+   (return_statement (identifier) @variable)
+   (yield_statement (identifier) @variable)
+
+   ;; Type
+   (type_parameter
+    (identifier) @type)
+   (type_argument_list
+    (identifier) @type)
+   (generic_name
+    (identifier) @type)
+   (implicit_type) @type
+   (predefined_type) @type
+   (nullable_type) @type
+   ["operator"] @type
+
+   ;; Exprs
+   (binary_expression (identifier) @variable (identifier) @variable)
+   (binary_expression (identifier)* @variable)
+   (conditional_expression (identifier) @variable)
+   (prefix_unary_expression (identifier)* @variable)
+   (postfix_unary_expression (identifier)* @variable)
+   (type_of_expression (identifier) @variable)
+   (assignment_expression (identifier) @variable)
+   (cast_expression (identifier) @type)
+
+   ;; Preprocessor
+   (preprocessor_directive) @constant
+   (preprocessor_call (identifier) @string)
+
+   ;; Loop
+   (for_each_statement (identifier) @type (identifier) @variable)
+   (for_each_statement (implicit_type) @type (identifier) @variable)
+   (for_each_statement (predefined_type) @type (identifier) @variable)
+
+   ;; Exception
+   (catch_declaration (identifier) @type (identifier) @variable)
+   (catch_declaration (identifier) @type)
+
+   ;; Switch
+   (switch_statement (identifier) @variable)
+   (switch_expression (identifier) @variable)
+
+   ;; If
+   (if_statement (identifier) @variable)
+
+   ;; Declaration expression
+   (declaration_expression (implicit_type) (identifier) @variable)
+
+   ;; Arrow expression
+   (arrow_expression_clause (identifier) @variable)
+
+   ;; Other
+   (label_name) @variable
+   (qualified_name (identifier) @type)
+   (using_directive (identifier)* @type)
+   (await_expression (identifier)* @function)
+   (invocation_expression (identifier) @function)
+   (element_access_expression (identifier) @variable)
+   (conditional_access_expression (identifier) @variable)
+   (member_binding_expression (identifier) @variable)
+   (member_access_expression (identifier) @function)
+   (name_colon (identifier)* @variable)
+   (name_equals (identifier) @type)
+   (field_declaration)
+   (argument (identifier) @variable)
+   ]
+  "Default patterns for tree-sitter support.")
+
+;;; Tree-sitter indentation
+
+(defgroup csharp-mode-indent nil "Indent lines using Tree-sitter as backend"
+  :group 'tree-sitter)
+
+(defcustom csharp-mode-indent-offset 4
+  "Indent offset for csharp-mode"
+  :type 'integer
+  :group 'csharp)
+
+(defvar csharp-mode-indent-scopes
+  '((indent-all . ;; these nodes are always indented
+                (accessor_declaration
+                 break_statement
+                 arrow_expression_clause
+                 parameter_list
+                 conditional_expression
+                 "."))
+    (indent-rest . ;; if parent node is one of these and node is not first → indent
+                 (
+                  binary_expression
+                  switch_section
+                  ))
+    (indent-body . ;; if parent node is one of these and current node is in middle → indent
+                 (block
+                  anonymous_object_creation_expression
+                  enum_member_declaration_list
+                  initializer_expression
+                  expression_statement
+                  declaration_list
+                  attribute_argument_list
+                  switch_body))
+
+    (paren-indent . ;; if parent node is one of these → indent to paren opener
+                  (parenthesized_expression))
+    (align-char-to . ;; chaining char → node types we move parentwise to find the first chaining char
+                   ())
+    (aligned-siblings . ;; siblings (nodes with same parent) should be aligned to the first child
+                      (parameter))
+
+    (multi-line-text . ;; if node is one of these, then don't modify the indent
+                     ;; this is basically a peaceful way out by saying "this looks like something
+                     ;; that cannot be indented using AST, so best I leave it as-is"
+                     (comment
+                      preprocessor_call
+                      labeled_statement))
+    (outdent . ;; these nodes always outdent (1 shift in opposite direction)
+             (;; "}"
+              case_switch_label
+              ))
+    )
+  "Scopes for indenting in C#.")
+
+;;;###autoload
+(define-derived-mode csharp-tree-sitter-mode prog-mode "C#"
+  "Major mode for editing Csharp code.
+
+Key bindings:
+\\{csharp-mode-map}"
+  :group 'csharp
+
+  (setq csharp-mode-syntax-table nil)
+  (setq csharp-mode-map nil)
+  (setq-local tree-sitter-indent-current-scopes csharp-mode-indent-scopes)
+  (setq-local tree-sitter-indent-offset csharp-mode-indent-offset)
+  (setq-local indent-line-function #'tree-sitter-indent-line)
+
+  ;; https://github.com/ubolonton/emacs-tree-sitter/issues/84
+  (unless font-lock-defaults
+    (setq font-lock-defaults '(nil)))
+  (setq-local tree-sitter-hl-default-patterns csharp-mode-tree-sitter-patterns)
+  ;; Comments
+  (setq-local comment-start "// ")
+  (setq-local comment-end "")
+
+  (tree-sitter-hl-mode))
+
+;;;###autoload
+(add-to-list 'tree-sitter-major-mode-language-alist '(csharp-tree-sitter-mode . c-sharp))
+
+(provide 'csharp-tree-sitter)
+
+;;; csharp-tree-sitter.el ends here

test-files/indentation-tests.cs

@@ -119,7 +119,6 @@ public void Test()
                 PropB = 2
             };
 
-            // Commented out for rework -- Theodor Thornhill
             // yield return new InnerA.InnerB {
             //     PropA = 1,
             //     PropB = 2
@@ -131,7 +130,6 @@ public void Test()
                 May = "Yay"
             };
 
-            // Commented out for rework -- Theodor Thornhill
             // yield return new InnerA.InnerB
             // {
             //     Boo = "Foo",