--- /dev/null
+;;; rust-ts-mode.el --- tree-sitter support for Rust -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2022 Free Software Foundation, Inc.
+
+;; Author : Randy Taylor <dev@rjt.dev>
+;; Maintainer : Randy Taylor <dev@rjt.dev>
+;; Created : December 2022
+;; Keywords : rust 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:
+;;
+
+;;; Code:
+
+(require 'treesit)
+(eval-when-compile (require 'rx))
+
+(declare-function treesit-parser-create "treesit.c")
+(declare-function treesit-induce-sparse-tree "treesit.c")
+(declare-function treesit-node-child "treesit.c")
+(declare-function treesit-node-child-by-field-name "treesit.c")
+(declare-function treesit-node-start "treesit.c")
+(declare-function treesit-node-type "treesit.c")
+
+(defcustom rust-ts-mode-indent-offset 4
+ "Number of spaces for each indentation step in `rust-ts-mode'."
+ :version "29.1"
+ :type 'integer
+ :safe 'integerp
+ :group 'rust)
+
+(defvar rust-ts-mode--syntax-table
+ (let ((table (make-syntax-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 ?> "." table)
+ (modify-syntax-entry ?/ ". 124b" table)
+ (modify-syntax-entry ?* ". 23" table)
+ (modify-syntax-entry ?\n "> b" table)
+ (modify-syntax-entry ?\^m "> b" table)
+ table)
+ "Syntax table for `rust-ts-mode'.")
+
+(defvar rust-ts-mode--indent-rules
+ `((rust
+ ((node-is ")") parent-bol 0)
+ ((node-is "]") parent-bol 0)
+ ((node-is "}") (and parent parent-bol) 0)
+ ((parent-is "arguments") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "await_expression") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "array_expression") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "binary_expression") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "block") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "declaration_list") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "enum_variant_list") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "field_declaration_list") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "field_expression") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "field_initializer_list") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "let_declaration") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "macro_definition") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "parameters") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "token_tree") parent-bol rust-ts-mode-indent-offset)
+ ((parent-is "use_list") parent-bol rust-ts-mode-indent-offset)))
+ "Tree-sitter indent rules for `rust-ts-mode'.")
+
+(defvar rust-ts-mode--builtin-macros
+ '("concat_bytes" "concat_idents" "const_format_args"
+ "format_args_nl" "log_syntax" "trace_macros" "assert" "assert_eq"
+ "assert_ne" "cfg" "column" "compile_error" "concat" "dbg"
+ "debug_assert" "debug_assert_eq" "debug_assert_ne" "env" "eprint"
+ "eprintln" "file" "format" "format_args" "include" "include_bytes"
+ "include_str" "is_x86_feature_detected" "line" "matches"
+ "module_path" "option_env" "panic" "print" "println" "stringify"
+ "thread_local" "todo" "try" "unimplemented" "unreachable" "vec"
+ "write" "writeln")
+ "Rust built-in macros for tree-sitter font-locking.")
+
+(defvar rust-ts-mode--keywords
+ '("as" "async" "await" "break" "const" "continue" "dyn" "else"
+ "enum" "extern" "fn" "for" "if" "impl" "in" "let" "loop" "match"
+ "mod" "move" "pub" "ref" "return" "static" "struct" "trait" "type"
+ "union" "unsafe" "use" "where" "while" (crate) (self) (super)
+ (mutable_specifier))
+ "Rust keywords for tree-sitter font-locking.")
+
+(defvar rust-ts-mode--operators
+ '("!" "!=" "%" "%=" "&" "&=" "&&" "*" "*=" "+" "+=" "," "-" "-="
+ "->" "." ".." "..=" "..." "/" "/=" ":" ";" "<<" "<<=" "<" "<="
+ "=" "==" "=>" ">" ">=" ">>" ">>=" "@" "^" "^=" "|" "|=" "||" "?")
+ "Rust operators for tree-sitter font-locking.")
+
+(defvar rust-ts-mode--font-lock-settings
+ (treesit-font-lock-rules
+ :language 'rust
+ :feature 'attribute
+ '((attribute_item) @font-lock-constant-face
+ (inner_attribute_item) @font-lock-constant-face)
+
+ :language 'rust
+ :feature 'bracket
+ '((["(" ")" "[" "]" "{" "}"]) @font-lock-bracket-face)
+
+ :language 'rust
+ :feature 'builtin
+ `((macro_invocation
+ macro: ((identifier) @font-lock-builtin-face
+ (:match ,(rx-to-string
+ `(seq bol
+ (or ,@rust-ts-mode--builtin-macros)
+ eol))
+ @font-lock-builtin-face)))
+ ((identifier) @font-lock-type-face
+ (:match "^\\(:?Err\\|Ok\\|None\\|Some\\)$" @font-lock-type-face)))
+
+ :language 'rust
+ :feature 'comment
+ '(([(block_comment) (line_comment)]) @font-lock-comment-face)
+
+ :language 'rust
+ :feature 'constant
+ `((boolean_literal) @font-lock-constant-face
+ ((identifier) @font-lock-constant-face
+ (:match "^[A-Z][A-Z\\d_]*$" @font-lock-constant-face)))
+
+ :language 'rust
+ :feature 'delimiter
+ '((["," "." ";" ":" "::"]) @font-lock-delimiter-face)
+
+ :language 'rust
+ :feature 'function
+ '((call_expression
+ function:
+ [(identifier) @font-lock-function-name-face
+ (field_expression
+ field: (field_identifier) @font-lock-function-name-face)
+ (scoped_identifier
+ name: (identifier) @font-lock-function-name-face)])
+ (function_item (identifier) @font-lock-function-name-face)
+ (generic_function
+ function: [(identifier) @font-lock-function-name-face
+ (field_expression
+ field: (field_identifier) @font-lock-function-name-face)
+ (scoped_identifier
+ name: (identifier) @font-lock-function-name-face)])
+ (macro_definition "macro_rules!" @font-lock-constant-face)
+ (macro_definition (identifier) @font-lock-preprocessor-face)
+ (macro_invocation macro: (identifier) @font-lock-preprocessor-face))
+
+ :language 'rust
+ :feature 'keyword
+ `([,@rust-ts-mode--keywords] @font-lock-keyword-face)
+
+ :language 'rust
+ :feature 'number
+ '([(float_literal) (integer_literal)] @font-lock-number-face)
+
+ :language 'rust
+ :feature 'operator
+ `([,@rust-ts-mode--operators] @font-lock-operator-face)
+
+ :language 'rust
+ :feature 'string
+ '([(char_literal)
+ (raw_string_literal)
+ (string_literal)] @font-lock-string-face)
+
+ :language 'rust
+ :feature 'type
+ `((call_expression
+ function: (scoped_identifier
+ path: (identifier) @font-lock-type-face))
+ (enum_variant name: (identifier) @font-lock-type-face)
+ (match_arm
+ pattern: (match_pattern (_ type: (identifier) @font-lock-type-face)))
+ (match_arm
+ pattern: (match_pattern
+ (_ type: (scoped_identifier
+ path: (identifier) @font-lock-type-face))))
+ (mod_item name: (identifier) @font-lock-constant-face)
+ (primitive_type) @font-lock-type-face
+ (type_identifier) @font-lock-type-face
+ (scoped_identifier name: (identifier) @font-lock-type-face)
+ (scoped_identifier path: (identifier) @font-lock-constant-face)
+ (scoped_identifier
+ (scoped_identifier
+ path: (identifier) @font-lock-constant-face))
+ ((scoped_identifier
+ path: [(identifier) @font-lock-type-face
+ (scoped_identifier
+ name: (identifier) @font-lock-type-face)])
+ (:match "^[A-Z]" @font-lock-type-face))
+ (scoped_type_identifier path: (identifier) @font-lock-constant-face)
+ (scoped_use_list
+ path: [(identifier) @font-lock-constant-face
+ (scoped_identifier (identifier) @font-lock-constant-face)])
+ (type_identifier) @font-lock-type-face
+ (use_as_clause alias: (identifier) @font-lock-type-face)
+ (use_list (identifier) @font-lock-type-face))
+
+ :language 'rust
+ :feature 'variable
+ '((identifier) @font-lock-variable-name-face
+ ;; Everything in a token_tree is an identifier.
+ (token_tree (identifier) @default))
+
+ :language 'rust
+ :feature 'escape-sequence
+ :override t
+ '((escape_sequence) @font-lock-escape-face)
+
+ :language 'rust
+ :feature 'property
+ :override t
+ '((field_identifier) @font-lock-property-face
+ (shorthand_field_initializer (identifier) @font-lock-property-face))
+
+ :language 'rust
+ :feature 'error
+ :override t
+ '((ERROR) @font-lock-warning-face))
+ "Tree-sitter font-lock settings for `rust-ts-mode'.")
+
+(defun rust-ts-mode--imenu ()
+ "Return Imenu alist for the current buffer."
+ (let* ((node (treesit-buffer-root-node))
+ (enum-tree (treesit-induce-sparse-tree
+ node "enum_item" nil))
+ (enum-index (rust-ts-mode--imenu-1 enum-tree))
+ (func-tree (treesit-induce-sparse-tree
+ node "function_item" nil))
+ (func-index (rust-ts-mode--imenu-1 func-tree))
+ (impl-tree (treesit-induce-sparse-tree
+ node "impl_item" nil))
+ (impl-index (rust-ts-mode--imenu-1 impl-tree))
+ (mod-tree (treesit-induce-sparse-tree
+ node "mod_item" nil))
+ (mod-index (rust-ts-mode--imenu-1 mod-tree))
+ (struct-tree (treesit-induce-sparse-tree
+ node "struct_item" nil))
+ (struct-index (rust-ts-mode--imenu-1 struct-tree))
+ (type-tree (treesit-induce-sparse-tree
+ node "type_item" nil))
+ (type-index (rust-ts-mode--imenu-1 type-tree)))
+ (append
+ (when mod-index `(("Module" . ,mod-index)))
+ (when enum-index `(("Enum" . ,enum-index)))
+ (when impl-index `(("Impl" . ,impl-index)))
+ (when type-index `(("Type" . ,type-index)))
+ (when struct-index `(("Struct" . ,struct-index)))
+ (when func-index `(("Fn" . ,func-index))))))
+
+(defun rust-ts-mode--imenu-1 (node)
+ "Helper for `rust-ts-mode--imenu'.
+Find string representation for NODE and set marker, then recurse
+the subtrees."
+ (let* ((ts-node (car node))
+ (children (cdr node))
+ (subtrees (mapcan #'rust-ts-mode--imenu-1
+ children))
+ (name (when ts-node
+ (pcase (treesit-node-type ts-node)
+ ("enum_item"
+ (treesit-node-text
+ (treesit-node-child-by-field-name ts-node "name") t))
+ ("function_item"
+ (treesit-node-text
+ (treesit-node-child-by-field-name ts-node "name") t))
+ ("impl_item"
+ (let ((trait-node (treesit-node-child-by-field-name ts-node "trait")))
+ (concat
+ (treesit-node-text
+ trait-node t)
+ (when trait-node
+ " for ")
+ (treesit-node-text
+ (treesit-node-child-by-field-name ts-node "type") t))))
+ ("mod_item"
+ (treesit-node-text
+ (treesit-node-child-by-field-name ts-node "name") t))
+ ("struct_item"
+ (treesit-node-text
+ (treesit-node-child-by-field-name ts-node "name") t))
+ ("type_item"
+ (treesit-node-text
+ (treesit-node-child-by-field-name ts-node "name") t)))))
+ (marker (when ts-node
+ (set-marker (make-marker)
+ (treesit-node-start ts-node)))))
+ (cond
+ ((or (null ts-node) (null name)) subtrees)
+ (subtrees
+ `((,name ,(cons name marker) ,@subtrees)))
+ (t
+ `((,name . ,marker))))))
+
+;;;###autoload
+(add-to-list 'auto-mode-alist '("\\.rs\\'" . rust-ts-mode))
+
+;;;###autoload
+(define-derived-mode rust-ts-mode prog-mode "Rust"
+ "Major mode for editing Rust, powered by tree-sitter."
+ :group 'rust
+ :syntax-table rust-ts-mode--syntax-table
+
+ (when (treesit-ready-p 'rust)
+ (treesit-parser-create 'rust)
+
+ ;; Comments.
+ (setq-local comment-start "// ")
+ (setq-local comment-end "")
+ (setq-local comment-start-skip (rx (or (seq "/" (+ "/"))
+ (seq "/" (+ "*")))
+ (* (syntax whitespace))))
+ (setq-local comment-end-skip
+ (rx (* (syntax whitespace))
+ (group (or (syntax comment-end)
+ (seq (+ "*") "/")))))
+
+ ;; Font-lock.
+ (setq-local treesit-font-lock-settings rust-ts-mode--font-lock-settings)
+ (setq-local treesit-font-lock-feature-list
+ '(( comment)
+ ( keyword string)
+ ( attribute builtin constant escape-sequence
+ function number property type variable)
+ ( bracket delimiter error operator)))
+
+ ;; Imenu.
+ (setq-local imenu-create-index-function #'rust-ts-mode--imenu)
+ (setq-local which-func-functions nil)
+
+ ;; Indent.
+ (setq-local indent-tabs-mode nil
+ treesit-simple-indent-rules rust-ts-mode--indent-rules)
+
+ ;; Navigation.
+ (setq-local treesit-defun-type-regexp
+ (regexp-opt '("enum_item"
+ "function_item"
+ "impl_item"
+ "struct_item")))
+
+ (treesit-major-mode-setup)))
+
+(provide 'rust-ts-mode)
+
+;;; rust-ts-mode.el ends here
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