feature/tree-sitter 7bc615fd23 5/6: Tweaks on c-ts-mode fontification rules

[Yuan Fu]

branch: feature/tree-sitter
commit 7bc615fd23c1304f8682f2443db235fbc37bfde9
Author: Yuan Fu <casouri@gmail.com>
Commit: Yuan Fu <casouri@gmail.com>

    Tweaks on c-ts-mode fontification rules
    
    Changes:
    1. Remove some :override flags
    2. Fontify "!" in font-lock-negation-char-face
    3. Use some new faces like font-lock-escape-face and
       font-lock-property-face
    4. Move all type fontification into 'type' feature.  Previously some
       are in 'definition' feature.
    5. Simplify definition feature, and fontify identifiers in definitions
       recursively.
    6. Change 'statement' feature to 'label'
    7. New feature 'assignment'
    8. Remove some rules from 'expression' feature
    
    * lisp/progmodes/c-ts-mode.el (c-ts-mode--font-lock-settings): See
    above.
    (c-ts-mode--fontify-declarator): New function.
    (c-ts-mode): Update feature-list.
---
 lisp/progmodes/c-ts-mode.el | 137 ++++++++++++++++++++++----------------------
 1 file changed, 70 insertions(+), 67 deletions(-)

diff --git a/lisp/progmodes/c-ts-mode.el b/lisp/progmodes/c-ts-mode.el
index d4f25f7845..b951031d81 100644
--- a/lisp/progmodes/c-ts-mode.el
+++ b/lisp/progmodes/c-ts-mode.el
@@ -190,12 +190,11 @@ MODE is either `c' or `cpp'."
 MODE is either `c' or `cpp'."
   (treesit-font-lock-rules
    :language mode
-   :override t
    :feature 'comment
    `((comment) @font-lock-comment-face
      (comment) @contextual)
+
    :language mode
-   :override t
    :feature 'preprocessor
    `((preproc_directive) @font-lock-preprocessor-face
 
@@ -214,40 +213,43 @@ MODE is either `c' or `cpp'."
      (preproc_defined) @font-lock-preprocessor-face
      (preproc_defined (identifier) @font-lock-variable-name-face)
      [,@c-ts-mode--preproc-keywords] @font-lock-preprocessor-face)
+
    :language mode
-   :override t
    :feature 'constant
    `((true) @font-lock-constant-face
      (false) @font-lock-constant-face
      (null) @font-lock-constant-face
      ,@(when (eq mode 'cpp)
          '((this) @font-lock-constant-face)))
+
    :language mode
-   :override t
    :feature 'keyword
    `([,@(c-ts-mode--keywords mode)] @font-lock-keyword-face
      ,@(when (eq mode 'cpp)
          '((auto) @font-lock-keyword-face)))
+
    :language mode
-   :override t
    :feature 'operator
-   `([,@c-ts-mode--operators] @font-lock-builtin-face)
-   :language mode
    :override t
+   `([,@c-ts-mode--operators] @font-lock-operator-face
+     "!" @font-lock-negation-char-face)
+
+   :language mode
    :feature 'string
    `((string_literal) @font-lock-string-face
-     ((string_literal)) @contextual
      (system_lib_string) @font-lock-string-face
-     (escape_sequence) @font-lock-string-face)
+     (escape_sequence) @font-lock-escape-face)
+
    :language mode
-   :override t
    :feature 'literal
    `((number_literal) @font-lock-constant-face
      (char_literal) @font-lock-constant-face)
+
    :language mode
-   :override t
    :feature 'type
    `((primitive_type) @font-lock-type-face
+     (type_identifier) @font-lock-type-face
+     (sized_type_specifier) @font-lock-type-face
      ,@(when (eq mode 'cpp)
          '((type_qualifier) @font-lock-type-face
 
@@ -255,91 +257,92 @@ MODE is either `c' or `cpp'."
             scope: (namespace_identifier) @font-lock-type-face)
 
            (operator_cast) type: (type_identifier) @font-lock-type-face)))
+
    :language mode
-   :override t
    :feature 'definition
+   ;; Highlights identifiers in declarations.
    `((declaration
-      declarator: (identifier) @font-lock-variable-name-face)
-
-     (declaration
-      type: (type_identifier) @font-lock-type-face)
+      declarator: (_) @font-lock-variable-name-face)
 
      (field_declaration
-      declarator: (field_identifier) @font-lock-variable-name-face)
-
-     (field_declaration
-      type: (type_identifier) @font-lock-type-face)
-
-     (parameter_declaration
-      type: (type_identifier) @font-lock-type-face)
+      declarator: (_) @c-ts-mode--fontify-struct-declarator)
 
      (function_definition
-      type: (type_identifier) @font-lock-type-face)
+      declarator: (_) @c-ts-mode--fontify-struct-declarator)
 
-     (function_declarator
-      declarator: (identifier) @font-lock-function-name-face)
-
-     (array_declarator
-      declarator: (identifier) @font-lock-variable-name-face)
-
-     (init_declarator
-      declarator: (identifier) @font-lock-variable-name-face)
-
-     (struct_specifier
-      name: (type_identifier) @font-lock-type-face)
-
-     (sized_type_specifier) @font-lock-type-face
-
-     (enum_specifier
-      name: (type_identifier) @font-lock-type-face)
+     ;; Should we highlight identifiers in the parameter list?
+     ;; (parameter_declaration
+     ;;  declarator: (_) @c-ts-mode--fontify-struct-declarator)
 
      (enumerator
-      name: (identifier) @font-lock-variable-name-face)
-
-     (parameter_declaration
-      type: (_) @font-lock-type-face
-      declarator: (identifier) @font-lock-variable-name-face)
-
-     (pointer_declarator
-      declarator: (identifier) @font-lock-variable-name-face)
+      name: (identifier) @font-lock-variable-name-face))
 
-     (pointer_declarator
-      declarator: (field_identifier) @font-lock-variable-name-face))
    :language mode
-   :override t
-   :feature 'expression
+   :feature 'assignment
+   ;; TODO: Recursively highlight identifiers in parenthesized
+   ;; expressions, see `c-ts-mode--fontify-struct-declarator' for
+   ;; inspiration.
    '((assignment_expression
       left: (identifier) @font-lock-variable-name-face)
+     (assignment_expression
+      left: (field_expression field: (_) @font-lock-property-face))
+     (assignment_expression
+      left: (pointer_expression
+             (identifier) @font-lock-variable-name-face))
+     (assignment_expression
+      left: (subscript_expression
+             (identifier) @font-lock-variable-name-face)))
 
-     (call_expression
+   :language mode
+   :feature 'expression
+   '((call_expression
       function: (identifier) @font-lock-function-name-face)
-
-     (field_expression
-      field: (field_identifier) @font-lock-variable-name-face)
-
      (field_expression
       argument: (identifier) @font-lock-variable-name-face
-      field: (field_identifier) @font-lock-variable-name-face)
-
+      field: (field_identifier) @font-lock-property-face)
      (pointer_expression
-      argument: (identifier) @font-lock-variable-name-face))
+      (identifier) @font-lock-variable-name-face))
+
    :language mode
-   :override t
-   :feature 'statement
+   :feature 'label
    '((expression_statement (identifier) @font-lock-variable-name-face)
      (labeled_statement
       label: (statement_identifier) @font-lock-type-face))
+
    :language mode
-   :override t
    :feature 'error
    '((ERROR) @font-lock-warning-face)
+
    :language mode
    :feature 'emacs-devel
-   :override 't
    '(((call_expression function: (identifier) @fn)
       @c-ts-mode--fontify-defun
       (:match "^DEFUN$" @fn)))))
 
+(defun c-ts-mode--fontify-declarator (node override start end &rest args)
+  "Fontify a declarator (whatever under the \"declarator\" field).
+For NODE, OVERRIDE, START, END, and ARGS, see
+`treesit-font-lock-rules'."
+  (pcase (treesit-node-type node)
+    ((or "attributed_declarator" "parenthesized_declarator")
+     (apply #'c-ts-mode--fontify-declarator
+            (treesit-node-child node 0 t) override start end args))
+    ("pointer_declarator"
+     (apply #'c-ts-mode--fontify-declarator
+            (treesit-node-child node -1) override start end args))
+    ((or "function_declarator" "array_declarator" "init_declarator")
+     (apply #'c-ts-mode--fontify-declarator
+            (treesit-node-child-by-field-name node "declarator")
+            override start end args))
+    ((or "identifier" "field_identifier")
+     (treesit-fontify-with-override
+      (max (treesit-node-start node) start)
+      (min (treesit-node-end node) end)
+      (pcase (treesit-node-type (treesit-node-parent node))
+        ("function_declarator" 'font-lock-function-name-face)
+        (_ 'font-lock-variable-name-face))
+      override))))
+
 (defun c-ts-mode--fontify-defun (node override start end &rest _)
   "Correctly fontify the DEFUN macro.
 For NODE, OVERRIDE, START, and END, see
@@ -468,9 +471,9 @@ the subtrees."
   (setq-local which-func-functions nil)
 
   (setq-local treesit-font-lock-feature-list
-              '((comment preprocessor operator constant string literal keyword)
-                (type definition expression statement)
-                (error))))
+              '((comment preprocessor constant string literal keyword)
+                (type definition label assignment)
+                (expression error operator))))
 
 ;;;###autoload
 (define-derived-mode c-ts-mode c-ts-mode--base-mode "C"