From: Yuan Fu <casouri@gmail.com>
Date: Mon, 27 Feb 2023 02:05:13 +0000 (-0800)
Subject: New tree-sitter indent anchor standalone-parent used by c-ts-mode
X-Git-Tag: emacs-29.0.90~305
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=0f15286c5396e3415e0f40c21b6f6d7554f46a5e;p=emacs.git
New tree-sitter indent anchor standalone-parent used by c-ts-mode
When writing c-ts-mode Theo used parent-bol which works well except
one case:
1 for (int i=0;
2 i < 5;
3 i++) {
4 func(i);
5 }
In this case, when indenting "func(i)", parent-bol returns the start
of "i++" on line 3, instead of the "correct" anchor, the start of
"for" on line 1. parent-bol would have worked if the "for (...) {"
part is in one line.
To support this case I tried numerous things and added a bunch of
stuff, culminating in c-ts-common-statement-offset. It's complicated,
requires extra setup, and slow.
Not anymore! I think the new anchor standalone-parent really captures
the logic behind how people expect indentation to work. It's simple
and fast, and requires no setup.
* doc/lispref/modes.texi (Parser-based Indentation): Update manual.
* lisp/progmodes/c-ts-mode.el:
(c-ts-mode--standalone-grandparent): New anchor.
(c-ts-mode--indent-styles): Replace c-ts-common-statement-offset with
standalone-parent.
(c-ts-base-mode): Add comment.
* lisp/treesit.el:
(treesit-simple-indent-presets): New anchor standalone-parent.
---
diff --git a/doc/lispref/modes.texi b/doc/lispref/modes.texi
index 4c40f414ca0..11892aaa40e 100644
--- a/doc/lispref/modes.texi
+++ b/doc/lispref/modes.texi
@@ -5093,7 +5093,15 @@ This anchor is a function that is called with 3 arguments: @var{node},
@item parent-bol
This anchor is a function that is called with 3 arguments: @var{node},
@var{parent}, and @var{bol}, and returns the first non-space character
-on the line of @var{parent}.
+on the line which @var{parent}'s start is on.
+
+@item parent-bol
+This anchor is a function that is called with 3 arguments: @var{node},
+@var{parent}, and @var{bol}. It finds the first ancestor node
+(parent, grandparent, etc) of @var{node} that starts on its own line,
+and return the start of that node. ``Starting on its own line'' means
+there is only whitespace character before the node on the line which
+the node's start is on.
@item prev-sibling
This anchor is a function that is called with 3 arguments: @var{node},
diff --git a/lisp/progmodes/c-ts-mode.el b/lisp/progmodes/c-ts-mode.el
index 041461f220a..2c79cf46308 100644
--- a/lisp/progmodes/c-ts-mode.el
+++ b/lisp/progmodes/c-ts-mode.el
@@ -279,6 +279,12 @@ doesn't have a child."
;; prev-sibling doesn't have a child.
(treesit-node-start prev-sibling)))
+(defun c-ts-mode--standalone-grandparent (_node parent bol &rest args)
+ "Like the standalone-parent anchor but pass it the grandparent.
+PARENT, BOL, ARGS are the same as other anchor functions."
+ (apply (alist-get 'standalone-parent treesit-simple-indent-presets)
+ parent (treesit-node-parent parent) bol args))
+
(defun c-ts-mode--indent-styles (mode)
"Indent rules supported by `c-ts-mode'.
MODE is either `c' or `cpp'."
@@ -300,9 +306,9 @@ MODE is either `c' or `cpp'."
((parent-is "comment") prev-adaptive-prefix 0)
;; Labels.
- ((node-is "labeled_statement") parent-bol 0)
+ ((node-is "labeled_statement") standalone-parent 0)
((parent-is "labeled_statement")
- point-min c-ts-common-statement-offset)
+ c-ts-mode--standalone-grandparent c-ts-mode-indent-offset)
((node-is "preproc") point-min 0)
((node-is "#endif") point-min 0)
@@ -330,7 +336,7 @@ MODE is either `c' or `cpp'."
;; Closing bracket. This should be before initializer_list
;; (and probably others) rule because that rule (and other
;; similar rules) will match the closing bracket. (Bug#61398)
- ((node-is "}") point-min c-ts-common-statement-offset)
+ ((node-is "}") standalone-parent 0)
,@(when (eq mode 'cpp)
'(((node-is "access_specifier") parent-bol 0)
;; Indent the body of namespace definitions.
@@ -341,25 +347,25 @@ MODE is either `c' or `cpp'."
((match nil "initializer_list" nil 1 1) parent-bol c-ts-mode-indent-offset)
((match nil "initializer_list" nil 2) c-ts-mode--anchor-prev-sibling 0)
;; Statement in enum.
- ((match nil "enumerator_list" nil 1 1) point-min c-ts-common-statement-offset)
+ ((match nil "enumerator_list" nil 1 1) standalone-parent c-ts-mode-indent-offset)
((match nil "enumerator_list" nil 2) c-ts-mode--anchor-prev-sibling 0)
;; Statement in struct and union.
- ((match nil "field_declaration_list" nil 1 1) point-min c-ts-common-statement-offset)
+ ((match nil "field_declaration_list" nil 1 1) standalone-parent c-ts-mode-indent-offset)
((match nil "field_declaration_list" nil 2) c-ts-mode--anchor-prev-sibling 0)
;; Statement in {} blocks.
- ((match nil "compound_statement" nil 1 1) point-min c-ts-common-statement-offset)
+ ((match nil "compound_statement" nil 1 1) standalone-parent c-ts-mode-indent-offset)
((match nil "compound_statement" nil 2) c-ts-mode--anchor-prev-sibling 0)
;; Opening bracket.
- ((node-is "compound_statement") point-min c-ts-common-statement-offset)
+ ((node-is "compound_statement") standalone-parent c-ts-mode-indent-offset)
;; Bug#61291.
- ((match "expression_statement" nil "body") point-min c-ts-common-statement-offset)
+ ((match "expression_statement" nil "body") standalone-parent c-ts-mode-indent-offset)
;; These rules are for cases where the body is bracketless.
;; Tested by the "Bracketless Simple Statement" test.
- ((parent-is "if_statement") point-min c-ts-common-statement-offset)
- ((parent-is "for_statement") point-min c-ts-common-statement-offset)
- ((parent-is "while_statement") point-min c-ts-common-statement-offset)
- ((parent-is "do_statement") point-min c-ts-common-statement-offset)
+ ((parent-is "if_statement") standalone-parent c-ts-mode-indent-offset)
+ ((parent-is "for_statement") standalone-parent c-ts-mode-indent-offset)
+ ((parent-is "while_statement") standalone-parent c-ts-mode-indent-offset)
+ ((parent-is "do_statement") standalone-parent c-ts-mode-indent-offset)
,@(when (eq mode 'cpp)
`(((node-is "field_initializer_list") parent-bol ,(* c-ts-mode-indent-offset 2)))))))
@@ -836,6 +842,8 @@ the semicolon. This function skips the semicolon."
(when (eq c-ts-mode-indent-style 'linux)
(setq-local indent-tabs-mode t))
(setq-local c-ts-common-indent-offset 'c-ts-mode-indent-offset)
+ ;; This setup is not needed anymore, but we might find uses for it
+ ;; later, so I'm keeping it.
(setq-local c-ts-common-indent-type-regexp-alist
`((block . ,(rx (or "compound_statement"
"field_declaration_list"
diff --git a/lisp/treesit.el b/lisp/treesit.el
index 1decfc3d7cf..6b4db2a990c 100644
--- a/lisp/treesit.el
+++ b/lisp/treesit.el
@@ -1227,6 +1227,16 @@ See `treesit-simple-indent-presets'.")
(goto-char (treesit-node-start parent))
(back-to-indentation)
(point))))
+ (cons 'standalone-parent
+ (lambda (_n parent &rest _)
+ (save-excursion
+ (catch 'term
+ (while parent
+ (goto-char (treesit-node-start parent))
+ (when (looking-back (rx bol (* whitespace))
+ (line-beginning-position))
+ (throw 'term (point)))
+ (setq parent (treesit-node-parent parent)))))))
(cons 'prev-sibling (lambda (node &rest _)
(treesit-node-start
(treesit-node-prev-sibling node))))
@@ -1323,6 +1333,11 @@ parent-bol
Returns the beginning of non-space characters on the line where
PARENT is on.
+standalone-parent
+
+ Finds the first ancestor node (parent, grandparent, etc) that
+ starts on its own line, and return the start of that node.
+
prev-sibling
Returns the start of NODE's previous sibling.