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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.
This commit is contained in:
Yuan Fu
parent
267fc6d00c
commit
0f15286c53
@ -5093,7 +5093,15 @@ This anchor is a function that is called with 3 arguments: @var{node},
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@item parent-bol
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This anchor is a function that is called with 3 arguments: @var{node},
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@var{parent}, and @var{bol}, and returns the first non-space character
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on the line of @var{parent}.
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on the line which @var{parent}'s start is on.
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@item parent-bol
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This anchor is a function that is called with 3 arguments: @var{node},
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@var{parent}, and @var{bol}. It finds the first ancestor node
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(parent, grandparent, etc) of @var{node} that starts on its own line,
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and return the start of that node. ``Starting on its own line'' means
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there is only whitespace character before the node on the line which
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the node's start is on.
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@item prev-sibling
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This anchor is a function that is called with 3 arguments: @var{node},
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@ -279,6 +279,12 @@ doesn't have a child."
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;; prev-sibling doesn't have a child.
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(treesit-node-start prev-sibling)))
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(defun c-ts-mode--standalone-grandparent (_node parent bol &rest args)
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"Like the standalone-parent anchor but pass it the grandparent.
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PARENT, BOL, ARGS are the same as other anchor functions."
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(apply (alist-get 'standalone-parent treesit-simple-indent-presets)
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parent (treesit-node-parent parent) bol args))
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(defun c-ts-mode--indent-styles (mode)
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"Indent rules supported by `c-ts-mode'.
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MODE is either `c' or `cpp'."
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@ -300,9 +306,9 @@ MODE is either `c' or `cpp'."
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((parent-is "comment") prev-adaptive-prefix 0)
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;; Labels.
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((node-is "labeled_statement") parent-bol 0)
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((node-is "labeled_statement") standalone-parent 0)
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((parent-is "labeled_statement")
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point-min c-ts-common-statement-offset)
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c-ts-mode--standalone-grandparent c-ts-mode-indent-offset)
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((node-is "preproc") point-min 0)
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((node-is "#endif") point-min 0)
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@ -330,7 +336,7 @@ MODE is either `c' or `cpp'."
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;; Closing bracket. This should be before initializer_list
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;; (and probably others) rule because that rule (and other
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;; similar rules) will match the closing bracket. (Bug#61398)
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((node-is "}") point-min c-ts-common-statement-offset)
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((node-is "}") standalone-parent 0)
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,@(when (eq mode 'cpp)
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'(((node-is "access_specifier") parent-bol 0)
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;; Indent the body of namespace definitions.
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@ -341,25 +347,25 @@ MODE is either `c' or `cpp'."
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((match nil "initializer_list" nil 1 1) parent-bol c-ts-mode-indent-offset)
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((match nil "initializer_list" nil 2) c-ts-mode--anchor-prev-sibling 0)
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;; Statement in enum.
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((match nil "enumerator_list" nil 1 1) point-min c-ts-common-statement-offset)
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((match nil "enumerator_list" nil 1 1) standalone-parent c-ts-mode-indent-offset)
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((match nil "enumerator_list" nil 2) c-ts-mode--anchor-prev-sibling 0)
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;; Statement in struct and union.
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((match nil "field_declaration_list" nil 1 1) point-min c-ts-common-statement-offset)
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((match nil "field_declaration_list" nil 1 1) standalone-parent c-ts-mode-indent-offset)
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((match nil "field_declaration_list" nil 2) c-ts-mode--anchor-prev-sibling 0)
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;; Statement in {} blocks.
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((match nil "compound_statement" nil 1 1) point-min c-ts-common-statement-offset)
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((match nil "compound_statement" nil 1 1) standalone-parent c-ts-mode-indent-offset)
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((match nil "compound_statement" nil 2) c-ts-mode--anchor-prev-sibling 0)
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;; Opening bracket.
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((node-is "compound_statement") point-min c-ts-common-statement-offset)
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((node-is "compound_statement") standalone-parent c-ts-mode-indent-offset)
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;; Bug#61291.
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((match "expression_statement" nil "body") point-min c-ts-common-statement-offset)
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((match "expression_statement" nil "body") standalone-parent c-ts-mode-indent-offset)
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;; These rules are for cases where the body is bracketless.
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;; Tested by the "Bracketless Simple Statement" test.
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((parent-is "if_statement") point-min c-ts-common-statement-offset)
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((parent-is "for_statement") point-min c-ts-common-statement-offset)
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((parent-is "while_statement") point-min c-ts-common-statement-offset)
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((parent-is "do_statement") point-min c-ts-common-statement-offset)
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((parent-is "if_statement") standalone-parent c-ts-mode-indent-offset)
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((parent-is "for_statement") standalone-parent c-ts-mode-indent-offset)
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((parent-is "while_statement") standalone-parent c-ts-mode-indent-offset)
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((parent-is "do_statement") standalone-parent c-ts-mode-indent-offset)
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,@(when (eq mode 'cpp)
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`(((node-is "field_initializer_list") parent-bol ,(* c-ts-mode-indent-offset 2)))))))
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@ -836,6 +842,8 @@ the semicolon. This function skips the semicolon."
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(when (eq c-ts-mode-indent-style 'linux)
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(setq-local indent-tabs-mode t))
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(setq-local c-ts-common-indent-offset 'c-ts-mode-indent-offset)
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;; This setup is not needed anymore, but we might find uses for it
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;; later, so I'm keeping it.
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(setq-local c-ts-common-indent-type-regexp-alist
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`((block . ,(rx (or "compound_statement"
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"field_declaration_list"
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@ -1227,6 +1227,16 @@ See `treesit-simple-indent-presets'.")
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(goto-char (treesit-node-start parent))
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(back-to-indentation)
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(point))))
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(cons 'standalone-parent
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(lambda (_n parent &rest _)
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(save-excursion
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(catch 'term
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(while parent
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(goto-char (treesit-node-start parent))
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(when (looking-back (rx bol (* whitespace))
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(line-beginning-position))
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(throw 'term (point)))
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(setq parent (treesit-node-parent parent)))))))
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(cons 'prev-sibling (lambda (node &rest _)
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(treesit-node-start
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(treesit-node-prev-sibling node))))
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@ -1323,6 +1333,11 @@ parent-bol
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Returns the beginning of non-space characters on the line where
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PARENT is on.
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standalone-parent
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Finds the first ancestor node (parent, grandparent, etc) that
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starts on its own line, and return the start of that node.
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prev-sibling
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Returns the start of NODE's previous sibling.
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