Allow indentation styles by use of function in tree-sitter

Allow indentation styles by use of function in tree-sitter

[Theodor Thornhill]

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Hi Yuan!

I was thinking that a quick way to enable indentation styles and
customizable indentation styles is to also accept a function in
tree-sitter-simple-indent.

What do you think of the suggested patch?

That would allow a defcustom such as
```
(defcustom c-ts-mode-indent-rule-function #'c-ts-mode--some-specific-style
  "Indentation style of choice"
  :group 'c)
```

and in the major-mode init:
```
    (setq-local treesit-simple-indent-rules c-ts-mode-indent-rule-function)
```

-- 
Theo

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From 9dc7d1151eb15880285d4015efa1579f9e8817ed Mon Sep 17 00:00:00 2001
From: Theodor Thornhill <theo@thornhill.no>
Date: Sun, 6 Nov 2022 13:48:39 +0100
Subject: [PATCH] Make treesit-simple-indent-rules accept function

* lisp/treesit.el (treesit-simple-indent): Make treesit-simple-indent
accept a function that returns a list of the same type as before.

(treesit-simple-indent-rules): Document said change.
---
 lisp/treesit.el | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lisp/treesit.el b/lisp/treesit.el
index 84be69d8b7..18c9abd658 100644
--- a/lisp/treesit.el
+++ b/lisp/treesit.el
@@ -882,7 +882,8 @@ treesit--indent-verbose
   "If non-nil, log progress when indenting.")
 
 (defvar-local treesit-simple-indent-rules nil
-  "A list of indent rule settings.
+  "A list, or a function that returns a list of indent rule settings.
+
 Each indent rule setting should be (LANGUAGE . RULES),
 where LANGUAGE is a language symbol, and RULES is a list of
 
@@ -1292,7 +1293,9 @@ treesit-simple-indent
              (cons nil nil))
     (let* ((language (treesit-node-language parent))
            (rules (alist-get language
-                             treesit-simple-indent-rules)))
+                             (if (functionp treesit-simple-indent-rules)
+                                 (funcall treesit-simple-indent-rules)
+                               treesit-simple-indent-rules))))
       (cl-loop for rule in rules
                for pred = (nth 0 rule)
                for anchor = (nth 1 rule)
-- 
2.34.1

Re: Allow indentation styles by use of function in tree-sitter

[Yuan Fu]

> On Nov 6, 2022, at 4:52 AM, Theodor Thornhill <theo@thornhill.no> wrote:
> 
> 
> Hi Yuan!
> 
> I was thinking that a quick way to enable indentation styles and
> customizable indentation styles is to also accept a function in
> tree-sitter-simple-indent.
> 
> What do you think of the suggested patch?
> 
> That would allow a defcustom such as
> ```
> (defcustom c-ts-mode-indent-rule-function #'c-ts-mode--some-specific-style
>  "Indentation style of choice"
>  :group 'c)
> ```
> 
> and in the major-mode init:
> ```
>    (setq-local treesit-simple-indent-rules c-ts-mode-indent-rule-function)
> ```

Hmmm, does assigning treesit-indent-function fit the bill?

Yuan

Re: Allow indentation styles by use of function in tree-sitter

[Theodor Thornhill]

Yuan Fu <casouri@gmail.com> writes:

>> On Nov 6, 2022, at 4:52 AM, Theodor Thornhill <theo@thornhill.no> wrote:
>> 
>> 
>> Hi Yuan!
>> 
>> I was thinking that a quick way to enable indentation styles and
>> customizable indentation styles is to also accept a function in
>> tree-sitter-simple-indent.
>> 
>> What do you think of the suggested patch?
>> 
>> That would allow a defcustom such as
>> ```
>> (defcustom c-ts-mode-indent-rule-function #'c-ts-mode--some-specific-style
>>  "Indentation style of choice"
>>  :group 'c)
>> ```
>> 
>> and in the major-mode init:
>> ```
>>    (setq-local treesit-simple-indent-rules c-ts-mode-indent-rule-function)
>> ```
>
> Hmmm, does assigning treesit-indent-function fit the bill?
>

I might be misunderstanding what you mean, but I don't want to change
the architecture, I just want the user to set their own as a
customization option in a major mode. The function will just return the
same stuff as it does now, but with a function as an available option
that will be a little more flexible.  See [0] for an example.  The user
can just set [1] to change the indent style.  A quick workaround could
be that each major mode just does this:
```
(setq-local treesit-simple-indent-rules
            (funcall c-ts-mode-indent-rule-function))
```
But that is a little less nice :-)


[0]: https://git.sr.ht/~theo/tree-sitter-modes/tree/master/item/c-ts-mode.el#L66-160
[1]: https://git.sr.ht/~theo/tree-sitter-modes/tree/master/item/c-ts-mode.el#L35-37

-- 
Theo

Re: Allow indentation styles by use of function in tree-sitter

[Yuan Fu]

> On Nov 7, 2022, at 12:00 AM, Theodor Thornhill <theo@thornhill.no> wrote:
> 
> Yuan Fu <casouri@gmail.com> writes:
> 
>>> On Nov 6, 2022, at 4:52 AM, Theodor Thornhill <theo@thornhill.no> wrote:
>>> 
>>> 
>>> Hi Yuan!
>>> 
>>> I was thinking that a quick way to enable indentation styles and
>>> customizable indentation styles is to also accept a function in
>>> tree-sitter-simple-indent.
>>> 
>>> What do you think of the suggested patch?
>>> 
>>> That would allow a defcustom such as
>>> ```
>>> (defcustom c-ts-mode-indent-rule-function #'c-ts-mode--some-specific-style
>>> "Indentation style of choice"
>>> :group 'c)
>>> ```
>>> 
>>> and in the major-mode init:
>>> ```
>>>   (setq-local treesit-simple-indent-rules c-ts-mode-indent-rule-function)
>>> ```
>> 
>> Hmmm, does assigning treesit-indent-function fit the bill?
>> 
> 
> I might be misunderstanding what you mean, but I don't want to change
> the architecture, I just want the user to set their own as a
> customization option in a major mode. The function will just return the
> same stuff as it does now, but with a function as an available option
> that will be a little more flexible.  See [0] for an example.  The user
> can just set [1] to change the indent style.  A quick workaround could
> be that each major mode just does this:
> ```
> (setq-local treesit-simple-indent-rules
>            (funcall c-ts-mode-indent-rule-function))
> ```
> But that is a little less nice :-)

Ah, I see what you mean. I think funcall is perfectly fine. I also think you can just define those styles as variables and use symbol-value.

Yuan