bug#24896: JSX prop indentation after fat arrow

[Felipe Ochoa]

So I've thought about this some more, and realized that this won't fix everything. There are still issues with greater-than and less-than as binary operators. Maybe a better idea is to give '{' and '}' comment syntax ('<' and '>') so that SGML ignores all the bracketed JS stuff. I've been trialing this with the following:

(defvar js-jsx-tag-syntax-table
  (let ((table (make-syntax-table sgml-tag-syntax-table)))
    (modify-syntax-entry ?\{ "<" table)
    (modify-syntax-entry ?\} ">" table)
    table))

(defun advice-js-jsx-indent-line (orig-fun)
  (interactive)
  (let ((sgml-tag-syntax-table js-jsx-tag-syntax-table))
    (apply orig-fun nil)))

(advice-add 'js-jsx-indent-line :around 'advice-js-jsx-indent-line)

and have gotten good results so far. This works for js-mode and js2-mode. If you're both happy with this approach, I'll convert the advice into a patch for `js-jsx-indent-line' and will send along!

On Fri, Dec 9, 2016 at 1:18 AM, Dmitry Gutov <dgutov@yandex.ru> wrote:

On 08.12.2016 13:12, Felipe Ochoa wrote:

syntax-propertize-function is outside my limited knowledge of emacs
internals. But to the extent that one could say "Outside of comments and
strings, propertize `=>' as punctuation," I imagine that would fix it.

Yes, it can help with that.

Also, this may be a dumb question, but are the tests in the "manual"
directory meant to be run manually? If not, how would I run the tests there?

You can e.g. 'cd test/manual/indent' and run 'make js-jsx.js.test', to compare the indentation in js-jsx.js against what the current js.el does.

And then finally, should I just email a patch with the proposed change &
tests for this?

An email with a diff attached could be enough.

But if you wanted to include a "proper" commit message as well, see CONTRIBUTE in the top directory.