moved ruby's electric indent to lua-mode

[ngzh]

Copied from ruby-mode.el

now, when typing a closing token like end, an automatically reindent
will be performed. it also works for elseelseifuntil. (I did a quick
scan on lua syntax, described in lua manual and don't think there will be
more keyword which trigger a reindent)

example:

1 function foo() 1 function foo()
2 return "foo" 2 return "foo"
3 en 3 end
^ type 'd' here will cause ^ to reindent

I'm been using this for almost a month and everything seems to be ok, though in fact I'm not very familiar with elisp, so better have a look at the code and do some extra test.

[immerrr]

Hi and thank you for the PR.

Electric indentation of block closing tokens is already implemented via abbrev-mode, see lua-mode-abbrev-table as well as lua-electric-flag variable. That being said, there were plans of migrating to electric-indent infrastructure, but unfortunately that is only available since emacs-24.4 and some still use older versions.

If you don't mind doing some refactoring to select the one that is appropriate for the running version of emacs on top of your slightly adapted copy-n-paste, I'll gladly accept that.

[ngzh]

Thanks for your quick reply.

I'm using emacs 24.5 actually, so I guess there may be some surprise for me since electric indent doesn't work for me out of the box(I've tried toggle lua-toggle-electric-state but didn't see any difference)

And as for the code I copied, I'll try to make them clean to provide those who need a fallback. Got to learn something but that will be OK, just need some time.

[immerrr]

@fangzhouuu you might need to enable abbrev-mode, it got disabled by default in one of the recent releases

[ngzh]

Well I've enable abbrev-mode but it still not working for end else elseif(works for brackets). It could be the the effect of other package since I copied a huge bunch of code in my config file. I might have to setup a clean emacs dev envirnoment using a VM or a docker container.

[immerrr]

You can do emacs -Q -l path/to/lua-mode.el to try out a fresh emacs env.

If you have cask, you can use make tryout command from lua-mode directory.

[immerrr]

Also, there are tests for electric indentation functionality:

lua-mode/test/test-electric-mode.el

Lines 35 to 71 in 0b41d44

	(it "works with end"
	(with-lua-buffer
	(execute-kbd-macro (kbd"if SPC foo SPC then M-j"))
	(execute-kbd-macro (kbd"'baz' M-j"))
	(should (eq (current-indentation) lua-indent-level))
	(abbrev-mode1)
	(execute-kbd-macro (kbd"end M-j"))
	(beginning-of-line0)
	(should (eq (current-indentation) 0))))
	(it "works with else"
	(with-lua-buffer
	(execute-kbd-macro (kbd"if SPC foo SPC then M-j"))
	(execute-kbd-macro (kbd"'baz' M-j"))
	(should (eq (current-indentation) lua-indent-level))
	(abbrev-mode1)
	(execute-kbd-macro (kbd"else M-j"))
	(beginning-of-line0)
	(should (eq (current-indentation) 0))))
	(it "works with elseif"
	(with-lua-buffer
	(execute-kbd-macro (kbd"if SPC foo SPC then"))
	(newline-and-indent)
	(execute-kbd-macro (kbd"'baz'"))
	(newline-and-indent)
	(should (eq (current-indentation) lua-indent-level))
	(abbrev-mode1)
	(execute-kbd-macro (kbd"elseif"))
	(newline-and-indent)
	(beginning-of-line0)
	(should (eq (current-indentation) 0)))))