BUG: ruby-mode.el : '/=' operator breaks following indentati

Ruby
1

Using emacs 21.4, ruby-mode.el from Ruby 1.8.5 (byte-compiled), if I
open a file with the following code …

def foo
x /= y
bar
end

…move the cursor to the word “bar” and press Tab, nothing happens!
If I replace “/=” with “*=” then Tab fixes the indentation as I’d
expect.

Any suggestions for debugging this? I’ve hacked elisp a few times but
major mode definitions are beyond my experience.

Regards,

Jeremy H.

2

On 11/30/06, Jeremy H. [email protected] wrote:

expect.

Any suggestions for debugging this? I’ve hacked elisp a few times but
major mode definitions are beyond my experience.

The issue is probably that it’s treating the “/=” as the beginning of
a multiline regexp. A common fix for these sorts of “mistaken
delimiters” is to put a comment at the end of the line containing a
closing delimiter:

def foo
x /= y #/
bar
end

Not ideal, but it might get you by.

BTW, there’s a newer ruby-mode.el in the ruby CVS repository. It
still doesn’t fix this, although the behavior is slightly different
(it doesn’t indent the “bar” at all, as if in a multiline string).

G.

3

11/30/06, George O. [email protected] wrote:

BTW, there’s a newer ruby-mode.el in the ruby CVS repository. It
still doesn’t fix this, although the behavior is slightly different
(it doesn’t indent the “bar” at all, as if in a multiline string).

Oops, I misread. It sounds like it is the same behavior. Still, it
might be a newer version.

4

On 2006-11-30, George O. [email protected] wrote:

The issue is probably that it’s treating the “/=” as the beginning
of a multiline regexp. A common fix for these sorts of “mistaken
delimiters” is to put a comment at the end of the line containing a
closing delimiter:

def foo
x /= y #/
bar
end

Thanks, that works. A slightly better fix is to add a ‘;’ as well to
convince the major mode that the statement has ended, otherwise it
adds extra indentation to the next line.

def foo
x /= y # / ;
bar
end

I wonder how the Ruby parser decides that /= is an operator and not
the start of a regexp?

Regards,

Jeremy H.

5

On 11/30/06, Jeremy H. [email protected] wrote:

Thanks, that works. A slightly better fix is to add a ‘;’ as well to
convince the major mode that the statement has ended, otherwise it
adds extra indentation to the next line.

def foo
x /= y # / ;
bar
end

Hmm, my ruby-mode doesn’t seem to need the ‘;’. I’m using the CVS
HEAD version with XEmacs 21.4.19.

I wonder how the Ruby parser decides that /= is an operator and not
the start of a regexp?

It’s just the way the grammar is defined. For it to be a regexp,
you’d need parens on the call to #x.

g@crash:~$ cat test.rb
x /=/
g@crash:~$ ruby test.rb
test.rb:1: unterminated string meets end of file
test.rb:1: parse error, unexpected tSTRING_END, expecting
tSTRING_CONTENT or tREGEXP_END or tSTRING_DBEG or tSTRING_DVAR
g@crash:~$ cat test2.rb
x(/=/)
g@crash:~$ ruby test2.rb
test2.rb:1: undefined method `x’ for main:Object (NoMethodError)
g@crash:~$ ruby -v
ruby 1.8.4 (2005-12-24) [i686-linux]

The ruby-mode parser is much simpler than the one the ruby interpreter
uses. For a start, it’s not based on a proper grammar. I don’t
suppose someone’s tried to use semantic [1] or something to produce
something a little more robust?

[1] http://www.xemacs.org/Documentation/packages/html/semantic.html

6

On 2006-12-01, George O. [email protected] wrote:

Hmm, my ruby-mode doesn’t seem to need the ‘;’. I’m using the CVS
HEAD version with XEmacs 21.4.19.

Mine definitely does need it. I’m using stock Ruby 1.8.5 and GNU
Emacs 21.4 .

I wonder how the Ruby parser decides that /= is an operator and not
the start of a regexp?

It’s just the way the grammar is defined.

“Mommy, why is the sky blue?” “Hush child, it’s just the way the
physics is defined.” :slight_smile:

For it to be a regexp, you’d need parens on the call to #x.

Hmm, so after an identifier the parser tries to parse an infix
operator trying to parse an expression, whereas after an open paren
there can’t be an infix operator so it parses “/=” as the start of a
regexp? If so, I wonder how easy it would be to fix the emacs major
mode to do the same thing?

Thanks for your help.

Regards,

Jeremy H.

7

Hi,

In message “Re: BUG: ruby-mode.el : ‘/=’ operator breaks following
indentation”
on Thu, 30 Nov 2006 08:35:06 +0900, Jeremy H.
[email protected] writes:

|Using emacs 21.4, ruby-mode.el from Ruby 1.8.5 (byte-compiled), if I
|open a file with the following code …
|
|def foo
| x /= y
| bar
|end

Does this patch work for you?

						matz.

diff --git a/misc/ruby-mode.el b/misc/ruby-mode.el
index 38d5b71…33c5901 100755
— a/misc/ruby-mode.el
+++ b/misc/ruby-mode.el
@@ -383,6 +383,8 @@ The variable ruby-indent-level controls the amount
of indentation.
(t
(setq in-string (point))
(goto-char end))))

  •   ((looking-at "/=")
  • (goto-char pnt))
    ((looking-at “/”)
    (cond
    ((and (not (eobp)) (ruby-expr-beg 'expr-re))
8

On 2006-12-04, Yukihiro M. [email protected] wrote:

Does this patch work for you?

Yes. Thank you!

Jeremy H.