From: George Ogata <george.ogata@...>
Date: 2006-12-01T21:44:46+09:00
Subject: Re: BUG: ruby-mode.el : '/=' operator breaks following indentation

On 11/30/06, Jeremy Henty <jeremy@chaos.org.uk> 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