From: Ryan Davis <ryand-ruby@...>
Date: 2011-08-22T08:44:54+09:00
Subject: Re: Possble bug in Ruby parser (Fixnum#times within "case" statement)


On Aug 21, 2011, at 16:12 , Iņaki Baz Castillo wrote:

> Hi, I cannot find an explanation for the following issue so I think it's a bug:
> 

reformatted to be idiomatic and therefore readable:

> def kk
>   while case @state
>         when :init
>           10.times do |index|
>             puts "index = #{index}"
>           end
>           @state = :end
>           true
>         when :end
>           puts "END"
>         end
>     # zenspider: do nothing???
>   end
> end
> 
> @state = :init
> kk
> 
> Running the above code gives an error:
> 
> ~# ruby1.9.3 kk.rb
> 
> kk.rb:6: syntax error, unexpected keyword_do_cond, expecting keyword_end
>      10.times do |index|
>                 ^
> Why????

Because it is nonsensical and confuses the parser. I'm not really sure WHY you have a while in there at all but I can describe the components involved:

while expr [do] body end

That 'do' is important here... You've started a while loop, started the condition expression, left it hanging, and then hit the do in a place that doesn't make any sense to the condition expression... You have an unterminated case/when. You can see this in all of its grubby detail by running 'ruby -ycw kk.rb'

Since I can't make any sense of your code, I can only guess as to your intent and offer suggestions:

loop do
  # ... case, et al
end

or

def kk
  while (case @state
         when :init then
           10.times do |index|
             puts "index = #{index}"
           end
           @state = :end
           true
         when :end then
           puts "END"
         end) do
    # do nothing?
  end
end

or just get rid of your loop as it contributes nothing.