From: Ben Giddings <bg-rubytalk@...>
Date: 2005-03-17T04:43:50+09:00
Subject: Re: Examples for racc?

Jonathan Paisley wrote:
> Perhaps it is sufficient to scan the line a couple of times with some
> regular expressions? e.g.:
> 
> class GCCInvocation
>   def initialize(line)
>     @includes = []
>     @lang_opts = []
>     @output = ""
>     @defines = []
>     @sources = []
>     line = " " + line
>     line.gsub!(/ -I ?(\S+)/) { @includes << $1; "" }
>     line.gsub!(/ -f ?(\S+)/) { @lang_opts << $1; "" }
>     line.gsub!(/ -o ?(\S+)/) { @output = $1; "" } 
>     line.gsub!(/ -D ?(\S+)/) { @defines << $1; "" }
>     line.gsub!(/ ([^- ]\S+)/) { @sources << $1 }
>     @remainder = line.squeeze(' ')
>   end
> end

Yeah, that would work (with tweaked regexps), but I would imagine it 
would be less efficient.  Each regexp is essentially a complex parser, 
and so in your example above, you have five parsers per gcc line.  If I 
could do it in one parser, it would probably be quicker.  I also think 
it might be easier to avoid mistakes due to complex regexps.  I might 
try it though, it might be enough to do it the simple way.

Ben