From: "Brian Schröder" <ruby.brian@...>
Date: 2005-07-29T23:39:09+09:00
Subject: Re: Sed -> Ruby : .. and ...

On 29/07/05, Keith Fahlgren <keith@oreilly.com> wrote:
> Hi all,
> 
> Thanks for the helpful responses. Many corrected me, rightly, for
> writing a whole program rather than just using a one-liner and for
> modifying the file in place rather than setting up temporary files. I
> was concentrating on my task, making a template to replace thousands of
> lines of sed files rather than doing a single replacement.
> 
> My larger problem still revolved around doing a bunch matches inside an
> range.
> 
> On Thursday 28 July 2005 5:46 pm, mathew wrote:
> > working_file.gsub!(/(?=BEGIN RANGE)(.*?)(?=END RANGE)/m) {||
> >    $1.gsub(/MATCH/m, 'REPLACEMENT')
> > }
> 
> Matthew pointed out an easier way to get around it but I had rejected
> that method from the start because I wanted to be able to nest ranges
> (like I can in sed).
> 
> I think the problems with my inital attempts was assuming .read was
> returning an array rather than a string. Slapping .to_a to the end
> solved that bit and the program now works as expected, I think.
> 
> Here's my solution (though I'd still love comments):
> 
> 
> #!/usr/bin/env ruby
> files = ARGV
> 
> files.each do |arg|
>   puts "\nOpening file #{arg}"
>   f = File.open(arg)
>   working_file = f.read.to_a
>   f.close
>   working_file.each do |aline|
>     if aline =~ /BEGIN RANGE/ .. aline =~ /END RANGE/
>       #nest if lines like above as many times as needed for nested
> ranges
>       aline.sub!(/MATCH/,'REPLACEMENT')
>     end
>   end
> 
>   puts "\nDoing ACTION in #{arg}"
>   fnew = File.new("#{arg}.tmp", "w")
>   puts "\nWriting #{fnew} now"
>   fnew.print(working_file)
>   fnew.close
> end
> 
> 
> 
> Thanks,
> Keith
> 
> 

My approach would be something along these lines:

bschroed@black:~/svn/projekte/ruby-things$ cat test
test
Range1
test1
Range2
test2
EndRange2
test3
EndRange1
bschroed@black:~/svn/projekte/ruby-things$ cat ranges.rb
ARGV.each do | filename |
  result = []
  File.read(filename).split("\n").each do | line |
    if line =~ /^Range1/ .. line =~ /^EndRange1/
      if line =~ /^Range2/ .. line =~ /^EndRange2/
        result << "    - " + line
      else
        result << "  - " + line
      end
    else
      result << "- " + line
    end
  end

  puts filename
  puts "-" * filename.length
  puts result
  puts "-" * filename.length
  puts
end

bschroed@black:~/svn/projekte/ruby-things$ ruby ranges.rb test
test
----
- test
  - Range1
  - test1
    - Range2
    - test2
    - EndRange2
  - test3
  - EndRange1
----

regards,

Brian


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