basic eRuby implementation

eRuby.rb

#!/usr/bin/ruby
# via [ruby-list:48093]
def eRuby(eruby_source)
  source = eruby_source
  ruby = ''
  loop do
    break if source.empty?
    
    if source=~/<%=/m
      text = $`
      if text != ""
        ruby << "print(#{text.dump})\n"
      end
      source = $'
      if source=~/%>/m
        code = $`
        if code != ""
          ruby << "print(#{code})\n"
        end
        source=$'
        next
      else
        raise "<%= unmatch error"
      end
    end
    
    if source=~/<%/m
      text = $`
      if text != ""
        ruby << "print(#{text.dump})\n"
      end
      source = $'
      if source=~/%>/m
        code = $`
        if code != ""
          ruby << code << "\n"
        end
        source=$'
        next
      else
        raise "<% unmatch error"
      end
    end
    
    ruby << "print(#{source.dump})\n"
    break
  end
  ruby
end

if $0==__FILE__
  print eRuby(STDIN.read)
end