Convert 4-space indents to 2-space indents

indentity_correction.rb

#!/usr/bin/ruby

#########################
#
# Convert rubycode with 4-space indents
# to regulation 2-space indenting format.
#
# supply directory as argument:
#    > ruby indentity_correction.rb ./my_code_dir
#
#########################

def indents(num)
  ind = ""
  num.times {ind << " "}
  ind
end

dir = ARGV[0]

# get all (ruby) files that have 4-space indents but NO 2-space indents
two_space = %x{egrep -r '^ {2}[^ ]' #{dir} |  awk '{split($1,f,":");print f[1]}' | uniq}.split(/\n/)
four_space = %x{egrep -r '^ {4}[^ ]' #{dir} | awk '{split($1,f,":");print f[1]}' | egrep '\.(rb|rake)$' | uniq}.split(/\n/)

files = four_space - two_space

files.each do |f| 
  new_file = ""
  File.open(f,"r") do |infile|
    while (line = infile.gets)
      indent = /^ {4,}[^ ]/.match(line) 
      if indent
        len = indent[0].length-1 
        new_indent = len / 2 
        new_file << line.gsub(/^ {#{len}}/,indents(new_indent))
      else
        new_file << line
      end
    end
  end
  File.open(f,"w"){|f|f.puts new_file} if new_file != ""
end