R.I.G.B.Y. - Tabs v Spaces

git-pre-commit-replace-tabs.sh

#!/usr/bin/env ruby
files_modified = `git diff-index --cached --name-only HEAD`.split(/\n/)

# expand_tabs from Stack Overflow
#  -> http://stackoverflow.com/a/8900610/1431239
# This algorithm by Brian Candler (B.Candler@pobox.com) found on the
# org.ruby-lang.ruby-talk mailing list
# http://markmail.org/message/avdjw34ahxi447qk
# Date: 2003-5-31 13:35:09
# Subject: Re: expandtabs

def expand_tabs(s, tab_stops = 8)
  s.gsub(/([^\t\n]*)\t/) do
    $1 + " " * (tab_stops - ($1.size % tab_stops))
  end
end

files_modified.each do |f|
  # If we find opening tabs, then replace them
  lines = IO.readlines(f).map do |line|
    line = expand_tabs(line, 4)
  end

  # Write them back
  File.open(f, 'w') do |f|
    f.puts lines
  end

  # Spit out a message
  puts "[R.I.G.B.Y.] Changed tabs to spaces in #{f}."

  # Add this back to the index
  `git add #{f}`
end