Combine ranges in book index

gistfile1.txt

def combine_nums(line)
	line.gsub!(/(\d+), (?=(\d+))/) {  							# combine consecutive & identical numbers
		if $2.to_i - $1.to_i == 1								# (looks-ahead so as to check
			"#{$1}-"											# every set of two numbers)
		elsif $2.to_i == $1.to_i
			""
		else
			"#{$1}, "
		end
	}
	line.gsub!(/-(\d+), (\d+)/) {   							# remove numbers after ranges included in same
		if $2.to_i < $1.to_i
			"-#{$1}"
		else
			"#{$&}"
		end
	}
	line.gsub!(/(\d+)-(\d+-)+(\d+)/)	{ "#{$1}-#{$3}" }  		# remove inner numbers from ranges
	line.gsub!(/(\d)(\d\d)-\1(\d\d)/)	{ "#{$1}#{$2}-#{$3}"}	# make e.g. 323-343 into 323-43
	line.gsub!(/(\d0\d)-0(\d)/) 		{ "#{$1}-#{$2}"}		# make e.g. 306-08 into 306-8

	return line
end

if ARGV.empty?
	puts "Please supply a filename, or --clipboard"
elsif ARGV[0] == "--clipboard"
	require 'clipboard'
	clipout = []
	Clipboard.paste.split("\r").each { |line| clipout << combine_nums(line) }
	Clipboard.copy(clipout.join("\r"))
else
	File.open(ARGV[0]).each(sep="\r") do |line|						# Mac classic newlines
		puts combine_nums(line)
	end
end