global

def run(args, _input = $stdin, output = $stdout, error = $stderr) #:nodoc:
  @binary = nil
  args.options do |o|
    o.banner = "Usage: #{File.basename($0)} [options] oldfile newfile"
    o.separator ''
    o.on(
      '-c', '-C', '--context [LINES]', Integer,
      'Displays a context diff with LINES lines', 'of context. Default 3 lines.'
    ) do |ctx|
      @format = :context
      @lines  = ctx || 3
    end
    o.on(
      '-u', '-U', '--unified [LINES]', Integer,
      'Displays a unified diff with LINES lines', 'of context. Default 3 lines.'
    ) do |ctx|
      @format = :unified
      @lines  = ctx || 3
    end
    o.on('-e', 'Creates an \'ed\' script to change', 'oldfile to newfile.') do |_ctx|
      @format = :ed
    end
    o.on('-f', 'Creates an \'ed\' script to change', 'oldfile to newfile in reverse order.') do |_ctx|
      @format = :reverse_ed
    end
    o.on(
      '-a', '--text',
      'Treat the files as text and compare them', 'line-by-line, even if they do not seem', 'to be text.'
    ) do |_txt|
      @binary = false
    end
    o.on('--binary', 'Treats the files as binary.') do |_bin|
      @binary = true
    end
    o.on('-q', '--brief', 'Report only whether or not the files', 'differ, not the details.') do |_ctx|
      @format = :report
    end
    o.on_tail('--help', 'Shows this text.') do
      error << o
      return 0
    end
    o.on_tail('--version', 'Shows the version of Diff::LCS.') do
      error << Diff::LCS::Ldiff::BANNER
      return 0
    end
    o.on_tail ''
    o.on_tail 'By default, runs produces an "old-style" diff, with output like UNIX diff.'
    o.parse!
  end
  unless args.size == 2
    error << args.options
    return 127
  end
  # Defaults are for old-style diff
  @format ||= :old
  @lines  ||= 0
  file_old, file_new = *ARGV
  case @format
  when :context
    char_old = '*' * 3
    char_new = '-' * 3
  when :unified
    char_old = '-' * 3
    char_new = '+' * 3
  end
  # After we've read up to a certain point in each file, the number of
  # items we've read from each file will differ by FLD (could be 0).
  file_length_difference = 0
  if @binary.nil? or @binary
    data_old = IO.read(file_old)
    data_new = IO.read(file_new)
    # Test binary status
    if @binary.nil?
      old_txt = data_old[0, 4096].scan(/\0/).empty?
      new_txt = data_new[0, 4096].scan(/\0/).empty?
      @binary = !old_txt or !new_txt
    end
    unless @binary
      data_old = data_old.split($/).map { |e| e.chomp }
      data_new = data_new.split($/).map { |e| e.chomp }
    end
  else
    data_old = IO.readlines(file_old).map { |e| e.chomp }
    data_new = IO.readlines(file_new).map { |e| e.chomp }
  end
  # diff yields lots of pieces, each of which is basically a Block object
  if @binary
    diffs = (data_old == data_new)
  else
    diffs = Diff::LCS.diff(data_old, data_new)
    diffs = nil if diffs.empty?
  end
  return 0 unless diffs
  if @format == :report
    output << "Files #{file_old} and #{file_new} differ\n"
    return 1
  end
  if (@format == :unified) or (@format == :context)
    ft = File.stat(file_old).mtime.localtime.strftime('%Y-%m-%d %H:%M:%S.000000000 %z')
    output << "#{char_old} #{file_old}\t#{ft}\n"
    ft = File.stat(file_new).mtime.localtime.strftime('%Y-%m-%d %H:%M:%S.000000000 %z')
    output << "#{char_new} #{file_new}\t#{ft}\n"
  end
  # Loop over hunks. If a hunk overlaps with the last hunk, join them.
  # Otherwise, print out the old one.
  oldhunk = hunk = nil
  if @format == :ed
    real_output = output
    output = []
  end
  diffs.each do |piece|
    begin
      hunk = Diff::LCS::Hunk.new(data_old, data_new, piece, @lines, file_length_difference)
      file_length_difference = hunk.file_length_difference
      next unless oldhunk
      next if @lines.positive? and hunk.merge(oldhunk)
      output << oldhunk.diff(@format) << "\n"
    ensure
      oldhunk = hunk
    end
  end
  last = oldhunk.diff(@format)
  last << "\n" if last.respond_to?(:end_with?) && !last.end_with?("\n")
  output << last
  output.reverse_each { |e| real_output << e.diff(:ed_finish) } if @format == :ed
  1
end