Rubocop with support for autocorrecting only within a specified line range

rubocop-auto-correct-range

#!/usr/bin/env ruby
DEBUG = false
start_line_index, end_line_index, filename = ARGV

start_line = start_line_index.to_i - 1
end_line = end_line_index.to_i - 1

source_lines = STDIN.readlines

lines_before = source_lines[0...start_line]
lines_after = source_lines[(end_line + 1)..-1]

start_comment = '# BEGIN AUTO CORRECT'
end_comment = '# END AUTO CORRECT'

unless start_line.zero?
  # Add comment to end of line before start line
  prev_line = start_line - 1
  line = source_lines[prev_line]
  source_lines[prev_line] = line.sub(/\n$/, "#{start_comment}\n")
end

# Add comment to end of last line
line = source_lines[end_line]
source_lines[end_line] = line.sub(/\n$/, "#{end_comment}\n")

if DEBUG
  puts 'lines_before'
  puts lines_before.join
  puts '=' * 30

  puts 'lines_after'
  puts lines_after.join
  puts '=' * 30

  puts 'annotated source'
  puts source_lines.join
  puts '=' * 30
end

cmd = "rubocop --auto-correct -o /dev/null -s #{filename}"
output_lines = nil
IO.popen(cmd, 'a+') do |f|
  f.puts source_lines.join
  f.close_write
  output_lines = f.readlines
end
output_lines.shift # remove first line of output

if DEBUG
  puts 'output'
  puts output_lines.join
  puts '=' * 30
end

begin_output = 0
if start_line != 0
  terminator = "#{start_comment}\n"
  line_with_comment = output_lines.index { |l| l.end_with? terminator }
  begin_output = line_with_comment + 1
end

end_terminator = "#{end_comment}\n"
line_with_end_comment = output_lines.index { |l| l.end_with? end_terminator }
end_output = line_with_end_comment

formatted_slice = output_lines[begin_output..end_output]
formatted_slice[-1] = formatted_slice[-1].sub(/ *#{end_comment}/, '')

if DEBUG
  puts 'formatted_slice'
  puts formatted_slice.join
  puts '=' * 30
end

print lines_before.join
print formatted_slice.join
print lines_after.join

vimrc

" Install plugin https://github.com/Chiel92/vim-autoformat
let g:formatdef_rubocop = "'~/.bin/rubocop-auto-correct-range '.a:firstline.' '.a:lastline.' '.bufname('%')"