class RuboCop::Cop::Style::Encoding

never - enforce no encoding comment in all files
always - enforce encoding comment in all files
characters, otherwise report an offense
when_needed - only enforce an encoding comment if there are non ASCII
default source file encoding. There are three styles:
for code that should support Ruby 1.9, since in 2.0+ utf-8 is the
Setting this check to “always” and “when_needed” makes sense only
comment or not.
This cop checks whether the source file has a utf-8 encoding

def autocorrect(range) 

def autocorrect(range)
  if @message == MSG_MISSING
    encoding = cop_config[AUTO_CORRECT_ENCODING_COMMENT]
    if encoding && encoding =~ ENCODING_PATTERN
      lambda do |corrector|
        corrector.insert_before(range, "#{encoding}\n")
      end
    else
      raise "#{encoding} does not match #{ENCODING_PATTERN}"
    end
  else
    # Need to remove unnecessary encoding comment
    lambda do |corrector|
      corrector.remove(range_with_surrounding_space(range, :right))
    end
  end
end

def encoding_line_number(processed_source) 

def encoding_line_number(processed_source)
  line_number = 0
  line_number += 1 if processed_source[line_number].start_with?(SHEBANG)
  line_number
end

def investigate(processed_source) 

def investigate(processed_source)
  return if processed_source.buffer.source.empty?
  line_number = encoding_line_number(processed_source)
  return unless (@message = offense(processed_source, line_number))
  range = processed_source.buffer.line_range(line_number + 1)
  add_offense(range, range, @message)
end

def offense(processed_source, line_number) 

def offense(processed_source, line_number)
  line = processed_source[line_number]
  encoding_present = line =~ ENCODING_PATTERN
  ascii_only = processed_source.buffer.source.ascii_only?
  always_encode = style == :always
  never_encode = style == :never
  encoding_omitable = never_encode || (!always_encode && ascii_only)
  if !encoding_present && !encoding_omitable
    MSG_MISSING
  elsif encoding_present && encoding_omitable
    MSG_UNNECESSARY
  end
end