SyntaxSuggest::ScanHistory#scan

# File tmp/rubies/ruby-3.3.0/lib/syntax_suggest/scan_history.rb, line 64
def scan(up:, down:)
  kw_count = 0
  end_count = 0

  up_index = before_lines.reverse_each.take_while do |line|
    kw_count += 1 if line.is_kw?
    end_count += 1 if line.is_end?
    up.call(line, kw_count, end_count)
  end.last&.index

  kw_count = 0
  end_count = 0

  down_index = after_lines.each.take_while do |line|
    kw_count += 1 if line.is_kw?
    end_count += 1 if line.is_end?
    down.call(line, kw_count, end_count)
  end.last&.index

  @before_index = if up_index && up_index < @before_index
    up_index
  else
    @before_index
  end

  @after_index = if down_index && down_index > @after_index
    down_index
  else
    @after_index
  end

  self
end