class Rouge::Lexers::VimL

def find_likely_mapping(mapping, word)
  min = 0
  max = mapping.size
  until max == min
    mid = (max + min) / 2
    cmp, _ = mapping[mid]
    case word <=> cmp
    when 1
      # too low
      min = mid + 1
    when -1
      # too high
      max = mid
    when 0
      # just right, abort!
      return mapping[mid]
    end
  end
  mapping[max - 1]
end