class ProgressBar::Format::Formatter

def self.process(format_string, max_length, bar)
  processed_string = format_string.dup
  format_string.non_bar_molecules.each do |molecule|
    processed_string.gsub!(molecule.full_key, molecule.lookup_value(bar, nil))
  end
  processed_string.gsub!(/%%/, '%')
  bar_length         = max_length -
                       processed_string.displayable_length +
                       format_string.bar_molecule_placeholder_length
  bar_length         = 0 if bar_length < 0
  format_string.bar_molecules.each do |molecule|
    processed_string.gsub!(molecule.full_key,
                           molecule.lookup_value(bar, bar_length))
  end
  processed_string
end