class ActionDispatch::Journey::Format

def self.required_path(symbol)
  Parameter.new symbol, ESCAPE_PATH
end

def self.required_segment(symbol)
  Parameter.new symbol, ESCAPE_SEGMENT
end

def evaluate(hash)
  parts = @parts.dup
  @parameters.each do |index|
    param = parts[index]
    value = hash[param.name]
    return ''.freeze unless value
    parts[index] = param.escape value
  end
  @children.each { |index| parts[index] = parts[index].evaluate(hash) }
  parts.join
end

def initialize(parts)
  @parts      = parts
  @children   = []
  @parameters = []
  parts.each_with_index do |object,i|
    case object
    when Journey::Format
      @children << i
    when Parameter
      @parameters << i
    end
  end
end