Crystal Lang: Screwing around, trying to figure out a simple way to parse a route w/ named parameters (and optional ones)

route-parser.cr

#idiotcoder.com
#eatcodegame.com

class RouteParser
  @default_regex_replacement = "w+"

  getter regex_variables = {} of String => String
  getter default_variables = {} of String => String
  getter matched_variables = [] of String

  def initialize(@route = "")
    extract_variables()
  end

  def regex(key : String, val : String)
    if @matched_variables.includes?(key)
      @regex_variables[key] = val
    end
    
    self
  end

  def default(key : String, val : String)
    if @matched_variables.includes?(key)
      @default_variables[key] = val
    end
    
    self
  end

  private def extract_variables
    # reset array so we can't call this multiple times
    @matched_variables = [] of String

    # start the process
    extract_variables(@route)
  end

  private def extract_variables(find : String)
    if found = find.match /(?:\:([A-Za-z]+))/
      if !found[1]?.nil?
        @matched_variables << found[1] if !@matched_variables.includes?(found[1])
        if !found.not_nil!.post_match.empty?
          extract_variables(found.post_match)
        end
      end
    end
  end

  def parse
    # replace [] with (?:)? optional groups
    route = @route.gsub("[", "(?:")
    route = route.gsub("]", ")?")
    route = route.gsub("/", "\\/")

    @matched_variables.each do |mv|
      rex = @regex_variables.fetch(mv, "\\" + @default_regex_replacement)
      route = route.sub(":" + mv, "(?<" + mv + ">" + rex + ")")
    end

    route
  end

end

str = "/post/:id[/:slug[/:other]]"
parser = RouteParser.new str
parser
  .default("id", "1")
  .default("slug", "")
  .default("other", "")
  .regex("id", %(\\d+))
  .regex("other", %([A-Za-z]+\\-\\d+))

route = "/post/10/custm_slug/page-10"

if found = route.match /^#{parser.parse}$/
  puts found.not_nil!["id"]?    # => 10
  puts found.not_nil!["slug"]?  # => custom_slug
  puts found.not_nil!["other"]? # => page-10
end

puts parser.matched_variables   # => ["id", "slug", "other"]
puts parser.default_variables   # => {"id" => "1", "slug" => "", "other" => ""}
puts parser.regex_variables     # => {"id" => "\\d+", "other" => "[A-Za-z]+\\-\\d+"}
puts parser.parse               # => \/post\/(?<id>\d+)(?:\/(?<slug>\w+)(?:\/(?<other>[A-Za-z]+\-\d+))?)?