Rack::URLMap takes a hash mapping urls or paths to apps, and dispatches accordingly. Support for HTTP/1.1 host names exists if the URLs start with http:// or https://.

URLMap modifies the SCRIPT_NAME and PATH_INFO such that the part relevant for dispatch is in the SCRIPT_NAME, and the rest in the PATH_INFO. This should be taken care of when you need to reconstruct the URL in order to create links.

URLMap dispatches in such a way that the longest paths are tried first, since they are most specific.

Methods
C
N
R
Constants
NEGATIVE_INFINITY = -1.0 / 0.0
 
INFINITY = 1.0 / 0.0
 
Class Public methods
new(map = {})
# File lib/rack/urlmap.rb, line 18
def initialize(map = {})
  remap(map)
end
Instance Public methods
call(env)
# File lib/rack/urlmap.rb, line 43
def call(env)
  path        = env[PATH_INFO]
  script_name = env[SCRIPT_NAME]
  http_host   = env[HTTP_HOST]
  server_name = env[SERVER_NAME]
  server_port = env[SERVER_PORT]

  is_same_server = casecmp?(http_host, server_name) ||
                   casecmp?(http_host, "#{server_name}:#{server_port}")

  @mapping.each do |host, location, match, app|
    unless casecmp?(http_host, host)              || casecmp?(server_name, host)              || (!host && is_same_server)
      next
    end

    next unless m = match.match(path.to_s)

    rest = m[1]
    next unless !rest || rest.empty? || rest[0] == ?/

    env[SCRIPT_NAME] = (script_name + location)
    env[PATH_INFO] = rest

    return app.call(env)
  end

  [404, {CONTENT_TYPE => "text/plain", "X-Cascade" => "pass"}, ["Not Found: #{path}"]]

ensure
  env[PATH_INFO]   = path
  env[SCRIPT_NAME] = script_name
end
remap(map)
# File lib/rack/urlmap.rb, line 22
def remap(map)
  @mapping = map.map { |location, app|
    if location =~ %r{\Ahttps?://(.*?)(/.*)}
      host, location = $1, $2
    else
      host = nil
    end

    unless location[0] == ?/
      raise ArgumentError, "paths need to start with /"
    end

    location = location.chomp('/')
    match = Regexp.new("^#{Regexp.quote(location).gsub('/', '/+')}(.*)", nil, 'n')

    [host, location, match, app]
  }.sort_by do |(host, location, _, _)|
    [host ? -host.size : INFINITY, -location.size]
  end
end