module Rack
# Rack::Cascade tries a request on several apps, and returns the
# first response that is not 404 or 405 (or in a list of configurable
# status codes).
class Cascade
NotFound = [404, {CONTENT_TYPE => "text/plain"}, []]
attr_reader :apps
def initialize(apps, catch=[404, 405])
@apps = []; @has_app = {}
apps.each { |app| add app }
@catch = {}
[*catch].each { |status| @catch[status] = true }
end
def call(env)
result = NotFound
last_body = nil
@apps.each do |app|
# The SPEC says that the body must be closed after it has been iterated
# by the server, or if it is replaced by a middleware action. Cascade
# replaces the body each time a cascade happens. It is assumed that nil
# does not respond to close, otherwise the previous application body
# will be closed. The final application body will not be closed, as it
# will be passed to the server as a result.
last_body.close if last_body.respond_to? :close
result = app.call(env)
last_body = result[2]
break unless @catch.include?(result[0].to_i)
end
result
end
def add(app)
@has_app[app] = true
@apps << app
end
def include?(app)
@has_app.include? app
end
alias_method :<<, :add
end
end
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