# frozen_string_literal: true require "active_support/inflector/methods" require "active_support/dependencies" module ActionDispatch class MiddlewareStack class Middleware attr_reader :args, :block, :klass def initialize(klass, args, block) @klass = klass @args = args @block = block end def name; klass.name; end def ==(middleware) case middleware when Middleware klass == middleware.klass when Class klass == middleware end end def inspect if klass.is_a?(Class) klass.to_s else klass.class.to_s end end def build(app) klass.new(app, *args, &block) end def build_instrumented(app) InstrumentationProxy.new(build(app), inspect) end end # This class is used to instrument the execution of a single middleware. # It proxies the `call` method transparently and instruments the method # call. class InstrumentationProxy EVENT_NAME = "process_middleware.action_dispatch" def initialize(middleware, class_name) @middleware = middleware @payload = { middleware: class_name, } end def call(env) ActiveSupport::Notifications.instrument(EVENT_NAME, @payload) do @middleware.call(env) end end end include Enumerable attr_accessor :middlewares def initialize(*args) @middlewares = [] yield(self) if block_given? end def each @middlewares.each { |x| yield x } end def size middlewares.size end def last middlewares.last end def [](i) middlewares[i] end def unshift(klass, *args, &block) middlewares.unshift(build_middleware(klass, args, block)) end def initialize_copy(other) self.middlewares = other.middlewares.dup end def insert(index, klass, *args, &block) index = assert_index(index, :before) middlewares.insert(index, build_middleware(klass, args, block)) end alias_method :insert_before, :insert def insert_after(index, *args, &block) index = assert_index(index, :after) insert(index + 1, *args, &block) end def swap(target, *args, &block) index = assert_index(target, :before) insert(index, *args, &block) middlewares.delete_at(index + 1) end def delete(target) middlewares.delete_if { |m| m.klass == target } end def use(klass, *args, &block) middlewares.push(build_middleware(klass, args, block)) end def build(app = nil, &block) instrumenting = ActiveSupport::Notifications.notifier.listening?(InstrumentationProxy::EVENT_NAME) middlewares.freeze.reverse.inject(app || block) do |a, e| if instrumenting e.build_instrumented(a) else e.build(a) end end end private def assert_index(index, where) i = index.is_a?(Integer) ? index : middlewares.index { |m| m.klass == index } raise "No such middleware to insert #{where}: #{index.inspect}" unless i i end def build_middleware(klass, args, block) Middleware.new(klass, args, block) end end end