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# 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
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