Class: Zizq::Middleware::Chain

Inherits:
Object
  • Object
show all
Defined in:
lib/zizq/middleware.rb,
sig/generated/zizq/middleware.rbs

Overview

A linked chain of middleware ending with a terminal.

Each middleware must implement #call(arg, chain) where chain is the next link. The terminal implements #call(arg).

When no middleware is registered, #call delegates directly to the terminal with zero overhead.

chain = Zizq::Middleware::Chain.new(dispatcher)
chain.use(LoggingMiddleware.new)
chain.use(MetricsMiddleware.new)
chain.call(job)
# MetricsMiddleware -> LoggingMiddleware -> dispatcher

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(terminal) ⇒ Chain

: (untyped) -> void

Parameters:

  • terminal (Object) 


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# File 'lib/zizq/middleware.rb', line 29

def initialize(terminal) #: (untyped) -> void
  @terminal = terminal
  @entries = [] #: Array[untyped]
  @built = nil #: untyped?
end

Instance Attribute Details

#terminal ⇒ Object

The terminal callable at the end of the chain.

Returns:

  • (Object) 


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# File 'lib/zizq/middleware.rb', line 27

def terminal
  @terminal
end

Instance Method Details

#build ⇒ Object

: () -> untyped

Returns:

  • (Object) 


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# File 'lib/zizq/middleware.rb', line 54

def build #: () -> untyped
  @built ||= if @entries.empty?
    @terminal
  else
    @entries.reverse.reduce(@terminal) do |next_link, mw|
      Link.new(mw, next_link)
    end
  end
end

#call(arg) ⇒ Object

Execute the chain with the given argument.

Parameters:

  • arg (Object)

Returns:

  • (Object) 


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# File 'lib/zizq/middleware.rb', line 48

def call(arg) #: (Arg) -> Ret
  build.call(arg)
end

#use(middleware) ⇒ Object

Append a middleware to the chain.

Parameters:

  • middleware (Object)

Returns:

  • (Object) 


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# File 'lib/zizq/middleware.rb', line 42

def use(middleware) #: (untyped) -> void
  @entries << middleware
  @built = nil
end