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# frozen_string_literal: true
# Released under the MIT License.
# Copyright, 2019-2025, by Samuel Williams.
require_relative "methods"
require_relative "headers"
require_relative "request"
require_relative "response"
module Protocol
module HTTP
# The middleware interface provides a convenient wrapper for implementing HTTP middleware.
#
# A middleware instance generally needs to respond to two methods:
#
# - `call(request)` -> `response`
# - `close()`
#
# The call method is called for each request. The close method is called when the server is shutting down.
#
# You do not need to use the Middleware class to implement middleware. You can implement the interface directly.
class Middleware < Methods
# Convert a block to a middleware delegate.
#
# @parameter block [Proc] The block to convert to a middleware delegate.
# @returns [Middleware] The middleware delegate.
def self.for(&block)
# Add a close method to the block.
def block.close
end
return self.new(block)
end
# Initialize the middleware with the given delegate.
#
# @parameter delegate [Object] The delegate object. A delegate is used for passing along requests that are not handled by *this* middleware.
def initialize(delegate)
@delegate = delegate
end
# @attribute [Object] The delegate object that is used for passing along requests that are not handled by *this* middleware.
attr :delegate
# Close the middleware. Invokes the close method on the delegate.
def close
@delegate.close
end
# Call the middleware with the given request. Invokes the call method on the delegate.
def call(request)
@delegate.call(request)
end
# A simple middleware that always returns a 200 response.
module Okay
# Close the middleware - idempotent no-op.
def self.close
end
# Call the middleware with the given request, always returning a 200 response.
#
# @parameter request [Request] The request object.
# @returns [Response] The response object, which always contains a 200 status code.
def self.call(request)
Response[200]
end
end
# A simple middleware that always returns a 404 response.
module NotFound
# Close the middleware - idempotent no-op.
def self.close
end
# Call the middleware with the given request, always returning a 404 response. This middleware is useful as a default.
#
# @parameter request [Request] The request object.
# @returns [Response] The response object, which always contains a 404 status code.
def self.call(request)
Response[404]
end
end
# A simple middleware that always returns "Hello World!".
module HelloWorld
# Close the middleware - idempotent no-op.
def self.close
end
# Call the middleware with the given request.
#
# @parameter request [Request] The request object.
# @returns [Response] The response object, whihc always contains "Hello World!".
def self.call(request)
Response[200, Headers["content-type" => "text/plain"], ["Hello World!"]]
end
end
end
end
end
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