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# frozen_string_literal: true
# Released under the MIT License.
# Copyright, 2019-2026, by Samuel Williams.
require_relative "../middleware"
module Protocol
module HTTP
class Middleware
# A convenient interface for constructing middleware stacks.
class Builder
# Initialize the builder with the given default application.
#
# @parameter default_app [Object] The default application to use if no middleware is specified.
def initialize(default_app = NotFound)
@use = []
@app = default_app
end
# Build the middleware application using the given block.
#
# @parameter block [Proc] The block to pass to the middleware constructor.
# @returns [Builder] The builder.
def build(&block)
if block_given?
if block.arity == 0
instance_exec(&block)
else
yield self
end
end
return self
end
# Use the given middleware with the given arguments and options.
#
# @parameter middleware [Class | Object] The middleware class to use.
# @parameter arguments [Array] The arguments to pass to the middleware constructor.
# @parameter options [Hash] The options to pass to the middleware constructor.
# @parameter block [Proc] The block to pass to the middleware constructor.
def use(middleware, *arguments, **options, &block)
@use << proc{|app| middleware.new(app, *arguments, **options, &block)}
end
# Specify the (default) middleware application to use.
#
# @parameter app [Middleware] The application to use if no middleware is able to handle the request.
def run(app)
@app = app
end
# Convert the builder to an application by chaining the middleware together.
#
# @returns [Middleware] The application.
def to_app
@use.reverse.inject(@app){|app, use| use.call(app)}
end
end
# Build a middleware application using the given block.
def self.build(*arguments, &block)
builder = Builder.new(*arguments)
builder.build(&block)
return builder.to_app
end
# Load a middleware application from the given path.
#
# @parameter path [String] The path to the middleware application.
# @parameter arguments [Array] The arguments to pass to the middleware constructor.
# @parameter options [Hash] The options to pass to the middleware constructor.
# @parameter block [Proc] The block to pass to the middleware constructor.
def self.load(path, *arguments, &block)
builder = Builder.new(*arguments)
binding = Builder::TOPLEVEL_BINDING.call(builder)
eval(File.read(path), binding, path)
if block_given?
builder.build(&block)
end
return builder.to_app
end
end
end
end
Protocol::HTTP::Middleware::Builder::TOPLEVEL_BINDING = ->(builder){builder.instance_eval{binding}}
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