socketry/falcon

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lib/falcon/adapters/output.rb

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# frozen_string_literal: true

# Copyright, 2018, by Samuel G. D. Williams. <http://www.codeotaku.com>
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

require 'protocol/http/body/readable'
require 'protocol/http/body/file'

module Falcon
    module Adapters
        # Wraps the rack response body.
        #
        # The `rack` body must respond to `each` and must only yield `String` values. If the body responds to `close`, it will be called after iteration. If the body is replaced by a middleware after action, the original body must be closed first, if it responds to `close`. If the body responds to `to_path`, it must return a String identifying the location of a file whose contents are identical to that produced by calling `each`; this may be used by the server as an alternative, possibly more efficient way to transport the response. The body commonly is an `Array` of strings, the application instance itself, or a `File`-like object.
        class Output < ::Protocol::HTTP::Body::Readable
            CONTENT_LENGTH = 'content-length'.freeze
            
            # Wraps an array into a buffered body.
            # @parameter status [Integer] The response status.
            # @parameter headers [Protocol::HTTP::Headers] The response headers.
            # @parameter body [Object] The `rack` response body.
            def self.wrap(status, headers, body)
                # In no circumstance do we want this header propagating out:
                if length = headers.delete(CONTENT_LENGTH)
                    # We don't really trust the user to provide the right length to the transport.
                    length = Integer(length)
                end
                
                if body.is_a?(::Protocol::HTTP::Body::Readable)
                    return body
                elsif status == 200 and body.respond_to?(:to_path)
                    # Don't mangle partial responsese (206)
                    return ::Protocol::HTTP::Body::File.open(body.to_path)
                elsif body.is_a?(Array)
                    length ||= body.sum(&:bytesize)
                    return self.new(body, length)
                else
                    return self.new(body, length)
                end
            end
            
            # Initialize the output wrapper.
            # @parameter body [Object] The rack response body.
            # @parameter length [Integer] The rack response length.
            def initialize(body, length)
                @length = length
                @body = body
                
                @chunks = nil
            end
            
            # The rack response body.
            attr :body
            
            # The content length of the rack response body.
            attr :length
            
            # Whether the body is empty.
            def empty?
                @length == 0 or (@body.respond_to?(:empty?) and @body.empty?)
            end
            
            # Whether the body can be read immediately.
            def ready?
                true
            end
            
            # Close the response body.
            def close(error = nil)
                if @body and @body.respond_to?(:close)
                    @body.close
                end
                
                @body = nil
                @chunks = nil
                
                super
            end
            
            # Enumerate the response body.
            # @yields {|chunk| ...}
            #     @parameter chunk [String]
            def each(&block)
                @body.each(&block)
            ensure
                self.close($!)
            end
            
            # Read the next chunk from the response body.
            # @returns [String | Nil]
            def read
                @chunks ||= @body.to_enum(:each)
                
                return @chunks.next
            rescue StopIteration
                return nil
            end
            
            def inspect
                "\#<#{self.class} length=#{@length.inspect} body=#{@body.class}>"
            end
        end
    end
end