› Protocol::HTTP › Source › Protocol › HTTP › Header › TE

class TE

The te header indicates the transfer encodings the client is willing to accept. AKA accept-transfer-encoding. How we ended up with te instead of accept-transfer-encoding is a mystery lost to time.

The te header allows a client to indicate which transfer encodings it can handle, and in what order of preference using quality factors.

Definitions

TOKEN = /[!#$%&'*+\-.0-9A-Z^_`a-z|~]+/

Transfer encoding token pattern

QVALUE = /0(\.[0-9]{0,3})?|1(\.[0]{0,3})?/

Quality value pattern (0.0 to 1.0)

TRANSFER_CODING = /\A(?<name>#{TOKEN})(\s*;\s*q=(?<q>#{QVALUE}))?\z/

Pattern for parsing transfer encoding with optional quality factor

CHUNKED = "chunked"

The chunked transfer encoding

GZIP = "gzip"

The gzip transfer encoding

DEFLATE = "deflate"

The deflate transfer encoding

COMPRESS = "compress"

The compress transfer encoding

IDENTITY = "identity"

The identity transfer encoding

TRAILERS = "trailers"

The trailers pseudo-encoding indicates willingness to accept trailer fields

TransferCoding

A single transfer coding entry with optional quality factor

Implementation

 
TransferCoding = Struct.new(:name, :q) do
	def quality_factor
		(q || 1.0).to_f
	end
	
	def <=> other
		other.quality_factor <=> self.quality_factor
	end
	
	def to_s
		if q && q != 1.0
			"#{name};q=#{q}"
		else
			name.to_s
		end
	end
end

def self.parse(value)

Parses a raw header value.

Signature
parameter　value　String

a raw header value containing comma-separated encodings.

returns　TE

a new instance with normalized (lowercase) encodings.

Implementation

 
def self.parse(value)
	self.new(value.downcase.split(COMMA))
end

def self.coerce(value)

Coerces a value into a parsed header object.

Signature
parameter　value　String | Array

the value to coerce.

returns　TE

a parsed header object with normalized values.

Implementation

 
def self.coerce(value)
	case value
	when Array
		self.new(value.map(&:downcase))
	else
		self.parse(value.to_s)
	end
end

def <<(value)

Adds one or more comma-separated values to the TE header. The values are converted to lowercase for normalization.

Signature
parameter　value　String

a raw header value containing one or more values separated by commas.

Implementation

 
def << value
	super(value.downcase)
end

def transfer_codings

Parse the te header value into a list of transfer codings with quality factors.

Signature
returns　Array(TransferCoding)

the list of transfer codings and their associated quality factors.

Implementation

 
def transfer_codings
	self.map do |value|
		if match = value.match(TRANSFER_CODING)
			TransferCoding.new(match[:name], match[:q])
		else
			raise ParseError.new("Could not parse transfer coding: #{value.inspect}")
		end
	end
end

def chunked?

Signature
returns　Boolean

whether the chunked encoding is accepted.

Implementation

 
def chunked?
	self.any?{|value| value.start_with?(CHUNKED)}
end

def gzip?

Signature
returns　Boolean

whether the gzip encoding is accepted.

Implementation

 
def gzip?
	self.any?{|value| value.start_with?(GZIP)}
end

def deflate?

Signature
returns　Boolean

whether the deflate encoding is accepted.

Implementation

 
def deflate?
	self.any?{|value| value.start_with?(DEFLATE)}
end

def compress?

Signature
returns　Boolean

whether the compress encoding is accepted.

Implementation

 
def compress?
	self.any?{|value| value.start_with?(COMPRESS)}
end

def identity?

Signature
returns　Boolean

whether the identity encoding is accepted.

Implementation

 
def identity?
	self.any?{|value| value.start_with?(IDENTITY)}
end

def trailers?

Signature
returns　Boolean

whether trailers are accepted.

Implementation

 
def trailers?
	self.any?{|value| value.start_with?(TRAILERS)}
end

def self.trailer?

Whether this header is acceptable in HTTP trailers. TE headers negotiate transfer encodings and must not appear in trailers.

Signature
returns　Boolean

false, as TE headers are hop-by-hop and control message framing.

Implementation

 
def self.trailer?
	false
end