Add stable weighted header preferences.

lib/protocol/http/header/accept.rb

@@ -113,9 +113,7 @@ def media_ranges
 				#
 				# @returns [Array(MediaRange)] the preferred media ranges.
 				def preferred_media_ranges
-					media_ranges.sort_by.with_index do |media_range, index|
-						[-media_range.quality_factor, index]
-					end
+					sort_by_quality_factor(media_ranges)
 				end
 
 				private

lib/protocol/http/header/accept_charset.rb

@@ -47,6 +47,15 @@ def charsets
 						end
 					end
 				end
+
+				# Parse the `accept-charset` header and order character sets by preference.
+				#
+				# Character sets with equal quality factors retain their original relative order.
+				#
+				# @returns [Array(Charset)] the preferred character sets.
+				def preferred_charsets
+					sort_by_quality_factor(charsets)
+				end
 			end
 		end
 	end

lib/protocol/http/header/accept_encoding.rb

@@ -50,6 +50,15 @@ def encodings
 						end
 					end
 				end
+
+				# Parse the `accept-encoding` header and order encodings by preference.
+				#
+				# Encodings with equal quality factors retain their original relative order.
+				#
+				# @returns [Array(Encoding)] the preferred encodings.
+				def preferred_encodings
+					sort_by_quality_factor(encodings)
+				end
 			end
 		end
 	end

lib/protocol/http/header/accept_language.rb

@@ -53,6 +53,15 @@ def languages
 						end
 					end
 				end
+
+				# Parse the `accept-language` header and order languages by preference.
+				#
+				# Languages with equal quality factors retain their original relative order.
+				#
+				# @returns [Array(Language)] the preferred languages.
+				def preferred_languages
+					sort_by_quality_factor(languages)
+				end
 			end
 		end
 	end

lib/protocol/http/header/split.rb

@@ -77,6 +77,14 @@ def self.trailer?
 				end
 
 			protected
+				# Order weighted values by descending quality while preserving their relative order.
+				# @parameter values [Enumerable] The values which respond to `#quality_factor`.
+				# @returns [Array] The ordered values.
+				def sort_by_quality_factor(values)
+					values.sort_by.with_index do |value, index|
+						[-value.quality_factor, index]
+					end
+				end
 
 				def reverse_find(&block)
 					reverse_each do |value|

lib/protocol/http/header/te.rb

@@ -113,6 +113,15 @@ def transfer_codings
 					end
 				end
 
+				# Parse the `te` header and order transfer codings by preference.
+				#
+				# Transfer codings with equal quality factors retain their original relative order.
+				#
+				# @returns [Array(TransferCoding)] the preferred transfer codings.
+				def preferred_transfer_codings
+					sort_by_quality_factor(transfer_codings)
+				end
+
 				# @returns [Boolean] whether the `chunked` encoding is accepted.
 				def chunked?
 					self.any?{|value| value.start_with?(CHUNKED)}

releases.md

@@ -2,7 +2,7 @@
 
 ## Unreleased
 
-  - Add stable preference ordering for `Accept` media ranges.
+  - Add stable preference ordering for weighted `Accept`, `Accept-Charset`, `Accept-Encoding`, `Accept-Language`, and `TE` values.
 
 ## v0.69.0
 

test/protocol/http/header/accept_charset.rb

@@ -14,7 +14,7 @@
 
 describe Protocol::HTTP::Header::AcceptCharset do
 	let(:header) {subject.parse(description)}
-	let(:charsets) {header.charsets.sort}
+	let(:charsets) {header.preferred_charsets}
 
 	with "utf-8, iso-8859-1;q=0.5, windows-1252;q=0.25" do
 		it "can parse charsets" do

test/protocol/http/header/accept_encoding.rb

@@ -14,7 +14,7 @@
 
 describe Protocol::HTTP::Header::AcceptEncoding do
 	let(:header) {subject.parse(description)}
-	let(:encodings) {header.encodings.sort}
+	let(:encodings) {header.preferred_encodings}
 
 	with "gzip, deflate;q=0.5, identity;q=0.25" do
 		it "can parse charsets" do

test/protocol/http/header/accept_language.rb

@@ -14,7 +14,7 @@
 
 describe Protocol::HTTP::Header::AcceptLanguage do
 	let(:header) {subject.parse(description)}
-	let(:languages) {header.languages.sort}
+	let(:languages) {header.preferred_languages}
 
 	with "da, en-gb;q=0.5, en;q=0.25" do
 		it "can parse languages" do

test/protocol/http/header/te.rb

@@ -62,12 +62,19 @@
 
 	with "gzip;q=0.5, deflate;q=0.8" do
 		it "handles multiple quality factors" do
-			codings = header.transfer_codings.sort
+			codings = header.preferred_transfer_codings
 			expect(codings[0].name).to be == "deflate"  # higher quality first
 			expect(codings[1].name).to be == "gzip"
 		end
 	end
 
+	with "gzip, deflate;q=0.5, compress;q=0.5" do
+		it "preserves relative order for equal quality factors" do
+			codings = header.preferred_transfer_codings
+			expect(codings.collect(&:name)).to be == %w{gzip deflate compress}
+		end
+	end
+
 	with "empty header value" do
 		let(:header) {subject.new}