Media Range Map

lib/protocol/http/media_types.rb

@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2016-2024, by Samuel Williams.
+
+module Protocol
+	module HTTP
+		class MediaTypes
+			WILDCARD = "*/*".freeze
+
+			def initialize
+				@map = {}
+			end
+
+			def freeze
+				return self if frozen?
+
+				@map.freeze
+				@map.each_value(&:freeze)
+
+				return super
+			end
+
+			# Given a list of content types (e.g. from browser_preferred_content_types), return the best converter. Media types can be an array of MediaRange or String values.
+			def for(media_ranges)
+				media_ranges.each do |media_range|
+					range_string = media_range.range_string
+
+					if object = @map[range_string]
+						return object
+					end
+				end
+
+				return nil
+			end
+
+			def []= media_range, object
+				@map[media_range] = object
+			end
+
+			def [] media_range
+				@map[media_range]
+			end
+
+			# Add a converter to the collection. A converter can be anything that responds to #content_type. Objects will be considered in the order they are added, subsequent objects cannot override previously defined media types. `object` must respond to #split('/', 2) which should give the type and subtype.
+			def << object
+				media_range = object.media_range
+
+				# We set the default if not specified already:
+				@map[WILDCARD] = object if @map.empty?
+
+				type = media_range.type
+				if type != "*"
+					@map["#{type}/*"] ||= object
+
+					subtype = media_range.subtype
+					if subtype != "*"
+						@map["#{type}/#{subtype}"] ||= object
+					end
+				end
+
+				return self
+			end
+		end
+	end
+end

test/protocol/http/media_types.rb

@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2016-2024, by Samuel Williams.
+
+require "protocol/http/accept/media_types"
+require "protocol/http/accept/media_types/map"
+require "protocol/http/accept/content_type"
+
+describe Protocol::HTTP::MediaTypes do
+	let(:converter) do
+		Struct.new(:content_type) do
+			def split(*args)
+				self.content_type.split(*args)
+			end
+		end
+	end
+
+	let(:text_html_converter) {converter.new("text/html")}
+
+	let(:text_plain_content_type) {Protocol::HTTP::Accept::ContentType.new("text", "plain", charset: "utf-8")}
+	let(:text_plain_converter) {converter.new(text_plain_content_type)}
+
+	let(:map) {subject.new}
+
+	it "should give the correct converter when specified completely" do
+		map << text_html_converter
+		map << text_plain_converter
+
+		media_types = Protocol::HTTP::Accept::MediaTypes.parse("text/plain, text/*, */*")
+		expect(map.for(media_types).first).to be == text_plain_converter
+
+		media_types = Protocol::HTTP::Accept::MediaTypes.parse("text/html, text/*, */*")
+		expect(map.for(media_types).first).to be == text_html_converter
+	end
+
+	it "should match the wildcard subtype converter" do
+		map << text_html_converter
+		map << text_plain_converter
+
+		media_types = Protocol::HTTP::Accept::MediaTypes.parse("text/*, */*")
+		expect(map.for(media_types).first).to be == text_html_converter
+
+		media_types = Protocol::HTTP::Accept::MediaTypes.parse("*/*")
+		expect(map.for(media_types).first).to be == text_html_converter
+	end
+
+	it "should fail to match if no media types match" do
+		map << text_plain_converter
+
+		expect(map.for(["application/json"])).to be_nil
+	end
+
+	it "should fail to match if no media types specified" do
+		expect(map.for(["text/*", "*/*"])).to be_nil
+	end
+
+	it "should freeze converters" do
+		map << text_html_converter
+
+		map.freeze
+
+		expect(text_html_converter).to be(:frozen?)
+	end
+
+	it "should assign and retrive media ranges" do
+		map["*/*"] = :test
+
+		expect(map["*/*"]).to be == :test
+	end
+end