etags: add strong and weak matchers

Author: zarqman

lib/protocol/http/header/etags.rb

@@ -8,15 +8,32 @@
 module Protocol
 	module HTTP
 		module Header
-			# This implementation is not strictly correct according to the RFC-specified format.
 			class ETags < Split
 				def wildcard?
 					self.include?('*')
 				end
 
+				# This implementation is not strictly correct according to the RFC-specified format.
 				def match?(etag)
 					wildcard? || self.include?(etag)
 				end
+				
+				# Useful with If-Match
+				def strong_match?(etag)
+					wildcard? || self.reject{|t| weak_tag?(t)}.include?(etag)
+				end
+				
+				# Useful with If-None-Match
+				def weak_match?(etag)
+					opposite_tag = weak_tag?(etag) ? etag[2..-1] : "W/#{etag}"
+					wildcard? || self.include?(etag) || self.include?(opposite_tag)
+				end
+				
+				private
+				
+				def weak_tag?(tag)
+					tag&.start_with? 'W/'
+				end
 			end
 		end
 	end

test/protocol/http/header/etags.rb

@@ -14,21 +14,43 @@
 		end
 
 		it "matches anything" do
-			expect(header).to be(:match?, "anything")
+			expect(header).to be(:match?, '"anything"')
 		end
 	end
 
-	with "abcd" do
+	with '"abcd"' do
 		it "is not a wildcard" do
 			expect(header).not.to be(:wildcard?)
 		end
 
 		it "matches itself" do
-			expect(header).to be(:match?, "abcd")
+			expect(header).to be(:match?, '"abcd"')
+		end
+		
+		it "strongly matches only another strong etag" do
+			expect(header).to be(:strong_match?, '"abcd"')
+			expect(header).not.to be(:strong_match?, 'W/"abcd"')
+		end
+		
+		it "weakly matches both weak and strong etags" do
+			expect(header).to be(:weak_match?, '"abcd"')
+			expect(header).to be(:weak_match?, 'W/"abcd"')
 		end
 
 		it "does not match anything else" do
-			expect(header).not.to be(:match?, "anything else")
+			expect(header).not.to be(:match?, '"anything else"')
+		end
+	end
+	
+	with 'W/"abcd"' do
+		it "never strongly matches" do
+			expect(header).not.to be(:strong_match?, '"abcd"')
+			expect(header).not.to be(:strong_match?, 'W/"abcd"')
+		end
+		
+		it "weakly matches both weak and strong etags" do
+			expect(header).to be(:weak_match?, '"abcd"')
+			expect(header).to be(:weak_match?, 'W/"abcd"')
 		end
 	end
 end