Add Format.accept_types and Format.accept_type. This allows `Form…

…at.content_type` to be provided with priority parameters for the `type`, and `aliases`. These are stripped out to allow `Format.reader_types` and so-forth, to continue to return values without parameters.

Fixes #327.

lib/rdf/format.rb

@@ -207,6 +207,19 @@ def self.reader_types
       reader_symbols.flat_map {|s| RDF::Format.for(s).content_type}.uniq
     end
 
+    ##
+    # Returns the set of content types with quality for available RDF::Reader subclasses.
+    #
+    # @example
+    #
+    #     accept_types = RDF::Format.accept_types
+    #     # => %w(text/html;q=0.5 text/turtle ...)
+    #
+    # @return [Array<String>]
+    def self.accept_types
+      reader_symbols.flat_map {|s| RDF::Format.for(s).accept_type}.uniq
+    end
+
     ##
     # Returns the set of format symbols for available RDF::Writer subclasses.
     #
@@ -400,6 +413,11 @@ class << self
     #   extensions, that should be mapped to the given MIME type and handled
     #   by this class.
     #
+    #   Optionally, both `type`, `alias`, and `aliases`, may be parameterized
+    #   for expressing quality.
+    #
+    #       content_type "text/html;q=0.4"
+    #
     #   @param  [String]                 type
     #   @param  [Hash{Symbol => Object}] options
     #   @option options [String]         :alias   (nil)
@@ -420,10 +438,14 @@ def self.content_type(type = nil, options = {})
         [@@content_type[self], @@content_types.map {
           |ct, cl| (cl.include?(self) && ct != @@content_type[self]) ?  ct : nil }].flatten.compact
       else
+        accept_type, type = type, type.split(';').first
         @@content_type[self] = type
         @@content_types[type] ||= []
         @@content_types[type] << self unless @@content_types[type].include?(self)
 
+        @@accept_types[accept_type] ||= []
+        @@accept_types[accept_type] << self unless @@accept_types[accept_type].include?(self)
+
         if extensions = (options[:extension] || options[:extensions])
           extensions = Array(extensions).map(&:to_sym)
           extensions.each do |ext|
@@ -433,13 +455,26 @@ def self.content_type(type = nil, options = {})
         end
         if aliases = (options[:alias] || options[:aliases])
           aliases = Array(aliases).each do |a|
-            @@content_types[a] ||= []
-            @@content_types[a] << self unless @@content_types[a].include?(self)
+            aa = a.split(';').first
+            @@accept_types[a] ||= []
+            @@accept_types[a] << self unless @@accept_types[a].include?(self)
+
+            @@content_types[aa] ||= []
+            @@content_types[aa] << self unless @@content_types[aa].include?(self)
           end
         end
       end
     end
 
+    ##
+    # Returns an array of values appropriate for an Accept header.
+    # Same as `self.content_type`, if no parameter is given when defined.
+    #
+    # @return [Array<String>]
+    def self.accept_type
+      @@accept_types.map {|t, formats| t if formats.include?(self)}.compact
+    end
+
     ##
     # Retrieves or defines file extensions for this RDF serialization format.
     #
@@ -488,6 +523,7 @@ def self.content_encoding(encoding = nil)
     @@content_type     = {} # @private
     @@content_types    = {} # @private
     @@content_encoding = {} # @private
+    @@accept_types     = {} # @private
     @@readers          = {} # @private
     @@writers          = {} # @private
     @@subclasses       = [] # @private

lib/rdf/nquads.rb

@@ -20,7 +20,7 @@ module NQuads
     # @see http://www.w3.org/TR/n-quads/
     # @since  0.4.0
     class Format < RDF::Format
-      content_type     'application/n-quads', extension: :nq, alias: ['text/x-nquads']
+      content_type     'application/n-quads', extension: :nq, alias: 'text/x-nquads;q=0.2'
       content_encoding 'utf-8'
 
       reader { RDF::NQuads::Reader }

lib/rdf/ntriples/format.rb

@@ -16,7 +16,7 @@ module RDF::NTriples
   # @see http://www.w3.org/TR/rdf-testcases/#ntriples
   # @see http://www.w3.org/TR/n-triples/
   class Format < RDF::Format
-    content_type     'application/n-triples', extension: :nt, alias: ['text/plain']
+    content_type     'application/n-triples', extension: :nt, alias: 'text/plain;q=0.2'
     content_encoding 'utf-8'
 
     reader { RDF::NTriples::Reader }

lib/rdf/util/file.rb

@@ -39,24 +39,7 @@ def self.headers options
       ##
       # @return [String] the value for an Accept header
       def self.default_accept_header
-        # Receive text/html and text/plain at a lower priority than other formats. Also special cases for other formats.
-        # TODO: Associate priority level when setting `content_type` and use in an alternative to `reader_types`, or to simply change `reader_types`.
-        reader_types = RDF::Format.reader_types.map do |t|
-          case t.to_s
-          when /text\/plain/
-            "#{t};q=0.2"
-          when /text\/(?:csv|tab-separated-values)/
-            "#{t};q=0.4"
-          when /text\/html/
-            "#{t};q=0.5"
-          when /application\/xhtml\+xml/
-            "#{t};q=0.7"
-          else
-            t
-          end
-        end
-
-        (reader_types + %w(*/*;q=0.1)).join(", ")
+        (RDF::Format.accept_types + %w(*/*;q=0.1)).join(", ")
       end
 
       ##

spec/format_spec.rb

@@ -4,7 +4,8 @@
 require 'rdf/nquads'
 
 class RDF::Format::FooFormat < RDF::Format
-  content_type     'application/test', extension: :test
+  content_type     'application/test;q=1',
+                   extension: :test
   reader { RDF::NTriples::Reader }
   def self.detect(sample)
     sample == "foo"
@@ -13,7 +14,9 @@ def self.to_sym; :foo_bar; end
 end
 
 class RDF::Format::BarFormat < RDF::Format
-  content_type     'application/test', extension: :test
+  content_type     'application/test',
+                   extension: :test,
+                   alias: 'application/x-test;q=0.1'
   reader { RDF::NTriples::Reader }
   def self.detect(sample)
     sample == "bar"
@@ -68,13 +71,21 @@ def self.to_sym; :foo_bar; end
 
   describe ".reader_types" do
     it "returns content-types of available readers" do
-      %w(
+      expect(RDF::Format.reader_types).to include(*%w(
         application/n-triples text/plain
         application/n-quads text/x-nquads
-        application/test
-      ).each do |ct|
-        expect(RDF::Format.reader_types).to include(ct)
-      end
+        application/test application/x-test
+      ))
+    end
+  end
+
+  describe ".accept_types" do
+    it "returns accept-types of available readers with quality" do
+      expect(RDF::Format.accept_types).to include(*%w(
+        application/n-triples text/plain;q=0.2
+        application/n-quads text/x-nquads;q=0.2
+        application/test application/x-test;q=0.1
+      ))
     end
   end
 

spec/util_file_spec.rb

@@ -31,7 +31,7 @@
     describe ".default_accept_header" do
       subject { RDF::Util::File::HttpAdapter.default_accept_header.split(", ") }
       before do
-        allow(RDF::Format).to receive(:reader_types).and_return(["text/html", "text/plain", "application/xhtml+xml", "text/csv", "text/tab-separated-values"])
+        allow(RDF::Format).to receive(:accept_types).and_return(["text/html;q=0.5", "text/plain;q=0.2", "application/xhtml+xml;q=0.7", "text/csv;q=0.4", "text/tab-separated-values;q=0.4"])
       end
       it "should demote text/plain to q=0.2" do
         expect(subject).to include "text/plain;q=0.2"