Add :uri option to Format,content_type, and uris and to_uri class methods. This allows retrieving the defined format URI for specified formats. (See https://www.w3.org/ns/formats/).

Author: gkellogg

lib/rdf/format.rb

@@ -23,7 +23,9 @@ module RDF
   #
   # @example Defining a new RDF serialization format class
   #   class RDF::NTriples::Format < RDF::Format
-  #     content_type     'application/n-triples', extension: :nt
+  #     content_type     'application/n-triples',
+  #                      extension: :nt,
+  #                      uri: RDF::URI("http://www.w3.org/ns/formats/N-Triples")
   #     content_encoding 'utf-8'
   #     
   #     reader RDF::NTriples::Reader
@@ -222,6 +224,19 @@ def self.file_extensions
       @@file_extensions
     end
 
+    ##
+    # Returns the unique URI for the format.
+    #
+    # @example retrieving a list of supported file format URIs
+    #
+    #     RDF::Format.uris.keys
+    #
+    # @see https://www.w3.org/ns/formats/
+    # @return [Hash{Symbol => URI}]
+    def self.uris
+      @@uris
+    end
+
     ##
     # Returns the set of format symbols for available RDF::Reader subclasses.
     #
@@ -465,6 +480,7 @@ class << self
     #   @option options [Array<String>]  :aliases (nil)
     #   @option options [Symbol]         :extension  (nil)
     #   @option options [Array<Symbol>]  :extensions (nil)
+    #   @option options [URI]            :uri   (nil)
     #   @return [void]
     #
     # @overload content_type
@@ -504,6 +520,10 @@ def self.content_type(type = nil, options = {})
             @@content_types[aa] << self unless @@content_types[aa].include?(self)
           end
         end
+        # URI identifying this format
+        if uri = options[:uri]
+          @@uris[RDF::URI(uri)] = self
+        end
       end
     end
 
@@ -517,7 +537,7 @@ def self.accept_type
     end
 
     ##
-    # Retrieves or defines file extensions for this RDF serialization format.
+    # Retrieves file extensions for this RDF serialization format.
     #
     # The return is an array where the first element is the cannonical
     # file extension for the format and following elements are alias file extensions.
@@ -527,6 +547,17 @@ def self.file_extension
       @@file_extensions.map {|ext, formats| ext if formats.include?(self)}.compact
     end
 
+    ##
+    # Retrieves any format URI defined for this format..
+    #
+    # @return [URI]
+    def self.uri
+      @@uris.invert[self]
+    end
+    class << self
+      alias_method :to_uri, :uri
+    end
+
   protected
 
     ##
@@ -568,6 +599,7 @@ def self.content_encoding(encoding = nil)
     @@readers          = {} # @private
     @@writers          = {} # @private
     @@subclasses       = [] # @private
+    @@uris             = {} # @private
 
     ##
     # @private

lib/rdf/nquads.rb

@@ -20,7 +20,10 @@ 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;q=0.2'
+      content_type     'application/n-quads',
+                       extension: :nq,
+                       alias: 'text/x-nquads;q=0.2',
+                       uri: RDF::URI("http://www.w3.org/ns/formats/N-Quads")
       content_encoding 'utf-8'
 
       reader { RDF::NQuads::Reader }

lib/rdf/ntriples/format.rb

@@ -16,7 +16,10 @@ 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;q=0.2'
+    content_type     'application/n-triples',
+                     extension: :nt,
+                     alias: 'text/plain;q=0.2',
+                     uri: RDF::URI("http://www.w3.org/ns/formats/N-Triples")
     content_encoding 'utf-8'
 
     reader { RDF::NTriples::Reader }

spec/format_spec.rb

@@ -5,7 +5,8 @@
 
 class RDF::Format::FooFormat < RDF::Format
   content_type     'application/test;q=1',
-                   extension: :test
+                   extension: :test,
+                   uri: "http://example.com/ns/formats/Foo"
   reader { RDF::NTriples::Reader }
   def self.detect(sample)
     sample == "foo"
@@ -16,7 +17,8 @@ def self.to_sym; :foo_bar; end
 class RDF::Format::BarFormat < RDF::Format
   content_type     'application/test',
                    extension: :test,
-                   alias: 'application/x-test;q=0.1'
+                   alias: 'application/x-test;q=0.1',
+                   uri: "http://example.com/ns/formats/Bar"
   reader { RDF::NTriples::Reader }
   def self.detect(sample)
     sample == "bar"
@@ -129,6 +131,16 @@ def self.to_sym; :foo_bar; end
     end
   end
 
+  describe ".uris" 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
+
   describe ".writer_symbols" do
     it "returns symbols of available writers" do
       %i(ntriples nquads).each do |sym|
@@ -152,6 +164,15 @@ def self.to_sym; :foo_bar; end
     end
   end
 
+  describe ".uris" do
+    it "matches format classes to URIs" do
+      RDF::Format.uris.each do |u, c|
+        expect(u).to be_a(RDF::URI)
+        expect(c).to respond_to(:content_type)
+      end
+    end
+  end
+
   RDF::Format.each do |format|
     context format.name do
       subject {format}
@@ -166,6 +187,20 @@ def self.to_sym; :foo_bar; end
     end
   end
 
+  describe RDF::NTriples::Format do
+    it "has a format URI" do
+      expect(described_class.uri).to eql RDF::URI('http://www.w3.org/ns/formats/N-Triples')
+      expect(described_class.to_uri).to eql RDF::URI('http://www.w3.org/ns/formats/N-Triples')
+    end
+  end
+
+  describe RDF::NQuads::Format do
+    it "has a format URI" do
+      expect(described_class.uri).to eql RDF::URI('http://www.w3.org/ns/formats/N-Quads')
+      expect(described_class.to_uri).to eql RDF::URI('http://www.w3.org/ns/formats/N-Quads')
+    end
+  end
+
   context "Examples" do
     require 'rdf/ntriples'
     subject {RDF::Format}