Update N-Triples/Quads ASCII escapes when writing literals based on p…

…roposed RDF 1.2 behavior.

lib/rdf/ntriples/writer.rb

@@ -131,11 +131,10 @@ def self.escape_ascii(u, encoding)
       when (0x0C)       then "\\f"
       when (0x0D)       then "\\r"
       when (0x22)       then "\\\""
-      when (0x27)       then "\\'"
       when (0x5C)       then "\\\\"
       when (0x00..0x1F) then escape_utf16(u)
       when (0x7F)       then escape_utf16(u)
-      when (0x00..0x7F) then u.chr
+      when (0x20..0x7E) then u.chr
       else
         raise ArgumentError.new("expected an ASCII character in (0x00..0x7F), but got 0x#{u.to_s(16)}")
       end

spec/ntriples_spec.rb

@@ -573,7 +573,7 @@
     end
   end
 
-  context "Writing a Statements" do
+  context "Writing Statements" do
     let(:statements) {[
       RDF::Statement(RDF::URI('s'), RDF::URI('p'), RDF::URI('o1')),
       RDF::Statement(RDF::URI('s'), RDF::URI('p'), RDF::URI('o2'))
@@ -600,6 +600,10 @@
       expect(writer.new.format_literal(RDF::Literal.new('Hello, world!'))).to eq '"Hello, world!"'
     end
 
+    it "should correctly format string literals" do
+      expect(writer.new.format_literal(RDF::Literal.new('Hello, world!', datatype: RDF::XSD.string))).to eq '"Hello, world!"'
+    end
+
     it "should correctly format language-tagged literals" do
       expect(writer.new.format_literal(RDF::Literal.new('Hello, world!', language: :en))).to eq '"Hello, world!"@en'
     end
@@ -858,7 +862,7 @@
         (0x20..0x21).each { |u| expect(writer.escape(u.chr, encoding)).to eq u.chr }
         expect(writer.escape(0x22.chr, encoding)).to eq "\\\""
         (0x23..0x26).each { |u| expect(writer.escape(u.chr, encoding)).to eq u.chr }
-        expect(writer.escape(0x27.chr, encoding)).to eq "\\'"
+        expect(writer.escape(0x27.chr, encoding)).to eq "'"
         (0x28..0x5B).each { |u| expect(writer.escape(u.chr, encoding)).to eq u.chr }
         expect(writer.escape(0x5C.chr, encoding)).to eq "\\\\"
         (0x5D..0x7E).each { |u| expect(writer.escape(u.chr, encoding)).to eq u.chr }
@@ -920,7 +924,7 @@
         (0x20..0x21).each { |u| expect(writer.escape(u.chr, encoding)).to eq u.chr }
         expect(writer.escape(0x22.chr, encoding)).to eq "\\\""
         (0x23..0x26).each { |u| expect(writer.escape(u.chr, encoding)).to eq u.chr }
-        expect(writer.escape(0x27.chr, encoding)).to eq "\\'"
+        expect(writer.escape(0x27.chr, encoding)).to eq "'"
         (0x28..0x5B).each { |u| expect(writer.escape(u.chr, encoding)).to eq u.chr }
         expect(writer.escape(0x5C.chr, encoding)).to eq "\\\\"
         (0x5D..0x7E).each { |u| expect(writer.escape(u.chr, encoding)).to eq u.chr }