Add support for N-Triples-star decoding

src/ntriples_lexer.xrl

@@ -24,6 +24,8 @@ Rules.
 {EOL}	                  :	{token, {eol, TokenLine}}.
 \.	                    :	{token, {'.', TokenLine}}.
 \^\^	                  :	{token, {'^^', TokenLine}}.
+\<\<	                  :	{token, {'<<', TokenLine}}.
+\>\>	                  :	{token, {'>>', TokenLine}}.
 {WHITESPACE}+           : skip_token.
 {COMMENT}               : skip_token.
 

src/ntriples_parser.yrl

@@ -1,7 +1,7 @@
 %% Grammar for N-Triples as specified in https://www.w3.org/TR/2014/REC-n-triples-20140225/
 
-Nonterminals ntriplesDoc nonEmptyNtriplesDoc triple subject predicate object literal eols.
+Nonterminals ntriplesDoc nonEmptyNtriplesDoc triple subject predicate object literal quoted_triple eols.
-Terminals iriref blank_node_label string_literal_quote langtag '^^' '.' eol.
+Terminals iriref blank_node_label string_literal_quote langtag '^^' '.' '<<' '>>' eol.
 Rootsymbol ntriplesDoc.
 
 eols -> eols eol.
@@ -24,15 +24,18 @@ triple -> subject predicate object '.' : { '$1', '$2', '$3' }.
 
 subject   -> iriref            : to_iri('$1').
 subject   -> blank_node_label  : to_bnode('$1').
+subject   -> quoted_triple     : '$1'.
 predicate -> iriref            : to_iri('$1').
 object    -> iriref            : to_iri('$1').
 object    -> blank_node_label  : to_bnode('$1').
 object    -> literal           : '$1'.
+object    -> quoted_triple     : '$1'.
 
 literal -> string_literal_quote '^^' iriref : to_literal('$1', {datatype, to_iri('$3')}).
 literal -> string_literal_quote langtag     : to_literal('$1', {language, to_langtag('$2')}).
 literal -> string_literal_quote             : to_literal('$1').
 
+quoted_triple -> '<<' subject predicate object '>>' : { '$2', '$3', '$4' }.
 
 Erlang code.
 

test/acceptance/ntriples_star_w3c_test.exs

@@ -0,0 +1,29 @@
+defmodule RDF.Star.NTriples.W3C.TestSuite do
+  @moduledoc """
+  The official RDF-star N-Triples Test Suite.
+
+  from <https://w3c.github.io/rdf-star/tests/nt/syntax/>
+  """
+
+  use ExUnit.Case, async: false
+
+  @ntriples_star_test_suite Path.join(RDF.TestData.dir(), "rdf-star/nt/syntax")
+
+  ExUnit.Case.register_attribute(__ENV__, :nt_test)
+
+  @ntriples_star_test_suite
+  |> File.ls!()
+  |> Enum.filter(fn file -> Path.extname(file) == ".nt" end)
+  |> Enum.each(fn file ->
+    @nt_test file: Path.join(@ntriples_star_test_suite, file)
+    if file |> String.contains?("-bad-") do
+      test "Negative syntax test: #{file}", context do
+        assert {:error, _} = RDF.NTriples.read_file(context.registered.nt_test[:file])
+      end
+    else
+      test "Positive syntax test: #{file}", context do
+        assert {:ok, %RDF.Graph{}} = RDF.NTriples.read_file(context.registered.nt_test[:file])
+      end
+    end
+  end)
+end

test/data/rdf-star/nt/syntax/manifest.ttl

@@ -0,0 +1,101 @@
+## Distributed under both the "W3C Test Suite License" [1]
+## and the "W3C 3-clause BSD License".
+## [1] https://www.w3.org/Consortium/Legal/2008/04-testsuite-license
+## [2] https://www.w3.org/Consortium/Legal/2008/03-bsd-license
+
+PREFIX rdf:    <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
+PREFIX rdfs:   <http://www.w3.org/2000/01/rdf-schema#>
+PREFIX mf:     <http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#>
+PREFIX rdft:   <http://www.w3.org/ns/rdftest#>
+PREFIX trs:    <https://w3c.github.io/rdf-star/tests/nt/syntax#>
+
+trs:manifest  rdf:type mf:Manifest ;
+    rdfs:label "N-Triples-star Syntax Tests" ;
+    mf:entries
+    (
+        trs:ntriples-star-1
+        trs:ntriples-star-2
+        trs:ntriples-star-3
+        trs:ntriples-star-4
+        trs:ntriples-star-5
+
+        trs:ntriples-star-bnode-1
+        trs:ntriples-star-bnode-2
+
+        trs:ntriples-star-nested-1
+        trs:ntriples-star-nested-2
+
+        trs:ntriples-star-bad-1
+        trs:ntriples-star-bad-2
+        trs:ntriples-star-bad-3
+        trs:ntriples-star-bad-4
+    ) .
+
+trs:ntriples-star-1 rdf:type rdft:TestNTriplesPositiveSyntax ;
+   mf:name      "N-Triples-star - subject quoted triple" ;
+   mf:action    <ntriples-star-syntax-1.nt> ;
+   .
+
+trs:ntriples-star-2 rdf:type rdft:TestNTriplesPositiveSyntax ;
+   mf:name      "N-Triples-star - object quoted triple" ;
+   mf:action    <ntriples-star-syntax-2.nt> ;
+   .
+
+trs:ntriples-star-3 rdf:type rdft:TestNTriplesPositiveSyntax ;
+   mf:name      "N-Triples-star - subject and object quoted triples" ;
+   mf:action    <ntriples-star-syntax-3.nt> ;
+   .
+
+trs:ntriples-star-4 rdf:type rdft:TestNTriplesPositiveSyntax ;
+   mf:name      "N-Triples-star - whitespace and terms" ;
+   mf:action    <ntriples-star-syntax-4.nt> ;
+   .
+
+trs:ntriples-star-5 rdf:type rdft:TestNTriplesPositiveSyntax ;
+   mf:name      "N-Triples-star - Nested, no whitespace" ;
+   mf:action    <ntriples-star-syntax-5.nt> ;
+   .
+
+# Blank nodes
+
+trs:ntriples-star-bnode-1 rdf:type rdft:TestNTriplesPositiveSyntax ;
+   mf:name      "N-Triples-star - Blank node subject" ;
+   mf:action    <ntriples-star-bnode-1.nt> ;
+   .
+
+trs:ntriples-star-bnode-2 rdf:type rdft:TestNTriplesPositiveSyntax ;
+   mf:name      "N-Triples-star - Blank node object" ;
+   mf:action    <ntriples-star-bnode-2.nt> ;
+   .
+   
+trs:ntriples-star-nested-1 rdf:type rdft:TestNTriplesPositiveSyntax ;
+   mf:name      "N-Triples-star - Nested subject term" ;
+   mf:action    <ntriples-star-nested-1.nt> ;
+   .
+
+trs:ntriples-star-nested-2 rdf:type rdft:TestNTriplesPositiveSyntax ;
+   mf:name      "N-Triples-star - Nested object term" ;
+   mf:action    <ntriples-star-nested-2.nt> ;
+   .
+
+## Bad syntax
+ 
+trs:ntriples-star-bad-1 rdf:type rdft:TestNTriplesNegativeSyntax ;
+    mf:name      "N-Triples-star - Bad - quoted triple as predicate" ;
+    mf:action    <ntriples-star-bad-syntax-1.nt> ;
+    .
+    
+trs:ntriples-star-bad-2 rdf:type rdft:TestNTriplesNegativeSyntax ;
+    mf:name      "N-Triples-star - Bad - quoted triple, literal subject" ;
+    mf:action    <ntriples-star-bad-syntax-2.nt> ;
+    .
+
+trs:ntriples-star-bad-3 rdf:type rdft:TestNTriplesNegativeSyntax ;
+    mf:name      "N-Triples-star - Bad - quoted triple, literal predicate" ;
+    mf:action    <ntriples-star-bad-syntax-3.nt> ;
+    .
+
+trs:ntriples-star-bad-4 rdf:type rdft:TestNTriplesNegativeSyntax ;
+    mf:name      "N-Triples-star - Bad - quoted triple, blank node predicate" ;
+    mf:action    <ntriples-star-bad-syntax-4.nt> ;
+    .

test/data/rdf-star/nt/syntax/ntriples-star-bad-syntax-1.nt

@@ -0,0 +1 @@
+<http://example/a> << <http://example/s> <http://example/p>  <http://example/o> >>  <http://example/z> .

test/data/rdf-star/nt/syntax/ntriples-star-bad-syntax-2.nt

@@ -0,0 +1 @@
+<< "XYZ" <http://example/p> <http://example/o> >> <http://example/q> <http://example/z> .

test/data/rdf-star/nt/syntax/ntriples-star-bad-syntax-3.nt

@@ -0,0 +1 @@
+<< <http://example/s> "XYZ" <http://example/o> >> <http://example/q> <http://example/z> .

test/data/rdf-star/nt/syntax/ntriples-star-bad-syntax-4.nt

@@ -0,0 +1 @@
+<< <http://example/s> _:label <http://example/o> >> <http://example/q> <http://example/z> .

test/data/rdf-star/nt/syntax/ntriples-star-bnode-1.nt

@@ -0,0 +1,2 @@
+_:b0 <http://example/p> <http://example/o> .
+<< _:b0 <http://example/p> <http://example/o> >> <http://example/q> "ABC" .

test/data/rdf-star/nt/syntax/ntriples-star-bnode-2.nt

@@ -0,0 +1,2 @@
+<http://example/s> <http://example/p> _:b1 .
+<< <http://example/s> <http://example/p> _:b1 >> <http://example/q> "456"^^<http://www.w3.org/2001/XMLSchema#integer> .

test/data/rdf-star/nt/syntax/ntriples-star-nested-1.nt

@@ -0,0 +1,3 @@
+<http://example/s> <http://example/p> <http://example/o> .
+<< <http://example/s> <http://example/p> <http://example/o> >> <http://example/r> <http://example/z> .
+<< << <http://example/s> <http://example/p> <http://example/o> >> <http://example/r> <http://example/z> >> <http://example/q> "1"^^<http://www.w3.org/2001/XMLSchema#integer> .

test/data/rdf-star/nt/syntax/ntriples-star-nested-2.nt

@@ -0,0 +1,3 @@
+<http://example/s> <http://example/p> <http://example/o> .
+<http://example/a> <http://example/q> << <http://example/s> <http://example/p> <http://example/o> >> .
+<< <http://example/a> <http://example/q> << <http://example/s> <http://example/p> <http://example/o> >> >> <http://example/r> <http://example/z> .

test/data/rdf-star/nt/syntax/ntriples-star-syntax-1.nt

@@ -0,0 +1 @@
+<< <http://example/s> <http://example/p> <http://example/o> >> <http://example/q> <http://example/z> .

test/data/rdf-star/nt/syntax/ntriples-star-syntax-2.nt

@@ -0,0 +1 @@
+<http://example/x> <http://example/p> << <http://example/s> <http://example/p> <http://example/o> >> .

test/data/rdf-star/nt/syntax/ntriples-star-syntax-3.nt

@@ -0,0 +1 @@
+<< <http://example/s1> <http://example/p1> <http://example/o1> >> <http://example/q> << <http://example/s2> <http://example/p2> <http://example/o2> >> .

test/data/rdf-star/nt/syntax/ntriples-star-syntax-4.nt

@@ -0,0 +1 @@
+<<<http://example/s1><http://example/p1><http://example/o1>>><http://example/q><<<http://example/s2><http://example/p2><http://example/o2>>>.

test/data/rdf-star/nt/syntax/ntriples-star-syntax-5.nt

@@ -0,0 +1 @@
+<<<<<http://example/s1><http://example/p1><http://example/o1>>><http://example/q1><<<http://example/s2><http://example/p2><http://example/o2>>>>><http://example/q2><<<<<http://example/s3><http://example/p3><http://example/o3>>><http://example/q3><<<http://example/s4><http://example/p4><http://example/o4>>>>>.