Fix some of the BlankNode representations to be Turtle-serializable

CHANGELOG.md

@@ -18,6 +18,10 @@ This project adheres to [Semantic Versioning](http://semver.org/) and
 - more compact Inspect form for `RDF.PrefixMap`
 - the `RDF.Turtle.Encoder` accepts `RDF.Vocabulary.Namespace` modules as `base`
 
+### Fixed
+
+- `RDF.BlankNode`s based on refs weren't serializable to Turtle
+
 
 [Compare v0.9.0...HEAD](https://github.com/rdf-elixir/rdf-ex/compare/v0.9.0...HEAD)
 

lib/rdf/blank_node.ex

@@ -31,14 +31,14 @@ defmodule RDF.BlankNode do
   @spec new(reference | String.t() | atom | integer) :: t
   def new(value)
 
-  def new(value) when is_binary(value),
-    do: %__MODULE__{value: value}
+  def new(string) when is_binary(string), do: %__MODULE__{value: string}
+  def new(atom) when is_atom(atom), do: atom |> to_string() |> new()
+  def new(integer) when is_integer(integer), do: new("b#{integer}")
 
-  def new(value) when is_reference(value),
-    do: value |> :erlang.ref_to_list() |> to_string |> String.replace(~r/\<|\>/, "") |> new
-
-  def new(value) when is_atom(value) or is_integer(value),
-    do: value |> to_string |> new
+  def new(ref) when is_reference(ref) do
+    "#Ref<" <> value = ref |> :erlang.ref_to_list() |> to_string()
+    value |> String.trim_trailing(">") |> new()
+  end
 
   @doc """
   Returns the internal string representation of a blank node.

test/unit/blank_node_test.exs

@@ -15,7 +15,7 @@ defmodule RDF.BlankNodeTest do
     end
 
     test "with a integer" do
-      assert BlankNode.new(42) == %BlankNode{value: "42"}
+      assert BlankNode.new(42) == %BlankNode{value: "b42"}
     end
 
     test "with a ref" do
@@ -23,4 +23,27 @@ defmodule RDF.BlankNodeTest do
       assert is_binary(value)
     end
   end
+
+  test "internal representation are valid Turtle blank node" do
+    [
+      BlankNode.new(),
+      BlankNode.new("foo"),
+      BlankNode.new(:foo),
+      BlankNode.new(42),
+      BlankNode.new(-42),
+      BlankNode.new(make_ref())
+    ]
+    |> Enum.each(fn bnode ->
+      assert {:ok, graph} =
+               [
+                 {EX.S1, EX.p1(), bnode},
+                 {EX.S2, EX.p1(), bnode}
+               ]
+               |> Graph.new()
+               |> RDF.Turtle.write_string!()
+               |> RDF.Turtle.read_string()
+
+      assert Graph.triple_count(graph) == 2
+    end)
+  end
 end

test/unit/nquads_encoder_test.exs

@@ -62,7 +62,7 @@ defmodule RDF.NQuads.EncoderTest do
                ])
              ) ==
                """
-               <http://example.org/#S1> <http://example.org/#p1> _:1 .
+               <http://example.org/#S1> <http://example.org/#p1> _:b1 .
                <http://example.org/#S1> <http://example.org/#p1> _:bar .
                <http://example.org/#S1> <http://example.org/#p1> _:foo .
                """
@@ -117,7 +117,7 @@ defmodule RDF.NQuads.EncoderTest do
                ])
              ) ==
                """
-               <http://example.org/#S1> <http://example.org/#p1> _:1 .
+               <http://example.org/#S1> <http://example.org/#p1> _:b1 .
                <http://example.org/#S1> <http://example.org/#p1> _:bar .
                <http://example.org/#S1> <http://example.org/#p1> _:foo <http://example.org/#G> .
                """

test/unit/ntriples_encoder_test.exs

@@ -62,7 +62,7 @@ defmodule RDF.NTriples.EncoderTest do
                ])
              ) ==
                """
-               <http://example.org/#S1> <http://example.org/#p1> _:1 .
+               <http://example.org/#S1> <http://example.org/#p1> _:b1 .
                <http://example.org/#S1> <http://example.org/#p1> _:bar .
                <http://example.org/#S1> <http://example.org/#p1> _:foo .
                """

test/unit/query/builder_test.exs

@@ -247,14 +247,14 @@ defmodule RDF.Query.BuilderTest do
     test "element count > 3" do
       assert Builder.path([EX.s(), EX.p1(), EX.p2(), EX.o()]) ==
                ok_bgp_struct([
-                 {EX.s(), EX.p1(), RDF.bnode("0")},
-                 {RDF.bnode("0"), EX.p2(), EX.o()}
+                 {EX.s(), EX.p1(), RDF.bnode("b0")},
+                 {RDF.bnode("b0"), EX.p2(), EX.o()}
                ])
 
       assert Builder.path([:s?, :p1?, :p2?, :o?]) ==
                ok_bgp_struct([
-                 {:s, :p1, RDF.bnode("0")},
-                 {RDF.bnode("0"), :p2, :o}
+                 {:s, :p1, RDF.bnode("b0")},
+                 {RDF.bnode("b0"), :p2, :o}
                ])
     end
 
@@ -280,8 +280,8 @@ defmodule RDF.Query.BuilderTest do
 
       assert Builder.path([EX.s(), :p1, :p2, EX.o()], context: property_map) ==
                ok_bgp_struct([
-                 {EX.s(), EX.p1(), RDF.bnode("0")},
-                 {RDF.bnode("0"), EX.p2(), EX.o()}
+                 {EX.s(), EX.p1(), RDF.bnode("b0")},
+                 {RDF.bnode("b0"), EX.p2(), EX.o()}
                ])
 
       assert Builder.path([EX.s(), :p1, :p2, :o?], context: property_map, with_elements: true) ==

test/unit/turtle_encoder_test.exs

@@ -177,10 +177,10 @@ defmodule RDF.Turtle.EncoderTest do
              ) ==
                """
                <http://example.org/#S1>
-                   <http://example.org/#p1> _:1, _:bar, _:foo .
+                   <http://example.org/#p1> _:b1, _:bar, _:foo .
 
                <http://example.org/#S2>
-                   <http://example.org/#p1> _:1, _:bar, _:foo .
+                   <http://example.org/#p1> _:b1, _:bar, _:foo .
                """
     end