Change RDF.String.new/2 to produce language strings when language given

CHANGELOG.md

@@ -24,6 +24,8 @@ This project adheres to [Semantic Versioning](http://semver.org/) and
 ### Changed
 
 - Elixir 1.4 is no longer supported
+- `RDF.String.new/2` and `RDF.String.new!/2` produce a `rdf:langString` when 
+  given a language tag
 
 
 ### Fixed

VERSION

@@ -1 +1 @@
-0.4.2-dev
+0.5.0-dev

lib/rdf/datatype.ex

@@ -210,6 +210,8 @@ defmodule RDF.Datatype do
         convert: 2,
         valid?: 1,
         equal_value?: 2,
+        new: 2,
+        new!: 2,
       ]
     end
   end

lib/rdf/datatypes/string.ex

@@ -5,6 +5,14 @@ defmodule RDF.String do
 
   use RDF.Datatype, id: RDF.Datatype.NS.XSD.string
 
+  def new(value, opts) when is_list(opts), do: new(value, Map.new(opts))
+  def new(value, %{language: _} = opts), do: RDF.LangString.new!(value, opts)
+  def new(value, opts), do: super(value, opts)
+
+  def new!(value, opts) when is_list(opts), do: new!(value, Map.new(opts))
+  def new!(value, %{language: _} = opts), do: RDF.LangString.new!(value, opts)
+  def new!(value, opts), do: super(value, opts)
+
 
   def build_literal_by_lexical(lexical, opts) do
     build_literal(lexical, nil, opts)

test/support/rdf_datatype_case.ex

@@ -20,6 +20,8 @@ defmodule RDF.Datatype.Test.Case do
     valid       = Keyword.get(opts, :valid)
     invalid     = Keyword.get(opts, :invalid)
 
+    allow_language = Keyword.get(opts, :allow_language, false)
+
     quote do
       alias RDF.{Literal, Datatype}
       alias RDF.NS.XSD
@@ -81,9 +83,11 @@ defmodule RDF.Datatype.Test.Case do
             end
           end
 
-          test "language option is ignored" do
-            Enum.each @valid, fn {input, _} ->
-              assert unquote(datatype).new(input, language: "en") == unquote(datatype).new(input)
+          unless unquote(allow_language) do
+            test "language option is ignored" do
+              Enum.each @valid, fn {input, _} ->
+                assert unquote(datatype).new(input, language: "en") == unquote(datatype).new(input)
+              end
             end
           end
         end

test/unit/datatypes/string_test.exs

@@ -9,6 +9,21 @@ defmodule RDF.StringTest do
       true  => { "true"  , nil     , "true"  },
       false => { "false" , nil     , "false" },
     },
-    invalid: []
+    invalid: [],
+    allow_language: true
+
+  describe "new" do
+    test "when given a language tag it produces a rdf:langString" do
+      assert RDF.String.new("foo", language: "en") ==
+             RDF.LangString.new("foo", language: "en")
+    end
+  end
+
+  describe "new!" do
+    test "when given a language tag it produces a rdf:langString" do
+      assert RDF.String.new!("foo", language: "en") ==
+             RDF.LangString.new!("foo", language: "en")
+    end
+  end
 
 end