From 529714ec1cdc8e25d8a6541ec1266f79915ad10b Mon Sep 17 00:00:00 2001
From: Marcel Otto <marcelotto@gmx.de>
Date: Mon, 10 Jul 2017 01:41:36 +0200
Subject: [PATCH] Use base URI in URIs of @prefix and @base directives

---
 lib/rdf/serializations/turtle_decoder.ex | 21 +++++++++++++++---
 lib/rdf/uri_helper.ex                    | 28 +++++++++++++++++++-----
 2 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/lib/rdf/serializations/turtle_decoder.ex b/lib/rdf/serializations/turtle_decoder.ex
index 787b68d..db4cb43 100644
--- a/lib/rdf/serializations/turtle_decoder.ex
+++ b/lib/rdf/serializations/turtle_decoder.ex
@@ -63,11 +63,26 @@ defmodule RDF.Turtle.Decoder do
   end
 
   defp directive({:prefix, {:prefix_ns, _, ns}, iri}, state) do
-    State.add_namespace(state, ns, iri)
+    if RDF.URI.Helper.absolute_iri?(iri) do
+      State.add_namespace(state, ns, iri)
+    else
+      with absolute_uri = RDF.URI.Helper.absolute_iri(iri, state.base_uri) do
+        State.add_namespace(state, ns, URI.to_string(absolute_uri))
+      end
+    end
   end
 
-  defp directive({:base, uri}, state) do
-    %State{state | base_uri: RDF.uri(uri)}
+  defp directive({:base, uri}, %State{base_uri: base_uri} = state) do
+    cond do
+      RDF.URI.Helper.absolute_iri?(uri) ->
+        %State{state | base_uri: RDF.uri(uri)}
+      base_uri != nil ->
+        with absolute_uri = RDF.URI.Helper.absolute_iri(uri, base_uri) do
+          %State{state | base_uri: absolute_uri}
+        end
+      true ->
+        raise "Could not resolve resolve relative IRI '#{uri}', no base uri provided"
+    end
   end
 
 
diff --git a/lib/rdf/uri_helper.ex b/lib/rdf/uri_helper.ex
index 0e2ff04..3ef55fe 100644
--- a/lib/rdf/uri_helper.ex
+++ b/lib/rdf/uri_helper.ex
@@ -17,13 +17,29 @@ defmodule RDF.URI.Helper do
   characters are treated in URI references, per [section 6.5 of RFC3987](http://tools.ietf.org/html/rfc3987#section-6.5)
   """
   def absolute_iri(value, base_iri) do
-    case URI.parse(value) do
-      # absolute?
-      uri = %URI{scheme: scheme} when not is_nil(scheme) -> uri
-      # relative
-      _ when is_nil(base_iri) -> nil
-      _ -> URI.merge(base_iri, value)
+    uri =
+      case URI.parse(value) do
+        # absolute?
+        uri = %URI{scheme: scheme} when not is_nil(scheme) -> uri
+        # relative
+        _ when is_nil(base_iri) -> nil
+        _ -> URI.merge(base_iri, value)
+      end
+    if String.ends_with?(value, "#") do
+      %URI{uri | fragment: ""}
+    else
+      uri
     end
   end
 
+  @doc """
+  Checks if the given value is an absolute IRI.
+
+  An absolute IRI is defined in [RFC3987](http://www.ietf.org/rfc/rfc3987.txt)
+  containing a scheme along with a path and optional query and fragment segments.
+
+  see <https://www.w3.org/TR/json-ld-api/#dfn-absolute-iri>
+  """
+  def absolute_iri?(value), do: RDF.uri?(value)
+
 end