From deeed3224f89ecea187f906d3c4e8c900bd0dace Mon Sep 17 00:00:00 2001
From: Marcel Otto <marcelotto@gmx.de>
Date: Wed, 24 May 2017 23:37:09 +0200
Subject: [PATCH] core: RDF.Data protocol

---
 lib/rdf/data.ex | 66 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 lib/rdf/data.ex

diff --git a/lib/rdf/data.ex b/lib/rdf/data.ex
new file mode 100644
index 0000000..b669d30
--- /dev/null
+++ b/lib/rdf/data.ex
@@ -0,0 +1,66 @@
+defprotocol RDF.Data do
+  @moduledoc """
+  An abstraction over the different data structures for collections of RDF statements.
+  """
+
+  @doc """
+  Add statements to a RDF data structure.
+  """
+  def add(data, statements)
+
+  @doc """
+  Adds statements to a RDF data structure and overwrites all existing statements with the same subjects and predicates.
+  """
+  def put(data, statements)
+
+  @doc """
+  Deletes statements from a RDF data structure.
+  """
+  def delete(data, statements)
+
+  @doc """
+  Deletes one statement from a RDF data structure and returns a tuple with deleted statement and the changed data structure.
+  """
+  def pop(data)
+
+  @doc """
+  Checks if the given statement exists within a RDF data structure.
+  """
+  def include?(data, statements)
+
+  @doc """
+  Returns the list of all statements of a RDF data structure.
+  """
+  def statements(data)
+
+  @doc """
+  Returns the set of all resources which are subject of the statements of a RDF data structure.
+  """
+  def subjects(data)
+
+  @doc """
+  Returns the set of all properties used within the statements of RDF data structure.
+  """
+  def predicates(data)
+
+  @doc """
+  Returns the  set of all resources used in the objects within the statements of a RDF data structure.
+  """
+  def objects(data)
+
+  @doc """
+  Returns the set of all resources used within the statements of a RDF data structure
+  """
+  def resources(data)
+
+  @doc """
+  Returns the count of all resources which are subject of the statements of a RDF data structure.
+  """
+  def subject_count(data)
+
+  @doc """
+  Returns the count of all statements of a RDF data structure.
+  """
+  def statement_count(data)
+
+end