Add RDF.Data.descriptions/1

CHANGELOG.md

@@ -9,7 +9,8 @@ This project adheres to [Semantic Versioning](http://semver.org/) and
 
 ### Added
 
-- Turtle decoder 
+- Turtle decoder
+- `RDF.Data.descriptions/1` returns all descriptions of a RDF data structure 
 
 ### Changed
 

README.md

@@ -529,6 +529,7 @@ The `RDF.Data` protocol offers various functions to access the contents of RDF d
 - `RDF.Data.objects/1` returns the set of all resources on the object position of statements. Note: Literals not included.
 - `RDF.Data.resources/1` returns the set of all used resources at any position in the contained RDF statements.
 - `RDF.Data.description/2` returns all statements from a data structure about the given resource as a `RDF.Description`. It will be empty if no such statements exist. On a `RDF.Dataset` it will aggregate the statements about the resource from all graphs.
+- `RDF.Data.descriptions/1` returns all `RDF.Description`s within a data structure (possible aggregated in the case of a `RDF.Dataset`)
 - `RDF.Data.statements/1` returns a list of all contained RDF statements.
 
 The `get` functions return individual elements of a RDF data structure:

lib/rdf/data.ex

@@ -49,6 +49,14 @@ defprotocol RDF.Data do
   """
   def description(data, subject)
 
+  @doc """
+  Returns all `RDF.Description`s within a RDF data structure.
+
+  Note: On a `RDF.Dataset` this will return aggregated `RDF.Description`s about
+  the same subject from all graphs.
+  """
+  def descriptions(data)
+
   @doc """
   Returns the set of all resources which are subject of the statements of a RDF data structure.
   """
@@ -131,6 +139,8 @@ defimpl RDF.Data, for: RDF.Description do
     end
   end
 
+  def descriptions(description), do: [description]
+
   def subjects(%RDF.Description{subject: subject}), do: MapSet.new([subject])
   def predicates(description), do: RDF.Description.predicates(description)
   def objects(description),    do: RDF.Description.objects(description)
@@ -188,6 +198,8 @@ defimpl RDF.Data, for: RDF.Graph do
   def description(graph, subject),
     do: RDF.Graph.description(graph, subject) || RDF.Description.new(subject)
 
+  def descriptions(graph), do: RDF.Graph.descriptions(graph)
+
   def subjects(graph),   do: RDF.Graph.subjects(graph)
   def predicates(graph), do: RDF.Graph.predicates(graph)
   def objects(graph),    do: RDF.Graph.objects(graph)
@@ -232,6 +244,12 @@ defimpl RDF.Data, for: RDF.Dataset do
     end
   end
 
+  def descriptions(dataset) do
+    dataset
+    |> subjects
+    |> Enum.map(&(description(dataset, &1)))
+  end
+
   def subjects(dataset),   do: RDF.Dataset.subjects(dataset)
   def predicates(dataset), do: RDF.Dataset.predicates(dataset)
   def objects(dataset),    do: RDF.Dataset.objects(dataset)

lib/rdf/graph.ex

@@ -351,6 +351,12 @@ defmodule RDF.Graph do
   def description(%RDF.Graph{descriptions: descriptions}, subject),
     do: Map.get(descriptions, convert_subject(subject))
 
+  @doc """
+  All `RDF.Description`s within a `RDF.Graph`.
+  """
+  def descriptions(%RDF.Graph{descriptions: descriptions}),
+    do: Map.values(descriptions)
+
 
   @doc """
   Gets and updates the description of the given subject, in a single pass.

test/unit/data_test.exs

@@ -107,6 +107,10 @@ defmodule RDF.DataTest do
       assert RDF.Data.description(description, uri(EX.Other)) == Description.new(EX.Other)
     end
 
+    test "descriptions", %{description: description} do
+      assert RDF.Data.descriptions(description) == [description]
+    end
+
     test "subjects", %{description: description} do
       assert RDF.Data.subjects(description) == MapSet.new([uri(EX.S)])
     end
@@ -225,6 +229,11 @@ defmodule RDF.DataTest do
       assert RDF.Data.description(graph, uri(EX.Other)) == Description.new(EX.Other)
     end
 
+    test "descriptions", %{graph: graph, description: description} do
+      assert RDF.Data.descriptions(graph) ==
+              [description, EX.S2 |> EX.p2(EX.O3, EX.O4)]
+    end
+
     test "subjects", %{graph: graph} do
       assert RDF.Data.subjects(graph) == MapSet.new([uri(EX.S), uri(EX.S2)])
     end
@@ -323,6 +332,15 @@ defmodule RDF.DataTest do
       assert RDF.Data.description(dataset, uri(EX.Other)) == Description.new(EX.Other)
     end
 
+    test "descriptions", %{dataset: dataset, description: description} do
+      description_aggregate = Description.add(description, {EX.S, EX.p3, EX.O5})
+      assert RDF.Data.descriptions(dataset) == [
+              description_aggregate,
+              (EX.S2 |> EX.p2(EX.O3, EX.O4)),
+              (EX.S3 |> EX.p3(EX.O5))
+            ]
+    end
+
     test "statements", %{dataset: dataset} do
       assert RDF.Data.statements(dataset) == Dataset.statements(dataset)
     end