/// <summary>Parses RDF in the form of N-Quads.</summary>
/// <remarks>Parses RDF in the form of N-Quads.</remarks>
/// <param name="input">the N-Quads input to parse.</param>
/// <returns>an RDF dataset.</returns>
/// <exception cref="JsonLD.Core.JsonLdError"></exception>
public static RDFDataset ParseNQuads(string input)
{
// build RDF dataset
RDFDataset dataset = new RDFDataset();
// split N-Quad input into lines
string[] lines = RDFDatasetUtils.Regex.Eoln.Split(input);
int lineNumber = 0;
foreach (string line in lines)
{
lineNumber++;
// skip empty lines
if (RDFDatasetUtils.Regex.EmptyOrComment.Matcher(line).Matches())
{
continue;
}
// parse quad
Matcher match = RDFDatasetUtils.Regex.Quad.Matcher(line);
if (!match.Matches())
{
throw new JsonLdError(JsonLdError.Error.SyntaxError, "Error while parsing N-Quads; invalid quad. line:"
+ lineNumber);
}
// get subject
RDFDataset.Node subject;
if (match.Group(1) != null)
{
var subjectIri = Unescape(match.Group(1));
AssertAbsoluteIri(subjectIri);
subject = new RDFDataset.IRI(subjectIri);
}
else
{
subject = new RDFDataset.BlankNode(Unescape(match.Group(2)));
}
// get predicate
var predicateIri = Unescape(match.Group(3));
AssertAbsoluteIri(predicateIri);
RDFDataset.Node predicate = new RDFDataset.IRI(predicateIri);
// get object
RDFDataset.Node @object;
if (match.Group(4) != null)
{
var objectIri = Unescape(match.Group(4));
AssertAbsoluteIri(objectIri);
@object = new RDFDataset.IRI(objectIri);
}
else
{
if (match.Group(5) != null)
{
@object = new RDFDataset.BlankNode(Unescape(match.Group(5)));
}
else
{
string language = Unescape(match.Group(8));
string datatype = match.Group(7) != null?Unescape(match.Group(7)) : match.Group
(8) != null ? JSONLDConsts.RdfLangstring : JSONLDConsts.XsdString;
AssertAbsoluteIri(datatype);
string unescaped = Unescape(match.Group(6));
@object = new RDFDataset.Literal(unescaped, datatype, language);
}
}
// get graph name ('@default' is used for the default graph)
string name = "@default";
if (match.Group(9) != null)
{
name = Unescape(match.Group(9));
AssertAbsoluteIri(name);
}
else
{
if (match.Group(10) != null)
{
name = Unescape(match.Group(10));
}
}
RDFDataset.Quad triple = new RDFDataset.Quad(subject, predicate, @object, name);
// initialise graph in dataset
if (!dataset.ContainsKey(name))
{
IList <RDFDataset.Quad> tmp = new List <RDFDataset.Quad>();
tmp.Add(triple);
dataset[name] = tmp;
}
else
{
// add triple if unique to its graph
IList <RDFDataset.Quad> triples = (IList <RDFDataset.Quad>)dataset[name];
if (!triples.Contains(triple))
{
triples.Add(triple);
}
}
}
return(dataset);
}
/// <summary>Creates an array of RDF triples for the given graph.</summary>
/// <remarks>Creates an array of RDF triples for the given graph.</remarks>
/// <param name="graph">the graph to create RDF triples for.</param>
internal virtual void GraphToRDF(string graphName, JObject graph
)
{
// 4.2)
IList <RDFDataset.Quad> triples = new List <RDFDataset.Quad>();
// 4.3)
IEnumerable <string> subjects = graph.GetKeys();
// Collections.sort(subjects);
foreach (string id in subjects)
{
if (JsonLdUtils.IsRelativeIri(id))
{
continue;
}
JObject node = (JObject)graph[id];
JArray properties = new JArray(node.GetKeys());
properties.SortInPlace();
foreach (string property in properties)
{
var localProperty = property;
JArray values;
// 4.3.2.1)
if ("@type".Equals(localProperty))
{
values = (JArray)node["@type"];
localProperty = JSONLDConsts.RdfType;
}
else
{
// 4.3.2.2)
if (JsonLdUtils.IsKeyword(localProperty))
{
continue;
}
else
{
// 4.3.2.3)
if (localProperty.StartsWith("_:") && !api.opts.GetProduceGeneralizedRdf())
{
continue;
}
else
{
// 4.3.2.4)
if (JsonLdUtils.IsRelativeIri(localProperty))
{
continue;
}
else
{
values = (JArray)node[localProperty];
}
}
}
}
RDFDataset.Node subject;
if (id.IndexOf("_:") == 0)
{
// NOTE: don't rename, just set it as a blank node
subject = new RDFDataset.BlankNode(id);
}
else
{
subject = new RDFDataset.IRI(id);
}
// RDF predicates
RDFDataset.Node predicate;
if (localProperty.StartsWith("_:"))
{
predicate = new RDFDataset.BlankNode(localProperty);
}
else
{
predicate = new RDFDataset.IRI(localProperty);
}
foreach (JToken item in values)
{
// convert @list to triples
if (JsonLdUtils.IsList(item))
{
JArray list = (JArray)((JObject)item)["@list"];
RDFDataset.Node last = null;
RDFDataset.Node firstBNode = nil;
if (!list.IsEmpty())
{
last = ObjectToRDF(list[list.Count - 1]);
firstBNode = new RDFDataset.BlankNode(api.GenerateBlankNodeIdentifier());
}
triples.Add(new RDFDataset.Quad(subject, predicate, firstBNode, graphName));
for (int i = 0; i < list.Count - 1; i++)
{
RDFDataset.Node @object = ObjectToRDF(list[i]);
triples.Add(new RDFDataset.Quad(firstBNode, first, @object, graphName));
RDFDataset.Node restBNode = new RDFDataset.BlankNode(api.GenerateBlankNodeIdentifier
());
triples.Add(new RDFDataset.Quad(firstBNode, rest, restBNode, graphName));
firstBNode = restBNode;
}
if (last != null)
{
triples.Add(new RDFDataset.Quad(firstBNode, first, last, graphName));
triples.Add(new RDFDataset.Quad(firstBNode, rest, nil, graphName));
}
}
else
{
// convert value or node object to triple
RDFDataset.Node @object = ObjectToRDF(item);
if (@object != null)
{
triples.Add(new RDFDataset.Quad(subject, predicate, @object, graphName));
}
}
}
}
}
this[graphName] = triples;
}
