/// <summary>
/// Tries to parse Literal Tokens into Literal Nodes
/// </summary>
/// <param name="context">Parser Context</param>
/// <param name="lit">Literal Token</param>
/// <returns></returns>
private INode TryParseLiteral(Notation3ParserContext context, IToken lit)
{
IToken next;
String dturi;
switch (lit.TokenType)
{
case Token.LITERAL:
case Token.LONGLITERAL:
next = context.Tokens.Peek();
if (next.TokenType == Token.LANGSPEC)
{
//Has a Language Specifier
next = context.Tokens.Dequeue();
return context.Handler.CreateLiteralNode(lit.Value, next.Value);
}
else if (next.TokenType == Token.HATHAT)
{
//Discard the ^^
next = context.Tokens.Dequeue();
//Has a Datatype
next = context.Tokens.Dequeue();
if (next.TokenType == Token.DATATYPE)
{
try
{
if (next.Value.StartsWith("<"))
{
dturi = next.Value.Substring(1, next.Value.Length - 2);
return context.Handler.CreateLiteralNode(lit.Value, UriFactory.Create(Tools.ResolveUri(dturi, context.BaseUri.ToSafeString())));
}
else
{
dturi = Tools.ResolveQName(next.Value, context.Namespaces, context.BaseUri);
return context.Handler.CreateLiteralNode(lit.Value, UriFactory.Create(dturi));
}
}
catch (RdfException rdfEx)
{
throw new RdfParseException("Unable to resolve the Datatype '" + next.Value + "' due to the following error:\n" + rdfEx.Message, next, rdfEx);
}
}
else
{
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered, expected a Datatype Token after a ^^ datatype specifier", next);
}
}
else
{
//Just an untyped Literal
return context.Handler.CreateLiteralNode(lit.Value);
}
case Token.LITERALWITHDT:
LiteralWithDataTypeToken litdt = (LiteralWithDataTypeToken)lit;
try
{
if (litdt.DataType.StartsWith("<"))
{
dturi = litdt.DataType.Substring(1, litdt.DataType.Length - 2);
return context.Handler.CreateLiteralNode(litdt.Value, UriFactory.Create(Tools.ResolveUri(dturi, context.BaseUri.ToSafeString())));
}
else
{
dturi = Tools.ResolveQName(litdt.DataType, context.Namespaces, context.BaseUri);
return context.Handler.CreateLiteralNode(litdt.Value, UriFactory.Create(dturi));
}
}
catch (RdfException rdfEx)
{
throw new RdfParseException("Unable to resolve the Datatype '" + litdt.DataType + "' due to the following error:\n" + rdfEx.Message, litdt, rdfEx);
}
case Token.LITERALWITHLANG:
LiteralWithLanguageSpecifierToken langlit = (LiteralWithLanguageSpecifierToken)lit;
return context.Handler.CreateLiteralNode(langlit.Value, langlit.Language);
case Token.PLAINLITERAL:
//Attempt to infer Type
if (TurtleSpecsHelper.IsValidPlainLiteral(lit.Value, TurtleSyntax.Original))
{
if (TurtleSpecsHelper.IsValidDouble(lit.Value))
{
return context.Handler.CreateLiteralNode(lit.Value, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeDouble));
}
else if (TurtleSpecsHelper.IsValidInteger(lit.Value))
{
return context.Handler.CreateLiteralNode(lit.Value, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeInteger));
}
else if (TurtleSpecsHelper.IsValidDecimal(lit.Value))
{
return context.Handler.CreateLiteralNode(lit.Value, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeDecimal));
}
else
{
return context.Handler.CreateLiteralNode(lit.Value, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeBoolean));
}
}
else
{
throw ParserHelper.Error("The value '" + lit.Value + "' is not valid as a Plain Literal in Turtle", lit);
}
default:
throw ParserHelper.Error("Unexpected Token '" + lit.GetType().ToString() + "' encountered, expected a valid Literal Token to convert to a Node", lit);
}
}
/// <summary>
/// Tries to parse Object lists
/// </summary>
/// <param name="context">Parse Context</param>
/// <param name="subj">Subject of the Triples</param>
/// <param name="pred">Predicate of the Triples</param>
/// <param name="bnodeList">Whether this is a Blank Node Object list</param>
/// <param name="reverse">Indicates whether the asserted triples should have it's subject and object swapped</param>
private void TryParseObjectList(Notation3ParserContext context, INode subj, INode pred, bool bnodeList, bool reverse)
{
IToken objToken, next;
INode obj = null;
do
{
objToken = context.Tokens.Dequeue();
if (context.TraceParsing)
{
Console.WriteLine("Attempting to parse an Object List from the Object Token '" + objToken.GetType().ToString() + "'");
}
switch (objToken.TokenType)
{
case Token.BLANKNODE:
obj = context.Handler.CreateBlankNode();
break;
case Token.BLANKNODEWITHID:
obj = context.Handler.CreateBlankNode(objToken.Value.Substring(2));
break;
case Token.COMMA:
//Discard and continue - set object to null so we know we're expected to complete a triple
if (obj != null)
{
obj = null;
continue;
}
else
{
throw ParserHelper.Error("Unexpected Comma Triple terminator encountered, expected a valid Object for the current Triple", objToken);
}
case Token.COMMENT:
//Discard and ignore
continue;
case Token.DOT:
if (obj != null)
{
//OK to return if we've seen a valid Triple
return;
}
else
{
throw ParserHelper.Error("Unexpected Dot Triple terminator encountered, expected a valid Object for the current Triple", objToken);
}
case Token.EXCLAMATION:
case Token.HAT:
//Path
pred = this.TryParsePath(context, pred);
this.TryParseObjectList(context, subj, pred, bnodeList, reverse);
return;
case Token.LEFTBRACKET:
//Start of a collection so create a new Blank Node to be it's first subject
next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTBRACKET)
{
//Empty Collection => rdf:nil
context.Tokens.Dequeue();
obj = context.Handler.CreateUriNode(UriFactory.Create(NamespaceMapper.RDF + "nil"));
}
else
{
obj = context.Handler.CreateBlankNode();
this.TryParseCollection(context, obj);
}
break;
case Token.LEFTCURLYBRACKET:
//Start of a Graph Literal
next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTCURLYBRACKET)
{
//An Empty Graph Literal
context.Tokens.Dequeue();
obj = context.Handler.CreateGraphLiteralNode();
}
else
{
obj = this.TryParseGraphLiteral(context);
}
break;
case Token.LEFTSQBRACKET:
//Start of a Blank Node collection?
next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTSQBRACKET)
{
//An anonymous Blank Node
context.Tokens.Dequeue();
obj = context.Handler.CreateBlankNode();
}
else
{
//Start of a Blank Node Collection
obj = context.Handler.CreateBlankNode();
this.TryParsePredicateObjectList(context, obj, true);
}
break;
case Token.LITERAL:
case Token.LITERALWITHDT:
case Token.LITERALWITHLANG:
case Token.LONGLITERAL:
case Token.PLAINLITERAL:
obj = this.TryParseLiteral(context, objToken);
break;
case Token.RIGHTCURLYBRACKET:
if (context.GraphLiteralMode)
{
return;
}
else
{
throw ParserHelper.Error("Unexpected Right Curly Bracket encountered but not expecting the end of a Graph Literal", objToken);
}
case Token.RIGHTSQBRACKET:
if (bnodeList)
{
if (obj != null)
{
//Ok to return if we've seen a Triple
return;
}
else
{
throw ParserHelper.Error("Unexpected Right Square Bracket encountered, expecting a valid object for the current Blank Node Predicate Object list", objToken);
}
}
else
{
throw ParserHelper.Error("Unexpected Right Square Bracket encountered but not expecting the end of a Blank Node Predicate Object list", objToken);
}
case Token.SEMICOLON:
if (obj != null)
{
//Ok to return if we've seen a Triple
return;
}
else
{
throw ParserHelper.Error("Unexpected Semicolon Triple terminator encountered, expected a valid Object for the current Triple", objToken);
}
case Token.QNAME:
case Token.URI:
obj = ParserHelper.TryResolveUri(context, objToken);
break;
case Token.VARIABLE:
obj = context.Handler.CreateVariableNode(objToken.Value.Substring(1));
break;
case Token.EOF:
throw ParserHelper.Error("Unexpected end of file while trying to parse an Object list", objToken);
default:
throw ParserHelper.Error("Unexpected Token '" + objToken.GetType().ToString() + "' encountered while trying to parse an Object list", objToken);
}
//Watch out for Paths
next = context.Tokens.Peek();
if (next.TokenType == Token.EXCLAMATION || next.TokenType == Token.HAT)
{
context.Tokens.Dequeue();
obj = this.TryParsePath(context, obj);
}
//Assert the Triple
if (!reverse)
{
if (!context.Handler.HandleTriple(new Triple(subj, pred, obj, context.VariableContext))) ParserHelper.Stop();
}
else
{
//When reversed this means the predicate was Implied By (<=)
if (!context.Handler.HandleTriple(new Triple(obj, pred, subj, context.VariableContext))) ParserHelper.Stop();
}
//Expect a comma/semicolon/dot terminator if we are to continue
next = context.Tokens.Peek();
if (context.GraphLiteralMode)
{
if (next.TokenType != Token.COMMA && next.TokenType != Token.SEMICOLON && next.TokenType != Token.DOT && next.TokenType != Token.RIGHTCURLYBRACKET)
{
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered while trying to parse an Object list, expected a comma, semicolon or dot to terminate the current Triple or a } to terminate the Graph Literal", next);
}
}
else if (bnodeList)
{
//If in a Blank Node list a dot is not permitted but a ] is
if (next.TokenType != Token.COMMA && next.TokenType != Token.SEMICOLON && next.TokenType != Token.RIGHTSQBRACKET)
{
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered while trying to parse a Blank Node Object List, expected a comma, semicolon or ] to terminate the current Triple/list", next);
}
}
else if (next.TokenType != Token.COMMA && next.TokenType != Token.SEMICOLON && next.TokenType != Token.DOT)
{
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered while trying to parse an Object list, expected a comma, semicolon or dot to terminate the current Triple", next);
}
} while (true);
}
/// <summary>
/// Tries to parse forSome quantifiers
/// </summary>
/// <param name="context">Parser Context</param>
private void TryParseForSome(Notation3ParserContext context)
{
//We know the Token we've just got off the Queue was a ForSomeQuantifierToken
//Therefore the next Token(s) should be QNames/URIs leading to a DotToken
//Create a new Variable Context if one doesn't currently exist
if (context.VariableContext.Type == VariableContextType.None)
{
context.VariableContext = new VariableContext(VariableContextType.Existential);
}
else
{
context.VariableContext.InnerContext = new VariableContext(VariableContextType.Existential);
}
context.Tokens.Dequeue();
IToken next = context.Tokens.Dequeue();
while (next.TokenType != Token.DOT)
{
//Get Variables
switch (next.TokenType)
{
case Token.QNAME:
case Token.URI:
context.VariableContext.AddVariable(ParserHelper.TryResolveUri(context, next));
break;
default:
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered, expected a URI/QName for an Existential Variable as part of a @forSome directive", next);
}
next = context.Tokens.Dequeue();
//May optionally have a COMMA between each QName/URI
if (next.TokenType == Token.COMMA)
{
next = context.Tokens.Dequeue();
}
}
this.RaiseWarning("Parser does not know how to evaluate forSome Quantifiers");
}
/// <summary>
/// Tries to parse a Graph Literal
/// </summary>
/// <param name="context"></param>
private INode TryParseGraphLiteral(Notation3ParserContext context)
{
context.PushGraph();
//Watch out for nesting
//This counter starts as zero since the last right curly bracket will be discarded by the
//parser when it stops parsing the Graph Literal in one of the other functions
int nesting = 1;
IToken next = context.Tokens.Peek();
while (next.TokenType == Token.LEFTCURLYBRACKET)
{
context.Tokens.Dequeue();
next = context.Tokens.Peek();
nesting++;
}
do
{
next = context.Tokens.Peek();
if (next.TokenType == Token.FORALL)
{
this.TryParseForAll(context);
}
else if (next.TokenType == Token.FORSOME)
{
this.TryParseForSome(context);
}
else
{
this.TryParseTriples(context);
}
//If we've just seen a Right Curly bracket we've been terminated
if (context.Tokens.LastTokenType == Token.RIGHTCURLYBRACKET)
{
//Decrease the amount of expected nesting
nesting--;
break;
}
next = context.Tokens.Peek();
} while (next.TokenType != Token.RIGHTCURLYBRACKET);
IGraph subgraph = context.SubGraph;
context.PopGraph();
//Expect the correct number of closing brackets
while (nesting > 0)
{
next = context.Tokens.Dequeue();
if (next.TokenType != Token.RIGHTCURLYBRACKET)
{
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered, expected a Right Curly Bracket to terminate a Graph Literal", next);
}
nesting--;
}
return context.Handler.CreateGraphLiteralNode(subgraph);
}
/// <summary>
/// Tries to parse Collections
/// </summary>
/// <param name="context">Parser Context</param>
/// <param name="firstSubj">Blank Node which is the head of the collection</param>
private void TryParseCollection(Notation3ParserContext context, INode firstSubj)
{
//The opening bracket of the collection will already have been discarded when we get called
IToken next, temp;
INode subj = firstSubj;
INode obj = null, nextSubj;
INode rdfFirst = context.Handler.CreateUriNode(UriFactory.Create(NamespaceMapper.RDF + "first"));
INode rdfRest = context.Handler.CreateUriNode(UriFactory.Create(NamespaceMapper.RDF + "rest"));
INode rdfNil = context.Handler.CreateUriNode(UriFactory.Create(NamespaceMapper.RDF + "nil"));
do
{
next = context.Tokens.Dequeue();
if (context.TraceParsing)
{
Console.WriteLine("Trying to parse a Collection item from Token '" + next.GetType().ToString() + "'");
}
switch (next.TokenType)
{
case Token.BLANKNODE:
obj = context.Handler.CreateBlankNode();
break;
case Token.BLANKNODEWITHID:
obj = context.Handler.CreateBlankNode(next.Value.Substring(2));
break;
case Token.COMMENT:
//Discard and continue
continue;
case Token.LEFTBRACKET:
//Nested Collection?
temp = context.Tokens.Peek();
if (temp.TokenType == Token.RIGHTBRACKET)
{
//Empty Collection => rdf:nil
context.Tokens.Dequeue();
obj = rdfNil;
}
else
{
//Collection
obj = context.Handler.CreateBlankNode();
this.TryParseCollection(context, obj);
}
break;
case Token.LEFTCURLYBRACKET:
//Graph Literal
temp = context.Tokens.Peek();
if (temp.TokenType == Token.RIGHTCURLYBRACKET)
{
//Empty Graph Literal
context.Tokens.Dequeue();
obj = context.Handler.CreateGraphLiteralNode();
}
else
{
//Graph Literal
obj = this.TryParseGraphLiteral(context);
}
break;
case Token.LEFTSQBRACKET:
//Allowed Blank Node Collections as part of a Collection
temp = context.Tokens.Peek();
if (temp.TokenType == Token.RIGHTSQBRACKET)
{
//Anonymous Blank Node
context.Tokens.Dequeue();
obj = context.Handler.CreateBlankNode();
}
else
{
//Blank Node Collection
obj = context.Handler.CreateBlankNode();
this.TryParsePredicateObjectList(context, obj, true);
}
break;
case Token.LITERAL:
case Token.LITERALWITHDT:
case Token.LITERALWITHLANG:
case Token.LONGLITERAL:
case Token.PLAINLITERAL:
obj = this.TryParseLiteral(context, next);
break;
case Token.RIGHTBRACKET:
//We might terminate here if someone put a comment before the end of the Collection
if (!context.Handler.HandleTriple(new Triple(subj, rdfFirst, obj, context.VariableContext))) ParserHelper.Stop();
if (!context.Handler.HandleTriple(new Triple(subj, rdfRest, rdfNil, context.VariableContext))) ParserHelper.Stop();
return;
case Token.QNAME:
case Token.URI:
obj = ParserHelper.TryResolveUri(context, next);
break;
case Token.VARIABLE:
obj = context.Handler.CreateVariableNode(next.Value.Substring(1));
break;
default:
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered while trying to parse a Collection", next);
}
//Watch out for Paths
next = context.Tokens.Peek();
if (next.TokenType == Token.EXCLAMATION || next.TokenType == Token.HAT)
{
context.Tokens.Dequeue();
obj = this.TryParsePath(context, obj);
}
//Assert the relevant Triples
if (!context.Handler.HandleTriple(new Triple(subj, rdfFirst, obj, context.VariableContext))) ParserHelper.Stop();
if (context.Tokens.Peek().TokenType == Token.RIGHTBRACKET)
{
//End of the Collection
context.Tokens.Dequeue();
if (!context.Handler.HandleTriple(new Triple(subj, rdfRest, rdfNil, context.VariableContext))) ParserHelper.Stop();
return;
}
else
{
//More stuff in the collection
nextSubj = context.Handler.CreateBlankNode();
if (!context.Handler.HandleTriple(new Triple(subj, rdfRest, nextSubj, context.VariableContext))) ParserHelper.Stop();
subj = nextSubj;
}
} while (true);
}
/// <summary>
/// Tries to parse declarations
/// </summary>
/// <param name="context">Parse Context</param>
private void TryParseDirective(Notation3ParserContext context)
{
if (context.TraceParsing)
{
Console.WriteLine("Attempting to parse a Directive");
}
//We expect either a Base Directive/Prefix/Keywords Directive
IToken directive = context.Tokens.Dequeue();
if (directive.TokenType == Token.BASEDIRECTIVE)
{
//Then expect a Uri for the Base Uri
IToken u = context.Tokens.Dequeue();
if (u.TokenType == Token.URI)
{
//Set the Base Uri resolving against the current Base if any
Uri baseUri = ((IUriNode)ParserHelper.TryResolveUri(context, u)).Uri;
context.BaseUri = baseUri;
if (!context.Handler.HandleBaseUri(baseUri)) ParserHelper.Stop();
}
else
{
throw ParserHelper.Error("Unexpected Token '" + u.GetType().ToString() + "' encountered, expected a URI after a Base Directive", u);
}
}
else if (directive.TokenType == Token.PREFIXDIRECTIVE)
{
//Expect a Prefix then a Uri
IToken pre = context.Tokens.Dequeue();
if (pre.TokenType == Token.PREFIX)
{
IToken ns = context.Tokens.Dequeue();
if (ns.TokenType == Token.URI)
{
//Register a Namespace resolving the Namespace Uri against the Base Uri
Uri nsUri = ((IUriNode)ParserHelper.TryResolveUri(context, ns)).Uri;
String nsPrefix = (pre.Value.Length > 1) ? pre.Value.Substring(0, pre.Value.Length-1) : String.Empty;
context.Namespaces.AddNamespace(nsPrefix, nsUri);
if (!context.Handler.HandleNamespace(pre.Value.Substring(0, pre.Value.Length - 1), nsUri)) ParserHelper.Stop();
}
else
{
throw ParserHelper.Error("Unexpected Token '" + ns.GetType().ToString() + "' encountered, expected a URI after a Prefix Directive", pre);
}
}
else
{
throw ParserHelper.Error("Unexpected Token '" + pre.GetType().ToString() + "' encountered, expected a Prefix after a Prefix Directive", pre);
}
}
else if (directive.TokenType == Token.KEYWORDDIRECTIVE)
{
//Expect zero/more keywords followed by a dot
context.KeywordsMode = true;
IToken next = context.Tokens.Dequeue();
while (next.TokenType != Token.DOT)
{
//Error if not a Keyword Definition
if (next.TokenType != Token.KEYWORDDEF)
{
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered when a CustomKeywordDefinitionToken was expected", next);
}
//Add to Keywords List
if (!context.Keywords.Contains(next.Value))
{
context.Keywords.Add(next.Value);
}
next = context.Tokens.Dequeue();
}
return;
}
else
{
throw ParserHelper.Error("Unexpected Token '" + directive.GetType().ToString() + "' encountered, expected a Base/Prefix/Keywords Directive after an @ symbol", directive);
}
//All declarations are terminated with a Dot
IToken terminator = context.Tokens.Dequeue();
if (terminator.TokenType != Token.DOT)
{
throw ParserHelper.Error("Unexpected Token '" + terminator.GetType().ToString() + "' encountered, expected a Dot Line Terminator to terminate a Prefix/Base Directive", terminator);
}
}
/// <summary>
/// Internal method which does the parsing of the input
/// </summary>
/// <param name="context">Parser Context</param>
private void Parse(Notation3ParserContext context)
{
try
{
context.Handler.StartRdf();
//Initialise Buffer and start parsing
context.Tokens.InitialiseBuffer(10);
IToken next = context.Tokens.Dequeue();
if (next.TokenType != Token.BOF)
{
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered, expected a BOF Token", next);
}
do
{
next = context.Tokens.Peek();
switch (next.TokenType)
{
case Token.BASEDIRECTIVE:
case Token.PREFIXDIRECTIVE:
case Token.KEYWORDDIRECTIVE:
this.TryParseDirective(context);
break;
case Token.FORALL:
this.TryParseForAll(context);
break;
case Token.FORSOME:
this.TryParseForSome(context);
break;
case Token.COMMENT:
//Discard and ignore
context.Tokens.Dequeue();
break;
case Token.BLANKNODE:
case Token.BLANKNODEWITHID:
case Token.LEFTBRACKET:
case Token.LEFTCURLYBRACKET:
case Token.LEFTSQBRACKET:
case Token.LITERAL:
case Token.LITERALWITHDT:
case Token.LITERALWITHLANG:
case Token.LONGLITERAL:
case Token.PLAINLITERAL:
case Token.QNAME:
case Token.URI:
//Valid Subject of a Triple
this.TryParseTriples(context);
break;
case Token.KEYWORDA:
//'a' Keyword only valid as Predicate
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered, the 'a' Keyword is only valid as a Predicate in Notation 3", next);
case Token.EOF:
//OK - the loop will now terminate since we've seen the End of File
break;
default:
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered", next);
}
} while (next.TokenType != Token.EOF);
context.Handler.EndRdf(true);
}
catch (RdfParsingTerminatedException)
{
context.Handler.EndRdf(true);
//Discard this - it justs means the Handler told us to stop
}
catch
{
context.Handler.EndRdf(false);
throw;
}
}
/// <summary>
/// Loads RDF using a RDF handler by reading Notation 3 syntax from the given input
/// </summary>
/// <param name="handler">RDF Handler to use</param>
/// <param name="input">Input to read from</param>
public void Load(IRdfHandler handler, TextReader input)
{
if (handler == null) throw new RdfParseException("Cannot read RDF into a null RDF Handler");
if (input == null) throw new RdfParseException("Cannot read RDF from a null TextReader");
try
{
Notation3ParserContext context = new Notation3ParserContext(handler, new Notation3Tokeniser(input), this._queueMode, this._traceParsing, this._traceTokeniser);
this.Parse(context);
input.Close();
}
catch
{
try
{
input.Close();
}
catch
{
//No catch actions, just trying to clean up
}
throw;
}
}
/// <summary>
/// Tries to parse Triples
/// </summary>
/// <param name="context">Parser Context</param>
private void TryParseTriples(Notation3ParserContext context)
{
IToken subjToken = context.Tokens.Dequeue();
IToken next;
INode subj;
if (context.TraceParsing)
{
Console.WriteLine("Attempting to parse Triples from the Subject Token '" + subjToken.GetType().ToString() + "'");
}
switch (subjToken.TokenType)
{
case Token.BLANKNODE:
subj = context.Handler.CreateBlankNode();
break;
case Token.BLANKNODEWITHID:
subj = context.Handler.CreateBlankNode(subjToken.Value.Substring(2));
break;
case Token.LEFTBRACKET:
//Start of a collection so create a new Blank Node to be it's first subject
next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTBRACKET)
{
//An Empty Collection => rdf:nil
context.Tokens.Dequeue();
subj = context.Handler.CreateUriNode(UriFactory.Create(NamespaceMapper.RDF + "nil"));
}
else
{
subj = context.Handler.CreateBlankNode();
this.TryParseCollection(context, subj);
}
break;
case Token.LEFTCURLYBRACKET:
//Start of a Graph Literal
next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTCURLYBRACKET)
{
//An Empty Graph Literal
context.Tokens.Dequeue();
subj = context.Handler.CreateGraphLiteralNode();
}
else
{
subj = this.TryParseGraphLiteral(context);
}
break;
case Token.LEFTSQBRACKET:
//Start of a Blank Node collection?
next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTSQBRACKET)
{
//An anoynmous Blank Node
context.Tokens.Dequeue();
subj = context.Handler.CreateBlankNode();
}
else
{
//Start of a Blank Node Collection
subj = context.Handler.CreateBlankNode();
this.TryParsePredicateObjectList(context, subj, true);
}
break;
case Token.LITERAL:
case Token.LITERALWITHDT:
case Token.LITERALWITHLANG:
case Token.LONGLITERAL:
case Token.PLAINLITERAL:
//Literal Subjects valid in N3
subj = this.TryParseLiteral(context, subjToken);
break;
case Token.QNAME:
case Token.URI:
subj = ParserHelper.TryResolveUri(context, subjToken);
break;
case Token.VARIABLE:
subj = context.Handler.CreateVariableNode(subjToken.Value.Substring(1));
break;
default:
throw ParserHelper.Error("Unexpected Token '" + subjToken.GetType().ToString() + "' encountered, this Token is not valid as the subject of a Triple", subjToken);
}
if (context.Tokens.LastTokenType == Token.RIGHTSQBRACKET || context.Tokens.LastTokenType == Token.RIGHTCURLYBRACKET)
{
//Allowed to state a Blank Node collection or a Graph Literal on it's own in N3
next = context.Tokens.Peek();
if (next.TokenType == Token.DOT)
{
context.Tokens.Dequeue();
return;
}
}
this.TryParsePredicateObjectList(context, subj, false);
}
/// <summary>
/// Tries to parse Predicate Object lists
/// </summary>
/// <param name="context">Parse Context</param>
/// <param name="subj">Subject of the Triples</param>
/// <param name="bnodeList">Whether this is a Blank Node Predicate Object list</param>
private void TryParsePredicateObjectList(Notation3ParserContext context, INode subj, bool bnodeList)
{
IToken predToken, next;
INode pred = null;
bool reverse = false;
do
{
predToken = context.Tokens.Dequeue();
if (context.TraceParsing)
{
Console.WriteLine("Attempting to parse Predicate Object List from the Predicate Token '" + predToken.GetType().ToString() + "'");
}
switch (predToken.TokenType)
{
case Token.BLANKNODE:
pred = context.Handler.CreateBlankNode();
break;
case Token.BLANKNODEWITHID:
pred = context.Handler.CreateBlankNode(predToken.Value.Substring(2));
break;
case Token.COMMENT:
//Discard and continue
continue;
case Token.EQUALS:
//= Keyword
pred = context.Handler.CreateUriNode(UriFactory.Create(SameAsUri));
break;
case Token.EXCLAMATION:
case Token.HAT:
//Path
subj = this.TryParsePath(context, subj);
this.TryParsePredicateObjectList(context, subj, bnodeList);
return;
case Token.IMPLIEDBY:
//<= keyword
pred = context.Handler.CreateUriNode(UriFactory.Create(ImpliesUri));
reverse = true;
break;
case Token.IMPLIES:
//=> keyword
pred = context.Handler.CreateUriNode(UriFactory.Create(ImpliesUri));
break;
case Token.KEYWORDA:
//'a' Keyword
pred = context.Handler.CreateUriNode(UriFactory.Create(NamespaceMapper.RDF + "type"));
break;
case Token.LEFTBRACKET:
//Start of a collection so create a new Blank Node to be it's first subject
next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTBRACKET)
{
//An Empty Collection => rdf:nil
context.Tokens.Dequeue();
pred = context.Handler.CreateUriNode(UriFactory.Create(NamespaceMapper.RDF + "nil"));
}
else
{
pred = context.Handler.CreateBlankNode();
this.TryParseCollection(context, pred);
}
break;
case Token.LEFTCURLYBRACKET:
//Graph Literals not allowed as Predicates
throw ParserHelper.Error("Unexpected Left Curly Bracket encountered, Graph Literals are not valid as Predicates in Notation 3", predToken);
case Token.LEFTSQBRACKET:
//Start of a Blank Node collection?
next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTSQBRACKET)
{
//An anoynmous Blank Node
context.Tokens.Dequeue();
pred = context.Handler.CreateBlankNode();
}
else
{
//Start of a Blank Node Collection
pred = context.Handler.CreateBlankNode();
this.TryParsePredicateObjectList(context, pred, true);
}
break;
case Token.RIGHTCURLYBRACKET:
if (context.GraphLiteralMode)
{
return;
}
else
{
throw ParserHelper.Error("Unexpected Right Curly Bracket encountered but not expecting the end of a Graph Literal", predToken);
}
case Token.RIGHTSQBRACKET:
//If the last token was a semicolon and we're parsing a Blank Node Predicate Object list
//then a trailing semicolon is permitted
if (bnodeList)
{
if (context.Tokens.LastTokenType == Token.SEMICOLON)
{
return;
}
else
{
//If Predicate is not null then we've seen at least one valid Triple and this is just the end of the Blank Node Predicate Object list
if (pred != null)
{
return;
}
else
{
throw ParserHelper.Error("Unexpected Right Square Bracket encountered while trying to parse a Blank Node Predicate Object list, expected a valid Predicate", predToken);
}
}
}
else
{
throw ParserHelper.Error("Unexpected Right Square Bracket encountered while trying to parse a Predicate Object list", predToken);
}
case Token.QNAME:
case Token.URI:
pred = ParserHelper.TryResolveUri(context, predToken);
break;
case Token.VARIABLE:
pred = context.Handler.CreateVariableNode(predToken.Value.Substring(1));
break;
case Token.EOF:
throw ParserHelper.Error("Unexpected end of file while trying to parse a Predicate Object list", predToken);
default:
throw ParserHelper.Error("Unexpected Token '" + predToken.GetType().ToString() + "' encountered while trying to parse a Predicate Object list", predToken);
}
this.TryParseObjectList(context, subj, pred, bnodeList, reverse);
if (context.Tokens.LastTokenType == Token.DOT && !bnodeList) return; //Dot terminates a normal Predicate Object list
if (context.Tokens.LastTokenType == Token.RIGHTSQBRACKET && bnodeList) return; //Trailing semicolon may terminate a Blank Node Predicate Object list
if (context.Tokens.LastTokenType == Token.SEMICOLON && context.Tokens.Peek().TokenType == Token.DOT)
{
//Dot terminates a Predicate Object list with a trailing semicolon
context.Tokens.Dequeue();
return;
}
if (context.Tokens.LastTokenType == Token.RIGHTCURLYBRACKET && context.GraphLiteralMode) return; //Right Curly Bracket terminates a Graph Literal
} while (true);
}
private INode TryParsePath(Notation3ParserContext context, INode firstItem)
{
IToken next;
INode secondItem;
bool forward = (context.Tokens.LastTokenType == Token.EXCLAMATION);
//Actual path is represented by a new Blank Node
INode path = context.Handler.CreateBlankNode();
INode pathHead = path;
do
{
//Get next thing which should be a Path Item
next = context.Tokens.Dequeue();
switch (next.TokenType)
{
case Token.QNAME:
secondItem = context.Handler.CreateUriNode(UriFactory.Create(Tools.ResolveQName(next.Value, context.Namespaces, context.BaseUri)));
break;
case Token.LITERAL:
case Token.LONGLITERAL:
case Token.LITERALWITHDT:
case Token.LITERALWITHLANG:
secondItem = this.TryParseLiteral(context, next);
break;
case Token.URI:
secondItem = context.Handler.CreateUriNode(UriFactory.Create(Tools.ResolveUri(next.Value, context.BaseUri.ToSafeString())));
break;
default:
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered, only Literals, QNames and URIs are valid as Path Items", next);
}
if (forward)
{
if (!context.Handler.HandleTriple(new Triple(firstItem, secondItem, path, context.VariableContext))) ParserHelper.Stop();
}
else
{
if (!context.Handler.HandleTriple(new Triple(path, secondItem, firstItem, context.VariableContext))) ParserHelper.Stop();
}
//Does the Path continue?
next = context.Tokens.Peek();
if (next.TokenType == Token.EXCLAMATION || next.TokenType == Token.HAT)
{
context.Tokens.Dequeue();
firstItem = path;
path = context.Handler.CreateBlankNode();
forward = (context.Tokens.LastTokenType == Token.EXCLAMATION);
}
else
{
return pathHead;
}
} while (true);
}
