private void TryParsePredicateObjectList(SparqlQueryParserContext context, GraphPattern p, int expectedCount)
{
PatternItem subj, pred, obj;
//Subject is first thing on the Stack
subj = this.TryCreatePatternItem(context, context.LocalTokens.Pop());
//Start grabbing other stuff off the Stack and Parsing
IToken next, lit, temp;
ISparqlPath path;
do
{
//Peek at the Next Token
next = context.Tokens.Peek();
switch (next.TokenType)
{
case Token.COMMENT:
//Ignore Comments
context.Tokens.Dequeue();
break;
case Token.VARIABLE:
context.LocalTokens.Push(next);
context.Query.AddVariable(next.Value);
context.Tokens.Dequeue();
break;
case Token.URI:
case Token.QNAME:
case Token.LITERAL:
case Token.LONGLITERAL:
case Token.PLAINLITERAL:
case Token.KEYWORDA:
context.LocalTokens.Push(next);
context.Tokens.Dequeue();
break;
case Token.HAT:
case Token.DIVIDE:
case Token.BITWISEOR:
case Token.MULTIPLY:
case Token.PLUS:
case Token.QUESTION:
case Token.NEGATION:
//If we see any of these Tokens then it's a Property Path
if (context.SyntaxMode == SparqlQuerySyntax.Sparql_1_0) throw new RdfParseException("Property Paths are not permitted in SPARQL 1.0");
if (context.LocalTokens.Count == expectedCount - 1)
{
path = context.PathParser.Parse(context, context.LocalTokens.Pop());
PathToken pathToken = new PathToken(path);
context.LocalTokens.Push(pathToken);
}
else if ((next.TokenType == Token.HAT || next.TokenType == Token.NEGATION) && context.LocalTokens.Count == expectedCount - 2)
{
// ^ and ! may be used to start a pattern
context.Tokens.Dequeue();
path = context.PathParser.Parse(context, next);
PathToken pathToken = new PathToken(path);
context.LocalTokens.Push(pathToken);
}
else
{
throw ParserHelper.Error("Encountered a '" + next.GetType().ToString() + "' Token which is valid only after a Predicate to indicate Path Cardinality", next);
}
break;
case Token.BLANKNODE:
case Token.BLANKNODEWITHID:
//Generate a new Blank Node ID if required
if (next.TokenType == Token.BLANKNODE)
{
next = new BlankNodeWithIDToken(context.GetNewBlankNodeID(), 0, 0, 0);
}
//Check list of Blank Node usages
if (context.BlankNodeIDUsages.ContainsKey(next.Value))
{
if (context.BlankNodeIDUsages[next.Value] != context.GraphPatternID)
{
throw ParserHelper.Error("Invalid use of Blank Node Label '" + next.Value + "', this Label has already been used in a different Graph Pattern", next);
}
}
else
{
context.BlankNodeIDUsages.Add(next.Value, context.GraphPatternID);
}
context.LocalTokens.Push(next);
context.Tokens.Dequeue();
break;
case Token.HATHAT:
//Get the next Token which should be a Datatype Token
context.Tokens.Dequeue();
next = context.Tokens.Peek();
if (next.TokenType == Token.DATATYPE)
{
//Get the previous Token off the Stack and ensure it's a Literal
lit = context.LocalTokens.Pop();
if (lit.TokenType == Token.LITERAL || lit.TokenType == Token.LONGLITERAL)
{
//Create a DataTyped Literal
context.LocalTokens.Push(new LiteralWithDataTypeToken(lit, (DataTypeToken)next));
}
else
{
throw ParserHelper.Error("Unexpected Datatype Token, a Datatype may only be specified after a quoted Literal/Long Literal", lit);
}
}
else
{
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered, expected a Datatype Token to follow a ^^ Token to specify the Datatype of a previous Literal Token", next);
}
context.Tokens.Dequeue();
break;
case Token.LEFTSQBRACKET:
//Start of Blank Node Collection
//Create a new Blank Node Token
BlankNodeWithIDToken bnode = new BlankNodeWithIDToken(context.GetNewBlankNodeID(), 0, 0, 0);
//Push twice, once for Object of the current Triple
context.LocalTokens.Push(bnode);
context.Tokens.Dequeue();
next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTSQBRACKET)
{
//Single anonymous blank node
context.Tokens.Dequeue();
break;
}
//Blank Node Collection
//Push again for Subject of new Triple
context.LocalTokens.Push(bnode);
//Recursively call self to parse the new Triple list
this.TryParsePredicateObjectList(context, p, expectedCount + 2);
break;
case Token.RIGHTSQBRACKET:
//End of Blank Node Collection
//Allow for trailing semicolon
if (context.LocalTokens.Count == expectedCount - 2 && context.Tokens.LastTokenType == Token.SEMICOLON)
{
context.Tokens.Dequeue();
return;
}
//Check length of Stack
if (context.LocalTokens.Count < expectedCount)
{
throw ParserHelper.Error("Encountered a Right Square Bracket Token to terminate a Blank Node Collection within a Triple Pattern but there are not enough Tokens to form a valid Triple Pattern", next);
}
else if (context.LocalTokens.Count > expectedCount)
{
throw ParserHelper.Error("Encountered a Right Square Bracket Token to terminate a Blank Node Collection within a Triple Pattern but there are too many Tokens to form a valid Triple Pattern", next);
}
obj = this.TryCreatePatternItem(context, context.LocalTokens.Pop());
pred = this.TryCreatePatternItem(context, context.LocalTokens.Pop());
//Add Pattern to the Graph Pattern
p.AddTriplePattern(new TriplePattern(subj, pred, obj));
context.Tokens.Dequeue();
return;
case Token.LEFTBRACKET:
//Property Path if it's the Predicate or Collection if it's the Object
if (context.LocalTokens.Count == expectedCount - 2)
{
//Property Path
if (context.SyntaxMode == SparqlQuerySyntax.Sparql_1_0) throw new RdfParseException("Property Paths are not permitted in SPARQL 1.0");
path = context.PathParser.Parse(context, context.Tokens.Dequeue());
PathToken pathToken = new PathToken(path);
context.LocalTokens.Push(pathToken);
}
else
{
//Collection
context.Tokens.Dequeue();
this.TryParseCollection(context, p, false);
}
break;
case Token.LANGSPEC:
//Get the previous Token off the Stack and ensure it's a Literal
lit = context.LocalTokens.Pop();
if (lit.TokenType == Token.LITERAL || lit.TokenType == Token.LONGLITERAL)
{
//Create a Language Specified Literal
context.LocalTokens.Push(new LiteralWithLanguageSpecifierToken(lit, (LanguageSpecifierToken)next));
}
else
{
throw ParserHelper.Error("Unexpected Language Specifier Token, a Language Specifier may only be specified after a quoted Literal/Long Literal", lit);
}
context.Tokens.Dequeue();
break;
case Token.COMMA:
//End of a Triple Pattern
//Check length of stack
if (context.LocalTokens.Count < expectedCount)
{
throw ParserHelper.Error("Encountered a Comma Token to terminate a Triple Pattern but there are not enough Tokens to form a valid Triple Pattern", next);
}
else if (context.LocalTokens.Count > expectedCount)
{
throw ParserHelper.Error("Encountered a Comma Token to terminate a Triple Pattern but there are too many Tokens to form a valid Triple Pattern", next);
}
obj = this.TryCreatePatternItem(context, context.LocalTokens.Pop());
temp = context.LocalTokens.Pop();
if (temp.TokenType == Token.PATH)
{
path = ((PathToken)temp).Path;
p.AddTriplePattern(new PropertyPathPattern(subj, path, obj));
}
else
{
pred = this.TryCreatePatternItem(context, temp);
//Add Pattern to the Graph Pattern
p.AddTriplePattern(new TriplePattern(subj, pred, obj));
}
//Push Predicate back on Stack
context.LocalTokens.Push(temp);
context.Tokens.Dequeue();
break;
case Token.SEMICOLON:
//End of a Triple Pattern
//Check length of stack
if (context.LocalTokens.Count < expectedCount)
{
throw ParserHelper.Error("Encountered a Semicolon Token to terminate a Triple Pattern but there are not enough Tokens to form a valid Triple Pattern", next);
}
else if (context.LocalTokens.Count > expectedCount)
{
throw ParserHelper.Error("Encountered a Semicolon Token to terminate a Triple Pattern but there are too many Tokens to form a valid Triple Pattern", next);
}
obj = this.TryCreatePatternItem(context, context.LocalTokens.Pop());
temp = context.LocalTokens.Pop();
if (temp.TokenType == Token.PATH)
{
path = ((PathToken)temp).Path;
p.AddTriplePattern(new PropertyPathPattern(subj, path, obj));
}
else
{
pred = this.TryCreatePatternItem(context, temp);
//Add Pattern to the Graph Pattern
p.AddTriplePattern(new TriplePattern(subj, pred, obj));
}
context.Tokens.Dequeue();
break;
case Token.DOT:
//End of the Triple Patterns
//Allow for trailing semicolon and Blank Node Collection lists
if (context.LocalTokens.Count == expectedCount - 2 && (context.Tokens.LastTokenType == Token.SEMICOLON || (context.Tokens.LastTokenType == Token.RIGHTSQBRACKET && p.TriplePatterns.Count > 0)))
{
if (context.Tokens.LastTokenType == Token.RIGHTSQBRACKET)
{
context.Tokens.Dequeue();
}
return;
}
//Check length of Stack
if (context.LocalTokens.Count < expectedCount)
{
throw ParserHelper.Error("Encountered a DOT Token to terminate a Triple Pattern but there are not enough Tokens to form a valid Triple Pattern", next);
}
else if (context.LocalTokens.Count > expectedCount)
{
throw ParserHelper.Error("Encountered a DOT Token to terminate a Triple Pattern but there are too many Tokens to form a valid Triple Pattern", next);
}
obj = this.TryCreatePatternItem(context, context.LocalTokens.Pop());
temp = context.LocalTokens.Pop();
if (temp.TokenType == Token.PATH)
{
path = ((PathToken)temp).Path;
p.AddTriplePattern(new PropertyPathPattern(subj, path, obj));
}
else
{
pred = this.TryCreatePatternItem(context, temp);
//Add Pattern to the Graph Pattern
p.AddTriplePattern(new TriplePattern(subj, pred, obj));
}
context.Tokens.Dequeue();
return;
case Token.LEFTCURLYBRACKET:
case Token.RIGHTCURLYBRACKET:
case Token.OPTIONAL:
case Token.EXISTS:
case Token.NOTEXISTS:
case Token.UNSAID:
case Token.MINUS_P:
case Token.SERVICE:
case Token.GRAPH:
case Token.FILTER:
//End of the Triple Patterns
//Allow for trailing semicolon and Blank Node Collection lists
if (context.LocalTokens.Count == expectedCount - 2 && (context.Tokens.LastTokenType == Token.SEMICOLON || ((context.Tokens.LastTokenType == Token.RIGHTSQBRACKET || context.Tokens.LastTokenType == Token.RIGHTBRACKET) && p.TriplePatterns.Count > 0)))
{
return;
}
//Check length of Stack
if (context.LocalTokens.Count < expectedCount)
{
temp = context.LocalTokens.Peek();
if (next.TokenType == Token.LEFTCURLYBRACKET && context.SyntaxMode != SparqlQuerySyntax.Sparql_1_0 && context.LocalTokens.Count == expectedCount - 1 && (temp.TokenType == Token.QNAME || temp.TokenType == Token.URI || temp.TokenType == Token.KEYWORDA))
{
//In this case this should be a Cardinality Modifier on a path (we hope)
path = context.PathParser.Parse(context, context.LocalTokens.Pop());
IToken pathToken = new PathToken(path);
context.LocalTokens.Push(pathToken);
continue;
}
else
{
throw ParserHelper.Error("Encountered a Token which terminates a Triple Pattern but there are not enough Tokens to form a valid Triple Pattern", next);
}
}
else if (context.LocalTokens.Count > expectedCount)
{
throw ParserHelper.Error("Encountered a Token which terminates a Triple Pattern but there are too many Tokens to form a valid Triple Pattern", next);
}
obj = this.TryCreatePatternItem(context, context.LocalTokens.Pop());
temp = context.LocalTokens.Pop();
if (temp.TokenType == Token.PATH)
{
path = ((PathToken)temp).Path;
p.AddTriplePattern(new PropertyPathPattern(subj, path, obj));
}
else
{
pred = this.TryCreatePatternItem(context, temp);
//Add Pattern to the Graph Pattern
p.AddTriplePattern(new TriplePattern(subj, pred, obj));
}
return;
default:
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' while trying to Parse Triple Patterns", next);
}
} while (true);
}
private void TryParseCollection(SparqlQueryParserContext context, GraphPattern p, bool nested)
{
//Check the next Token
IToken next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTBRACKET)
{
//Empty Collection
context.Tokens.Dequeue();
if (!nested)
{
//Push an rdf:nil Uri on the Stack
context.LocalTokens.Push(new UriToken("<" + NamespaceMapper.RDF + "nil>", next.StartLine, next.StartPosition, next.EndPosition));
}
}
else
{
//Push a Blank Node Token onto the stack for the start of the collection
BlankNodeWithIDToken blank;
if (!nested)
{
blank = new BlankNodeWithIDToken(context.GetNewBlankNodeID(), next.StartLine, next.StartPosition, next.EndPosition);
context.LocalTokens.Push(blank);
}
else
{
blank = new BlankNodeWithIDToken("_:sparql-autos" + context.BlankNodeID, next.StartLine, next.StartPosition, next.EndPosition);
}
bool first = true;
IUriNode rdfFirst, rdfRest, rdfNil;
rdfFirst = new UriNode(null, new Uri(NamespaceMapper.RDF + "first"));
rdfRest = new UriNode(null, new Uri(NamespaceMapper.RDF + "rest"));
rdfNil = new UriNode(null, new Uri(NamespaceMapper.RDF + "nil"));
do
{
next = context.Tokens.Peek();
switch (next.TokenType)
{
case Token.BLANKNODE:
case Token.BLANKNODEWITHID:
case Token.KEYWORDA:
case Token.LITERAL:
case Token.LONGLITERAL:
case Token.PLAINLITERAL:
case Token.QNAME:
case Token.URI:
case Token.VARIABLE:
//Create the Triple pattern
if (first)
{
//rdf:first Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfFirst), this.TryCreatePatternItem(context, next)));
first = false;
}
else
{
//Get new Blank Node ID
BlankNodeWithIDToken blank2 = new BlankNodeWithIDToken(context.GetNewBlankNodeID(), next.StartLine,next.StartPosition,next.EndPosition);
//rdf:rest Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfRest), this.TryCreatePatternItem(context, blank2)));
blank = blank2;
//rdf:first Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfFirst), this.TryCreatePatternItem(context, next)));
}
break;
case Token.LEFTSQBRACKET:
//Is the next token a Right Square Bracket?
//ie. a [] for an anonymous blank node
context.Tokens.Dequeue();
next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTSQBRACKET)
{
BlankNodeWithIDToken anon = new BlankNodeWithIDToken(context.GetNewBlankNodeID(), next.StartLine, next.StartPosition, next.EndPosition);
if (first)
{
//rdf:first Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfFirst), this.TryCreatePatternItem(context, anon)));
first = false;
}
else
{
//Get new Blank Node ID
BlankNodeWithIDToken blank2 = new BlankNodeWithIDToken(context.GetNewBlankNodeID(), next.StartLine, next.StartPosition, next.EndPosition);
//rdf:rest Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfRest), this.TryCreatePatternItem(context, blank2)));
blank = blank2;
//rdf:first Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfFirst), this.TryCreatePatternItem(context, anon)));
}
}
else
{
BlankNodeWithIDToken anon = new BlankNodeWithIDToken(context.GetNewBlankNodeID(), next.StartLine, next.StartPosition, next.EndPosition);
if (first)
{
//rdf:first Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfFirst), this.TryCreatePatternItem(context, anon)));
first = false;
}
else
{
//Get new Blank Node ID
BlankNodeWithIDToken blank2 = new BlankNodeWithIDToken(context.GetNewBlankNodeID(), next.StartLine, next.StartPosition, next.EndPosition);
//rdf:rest Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfRest), this.TryCreatePatternItem(context, blank2)));
blank = blank2;
//rdf:first Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfFirst), this.TryCreatePatternItem(context, anon)));
}
//Parse the Blank Node Collection
context.LocalTokens.Push(anon);
this.TryParsePredicateObjectList(context, p, context.LocalTokens.Count + 1);
continue;
}
break;
case Token.LEFTBRACKET:
BlankNodeWithIDToken innerCollection = new BlankNodeWithIDToken(context.GetNewBlankNodeID(), next.StartLine, next.StartPosition, next.EndPosition);
if (first)
{
//rdf:first Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfFirst), this.TryCreatePatternItem(context, innerCollection)));
first = false;
}
else
{
//Get new Blank Node ID
BlankNodeWithIDToken blank2 = new BlankNodeWithIDToken(context.GetNewBlankNodeID(), next.StartLine, next.StartPosition, next.EndPosition);
//rdf:rest Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfRest), this.TryCreatePatternItem(context, blank2)));
blank = blank2;
//rdf:first Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfFirst), this.TryCreatePatternItem(context, innerCollection)));
}
context.Tokens.Dequeue();
this.TryParseCollection(context, p, true);
continue;
case Token.RIGHTBRACKET:
//End of Collection
//rdf:rest Pattern
p.AddTriplePattern(new TriplePattern(this.TryCreatePatternItem(context, blank), new NodeMatchPattern(rdfRest), new NodeMatchPattern(rdfNil)));
break;
default:
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered while trying to parse a Collection", next);
}
context.Tokens.Dequeue();
} while (next.TokenType != Token.RIGHTBRACKET);
}
}
private void TryParseTriplePatterns(SparqlQueryParserContext context, GraphPattern p)
{
int lasttoken = context.Tokens.LastTokenType;
IToken next = context.Tokens.Dequeue();
//Allowed a Variable/RDF Term/Collection
//OR we might go straight to a OPTIONAL/GRAPH/UNION/FILTER/EXISTS/NOT EXISTS/LET
switch (next.TokenType)
{
case Token.COMMENT:
//Comments are discardable
this.TryParseTriplePatterns(context, p);
break;
case Token.VARIABLE:
//Variable
context.LocalTokens.Push(next);
context.Query.AddVariable(next.Value);
this.TryParsePredicateObjectList(context, p,2);
break;
case Token.URI:
case Token.QNAME:
case Token.LITERAL:
case Token.LONGLITERAL:
case Token.PLAINLITERAL:
//Must then be followed be a non-empty Property List
context.LocalTokens.Push(next);
this.TryParsePredicateObjectList(context, p,2);
break;
case Token.BLANKNODE:
case Token.BLANKNODEWITHID:
//Check list of Blank Node usages
if (context.BlankNodeIDUsages.ContainsKey(next.Value))
{
if (context.BlankNodeIDUsages[next.Value] != context.GraphPatternID)
{
throw ParserHelper.Error("Invalid use of Blank Node Label '" + next.Value + "', this Label has already been used in a different Graph Pattern", next);
}
}
else
{
context.BlankNodeIDUsages.Add(next.Value, context.GraphPatternID);
}
//Must then be followed be a non-empty Property List
context.LocalTokens.Push(next);
this.TryParsePredicateObjectList(context, p, 2);
break;
case Token.LET:
//LET assignment
this.TryParseLetAssignment(context, p);
break;
case Token.BIND:
//BIND assignment
this.TryParseBindAssignment(context, p);
break;
case Token.LEFTSQBRACKET:
//Start of Blank Node Collection
//Create a new Blank Node Token
BlankNodeWithIDToken bnode = new BlankNodeWithIDToken(context.GetNewBlankNodeID(), 0, 0, 0);
//Push twice, once for Subject of Collection
context.LocalTokens.Push(bnode);
next = context.Tokens.Peek();
if (next.TokenType == Token.RIGHTSQBRACKET)
{
//Single anonymous blank node
context.Tokens.Dequeue();
//Parse as Subject of Triples
this.TryParsePredicateObjectList(context, p, 2);
}
else
{
//Parse the Collection
this.TryParsePredicateObjectList(context, p, 2);
//Push again for subject of Triples
context.LocalTokens.Push(bnode);
this.TryParsePredicateObjectList(context, p, 2);
}
break;
case Token.LEFTBRACKET:
//Collection
this.TryParseCollection(context, p, false);
this.TryParsePredicateObjectList(context, p, 2);
break;
case Token.FILTER:
//FILTER Pattern
this.TryParseFilterClause(context, p);
break;
case Token.OPTIONAL:
//OPTIONAL Clause
this.TryParseOptionalClause(context, p);
break;
case Token.EXISTS:
case Token.NOTEXISTS:
case Token.UNSAID:
//EXISTS/NOT EXISTS clause
if (next.TokenType == Token.UNSAID && context.SyntaxMode != SparqlQuerySyntax.Extended) throw new RdfParseException("The UNSAID Keyword is only supported when syntax is set to Extended. It is an alias for NOT EXISTS which can be used when the syntax is set to SPARQL 1.1/Extended");
this.TryParseExistsClause(context, p, (next.TokenType == Token.EXISTS));
break;
case Token.MINUS_P:
//MINUS clause
this.TryParseMinusClause(context, p);
break;
case Token.SERVICE:
//SERVICE clause
this.TryParseServiceClause(context, p);
break;
case Token.SELECT:
//Sub-query
this.TryParseSubquery(context, p);
break;
case Token.GRAPH:
//GRAPH Clause
this.TryParseGraphClause(context, p);
break;
case Token.UNION:
//UNION Clause
this.TryParseUnionClause(context, p);
break;
case Token.LEFTCURLYBRACKET:
//Nested Graph Pattern
p.AddGraphPattern(this.TryParseGraphPattern(context, false));
//Simplify Subqueries
if (p.ChildGraphPatterns.Last().IsSubQuery)
{
GraphPattern temp = p.LastChildPattern();
p.AddTriplePattern(temp.TriplePatterns.First());
}
break;
case Token.DOT:
//Can Discard this if last character was the end of a nested Graph pattern
if (lasttoken == Token.RIGHTCURLYBRACKET || lasttoken == Token.RIGHTBRACKET)
{
//Can Discard this if the next character is not another DOT
next = context.Tokens.Peek();
if (next.TokenType != Token.DOT)
{
if (next.TokenType != Token.RIGHTCURLYBRACKET)
{
this.TryParseTriplePatterns(context, p);
}
else
{
return;
}
}
else
{
throw ParserHelper.Error("A DOT Token cannot follow another DOT Token within a Graph Pattern", next);
}
}
else if (lasttoken == Token.SEMICOLON)
{
//Allow Trailing Semicolon
return;
}
else
{
throw ParserHelper.Error("A DOT Token can only be used to terminate a Triple Pattern or a Nested Graph Pattern", next);
}
break;
default:
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered when the start of a Triple Pattern was expected", next);
}
}
