/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.jena.riot.lang ;
import static org.apache.jena.riot.tokens.TokenType.* ;
import org.apache.jena.graph.Node ;
import org.apache.jena.riot.Lang ;
import org.apache.jena.riot.RDFLanguages ;
import org.apache.jena.riot.system.ParserProfile ;
import org.apache.jena.riot.system.StreamRDF ;
import org.apache.jena.riot.tokens.Token ;
import org.apache.jena.riot.tokens.Tokenizer ;
import org.apache.jena.sparql.core.Quad ;
/** TriG.
*
* @see <a href="http://www.w3.org/TR/trig/">http://www.w3.org/TR/trig/</a>
*/
public class LangTriG extends LangTurtleBase {
public LangTriG(Tokenizer tokens, ParserProfile profile, StreamRDF dest) {
super(tokens, profile, dest) ;
}
@Override
public Lang getLang() {
return RDFLanguages.TRIG ;
}
@Override
protected final void oneTopLevelElement() {
//oneNamedGraphBlock() ;
oneNamedGraphBlock2() ;
}
// Version for proposed Turtle-in-TriG and keyword GRAPH
protected final void oneNamedGraphBlock2() {
// Which may not be a graph block.
Node graphNode = null ;
Token token = peekToken() ;
Token t = token ; // Keep for error message.
boolean mustBeNamedGraph = false ;
if ( lookingAt(KEYWORD) ) {
if ( token.getImage().equalsIgnoreCase("GRAPH") ) {
nextToken() ;
mustBeNamedGraph = true ;
token = peekToken() ;
// GRAPH <g>
// GRAPH []
} else
exception(t, "Keyword '" + token.getImage() + "' not allowed here") ;
}
// GRAPH dealt with.
// Starting points:
// [ ] { .... }
// :g { ... }
// :s :p :o .
// [ ] :p :o .
// [ :p 123 ] :p :o .
// () :p :o .
// (1 2) :p :o .
// XXX Find the Turtle code to do this for the Turtle case and refactor.
if ( lookingAt(LBRACKET) ) {
nextToken() ;
token = peekToken() ;
Node blank = profile.createBlankNode(graphNode, t.getLine(), t.getColumn()) ;
if ( lookingAt(RBRACKET) ) {
// Can be Turtle, "[] :predicate", or named graph "[] {"
nextToken() ;
if ( lookingAt(LBRACE) )
graphNode = blank ;
else {
if ( mustBeNamedGraph )
exception(t, "Keyword 'GRAPH' must start a named graph") ;
// [] :p ...
turtle(blank) ;
return ;
}
} else {
// [ :p ... ]
// [ :p ... ] :p ...
// XXX This fragment must be in Turtle somewhere
if ( mustBeNamedGraph )
exception(t, "Keyword 'GRAPH' must start a named graph") ;
triplesBlankNode(blank) ;
// Following predicate.
if ( peekPredicate() )
predicateObjectList(blank) ;
expectEndOfTriplesTurtle() ;
return ;
}
} else if ( token.isNode() ) {
// Either :s :p :o or :g { ... }
Node n = node() ;
nextToken() ;
token = peekToken() ;
if ( lookingAt(LBRACE) )
graphNode = n ;
else {
if ( mustBeNamedGraph )
exception(t, "Keyword 'GRAPH' must start a named graph") ;
turtle(n) ;
return ;
}
} else if ( lookingAt(LPAREN) ) {
// Turtle - list
turtle() ;
return ;
}
if ( mustBeNamedGraph && graphNode == null )
exception(t, "Keyword 'GRAPH' must be followed by a graph name") ;
// braced graph
bracedGraph(t, graphNode) ;
}
protected final void turtle(Node n) {
predicateObjectList(n) ;
expectEndOfTriplesTurtle() ;
}
protected final void turtle() {
// This does expectEndOfTriplesTurtle() ;
triplesSameSubject() ;
}
// Old version , tradition trig with RDF 1.1 Turtle tokens.
protected final void oneNamedGraphBlock() {
// Directives are only between graph blocks.
Node graphNode = null ;
Token token = peekToken() ;
Token t = token ; // Keep for error message.
// [ ] { ... }
if ( lookingAt(LBRACKET) ) {
nextToken() ;
token = peekToken() ;
if ( lookingAt(RBRACKET) )
exception(t, "Broken term: [ not followed by ]") ;
graphNode = profile.createBlankNode(graphNode, t.getLine(), t.getColumn()) ;
nextToken() ;
} else {
// <uri> { ... }
// { ... }
if ( token.isNode() ) {
graphNode = node() ;
nextToken() ;
}
}
bracedGraph(t, graphNode) ;
}
private void bracedGraph(Token t, Node graphNode) {
if ( graphNode != null ) {
if ( graphNode.isURI() || graphNode.isBlank() )
setCurrentGraph(graphNode) ;
else
exception(t, "Not a legal graph name: " + graphNode) ;
} else
setCurrentGraph(Quad.tripleInQuad) ;
Token token = peekToken() ;
// = is optional and old style.
if ( lookingAt(EQUALS) ) {
if ( profile.isStrictMode() )
exception(token, "Use of = {} is not part of standard TriG: " + graphNode) ;
// Skip.
nextToken() ;
token = peekToken() ;
}
if ( !lookingAt(LBRACE) )
exception(token, "Expected start of graph: got %s", peekToken()) ;
nextToken() ;
// **** Turtle but no directives.
while (true) {
token = peekToken() ;
if ( lookingAt(RBRACE) )
break ;
// Unlike many operations in this parser suite,
// this does not assume that we are definitely entering
// this state and can throw an error if the first token
// is not acceptable.
triplesSameSubject() ;
}
// **** Turtle.
token = nextToken() ;
if ( lookingAt(RBRACE) )
exception(token, "Expected end of graph: got %s", token) ;
if ( !profile.isStrictMode() ) {
// Skip DOT after {}
token = peekToken() ;
if ( lookingAt(DOT) )
nextToken() ;
}
// End graph block.
setCurrentGraph(Quad.tripleInQuad) ;
}
@Override
protected void expectEndOfTriples() { expectEndOfTriplesBraceGraph() ; }
protected void expectEndOfTriplesBraceGraph() {
// The DOT is required by Turtle (strictly).
// It is not in N3 and SPARQL or TriG
// // To make trailing DOT illegal in strict TriG.
// if ( profile.isStrictMode() ) {
// expect("Triples not terminated by DOT", DOT) ;
// return ;
// }
if ( lookingAt(DOT) ) {
nextToken() ;
return ;
}
// Loose - DOT optional.
if ( lookingAt(RBRACE) )
// Don't consume the RBRACE - used to break the loop of triples
// blocks.
return ;
exception(peekToken(), "Triples not terminated properly: expected '.', '}' or EOF: got %s", peekToken()) ;
}
@Override
protected void emit(Node subject, Node predicate, Node object) {
Node graph = getCurrentGraph() ;
if ( graph == Quad.defaultGraphNodeGenerated )
graph = Quad.tripleInQuad ;
Quad quad = profile.createQuad(graph, subject, predicate, object, currLine, currCol) ;
dest.quad(quad) ;
}
}