/*
 * (c) Copyright 2009 Hewlett-Packard Development Company, LP
 * All rights reserved.
 * [See end of file]
 */

package org.openjena.riot.lang;

import static org.openjena.riot.tokens.TokenType.DOT ;
import static org.openjena.riot.tokens.TokenType.RBRACE ;
import org.openjena.atlas.lib.Sink ;
import org.openjena.riot.Lang ;
import org.openjena.riot.ParserProfile ;
import org.openjena.riot.tokens.Token ;
import org.openjena.riot.tokens.TokenType ;
import org.openjena.riot.tokens.Tokenizer ;

import com.hp.hpl.jena.graph.Node ;
import com.hp.hpl.jena.sparql.core.Quad ;

/** TriG language: http://www4.wiwiss.fu-berlin.de/bizer/TriG/
 *  Generalizations:
 *    Can have multiple default graph blocks.
 *    
 * 
 */
public class LangTriG extends LangTurtleBase<Quad>
{
    /*
        TriGDoc     ::=      ws* (statement ws*)*
        statement   ::=     directive ws* '.' | graph
        graph       ::=     graphName? ws* '='? ws* '{' ws* (triples ws* ('.' ws* triples ws*)* '.'? ws*)? '}' ws* '.'?
        graphName   ::=     resource
        
        We may add:
        statement   ::=     directive ws* '.' | graph | quad
        quad        ::=     subject predicate object resource?
          (i.e. raw inline nquads except with preifx names.
        
     */
    public LangTriG(String baseURI, Tokenizer tokens, 
                    ParserProfile profile, 
                    Sink<Quad> sink) 
    {
        super(baseURI, tokens, profile, sink) ;
    }
    
    //@Override
    public Lang getLang()   { return Lang.TRIG ; }

//    public enum BNodeLabelScope { document , graph }  
//    
//    public void setBNodeLabelScoping(BNodeLabelScope labelscope)
//    {
//        switch (labelscope) {
//            case document : 
//                super.labelmap = LabelToNode.createScopeByDocument() ;
//                break ;
//            case graph :
//                super.labelmap = LabelToNode.createScopeByGraph() ;
//                break ;
//        }
//    }
    
    @Override
    protected final void oneTopLevelElement()
    {
        oneNamedGraphBlock() ;
    }
    
    protected final void oneNamedGraphBlock()
    {
        // Directives are only between graphs.
        Node graphNode = Quad.tripleInQuad ;
        Token token = peekToken() ;

        // <foo> = { ... } .
        if ( token.isNode() )
        {
            Token t = token ;   // Keep for error message. 
            graphNode = node() ;
            nextToken() ;
            token = peekToken() ;

            if ( graphNode.isURI() )
                setCurrentGraph(graphNode) ; 
            else
                exception(t, "Not a legal graph name: "+graphNode) ;
        }
        else
            setCurrentGraph(Quad.tripleInQuad) ;

        // = is optional
        if ( token.getType() == TokenType.EQUALS )
        {
            // Skip.
            nextToken() ;
            token = peekToken() ;
        }
        
        if ( token.getType() != TokenType.LBRACE )
            exception(token, "Expected start of graph: got %s", peekToken()) ;
        nextToken() ;
        
        // **** Turtle but no directives.
        
        while(true)
        {
            token = peekToken() ;
            if ( token.hasType(TokenType.RBRACE) )
                break ;
            // No - this has Turtle termination rules.
            // Assume this is fixed then ....
            
            // Unlike many operations in this parser suite 
            // this does not assume that we are definitel entering
            // this sttae throws an error if the first token 
            triplesSameSubject() ;
        }
        
        // **** Turtle.
        token = nextToken() ;
        if ( token.getType() != TokenType.RBRACE )
            exception(token, "Expected end of graph: got %s", token) ;
        
        // Skip DOT
        token = peekToken() ;
        if ( token.hasType(TokenType.DOT) )
            nextToken() ;
        
        
        // End graph block.
        setCurrentGraph(Quad.tripleInQuad) ;
    }

    @Override
    protected void expectEndOfTriples()
    {
        // The DOT is required by Turtle (strictly).
        // It is not in N3 and SPARQL.
        
        if ( strict )
        {
            expect("Triples not terminated by DOT", DOT) ;
            return ;
        }
        
        if ( lookingAt(DOT) )
        {
            nextToken() ;
            return ;
        }
        
        // Loose - DOT optional.
        if ( lookingAt(RBRACE) )
            // Don't consume the RBRACE
            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) ;
        sink.send(quad) ;
    }
}

/*
 * (c) Copyright 2009 Hewlett-Packard Development Company, LP
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */