jena-core/src/main/java/org/apache/jena/n3/N3JenaWriter.java

/*
 * 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.
 */

// To do:
//   Better detection of illegal characters in qnames (? and = for example) 

package org.apache.jena.n3;

//import org.apache.commons.logging.*;
import java.io.OutputStream;
import java.io.Writer;

import org.apache.jena.JenaRuntime ;
import org.apache.jena.rdf.model.* ;

/** Entry point for N3 writers.  This writer will choose the actual writer
 *  to use by looking at the system property
 *  <code>org.apache.jena.n3.N3JenaWriter.writer</code> to get the
 *  writer name.
 *  <p>
 *  The following N3 writers are provided:
 *  <ul>
 *  <li>N3-PP: Pretty Printer (the default)</li>
 *  <li>N3-PLAIN: Plain, record/frame-oriented format</li> 
 *  <li>N3-TRIPLES: Triples, with prefixes.</li>
 *  </ul>
 *  </p>
 */



public class N3JenaWriter implements RDFWriter
{
    //static Logger logger = LoggerFactory.getLogger(N3JenaWriter.class) ;
    static public boolean DEBUG = false ;
    
    // Note: properties are URIs, not java convention package/class names.
    static protected final String propBase = "http://jena.hpl.hp.com/n3/properties/" ;
    
    /** System property name that sets the default N3 writer name */   
    static public final String propWriterName = propBase+"writer" ;

    /**
     * General name for the N3 writer.  Will make a decision on exactly which
     * writer to use (pretty writer, plain writer or simple writer) when created.
     * Default is the pretty writer but can be overridden with system property
     * <code>org.apache.jena.n3.N3JenaWriter.writer</code>.  
     */
     
    static public final String n3Writer              = "N3" ;

    /**
     * Turtle writer.
     */
    static public final String turtleWriter          = "TURTLE" ;
    static public final String turtleWriterAlt1      = "Turtle" ;
    static public final String turtleWriterAlt2      = "TTL" ;
    
    protected N3JenaWriterCommon writer = null ;
    
    public N3JenaWriter() { writer = chooseWriter() ; }
    public N3JenaWriter(N3JenaWriterCommon w) { writer = w ;}
    
    N3JenaWriterCommon chooseWriter()
    {
        // Choose the writer
        String writerName = JenaRuntime.getSystemProperty(propWriterName) ;
        if ( writerName == null )
            return new N3JenaWriterPP() ;
        if ( writerName.equals("N3") )
            return new N3JenaWriterPP() ;
        
//        if ( writerName.equals(n3WriterPrettyPrinter) )
//            return new N3JenaWriterPP() ;
//        
//        if ( writerName.equalsIgnoreCase(n3WriterPlain) )
//            return new N3JenaWriterCommon() ;
//        
//        if ( writerName.equalsIgnoreCase(n3WriterTriples) ||
//             writerName.equalsIgnoreCase(n3WriterTriplesAlt) )
//            return new N3JenaWriterTriples() ;
            
        if ( writerName.equalsIgnoreCase(turtleWriter) )
        {
            N3JenaWriterPP w = new N3JenaWriterPP() ;
            w.useWellKnownPropertySymbols = false ;
            return w ;
        }
        
        // Don't know or default.
        return new N3JenaWriterPP() ;
    }
    
    
    /** Write the model out in N3, encoded in in UTF-8
     * @see #write(Model,Writer,String)
     */

    @Override
    public void write(Model model, Writer out, String base) 
    {
        writer.write(model, out, base) ;
    }

    /** Write the model out in N3.  The writer should be one suitable for UTF-8 which
    * excludes a PrintWriter or a FileWriter which use default character set.
    *
    * Examples:
    * <pre>
    * try {
    *      Writer w =  new BufferedWriter(new OutputStreamWriter(output, "UTF-8")) ;
    *      model.write(w, base) ;
    *      try { w.flush() ; } catch (IOException ioEx) {...}
    *  } catch (java.io.UnsupportedEncodingException ex) {} //UTF-8 is required so can't happen
    * </pre>
    * or
    * <pre>
    * try {
    *     OutputStream out = new FileOutputStream(file) ;
    *     Writer w =  new BufferedWriter(new OutputStreamWriter(out, "UTF-8")) ;
    *     model.write(w, base) ;
    * }
    * catch (java.io.UnsupportedEncodingException ex) {}
    * catch (java.io.FileNotFoundException noFileEx) { ... }
    * </pre>
    * @see #write(Model,Writer,String)
    */

    @Override
    public void write(Model model, OutputStream out, String base) 
    {
        writer.write(model, out, base) ;
   }


    /**
     * @see org.apache.jena.rdf.model.RDFWriter#setProperty(java.lang.String, java.lang.Object)
     */
    @Override
    public Object setProperty(String propName, Object propValue) 
    {
        return writer.setProperty(propName, propValue) ;
    }

    /**
     * @see org.apache.jena.rdf.model.RDFWriter#setErrorHandler(org.apache.jena.rdf.model.RDFErrorHandler)
     */
    @Override
    public RDFErrorHandler setErrorHandler(RDFErrorHandler errHandler)
    {
        return writer.setErrorHandler(errHandler) ;
    }
   
}