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package com.bigdata.rdf.model;

import java.util.Date;
import java.util.UUID;

import javax.xml.datatype.XMLGregorianCalendar;

import org.openrdf.model.BNode;
import org.openrdf.model.Literal;
import org.openrdf.model.Resource;
import org.openrdf.model.URI;
import org.openrdf.model.Value;

/**
 * Class provides a document-scoped context for generating blank node
 * identifiers (IDs). This class is intended for use to generate blank node
 * identifiers (IDs) for a source document within a shared prefix. When that
 * prefix is mapped onto the term2id index, all blank nodes for the same source
 * document will tend to be mapped onto the same index partition (this is more
 * efficient since the ordered writes are more local). The prefix itself is a
 * {@link UUID}, which is how we ensure that blank nodes generated for different
 * sources are understood as distinct blank nodes by the database (this is
 * required).
 * 
 * Note: All {@link BigdataValue} instances are in fact created by the delegate
 * instances created by this class and by the delegate will appear to have been
 * created by the same factory. This is intentional - it makes the instances
 * reusable by the base factory.
 * 
 * Note: {@link #nextID()} is NOT thread-safe, but different documents that are
 * being passed concurrently will have a distinct instance of this factory and
 * processing a single document is generally single-threaded.
 * 
 * @author Bryan Thompson
 * @version $Id: BNodeContextFactory.java 2547 2010-03-24 20:44:07Z thompsonbry
 *          $
 */
public class BNodeContextFactory implements BigdataValueFactory {
	
    public String getNamespace() {
        return valueFactory.getNamespace();
    }
    
    public void remove(/*String namespace*/) {
        // NOP
	}

    /**
     * Provides the globally unique context for the generated blank node
     * identifiers.
     */
    private final UUID contextUuid = UUID.randomUUID();

    /**
     * The delegate factory.
     */
    private final BigdataValueFactory valueFactory;

	public BNodeContextFactory(final BigdataValueFactory valueFactory) {

        this.valueFactory = valueFactory;

    }

    /**
	 * A globally unique blank node identifier (ID) created with prefix shared
	 * by all blank nodes whose identifers are generated by this class.
     */
    protected String nextID() {

        return "_" + contextUuid + nextID++;

    }

    private int nextID;

	public BigdataBNode createBNode() {
        return valueFactory.createBNode(nextID());
    }

    /*
     * Delegate pattern.
     */

	@Override
    public BigdataValue asValue(Value v) {
        return valueFactory.asValue(v);
    }

    @Override
	public BigdataBNode createBNode(String id) {
        return valueFactory.createBNode(id);
    }

    @Override
	public BigdataBNode createBNode(BigdataStatement stmt) {
        return valueFactory.createBNode(stmt);
    }

    @Override
	public BigdataLiteral createLiteral(boolean arg0) {
        return valueFactory.createLiteral(arg0);
    }

    @Override
	public BigdataLiteral createLiteral(byte arg0) {
        return valueFactory.createLiteral(arg0);
    }

    @Override
	public BigdataLiteral createLiteral(double arg0) {
        return valueFactory.createLiteral(arg0);
    }

    @Override
	public BigdataLiteral createLiteral(float arg0) {
        return valueFactory.createLiteral(arg0);
    }

    @Override
	public BigdataLiteral createLiteral(int arg0, boolean unsigned) {
        return valueFactory.createLiteral(arg0, unsigned);
    }

    @Override
	public BigdataLiteral createLiteral(long arg0, boolean unsigned) {
        return valueFactory.createLiteral(arg0, unsigned);
    }

    @Override
	public BigdataLiteral createLiteral(short arg0, boolean unsigned) {
        return valueFactory.createLiteral(arg0, unsigned);
    }

    @Override
	public BigdataLiteral createLiteral(byte arg0, boolean unsigned) {
        return valueFactory.createLiteral(arg0, unsigned);
    }

    @Override
	public BigdataLiteral createLiteral(int arg0) {
        return valueFactory.createLiteral(arg0);
    }

    @Override
	public BigdataLiteral createLiteral(long arg0) {
        return valueFactory.createLiteral(arg0);
    }

    @Override
	public BigdataLiteral createLiteral(short arg0) {
        return valueFactory.createLiteral(arg0);
    }

    @Override
	public BigdataLiteral createLiteral(String label, String language) {
        return valueFactory.createLiteral(label, language);
    }

    @Override
	public BigdataLiteral createLiteral(String label, URI datatype) {
        return valueFactory.createLiteral(label, datatype);
    }
	
    @Override
	public BigdataLiteral createLiteral(String label, URI datatype, String language) {
	    return valueFactory.createLiteral(label, datatype, language);
	}

    @Override
	public BigdataLiteral createLiteral(String label) {
        return valueFactory.createLiteral(label);
    }

    @Override
	public BigdataLiteral createLiteral(XMLGregorianCalendar arg0) {
        return valueFactory.createLiteral(arg0);
    }

    @Override
    public BigdataLiteral createLiteral(Date arg0) {
        return valueFactory.createLiteral(arg0);
    }

    @Override
	public BigdataStatement createStatement(Resource s, URI p, Value o) {
        return valueFactory.createStatement(s, p, o);
    }

    @Override
	public BigdataStatement createStatement(Resource s, URI p, Value o,
            Resource c) {
        return valueFactory.createStatement(s, p, o, c);
    }

    @Override
	public BigdataStatement createStatement(Resource s, URI p, Value o,
            Resource c, StatementEnum type) {
        return valueFactory.createStatement(s, p, o, c, type, false);
    }
	
    @Override
	public BigdataStatement createStatement(Resource s, URI p, Value o,
            Resource c, StatementEnum type, boolean userFlag) {
        return valueFactory.createStatement(s, p, o, c, type, userFlag);
    }
	
    @Override
	public BigdataURI createURI(String namespace, String localName) {
        return valueFactory.createURI(namespace, localName);
    }

    @Override
	public BigdataURI createURI(String uriString) {
        return valueFactory.createURI(uriString);
    }

    @Override
	public BigdataValueSerializer getValueSerializer() {
        return valueFactory.getValueSerializer();
    }

    /**
	 * Recursive contexts are not available (should not be necessary, right?)
     */
    @Override
    public BigdataValueFactory newBNodeContext() {
        throw new UnsupportedOperationException();
    }

    @Override
    public BigdataResource asValue(Resource v) {
        return valueFactory.asValue(v);
    }

    @Override
    public BigdataURI asValue(URI v) {
        return valueFactory.asValue(v);
    }

    @Override
    public BigdataLiteral asValue(Literal v) {
        return valueFactory.asValue(v);
    }

    @Override
    public BigdataBNode asValue(BNode v) {
        return valueFactory.asValue(v);
    }

    @Override
    public BigdataLiteral createXSDDateTime(long timestamp) {
        return valueFactory.createXSDDateTime(timestamp);
    }

}