relation.java

Jena推理机

/*
 *  (c) Copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007 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.
 *
 * $Id: Relation.java,v 1.8 2007/01/02 11:51:42 andy_seaborne Exp $
 *
 */

package com.hp.hpl.jena.xmloutput.impl;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import com.hp.hpl.jena.util.iterator.IteratorIterator;
import com.hp.hpl.jena.util.iterator.Map1;
import com.hp.hpl.jena.util.iterator.Map1Iterator;

/**
 * A sparse 2 dimensional array of boolean indexed by Object.
 *
 * Complete with transitive closure algorithm.
 * @author jjc
 * @version  Release='$Name:  $' Revision='$Revision: 1.8 $' Date='$Date: 2007/01/02 11:51:42 $'
 */
class Relation {
    final private Map rows;
    final private Map cols;
    final private Set index;
    /** The empty Relation.
     */
    public Relation() {
        rows = new HashMap();
        cols = new HashMap();
        index = new HashSet();
    }
    /** <code>a</code> is now related to <code>b</code>
     *
     */
    synchronized public void set(Object a, Object b) {
        index.add(a);
        index.add(b);
        innerAdd(rows, a, b);
        innerAdd(cols, b, a);
    }
    /** Uniquely <code>a</code> is now related to uniquely <code>b</code>.
     *
     *  When this is called any other <code>a</code> related to this <code>b</code> is removed.
     *  When this is called any other <code>b</code> related to this <code>a</code> is removed.
     *
     */
    synchronized public void set11(Object a, Object b) {
        clearX(a, forward(a));
        clearX(backward(b), b);
        set(a, b);
    }
    /** Uniquely <code>a</code> is now related to <code>b</code>.
     *  Many <code>b</code>'s can be related to each <code>a</code>.
     *  When this is called any other <code>a</code> related to this <code>b</code> is removed.
     */
    synchronized public void set1N(Object a, Object b) {
        clearX(backward(b), b);
        set(a, b);
    }
    /** <code>a</code> is now related to uniquely <code>b</code>.
     *  Many <code>a</code>'s can be related to each <code>b</code>.
     *  When this is called any other <code>b</code> related to this <code>a</code> is removed.
     */
    synchronized public void setN1(Object a, Object b) {
        clearX(a, forward(a));
        set(a, b);
    }
    /** <code>a</code> is now related to <code>b</code>
     *
     */
    synchronized public void setNN(Object a, Object b) {
        set(a, b);
    }
    /** <code>a</code> is now <em>not</em> related to <code>b</code>
     *
     */
    synchronized public void clear(Object a, Object b) {
        innerClear(rows, a, b);
        innerClear(cols, b, a);
    }
    private void clearX(Set s, Object b) {
        if (s == null)
            return;
        Iterator it = s.iterator();
        while (it.hasNext())
            clear(it.next(), b);
    }
    private void clearX(Object a, Set s) {
        if (s == null)
            return;
        Iterator it = s.iterator();
        while (it.hasNext())
            clear(a, it.next());
    }
    static private void innerAdd(Map s, Object a, Object b) {
        Set vals = (Set) s.get(a);
        if (vals == null) {
            vals = new HashSet();
            s.put(a, vals);
        }
        vals.add(b);
    }
    static private void innerClear(Map s, Object a, Object b) {
        Set vals = (Set) s.get(a);
        if (vals != null) {
            vals.remove(b);
        }
    }
    /** Is <code>a</code> related to <code>b</code>?
     *
     */
    public boolean get(Object a, Object b) {
        Set vals = (Set) rows.get(a);
        return vals != null && vals.contains(b);
    }
    /**
     * Takes this to its transitive closure.
    See B. Roy. <b>Transitivit