/*
 	(c) Copyright 2005, 2006, 2007, 2008 Hewlett-Packard Development Company, LP
 	All rights reserved - see end of file.
 	$Id: Matcher.java,v 1.4 2008/01/02 12:07:57 andy_seaborne Exp $
*/

package com.hp.hpl.jena.graph.query;

import com.hp.hpl.jena.graph.Triple;

/**
    A Matcher knows how to match itself against a concrete triple (the triple
    to be matched) and a domain (of bindings to check and extend). It is part
    of the improved-we-hope PatternStage code.
    @author kers
*/
public abstract class Matcher
    {
    /**
        Answer true iff we match the triple <code>t</code> given the bindings
        in <code>d</code>, updating those bindings if appropriate; the bindings
        may be updated even if the match answers <code>false</code>.
    */
    public abstract boolean match( Domain d, Triple t );
    
    /**
       This matcher always answers <code>true</code> and doesn't even look at
       the domain, never mind update it.
    */
    public static final Matcher always = new Matcher() 
        {
        public boolean match( Domain d, Triple t )
            { return true; }
        };
    }

/*
 * (c) Copyright 2005, 2006, 2007, 2008 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.
*/