rule.java

这是外国一个开源推理机

/*  Sesame - Storage and Querying architecture for RDF and RDF Schema
 *  Copyright (C) 2003 OntoText Lab, Sirma AI OOD
 *
 *  Contact:
 *	Sirma AI OOD, OntoText Lab.
 *	38A, Christo Botev Blvd.
 *  1000 Sofia, Bulgaria
 *	tel. [phone]
 *	fax. [phone]
 *	[e-mail]
 *
 * 	http://www.ontotext.com/
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package org.openrdf.sesame.sailimpl.rdbms.rules;

/**
 * <p>Title: Custom Inference Rules</p>
 * <p>Description:</p>
 * The class is used to produce SQL queries used for statement and dependancy inferencing.
 * It keeps several TripleTemplates defining relationships between triples that lead
 * to the inference of new ones. The templates consist of three Component instances for
 * subject, predicate and object and can represent an URI, variable or regular expression.
 *
 * <p>Company: Ontotext Lab. Sirma AI</p>
 * @author Damyan Ognyanoff
 * @version 1.0
 */
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;

import org.openrdf.sesame.sailimpl.rdbms.CustomInferenceServices;
import org.openrdf.sesame.sailimpl.rdbms.TableNames;

public class Rule implements TableNames {

	final static String C_SELECT = "SELECT DISTINCT ";

	/**
	 * the map that hold id's (as Integer variables) fro each non-variable string found in the rules.
	 * These ids are afterwards matchd against the real ids of those resources with
	 * same URIs and used within generated SQL queries.
	 */
	static HashMap idMap = new HashMap();

	/**
	 * collection of all triple templates for the rule
	 */
	ArrayList premiseList;

	/**
	 * The consequent template
	 */
	TripleTemplate consequent;

	/**
	 * The name of the Rule
	 */
	String ruleName;

	ArrayList triggersRule = null;

	HashMap regExpByVars;

	void normalizeRegExpVar(Component var) {
		if (var.isRegExp()) {
			if (regExpByVars == null) {
				regExpByVars = new HashMap();
			}
			regExpByVars.put(var.value(), var);
		}
	}

	static String getFROM() {
		return " FROM " + NEW_TRIPLES_TABLE + " nt ";
	}

	static String getLEFT_JOIN(int id) {
		return "LEFT JOIN " + TRIPLES_TABLE + " t" + id + " ON ";
	}

	public static Iterator constantsIter() {
		return idMap.keySet().iterator();
	}

	public static String getId(Component constant) {
		Integer val = (Integer)idMap.get(constant.value());
		if (val == null) {
			if (!constant.isVar()) {
				val = setId(constant, idMap.size());
			}
			else {
				return null;
			}
		}
		return val.toString();
	}

	public static int getIntId(Component constant) {
		Integer val = (Integer)idMap.get(constant.value());
		if (val == null) {
			if (!constant.isVar()) {
				val = setId(constant, idMap.size());
			}
			else {
				return -1;
			}
		}
		return val.intValue();
	}

	public static Integer setId(Component constant, int id) {
		if (!constant.isVar()) {
			return setId(constant.value(), id);
		}
		return new Integer(id);
	}

	public static Integer setId(String constant, int id) {
		Integer i = new Integer(id);
		idMap.put(constant, i);
		return i;
	}

	public Rule(String name) {
		premiseList = new ArrayList();
		consequent = null;
		ruleName = name;
	}

	public void addPremise(TripleTemplate t) {
		if (!t.subject.isVar()) {
			getId(t.subject);
		}
		if (!t.predicate.isVar()) {
			getId(t.predicate);
		}
		if (!t.object.isVar()) {
			getId(t.object);
		}

		normalizeRegExpVar(t.subject);
		normalizeRegExpVar(t.predicate);
		normalizeRegExpVar(t.object);

		premiseList.add(t);
	}

	public void setConsequent(TripleTemplate t) {
		if (!t.subject.isVar()) {
			getId(t.subject);
		}
		if (!t.predicate.isVar()) {
			getId(t.predicate);
		}
		if (!t.object.isVar()) {
			getId(t.object);
		}

		normalizeRegExpVar(t.subject);
		normalizeRegExpVar(t.predicate);
		normalizeRegExpVar(t.object);

		consequent = t;
	}

	private boolean matchwasbyobject = false;

	String match(Component component, int until) {
		matchwasbyobject = false;
		if (!component.isVar()) {
			return Rule.getId(component);
		}
		int count = 0;
		Iterator iter = premiseList.iterator();
		while (iter.hasNext()) {
			if (count >= until) {
				break;
			}
			TripleTemplate tt = (TripleTemplate)iter.next();
			if (0 == component.compareTo(tt.subject)) {
				return "" + ((count == 0) ? "nt" : ("t" + count)) + ".subj";
			}
			if (0 == component.compareTo(tt.predicate)) {
				return "" + ((count == 0) ? "nt" : ("t" + count)) + ".pred";
			}
			if (0 == component.compareTo(tt.object)) {
				matchwasbyobject = true;
				return "" + ((count == 0) ? "nt" : ("t" + count)) + ".obj";
			}
			count++;
		}
		return null;
	}

	private String where = "";

	void processJoin(StringBuffer buffer, int id, TripleTemplate tt) {
		buffer.append(' ');
		buffer.append(Rule.getLEFT_JOIN(id));
		boolean bFirst = false;
		String s = match(tt.subject, id);
		if (s != null) {
			buffer.append("t" + id);
			buffer.append(".subj = ");
			buffer.append(s);
			if (matchwasbyobject) {
				if (where.length() != 0) {
					where += " AND ";
				}
				where += s + " > 0"; // non-literal restriction
			}
			bFirst = true;
		}
		s = match(tt.predicate, id);
		if (s != null) {
			if (bFirst) {
				buffer.append(" AND ");
			}
			buffer.append("t" + id);
			buffer.append(".pred= ");
			buffer.append(s);
			bFirst = true;
		}
		s = match(tt.object, id);
		if (s != null) {
			if (bFirst) {
				buffer.append(" AND ");
			}
			buffer.append("t" + id);
			buffer.append(".obj= ");
			buffer.append(s);
		}
		processjoinWithRegExpr(buffer, tt.subject, "t" + id, "subj");
		processjoinWithRegExpr(buffer, tt.predicate, "t" + id, "pred");
		processjoinWithRegExpr(buffer, tt.object, "t" + id, "obj");
	}

	public ArrayList getAllSQLs() {
		ArrayList result = new ArrayList();
		result.add(getSQL());
		if (premiseList.size() < 2) {
			return result;
		}
		for (int i = 1; i < premiseList.size(); i++) {
			Object f = premiseList.remove(0);
			premiseList.add(f);
			result.add(getSQL());
		}
		//restore
		Object f = premiseList.remove(0);
		premiseList.add(f);
		return result;
	}

	String getSQL() {
		alreadyJoined = null;
		where = "";
		StringBuffer buffer = new StringBuffer();
		buffer.append(C_SELECT);
		buffer.append(match(consequent.subject, premiseList.size()));
		buffer.append(',');
		buffer.append(match(consequent.predicate, premiseList.size()));
		buffer.append(',');
		buffer.append(match(consequent.object, premiseList.size()));
		buffer.append('\n');
		buffer.append(Rule.getFROM());
		buffer.append('\n');
		//    processjoinWithRegExpr(buffer, consequent.subj, "nt", "subj");
		//    processjoinWithRegExpr(buffer, consequent.pred, "nt", "pred");
		//    processjoinWithRegExpr(buffer, consequent.obj, "nt", "obj");
		for (int i = 1; i < premiseList.size(); i++) {
			TripleTemplate tt = (TripleTemplate)premiseList.get(i);
			processJoin(buffer, i, tt);
		}

		processJoin(buffer, premiseList.size(), consequent);

		TripleTemplate ttFirst = (TripleTemplate)premiseList.get(0);
		buffer.append(" WHERE ");
		boolean ifFirst = false;
		if (where.length() > 0) {
			buffer.append(where);
			ifFirst = true;
		}
		if (!ttFirst.subject.isVar()) {
			if (ifFirst) {
				buffer.append(" AND ");
			}
			buffer.append("nt.subj= ");
			buffer.append(getId(ttFirst.subject));
			ifFirst = true;
		}
		if (!ttFirst.predicate.isVar()) {
			if (ifFirst) {
				buffer.append(" AND ");
			}
			buffer.append("nt.pred = ");
			buffer.append(getId(ttFirst.predicate));
			ifFirst = true;
		}
		if (!ttFirst.object.isVar()) {
			if (ifFirst) {
				buffer.append(" AND ");
			}
			buffer.append("nt.obj = ");
			buffer.append(getId(ttFirst.object));
			ifFirst = true;
		}
		for (int i = 1; i < premiseList.size(); i++) {