logikusfacade.java

国外的一套开源CRM

/*
 * $Id: LogikusFacade.java,v 1.1 2003/08/19 01:12:57 jonesde Exp $
 *
 * Copyright (c) 1999 Steven J. Metsker.
 * Copyright (c) 2001 The Open For Business Project - www.ofbiz.org
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a
 *  copy of this software and associated documentation files (the "Software"),
 *  to deal in the Software without restriction, including without limitation
 *  the rights to use, copy, modify, merge, publish, distribute, sublicense,
 *  and/or sell copies of the Software, and to permit persons to whom the
 *  Software is furnished to do so, subject to the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included
 *  in all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 *  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 *  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 *  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT
 *  OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
 *  THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package org.ofbiz.rules.logikus;


import org.ofbiz.rules.parse.*;
import org.ofbiz.rules.parse.tokens.*;
import org.ofbiz.rules.engine.*;


/**
 * This class provides utility methods that simplify the use of the Logikus parser.
 *
 * @author Steven J. Metsker
 * @version 1.0
 */
public class LogikusFacade {

    /**
     * Translate one axiom string into an Axiom object.
     */
    public static Axiom axiom(String s) {
        return axiom(new TokenString(s));
    }

    /**
     * Parse the text of a Logikus program and return a
     * <code>Program</code> object.
     *
     * @param   String   the text of the program
     * @return a <code>Program</code> object
     * @exception   RuntimeException   if parsing fails
     */
    public static Program program(String s) {
        Program p = new Program();
        TokenStringSource tss = new TokenStringSource(
                new Tokenizer(s), ";");

        while (true) {
            TokenString ts = tss.nextTokenString();

            if (ts == null) { // no more token strings
                break;
            }
            p.addAxiom(axiom(ts));
        }
        return p;
    }

    /**
     * Parse the text of a Logikus query and return a
     * <code>Query</code> object.
     *
     * @param   String   the text of the query
     * @return a <code>Query</code> object
     * @exception   RuntimeException   if parsing fails
     */
    public static Query query(String s, AxiomSource as) {
        Object o = parse(new TokenString(s), LogikusParser.query(), "query");

        if (o instanceof Fact) {
            Fact f = (Fact) o;

            return new Query(as, f);
        }
        return new Query(as, (Rule) o);
    }

    /**
     * Translate the tokens for one axiom into an Axiom
     * object (either a Fact or a Rule);
     */
    protected static Axiom axiom(TokenString ts) {
        Parser p = new LogikusParser().axiom();
        Object o = parse(ts, p, "axiom");

        return (Axiom) o;
    }

    /**
     * Parse the given token string with the given parser,
     * throwing runtime exceptions if parsing fails
     * or is incomplete.
     */
    protected static Object parse(TokenString ts, Parser p, String type) {
        TokenAssembly ta = new TokenAssembly(ts);
        Assembly out = p.bestMatch(ta);

        if (out == null) {
            reportNoMatch(ts, type);
        }
        if (out.hasMoreElements()) {
            // allow an extra semicolon
            if (!out.remainder("").equals(";")) {
                reportLeftovers(out, type);
            }
        }
        return out.pop();
    }

    /**
     * Throws a runtime exception reporting an incomplete parse.
     */
    protected static Object reportLeftovers(Assembly out, String type) {
        throw new LogikusException("> Input for " + type +
                " appears complete after : \n> " + out.consumed(" ") + "\n");
    }

    /**
     * Throws a runtime exception reporting failed parse.
     */
    protected static void reportNoMatch(TokenString ts, String type) {
        // checkForUppercase(ts, type);
        throw new LogikusException("> Cannot parse " + type + " : " + ts + "\n");
    }

    /**
     * Throws an informative runtime exception if the provided
     * string begins with an uppercase letter.
     *
     * NOTE: This is not currently used.
     */
    protected static void checkForUppercase(TokenString ts, String type) {
        if (ts.length() > 0) {
            Token t = ts.tokenAt(0);
            String s = t.sval();

            if (s.length() > 0 &&
                Character.isUpperCase(s.charAt(0))) {
                throw new LogikusException("> Uppercase " + s +
                        " indicates a variable and cannot begin a " + type + ".\n");
            }
        }
    }
}