repetition.java

国外的一套开源CRM

package org.ofbiz.rules.parse;


import java.util.*;


/**
 * <p><b>Title:</b> Repetition
 * <p><b>Description:</b> None
 * <p>Copyright (c) 1999 Steven J. Metsker.
 * <p>Copyright (c) 2001 The Open For Business Project - www.ofbiz.org
 *
 * <p>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:
 *
 * <p>The above copyright notice and this permission notice shall be included
 *  in all copies or substantial portions of the Software.
 *
 * <p>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.
 *
 * <br>
 * <p>A <code>Repetition</code> matches its underlying parser
 * repeatedly against a assembly.
 *
 * @author Steven J. Metsker
 * @version 1.0
 */

public class Repetition extends Parser {

    /**
     * the parser this parser is a repetition of
     */
    protected Parser subparser;

    /**
     * the width of a random expansion
     */
    protected static final int EXPWIDTH = 4;

    /**
     * an assembler to apply at the beginning of a match
     */
    protected Assembler preAssembler;

    /**
     * Constructs a repetition of the given parser.
     *
     * @param   parser   the parser to repeat
     *
     * @return   a repetiton that will match the given
     *           parser repeatedly in successive matches
     */
    public Repetition(Parser p) {
        this(p, null);
    }

    /**
     * Constructs a repetition of the given parser with the
     * given name.
     *
     * @param   Parser   the parser to repeat
     *
     * @param   String   a name to be known by
     *
     * @return   a repetiton that will match the given
     *           parser repeatedly in successive matches
     */
    public Repetition(Parser subparser, String name) {
        super(name);
        this.subparser = subparser;
    }

    /**
     * Accept a "visitor" and a collection of previously visited
     * parsers.
     *
     * @param   pv   the visitor to accept
     *
     * @param   visited   a collection of previously visited parsers
     */
    public void accept(ParserVisitor pv, List visited) {
        pv.visitRepetition(this, visited);
    }

    /**
     * Return this parser's subparser.
     *
     * @return   Parser   this parser's subparser
     */
    public Parser getSubparser() {
        return subparser;
    }

    /**
     * Given a set of assemblies, this method applies a preassembler
     * to all of them, matches its subparser repeatedly against each
     * of them, applies its post-assembler against each, and returns
     * a new set of the assemblies that result from the matches.
     * <p>
     * For example, matching the regular expression <code>a*
     * </code> against <code>{^aaab}</code> results in <code>
     * {^aaab, a^aab, aa^ab, aaa^b}</code>.
     *
     * @return   a List of assemblies that result from
     *           matching against a beginning set of assemblies
     *
     * @param   in   a vector of assemblies to match against
     *
     */
    public List match(List in) {
        if (preAssembler != null) {
            Enumeration e = Collections.enumeration(in);

            while (e.hasMoreElements()) {
                preAssembler.workOn((Assembly) e.nextElement());
            }
        }
        List out = elementClone(in);
        List s = in; // a working state

        while (!s.isEmpty()) {
            s = subparser.matchAndAssemble(s);
            add(out, s);
        }
        return out;
    }

    /**
     * Create a collection of random elements that correspond to
     * this repetition.
     */
    protected List randomExpansion(int maxDepth, int depth) {
        List v = new ArrayList();

        if (depth >= maxDepth) {
            return v;
        }

        int n = (int) (EXPWIDTH * Math.random());

        for (int j = 0; j < n; j++) {
            List w = subparser.randomExpansion(maxDepth, depth++);
            Enumeration e = Collections.enumeration(w);

            while (e.hasMoreElements()) {
                v.add(e.nextElement());
            }
        }
        return v;
    }

    /**
     * Sets the object that will work on every assembly before
     * matching against it.
     *
     * @param   Assembler   the assembler to apply
     *
     * @return   Parser   this
     */
    public Parser setPreAssembler(Assembler preAssembler) {
        this.preAssembler = preAssembler;
        return this;
    }

    /**
     * Returns a textual description of this parser.
     */
    protected String unvisitedString(List visited) {
        return subparser.toString(visited) + "*";
    }
}