Counter.java

/* Copyright (2007-2012) Schibsted ASA
 * This file is part of Possom.
 *
 *   Possom 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 3 of the License, or
 *   (at your option) any later version.
 *
 *   Possom 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 Possom.  If not, see <http://www.gnu.org/licenses/>.
 */
package no.sesat.search.query.finder;

import no.sesat.commons.visitor.AbstractReflectionVisitor;
import java.io.Serializable;
import no.sesat.search.query.Clause;
import no.sesat.search.query.BinaryClause;
import no.sesat.search.query.LeafClause;
import no.sesat.search.query.UnaryClause;
import no.sesat.search.query.XorClause;
import no.sesat.search.query.parser.*;



/** Simple visitor used to count the number of leaves under a given clause.
 *
 *
 * @version $Id$
 */
public final class Counter extends AbstractReflectionVisitor implements Serializable {

    private Integer termCount = null;

    private Clause root = null;

    /** Get the count of leaves under this clause.
     * Subsequent calls with the same argument will return a cached result.
     * @param root the clause to count leaves within
     * @return the number of LeafClauses found under the root clause.
     */
    public synchronized int getTermCount(final Clause root) {

        if(root != this.root){
            termCount = 0;
            this.root = root;
            visit(root);
        }
        return termCount;
    }


    /**
     *
     * @param clause
     */
    protected void visitImpl(final UnaryClause clause) {
        clause.getFirstClause().accept(this);
    }

    /**
     *
     * @param clause
     */
    protected void visitImpl(final XorClause clause) {
        clause.getFirstClause().accept(this);
    }

    /**
     *
     * @param clause
     */
    protected void visitImpl(final BinaryClause clause) {
        clause.getFirstClause().accept(this);
        clause.getSecondClause().accept(this);
    }

    /**
     *
     * @param clause
     */
    protected void visitImpl(final LeafClause clause) {
        ++termCount;
    }

}