Query.java

/*
 * Copyright (2005-2012) 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;

import java.io.Serializable;
import no.sesat.search.query.finder.ParentFinder;
import no.sesat.search.query.token.TokenEvaluationEngine;


/** A Query represents a users inputted query string.
 * The query contains an heirarchy of Clause objects implemented against a visitor pattern
 * that visitors are free to use.
 *
 * @version $Id$
 *
 */
public interface Query extends Serializable {

    /** The root clause to the clause heirarchy.
     * Will always be an operation clause if more than one term exists in the query.
     * @return the root clause.
     */
    Clause getRootClause();

    /** The original string the user entered for the search.
     * This string should never be used programmatically or passed to search indexes.
     * It is only intended for display and feedback.
     *
     * @return the original user's query.
     */
    String getQueryString();

    /** The first term (leaf clause) in the query.
     *
     * @return the first leaf clause.
     */
    LeafClause getFirstLeafClause();

    /** Return the number of terms in this query.
     * Terms are represented by LeafClauses.
     ** @return
     */
    int getTermCount();

    /** Is the query blank (or just full of useless symbols).
     * @return
     */
    boolean isBlank();

    /** Returns the ParentFinder instance applicable for this query.
     * The ParentFinder keeps a cache of parent-finds so it's useful to store an instance against the Query like this.
     * @return the ParentFinder instance applicable for this query.
     */
    ParentFinder getParentFinder();

    /** Returns the object that holds State for any TokenEvaluationEngine actions.
     *
     * @return the object that holds State for any TokenEvaluationEngine actions.
     */
    TokenEvaluationEngine.State getEvaluationState();
}