ScalarFunction.java

/**
 * H2GIS is a library that brings spatial support to the H2 Database Engine
 * <http://www.h2database.com>. H2GIS is developed by CNRS
 * <http://www.cnrs.fr/>.
 *
 * This code is part of the H2GIS project. H2GIS 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;
 * version 3.0 of the License.
 *
 * H2GIS 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 <http://www.gnu.org/licenses/>.
 *
 *
 * For more information, please consult: <http://www.h2gis.org/>
 * or contact directly: info_at_h2gis.org
 */

package org.h2gis.api;

/**
 * Scalar function interface.
 * Scalar function in H2 can be defined through CREATE ALIAS, but in an OSGi context the class java name is not sufficient.
 * The full declaration of java name in H2 through osgi is BundleSymbolicName:BundleVersion:BinaryJavaName
 * Registering this interface as an OSGi service will add this function in h2sgis linked with a DataSource service.
 * @author Nicolas Fortin
 */
public interface ScalarFunction extends Function {
    /** Boolean, Deterministic functions must always return the same value for the same parameters.
     *  The result of such functions is cached if possible. */
    static final String PROP_DETERMINISTIC = "deterministic";
    /** Boolean, if nobuffer is true then this function will be called more often but will not cache the results in
     *  memory nor files */
    static final String PROP_NOBUFFER = "nobuffer";

    /**
     * Returns Java name of static methods in this class to expose in database,
     * theses methods are under the same alias but with different number of arguments.
     * @return The Java name of static methods or null if it has not be loaded
     */
    String getJavaStaticMethod();
}