org.h2gis.api.ScalarFunction Maven / Gradle / Ivy

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/*
 * 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 .
 *
 *
 * 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 H2GIS 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.
     */
    String PROP_DETERMINISTIC = "deterministic";

    /**
     * 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();
}