Subversion Repositories mkgmap

/*
 * Copyright (C) 2012.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3 or
 * version 2 as published by the Free Software Foundation.
 *
 * This program 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
 * General Public License for more details.
 */

package uk.me.parabola.mkgmap.osmstyle.function;

import uk.me.parabola.mkgmap.reader.osm.Element;
import uk.me.parabola.mkgmap.reader.osm.Node;

/**
 * The interface for all functions that can be used within a style file.<br>
 * The input parameter of a function is one element. The resulting value is a
 * string which can carry number values.
 * @author WanMil
 */
public interface StyleFunction {
       
    /**
     * Retrieves if the function accepts {@link Node} objects as input parameter.
     * @return <code>true</code> {@link Node} objects are supported; <code>false</code> .. are not supported
     */
    public boolean supportsNode();

    /**
     * Retrieves if the function accepts {@link Way} objects as input parameter.
     * @return <code>true</code> {@link Way} objects are supported; <code>false</code> .. are not supported
     */
    public boolean supportsWay();

    /**
     * Retrieves if the function accepts {@link Relation} objects as input parameter.
     * @return <code>true</code> {@link Relation} objects are supported; <code>false</code> .. are not supported
     */
    public boolean supportsRelation();
   
    /**
     * Calculates the function value for the given element.
     * @param el an element
     * @return the function value (<code>null</code> if it cannot be calculated)
     */
    public String calcValue(Element el);
   
        /**
         * Retrieves the function name. This is the part without function brackets (). It is
         * case sensitive but should be lower case.
         * @return the function name (e.g. length for length())
         */
        public String getName();
}