Subversion Repositories mkgmap

/*
 * Copyright (C) 2010.
 *
 * 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.eval;

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

/**
 * Interface for an operation in the style expression language.
 * Operations need have only one operand, use {@link BinaryOp} for
 * when they definitely have two.
 *
 * @author Steve Ratcliffe
 */
public interface Op {
        // The operation types.  They are represented by a mildly mnemonic character.
        public char EQUALS = '=';
        public char GT = 'g';
        public char GTE = 'G';
        public char LT = 'l';
        public char LTE = 'L';
        public char NOT_EQUALS = 'N';
        public char EXISTS = 'E';
        public char NOT_EXISTS = 'n';
        public char AND = '&';
        public char OR = '|';
        public char VALUE = 'V';
        public char OPEN_PAREN = '(';
        public char CLOSE_PAREN = ')';
        public char NOT = '!';
        public char REGEX = '~';

        /**
         * Evaluate the expression.
         * @param el The OSM element to be tested.
         * @return True if the expression is true for the given element.
         */
        public boolean eval(Element el);

        /**
         * Does this operation have a higher priority that the other one?
         * @param other The other operation.
         */
        public boolean hasHigherPriority(Op other);

        /**
         * Get the first operand.
         */
        public Op getFirst();

        public void setFirst(Op first);

        public char getType();

        /**
         * Get the value in a 'pure' form, without being quoted in any way.
         * If you want the expression in a form that can be printed and
         * used in a style file, then use toString().
         */
        public String value();

        public boolean isType(char value);

        public int priority();

        public String getTypeString();
}