Application: gvSIG desktop

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright (C) 2007-2013 gvSIG Association.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 3

 * of the License, or (at your option) any later version.

 *

 * 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.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 * For any additional information, do not hesitate to contact us

 * at info AT gvsig.com, or visit our website www.gvsig.com.

 */

package org.gvsig.remoteclient.wfs.filters;

import java.util.ArrayList;

/**

 * It parses a SQL expression (just the where part) and seperates

 * it in "sub-expresion". A sub-expresion could be a separator ('(' or ')'),

 * a logical operator ('And', 'Not' or 'Or') or a expresion (A op B).

 *  

 * @author Jorge Piera Llodr? (piera_jor@gva.es)

 */

public class ParseExpressions {

        /**

         * It parses a expression and return one arrayList with

         * the separated words

         * @param expression

         * @return

         */

        public ArrayList parseExpression(String expression){

                ArrayList expressions = new ArrayList();

                char[] chars = expression.toCharArray();

                int i=0;

                while (i<chars.length){

                        if (chars[i] == '('){

                                expressions.add("(");

                                i++;

                        }else if(chars[i] == ')'){

                                expressions.add(")");

                                i++;

                        }else if(chars[i] == ' '){

                                i++;

                        }else{

                                int desp = getShift(chars,i);

                                expressions.add(expression.substring(i,i + desp));

                                i = i + desp;

                        }

                }                

                return expressions;

        }

        /**

         * Gets the shift of the next expression.

         * @param chars

         * @param position

         * @return

         */

        private int getShift(char[] chars,int position){

                int shift = 0;

                shift = isAndOperator(chars,position);

                if (shift == 0){

                        shift = isOrOperator(chars,position);

                        if (shift == 0){

                                shift = isNotOperator(chars,position);

                                if (shift == 0){

                                        shift = isExpression(chars,position);

                                }

                        }

                }

                return shift;

        }

        private int isExpression(char[] chars,int position){

                int desp = 0;

                for (int i=position ;i<chars.length ; i++){

                        if (chars[i] == ')'){

                                break;                        

                        }                        

                        desp++;

                }

                return desp;

        }

        /**

         * Return true if the next array is a AND operator

         * @param chars

         * @param position

         * @return

         */

        private int isAndOperator(char[] chars,int position){

                if (chars[position] == 'A' && 

                                chars[position+1] == 'N' && 

                                chars[position+2] == 'D' &&

                                chars[position+3] == ' '){

                        return 3;

                }

                return 0;

        }

        /**

         * Return true if the next array is a OR operator

         * @param chars

         * @param position

         * @return

         */

        private int isOrOperator(char[] chars,int position){

                if (chars[position] == 'O' && 

                                chars[position+1] == 'R' && 

                                chars[position+2] == ' '){

                        return 2;

                }

                return 0;

        }

        /**

         * Return true if the next array is a NOT operator

         * @param chars

         * @param position

         * @return

         */

        private int isNotOperator(char[] chars,int position){

                if (chars[position] == 'N' && 

                                chars[position+1] == 'O' && 

                                chars[position+2] == 'T' &&

                                chars[position+3] == ' '){

                        return 3;

                }

                return 0;

        }

}