root/trunk/cdmlib/cdmlib-model/src/main/java/eu/etaxonomy/cdm/model/common/AbstractStringComparator.java

// $Id$
/**
 * Copyright (C) 2009 EDIT
 * European Distributed Institute of Taxonomy 
 * http://www.e-taxonomy.eu
 * 
 * The contents of this file are subject to the Mozilla Public License Version 1.1
 * See LICENSE.TXT at the top of this package for the full license terms.
 */
package eu.etaxonomy.cdm.model.common;

import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.springframework.stereotype.Component;

import eu.etaxonomy.cdm.model.taxon.TaxonNode;

/**
 * Abstract Comparator for Strings which allows define substitution rules which
 * are applied to the String to be compared before the actual comparison takes
 * place. By this it is e.g. possible to influence the position of objects in sorted lists etc.
 * <p>
 * <b>Intended usage</b>: To allow maximum flexibility the property
 * {@link #setSubstitutionRules(Map)} should be set in the spring application
 * context.
 * 
 * @author a.kohlbecker
 * @date 24.06.2009
 */
@Component
public abstract class AbstractStringComparator implements Comparator<TaxonNode> {

        protected Map<Pattern, String> substitutionRules = null;

        /**
         * Set the private field substitutionRules. The substitutionRules consist of
         * a regular expression as key and a string to be prepended as value.
         * 
         * @param rules
         */
        public void setSubstitutionRules(Map<String, String> substitutionRules) {
                this.substitutionRules = new HashMap<Pattern, String>(substitutionRules.size());
                for (String regex : substitutionRules.keySet()) {
                        this.substitutionRules.put(Pattern.compile(regex), substitutionRules.get(regex));
                }

        }

        /**
         * Applies the first matching <code>substitutionRules</code> set by
         * {@link #setSubstitutionRules()} to the given String. A rules is applied
         * in the following way: If the regular expression matches the given string
         * <code>s</code> the String mapped by the regular expression is prepended
         * to <code>s</code>.
         * 
         * @param s
         * @return
         */
        protected String applySubstitutionRules(String s) {
                if (substitutionRules == null) {
                        return s;
                }
                StringBuffer sb = new StringBuffer();
                for (Pattern pattern : substitutionRules.keySet()) {
                        if (pattern.matcher(s).matches()) {
                                sb.append(substitutionRules.get(pattern)).append(s);
                                return sb.toString();
                        }

                }
                return s;
        }

}