001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.wicket;
018
019import java.io.Serializable;
020import java.util.LinkedHashMap;
021import java.util.Map;
022import java.util.regex.Pattern;
023
024import org.apache.wicket.behavior.AttributeAppender;
025import org.apache.wicket.util.string.Strings;
026
027/**
028 * An AttributeModifier specialized in managing the <em>CSS style</em>
029 * attribute
030 */
031public abstract class StyleAttributeModifier extends AttributeAppender
032{
033        private static final Pattern STYLES_SPLITTER = Pattern.compile("\\s*;\\s*");
034        private static final Pattern KEY_VALUE_SPLITTER = Pattern.compile("\\s*:\\s*");
035
036        /**
037         * Constructor.
038         */
039        public StyleAttributeModifier()
040        {
041                super("style", null, ";");
042        }
043
044        @Override
045        protected Serializable newValue(String currentValue, String appendValue)
046        {
047                String[] styles;
048                if (Strings.isEmpty(currentValue))
049                {
050                        styles = new String[0];
051                }
052                else
053                {
054                        styles = STYLES_SPLITTER.split(currentValue.trim());
055                }
056                Map<String, String> oldStyles = new LinkedHashMap<>();
057                for (String style : styles)
058                {
059                        String[] keyValue = KEY_VALUE_SPLITTER.split(style, 2);
060                        oldStyles.put(keyValue[0], keyValue[1]);
061                }
062
063                Map<String, String> newStyles = update(oldStyles);
064
065                String separator = getSeparator();
066                StringBuilder result = new StringBuilder();
067                for (Map.Entry<String, String> entry : newStyles.entrySet())
068                {
069                        result
070                                .append(entry.getKey())
071                                .append(':')
072                                .append(entry.getValue())
073                                .append(separator);
074                }
075                return result.length() > 0 ? result.toString() : VALUELESS_ATTRIBUTE_REMOVE;
076        }
077
078        /**
079         * Callback to update the CSS class values for a tag.
080         *
081         * @param oldStyles
082         *          A map with the old style key/values
083         * @return A map with the new style key/values
084         */
085        protected abstract Map<String, String> update(Map<String, String> oldStyles);
086}