001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.util.io;
016    
017    import org.apache.tapestry.services.DataSqueezer;
018    
019    /**
020     * Interface which defines a class used to convert data for a specific Java type into a String
021     * format (squeeze it), or convert from a String back into a Java type (unsqueeze).
022     * <p>
023     * This interface is somewhat misnamed; this is more of the GoF Strategy pattern than GoF Adaptor
024     * pattern.
025     * 
026     * @author Howard Lewis Ship
027     */
028    
029    public interface SqueezeAdaptor
030    {
031        /**
032         * Returns one or more characters, each of which will be a prefix for this adaptor.
033         *
034         * @return The prefix for this squeezer.
035         */
036    
037        String getPrefix();
038    
039        /**
040         * Returns the class (or interface) which can be encoded by this adaptor.
041         *
042         * @return The class type that this adaptor can manage.
043         */
044    
045        Class getDataClass();
046    
047        /**
048         * Converts the data object into a String.
049         *
050         * @param squeezer
051         *          The squeezer that should be used to ultimately squeeze the data.
052         * @param data
053         *          The data to squeeze.
054         *
055         * @return String representation of data.
056         */
057    
058        String squeeze(DataSqueezer squeezer, Object data);
059    
060        /**
061         * Converts a String back into an appropriate object.
062         *
063         * @param squeezer
064         *          The squeezer to use to unsqueeze the data.
065         * @param string
066         *          The string data - as was returned from {@link #squeeze(org.apache.tapestry.services.DataSqueezer, Object)}.
067         *
068         * @return The re-constituded object representation of the string.
069         */
070    
071        Object unsqueeze(DataSqueezer squeezer, String string);
072    }