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
015package org.apache.tapestry.util.io;
016
017import 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
029public interface SqueezeAdaptor
030{
031    /**
032     * Returns one or more characters, each of which will be a prefix for this adaptor.
033     */
034
035    public String getPrefix();
036
037    /**
038     * Returns the class (or interface) which can be encoded by this adaptor.
039     */
040
041    public Class getDataClass();
042
043    /**
044     * Converts the data object into a String.
045     * 
046     * @throws IOException
047     *             if the object can't be converted.
048     */
049
050    public String squeeze(DataSqueezer squeezer, Object data);
051
052    /**
053     * Converts a String back into an appropriate object.
054     * 
055     * @throws IOException
056     *             if the String can't be converted.
057     */
058
059    public Object unsqueeze(DataSqueezer squeezer, String string);
060}