001    // Copyright 2008, 2011 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.tapestry5.services;
016    
017    /**
018     * Used to convert values used in event contexts to client string representations and back.
019     *
020     * @see org.apache.tapestry5.ValueEncoder
021     * @see org.apache.tapestry5.ioc.services.TypeCoercer
022     */
023    public interface ContextValueEncoder
024    {
025        /**
026         * Converts a context value into a client-side string (that will ultimately be encoded into a URL).
027         *
028         * @param value to convert (may not be null)
029         * @return string representation of the value
030         * @see org.apache.tapestry5.ValueEncoder#toClient(Object)
031         */
032        String toClient(Object value);
033    
034        /**
035         * Converts a client value back into a server-side object.
036         *
037         * @param requiredType required type to convert the string to
038         * @param clientValue  value obtained from context passed from client
039         * @return the client value converted or coerced into a server value
040         * @see org.apache.tapestry5.ValueEncoder#toValue(String)
041         */
042        <T> T toValue(Class<T> requiredType, String clientValue);
043    }