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
015package 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.commons.services.TypeCoercer
022 */
023public 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}