001// Copyright 2008, 2010 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
017import org.apache.tapestry5.EventContext;
018
019/**
020 * A service to provide utilities needed for event context encoding and decoding to and from (partial) URL paths. This
021 * is used for both component event contexts and page activation contexts.
022 */
023public interface ContextPathEncoder
024{
025    /**
026     * Encodes a single value via the {@link ContextValueEncoder} service, returning the resulting string. Even null
027     * is encoded, as per {@link URLEncoder#encode(String)}.
028     * 
029     * @since 5.2.2
030     */
031    String encodeValue(Object value);
032
033    /**
034     * Encodes the context values into a path string. Each context value (if non-null) is first value encoded into a
035     * string via the {@link org.apache.tapestry5.services.ContextValueEncoder} service. Those values are then encoded,
036     * via {@link URLEncoder#encode(String)} into URL-safe strings. The URL-safe strings are then concatenated
037     * together, separated with "/" characters.
038     * 
039     * @param context
040     *            an array of objects to encode as the context (may be null)
041     * @return the path-encoded context, or the blank string if the context is empty
042     */
043    String encodeIntoPath(Object[] context);
044
045    /**
046     * Encodes the context into a string. Returns the empty string if the context is empty.
047     * 
048     * @param context
049     *            to encode
050     * @return encoded values separated by "/" characters, or the empty string
051     * @since 5.1.0.2
052     */
053    String encodeIntoPath(EventContext context);
054
055    /**
056     * Inverse of {@link #encodeIntoPath(Object[])}; the path is split into strings, and the string are decoded and
057     * constructed into an {@link org.apache.tapestry5.EventContext}.
058     * 
059     * @param path
060     *            to decode, possibly empty or null
061     * @return corresponding event context
062     */
063    EventContext decodePath(String path);
064}