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    
015    package org.apache.tapestry5.services;
016    
017    import 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     */
023    public 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    }