001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     * 
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     * 
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.lang3.exception;
018    
019    import java.util.Set;
020    
021    /**
022     * Allows the storage and retrieval of contextual information based on label-value
023     * pairs for exceptions.
024     * 
025     * @see ContextedException
026     * @see ContextedRuntimeException
027     * @author Apache Software Foundation
028     * @author D. Ashmore
029     * @since 3.0
030     */
031    public interface ExceptionContext {
032    
033        /**
034         * Adds a contextual label-value pair into this context.
035         * <p>
036         * This label-value pair provides information useful for debugging. If the
037         * provided label already exists, it depends on the implementation what
038         * happens with the new value. 
039         * </p>
040         * 
041         * @param label  the label of the item to add, null not recommended
042         * @param value  the value of item to add, may be null
043         * @return context itself to allow method chaining
044         */
045        public ExceptionContext addValue(String label, Object value);
046    
047        /**
048         * Replaces a contextual label-value pair of this context.
049         * <p>
050         * This label-value pair provides information useful for debugging. If the
051         * label does not exist yet, it depends on the implementation what happens
052         * with the provided value.
053         * </p>
054         * 
055         * @param label  the label of the item to add, null not recommended
056         * @param value  the value of item to add, may be null
057         * @return context itself to allow method chaining
058         */
059        public ExceptionContext replaceValue(String label, Object value);
060    
061        /**
062         * Retrieves a contextual data value associated with the label.
063         * 
064         * @param label  the label to get the contextual value for, may be null
065         * @return the contextual value associated with the label, may be null
066         */
067        public Object getValue(String label);
068    
069        /**
070         * Retrieves the labels defined in the contextual data.
071         * 
072         * @return the set of labels, never null
073         */
074        public Set<String> getLabelSet();
075    
076        /**
077         * Implementors provide the given base message with context label/value item 
078         * information appended.
079         * 
080         * @param baseMessage  the base exception message <b>without</b> context information appended
081         * @return the exception message <b>with</b> context information appended, never null
082         */
083        public String getFormattedExceptionMessage(String baseMessage);
084    
085    }