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.jxpath;
018
019 import java.io.Serializable;
020
021 /**
022 * Pointers represent locations of objects and their properties
023 * in Java object graphs. JXPathContext has methods
024 * ({@link JXPathContext#getPointer(java.lang.String) getPointer()}
025 * and ({@link JXPathContext#iteratePointers(java.lang.String)
026 * iteratePointers()}, which, given an XPath, produce Pointers for the objects
027 * or properties described the the path. For example, <code>ctx.getPointer
028 * ("foo/bar")</code> will produce a Pointer that can get and set the property
029 * "bar" of the object which is the value of the property "foo" of the root
030 * object. The value of <code>ctx.getPointer("aMap/aKey[3]")</code> will be a
031 * pointer to the 3'rd element of the array, which is the value for the key
032 * "aKey" of the map, which is the value of the property "aMap" of the root
033 * object.
034 *
035 * @author Dmitri Plotnikov
036 * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
037 */
038 public interface Pointer extends Cloneable, Comparable, Serializable {
039
040 /**
041 * Returns the value of the object, property or collection element
042 * this pointer represents. May convert the value to one of the
043 * canonical InfoSet types: String, Number, Boolean, Set.
044 *
045 * For example, in the case of an XML element, getValue() will
046 * return the text contained by the element rather than
047 * the element itself.
048 * @return Object value
049 */
050 Object getValue();
051
052 /**
053 * Returns the raw value of the object, property or collection element
054 * this pointer represents. Never converts the object to a
055 * canonical type: returns it as is.
056 *
057 * For example, for an XML element, getNode() will
058 * return the element itself rather than the text it contains.
059 * @return Object node
060 */
061 Object getNode();
062
063 /**
064 * Modifies the value of the object, property or collection element
065 * this pointer represents.
066 * @param value value to set
067 */
068 void setValue(Object value);
069
070 /**
071 * Returns the node this pointer is based on.
072 * @return Object
073 */
074 Object getRootNode();
075
076 /**
077 * Returns a string that is a proper "canonical" XPath that corresponds to
078 * this pointer. Consider this example:
079 * <p><code>Pointer ptr = ctx.getPointer("//employees[firstName = 'John']")
080 * </code>
081 * <p>The value of <code>ptr.asPath()</code> will look something like
082 * <code>"/departments[2]/employees[3]"</code>, so, basically, it represents
083 * the concrete location(s) of the result of a search performed by JXPath.
084 * If an object in the pointer's path is a Dynamic Property object (like a
085 * Map), the asPath method generates an XPath that looks like this: <code>"
086 * /departments[@name = 'HR']/employees[3]"</code>.
087 * @return String path
088 */
089 String asPath();
090
091 /**
092 * Pointers are cloneable.
093 * @return cloned Object
094 */
095 Object clone();
096 }