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    }