    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    }