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