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16 package org.apache.commons.jxpath;
17
18 import java.io.Serializable;
19
20 /***
21 * Pointers represent locations of objects and their properties
22 * in Java object graphs. JXPathContext has methods
23 * ({@link JXPathContext#getPointer(java.lang.String) getPointer()}
24 * and ({@link JXPathContext#iteratePointers(java.lang.String)
25 * iteratePointers()}, which, given an XPath, produce Pointers for the objects
26 * or properties described the the path. For example, <code>ctx.getPointer
27 * ("foo/bar")</code> will produce a Pointer that can get and set the property
28 * "bar" of the object which is the value of the property "foo" of the root
29 * object. The value of <code>ctx.getPointer("aMap/aKey[3]")</code> will be a
30 * pointer to the 3'rd element of the array, which is the value for the key
31 * "aKey" of the map, which is the value of the property "aMap" of the root
32 * object.
33 *
34 * @author Dmitri Plotnikov
35 * @version $Revision: 1.9 $ $Date: 2004/02/29 14:17:42 $
36 */
37 public interface Pointer extends Cloneable, Comparable, Serializable {
38
39 /***
40 * Returns the value of the object, property or collection element
41 * this pointer represents. May convert the value to one of the
42 * canonical InfoSet types: String, Number, Boolean, Set.
43 *
44 * For example, in the case of an XML element, getValue() will
45 * return the text contained by the element rather than
46 * the element itself.
47 */
48 Object getValue();
49
50 /***
51 * Returns the raw value of the object, property or collection element
52 * this pointer represents. Never converts the object to a
53 * canonical type: returns it as is.
54 *
55 * For example, for an XML element, getNode() will
56 * return the element itself rather than the text it contains.
57 */
58 Object getNode();
59
60 /***
61 * Modifies the value of the object, property or collection element
62 * this pointer represents.
63 */
64 void setValue(Object value);
65
66 /***
67 * Returns the node this pointer is based on.
68 */
69 Object getRootNode();
70
71 /***
72 * Returns a string that is a proper "canonical" XPath that corresponds to
73 * this pointer. Consider this example:
74 * <p><code>Pointer ptr = ctx.getPointer("//employees[firstName = 'John']")
75 * </code>
76 * <p>The value of <code>ptr.asPath()</code> will look something like
77 * <code>"/departments[2]/employees[3]"</code>, so, basically, it represents
78 * the concrete location(s) of the result of a search performed by JXPath.
79 * If an object in the pointer's path is a Dynamic Property object (like a
80 * Map), the asPath method generates an XPath that looks like this: <code>"
81 * /departments[@name = 'HR']/employees[3]"</code>.
82 */
83 String asPath();
84
85 /***
86 * Pointers are cloneable
87 */
88 Object clone();
89 }