01: /*
02: * Copyright 1999-2004 The Apache Software Foundation
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
10: * Unless required by applicable law or agreed to in writing, software
11: * distributed under the License is distributed on an "AS IS" BASIS,
12: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13: * See the License for the specific language governing permissions and
14: * limitations under the License.
15: */
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: }
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