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Java > Open Source Codes > net > sf > saxon > om > Item


1 package net.sf.saxon.om;
2 import net.sf.saxon.trans.XPathException;
3
4 /**
5  * An Item is an object that can occur as a member of a sequence.
6  * It corresponds directly to the concept of an item in the XPath 2.0 data model.
7  * There are two kinds of Item: atomic values, and nodes.
8  * <p>
9  * This interface is part of the public Saxon API. As such (starting from Saxon 8.4),
10  * methods that form part of the stable API are labelled with a JavaDoc "since" tag
11  * to identify the Saxon release at which they were introduced.
12  *
13  * @author Michael H. Kay
14  * @since 8.4
15  */
16
17 public interface Item extends ValueRepresentation {
18
19     /**
20      * Get the value of the item as a string. For nodes, this is the string value of the
21      * node as defined in the XPath 2.0 data model, except that all nodes are treated as being
22      * untyped: it is not an error to get the string value of a node with a complex type.
23      * For atomic values, the method returns the result of casting the atomic value to a string.
24      * <p>
25      * If the calling code can handle any CharSequence, the method {@link #getStringValueCS} should
26      * be used. If the caller requires a string, this method is preferred.
27      *
28      * @return the string value of the item
29      * @see #getStringValueCS
30      * @since 8.4
31      */
32
33     public String JavaDoc getStringValue();
34
35     /**
36      * Get the string value of the item as a CharSequence. This is in some cases more efficient than
37      * the version of the method that returns a String. The method satisfies the rule that
38      * <code>X.getStringValueCS().toString()</code> returns a string that is equal to
39      * <code>X.getStringValue()</code>.
40      * <p>
41      * Note that two CharSequence values of different types should not be compared using equals(), and
42      * for the same reason they should not be used as a key in a hash table.
43      * <p>
44      * If the calling code can handle any CharSequence, this method should
45      * be used. If the caller requires a string, the {@link #getStringValue} method is preferred.
46      *
47      * @return the string value of the item
48      * @see #getStringValue
49      * @since 8.4
50      */
51
52     public CharSequence JavaDoc getStringValueCS();
53
54     /**
55      * Get the typed value of the item.
56      * <p>
57      * For a node, this is the typed value as defined in the XPath 2.0 data model. Since a node
58      * may have a list-valued data type, the typed value is in general a sequence, and it is returned
59      * in the form of a SequenceIterator.
60      * <p>
61      * If the node has not been validated against a schema, the typed value
62      * will be the same as the string value, either as an instance of xs:string or as an instance
63      * of xdt:untypedAtomic, depending on the node kind.
64      * <p>
65      * For an atomic value, this method returns an iterator over a singleton sequence containing
66      * the atomic value itself.
67      *
68      * @return an iterator over the items in the typed value of the node or atomic value. The
69      * items returned by this iterator will always be atomic values.
70      * @throws XPathException where no typed value is available, for example in the case of
71      * an element with complex content
72      * @since 8.4
73      */
74
75     public SequenceIterator getTypedValue() throws XPathException;
76
77
78 }
79
80
81
82 //
83 // The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
84 // you may not use this file except in compliance with the License. You may obtain a copy of the
85 // License at http://www.mozilla.org/MPL/
86 //
87 // Software distributed under the License is distributed on an "AS IS" basis,
88 // WITHOUT WARRANTY OF ANY KIND, either express or implied.
89 // See the License for the specific language governing rights and limitations under the License.
90 //
91 // The Original Code is: all this file.
92 //
93 // The Initial Developer of the Original Code is Michael H. Kay.
94 //
95 // Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
96 //
97 // Contributor(s): none.
98 //
99
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