1/*
2 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 * questions.
24 */
25package javax.xml.xpath;
26
27import java.util.Objects;
28import javax.xml.namespace.QName;
29import org.w3c.dom.Node;
30/**
31 * The {@code XPathEvaluationResult} interface represents the result of the
32 * evaluation of an XPath expression within the context of a particular node.
33 * The evaluation of an XPath expression can result in various result types as
34 * defined in XML Path Language (XPath) Version 1.0.
35 *
36 * @param <T> the object type returned by the XPath evaluation.
37 * @see <a href="http://www.w3.org/TR/xpath">XML Path Language (XPath) Version
38 * 1.0</a>
39 *
40 * @since 9
41 */
42public interface XPathEvaluationResult<T> {
43
44    /**
45     * XPathResultType represents possible return types of an XPath evaluation.
46     * Provided as an enum type, it allows the use of switch statement. At the
47     * same time, a mapping is provided between the original QName types in
48     * {@link XPathConstants} and class types used in the generic methods.
49     */
50    public static enum XPathResultType {
51        /**
52         * Any type that represents any of the 5 other types listed below.
53         * Maps to {@link XPathEvaluationResult}.
54         */
55        ANY(new QName("http://www.w3.org/1999/XSL/Transform", "any"), XPathEvaluationResult.class),
56        /**
57         * The XPath 1.0 boolean data type. Maps to Java {@link Boolean}.
58         */
59        BOOLEAN(XPathConstants.BOOLEAN, Boolean.class),
60        /**
61         * The XPath 1.0 Number data type. Maps to Java {@link Number}. Of the
62         * subtypes of Number, only Double, Integer and Long are required.
63         */
64        NUMBER(XPathConstants.NUMBER, Number.class),
65        /**
66         * The XPath 1.0 String data type. Maps to Java {@link String}.
67         */
68        STRING(XPathConstants.STRING, String.class),
69        /**
70         * The XPath 1.0 NodeSet data type. Maps to {@link org.w3c.dom.NodeList}.
71         */
72        NODESET(XPathConstants.NODESET, XPathNodes.class),
73        /**
74         * The XPath 1.0 NodeSet data type. Maps to {@link org.w3c.dom.Node}.
75         */
76        NODE(XPathConstants.NODE, Node.class);
77
78        final QName qnameType;
79        final Class<?> clsType;
80        XPathResultType(QName qnameType, Class<?> clsType) {
81            this.qnameType = qnameType;
82            this.clsType = clsType;
83        }
84
85        /**
86         * Compares this type to the specified class type.
87         * @param clsType class type
88         * @return true if the argument is not null and is a class type that
89         * matches that this type represents, false otherwise.
90         */
91        private boolean equalsClassType(Class<?> clsType) {
92            Objects.nonNull(clsType);
93            if (clsType.isAssignableFrom(this.clsType)) {
94                return true;
95            }
96            return false;
97        }
98
99        /**
100         * Returns the QName type as specified in {@link XPathConstants} that
101         * corresponds to the specified class type.
102         * @param clsType a class type that the enum type supports
103         * @return the QName type that matches with the specified class type,
104         * null if there is no match
105         */
106        static public QName getQNameType(Class<?> clsType) {
107            for (XPathResultType type : XPathResultType.values()) {
108                if (type.equalsClassType(clsType)) {
109                    return type.qnameType;
110                }
111            }
112            return null;
113        }
114    }
115
116    /**
117     * Return the result type as an enum specified by {@code XPathResultType}
118     * @return the result type
119     */
120    public XPathResultType type();
121
122    /**
123     * Returns the value of the result as the type {@code <T>} specified for the class.
124     *
125     * @return The value of the result.
126     */
127    public T value();
128
129}
130