1 /*
2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/expr/Expr.java,v 1.14 2006/11/30 18:49:26 elharo Exp $
3 * $Revision: 1.14 $
4 * $Date: 2006/11/30 18:49:26 $
5 *
6 * ====================================================================
7 *
8 * Copyright 2000-2002 bob mcwhirter & James Strachan.
9 * All rights reserved.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions are
13 * met:
14 *
15 * * Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 *
18 * * Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 *
22 * * Neither the name of the Jaxen Project nor the names of its
23 * contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
27 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
29 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
30 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
31 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
32 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
33 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
36 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 *
38 * ====================================================================
39 * This software consists of voluntary contributions made by many
40 * individuals on behalf of the Jaxen Project and was originally
41 * created by bob mcwhirter <bob@werken.com> and
42 * James Strachan <jstrachan@apache.org>. For more information on the
43 * Jaxen Project, please see <http://www.jaxen.org/>.
44 *
45 * $Id: Expr.java,v 1.14 2006/11/30 18:49:26 elharo Exp $
46 */
47
48
49
50 package org.jaxen.expr;
51
52 import java.io.Serializable;
53 import org.jaxen.Context;
54 import org.jaxen.JaxenException;
55
56 /***
57 * Represents an XPath expression. This is production 14 in the
58 * <a href="http://www.w3.org/TR/xpath#NT-Expr">XPath 1.0 specification</a>:
59 *
60 * <pre>[14] Expr ::= OrExpr</pre>
61 *
62 */
63 public interface Expr extends Serializable
64 {
65
66
67 /***
68 * Returns a String containing the XPath expression.
69 *
70 * @return the text form of this XPath expression
71 */
72 String getText();
73
74 /***
75 * Simplifies the XPath expression. For example, the expression
76 * <code>//para[1 = 1]</code> could be simplified to
77 * <code>//para</code>. In practice, this is usually a noop.
78 * Jaxen does not currently perform any simplification.
79 *
80 * @return the simplified expression
81 */
82 Expr simplify();
83
84
85 /***
86 * Evaluate the expression in the given context, and return the result.
87 * The result will be a <code>java.lang.Double</code> for expressions that
88 * return a number, a <code>java.lang.String</code> for expressions that
89 * return a string, a <code>java.lang.Boolean</code> for expressions that
90 * return a boolean, and a <code>java.util.List</code> for expressions that
91 * return a node-set. In the latter case, the elements of the list are
92 * the actual objects from the source document model. Copies are not made.
93 *
94 * @param context the context in which the expression is evaluated
95 * @return an object representing the result of the evaluation
96 * @throws JaxenException
97 */
98 Object evaluate(Context context) throws JaxenException;
99
100 }