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 }