1 /* 2 * Copyright (c) 2004 World Wide Web Consortium, 3 * 4 * (Massachusetts Institute of Technology, European Research Consortium for 5 * Informatics and Mathematics, Keio University). All Rights Reserved. This 6 * work is distributed under the W3C(r) Software License [1] in the hope that 7 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied 8 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 9 * 10 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231 11 */ 12 13 package org.w3c.dom.xpath; 14 15 import org.w3c.dom.Node; 16 import org.w3c.dom.DOMException; 17 18 /** 19 * The evaluation of XPath expressions is provided by 20 * <code>XPathEvaluator</code>. In a DOM implementation which supports the 21 * XPath 3.0 feature, as described above, the <code>XPathEvaluator</code> 22 * interface will be implemented on the same object which implements the 23 * <code>Document</code> interface permitting it to be obtained by the usual 24 * binding-specific method such as casting or by using the DOM Level 3 25 * getInterface method. In this case the implementation obtained from the 26 * Document supports the XPath DOM module and is compatible with the XPath 27 * 1.0 specification. 28 * <p>Evaluation of expressions with specialized extension functions or 29 * variables may not work in all implementations and is, therefore, not 30 * portable. <code>XPathEvaluator</code> implementations may be available 31 * from other sources that could provide specific support for specialized 32 * extension functions or variables as would be defined by other 33 * specifications. 34 * <p>See also the <a href='http://www.w3.org/TR/2004/NOTE-DOM-Level-3-XPath-20040226'>Document Object Model (DOM) Level 3 XPath Specification</a>. 35 */ 36 public interface XPathEvaluator { 37 /** 38 * Creates a parsed XPath expression with resolved namespaces. This is 39 * useful when an expression will be reused in an application since it 40 * makes it possible to compile the expression string into a more 41 * efficient internal form and preresolve all namespace prefixes which 42 * occur within the expression. 43 * @param expression The XPath expression string to be parsed. 44 * @param resolver The <code>resolver</code> permits translation of all 45 * prefixes, including the <code>xml</code> namespace prefix, within 46 * the XPath expression into appropriate namespace URIs. If this is 47 * specified as <code>null</code>, any namespace prefix within the 48 * expression will result in <code>DOMException</code> being thrown 49 * with the code <code>NAMESPACE_ERR</code>. 50 * @return The compiled form of the XPath expression. 51 * @exception XPathException 52 * INVALID_EXPRESSION_ERR: Raised if the expression is not legal 53 * according to the rules of the <code>XPathEvaluator</code>. 54 * @exception DOMException 55 * NAMESPACE_ERR: Raised if the expression contains namespace prefixes 56 * which cannot be resolved by the specified 57 * <code>XPathNSResolver</code>. 58 */ createExpression(String expression, XPathNSResolver resolver)59 public XPathExpression createExpression(String expression, 60 XPathNSResolver resolver) 61 throws XPathException, DOMException; 62 63 /** 64 * Adapts any DOM node to resolve namespaces so that an XPath expression 65 * can be easily evaluated relative to the context of the node where it 66 * appeared within the document. This adapter works like the DOM Level 3 67 * method <code>lookupNamespaceURI</code> on nodes in resolving the 68 * namespaceURI from a given prefix using the current information 69 * available in the node's hierarchy at the time lookupNamespaceURI is 70 * called. also correctly resolving the implicit xml prefix. 71 * @param nodeResolver The node to be used as a context for namespace 72 * resolution. 73 * @return <code>XPathNSResolver</code> which resolves namespaces with 74 * respect to the definitions in scope for a specified node. 75 */ createNSResolver(Node nodeResolver)76 public XPathNSResolver createNSResolver(Node nodeResolver); 77 78 /** 79 * Evaluates an XPath expression string and returns a result of the 80 * specified type if possible. 81 * @param expression The XPath expression string to be parsed and 82 * evaluated. 83 * @param contextNode The <code>context</code> is context node for the 84 * evaluation of this XPath expression. If the XPathEvaluator was 85 * obtained by casting the <code>Document</code> then this must be 86 * owned by the same document and must be a <code>Document</code>, 87 * <code>Element</code>, <code>Attribute</code>, <code>Text</code>, 88 * <code>CDATASection</code>, <code>Comment</code>, 89 * <code>ProcessingInstruction</code>, or <code>XPathNamespace</code> 90 * node. If the context node is a <code>Text</code> or a 91 * <code>CDATASection</code>, then the context is interpreted as the 92 * whole logical text node as seen by XPath, unless the node is empty 93 * in which case it may not serve as the XPath context. 94 * @param resolver The <code>resolver</code> permits translation of all 95 * prefixes, including the <code>xml</code> namespace prefix, within 96 * the XPath expression into appropriate namespace URIs. If this is 97 * specified as <code>null</code>, any namespace prefix within the 98 * expression will result in <code>DOMException</code> being thrown 99 * with the code <code>NAMESPACE_ERR</code>. 100 * @param type If a specific <code>type</code> is specified, then the 101 * result will be returned as the corresponding type.For XPath 1.0 102 * results, this must be one of the codes of the 103 * <code>XPathResult</code> interface. 104 * @param result The <code>result</code> specifies a specific result 105 * object which may be reused and returned by this method. If this is 106 * specified as <code>null</code>or the implementation does not reuse 107 * the specified result, a new result object will be constructed and 108 * returned.For XPath 1.0 results, this object will be of type 109 * <code>XPathResult</code>. 110 * @return The result of the evaluation of the XPath expression.For XPath 111 * 1.0 results, this object will be of type <code>XPathResult</code>. 112 * @exception XPathException 113 * INVALID_EXPRESSION_ERR: Raised if the expression is not legal 114 * according to the rules of the <code>XPathEvaluator</code>i 115 * <br>TYPE_ERR: Raised if the result cannot be converted to return the 116 * specified type. 117 * @exception DOMException 118 * NAMESPACE_ERR: Raised if the expression contains namespace prefixes 119 * which cannot be resolved by the specified 120 * <code>XPathNSResolver</code>. 121 * <br>WRONG_DOCUMENT_ERR: The Node is from a document that is not 122 * supported by this <code>XPathEvaluator</code>. 123 * <br>NOT_SUPPORTED_ERR: The Node is not a type permitted as an XPath 124 * context node or the request type is not permitted by this 125 * <code>XPathEvaluator</code>. 126 */ evaluate(String expression, Node contextNode, XPathNSResolver resolver, short type, Object result)127 public Object evaluate(String expression, 128 Node contextNode, 129 XPathNSResolver resolver, 130 short type, 131 Object result) 132 throws XPathException, DOMException; 133 134 } 135