001/* 002 * Copyright (c) 2004 World Wide Web Consortium, 003 * 004 * (Massachusetts Institute of Technology, European Research Consortium for 005 * Informatics and Mathematics, Keio University). All Rights Reserved. This 006 * work is distributed under the W3C(r) Software License [1] in the hope that 007 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied 008 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 009 * 010 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231 011 */ 012 013package org.w3c.dom.xpath; 014 015import org.w3c.dom.Node; 016import org.w3c.dom.DOMException; 017 018/** 019 * The evaluation of XPath expressions is provided by 020 * <code>XPathEvaluator</code>. In a DOM implementation which supports the 021 * XPath 3.0 feature, as described above, the <code>XPathEvaluator</code> 022 * interface will be implemented on the same object which implements the 023 * <code>Document</code> interface permitting it to be obtained by the usual 024 * binding-specific method such as casting or by using the DOM Level 3 025 * getInterface method. In this case the implementation obtained from the 026 * Document supports the XPath DOM module and is compatible with the XPath 027 * 1.0 specification. 028 * <p>Evaluation of expressions with specialized extension functions or 029 * variables may not work in all implementations and is, therefore, not 030 * portable. <code>XPathEvaluator</code> implementations may be available 031 * from other sources that could provide specific support for specialized 032 * extension functions or variables as would be defined by other 033 * specifications. 034 * <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>. 035 */ 036public interface XPathEvaluator { 037 /** 038 * Creates a parsed XPath expression with resolved namespaces. This is 039 * useful when an expression will be reused in an application since it 040 * makes it possible to compile the expression string into a more 041 * efficient internal form and preresolve all namespace prefixes which 042 * occur within the expression. 043 * @param expression The XPath expression string to be parsed. 044 * @param resolver The <code>resolver</code> permits translation of all 045 * prefixes, including the <code>xml</code> namespace prefix, within 046 * the XPath expression into appropriate namespace URIs. If this is 047 * specified as <code>null</code>, any namespace prefix within the 048 * expression will result in <code>DOMException</code> being thrown 049 * with the code <code>NAMESPACE_ERR</code>. 050 * @return The compiled form of the XPath expression. 051 * @exception XPathException 052 * INVALID_EXPRESSION_ERR: Raised if the expression is not legal 053 * according to the rules of the <code>XPathEvaluator</code>. 054 * @exception DOMException 055 * NAMESPACE_ERR: Raised if the expression contains namespace prefixes 056 * which cannot be resolved by the specified 057 * <code>XPathNSResolver</code>. 058 */ 059 public XPathExpression createExpression(String expression, 060 XPathNSResolver resolver) 061 throws XPathException, DOMException; 062 063 /** 064 * Adapts any DOM node to resolve namespaces so that an XPath expression 065 * can be easily evaluated relative to the context of the node where it 066 * appeared within the document. This adapter works like the DOM Level 3 067 * method <code>lookupNamespaceURI</code> on nodes in resolving the 068 * namespaceURI from a given prefix using the current information 069 * available in the node's hierarchy at the time lookupNamespaceURI is 070 * called. also correctly resolving the implicit xml prefix. 071 * @param nodeResolver The node to be used as a context for namespace 072 * resolution. 073 * @return <code>XPathNSResolver</code> which resolves namespaces with 074 * respect to the definitions in scope for a specified node. 075 */ 076 public XPathNSResolver createNSResolver(Node nodeResolver); 077 078 /** 079 * Evaluates an XPath expression string and returns a result of the 080 * specified type if possible. 081 * @param expression The XPath expression string to be parsed and 082 * evaluated. 083 * @param contextNode The <code>context</code> is context node for the 084 * evaluation of this XPath expression. If the XPathEvaluator was 085 * obtained by casting the <code>Document</code> then this must be 086 * owned by the same document and must be a <code>Document</code>, 087 * <code>Element</code>, <code>Attribute</code>, <code>Text</code>, 088 * <code>CDATASection</code>, <code>Comment</code>, 089 * <code>ProcessingInstruction</code>, or <code>XPathNamespace</code> 090 * node. If the context node is a <code>Text</code> or a 091 * <code>CDATASection</code>, then the context is interpreted as the 092 * whole logical text node as seen by XPath, unless the node is empty 093 * in which case it may not serve as the XPath context. 094 * @param resolver The <code>resolver</code> permits translation of all 095 * prefixes, including the <code>xml</code> namespace prefix, within 096 * the XPath expression into appropriate namespace URIs. If this is 097 * specified as <code>null</code>, any namespace prefix within the 098 * expression will result in <code>DOMException</code> being thrown 099 * 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 */ 127 public Object evaluate(String expression, 128 Node contextNode, 129 XPathNSResolver resolver, 130 short type, 131 Object result) 132 throws XPathException, DOMException; 133 134}