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
013 package org.w3c.dom.xpath;
014
015 import org.w3c.dom.Node;
016 import 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 */
036 public 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 }