/*
 * Copyright (c) 2002 World Wide Web Consortium,
 * (Massachusetts Institute of Technology, Institut National de
 * Recherche en Informatique et en Automatique, Keio University). All
 * Rights Reserved. This program is distributed under the W3C's Software
 * Intellectual Property License. This program is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE.
 * See W3C License http://www.w3.org/Consortium/Legal/ for more details.
 */

package org.w3c.dom.xpath;


import org.w3c.dom.Node;
import org.w3c.dom.DOMException;

/**
 *  The evaluation of XPath expressions is provided by 
 * <code>XPathEvaluator</code>. In a DOM implementation which supports the 
 * XPath 3.0 feature, as described above, the <code>XPathEvaluator</code> 
 * interface will be implemented on the same object which implements the 
 * <code>Document</code> interface permitting it to be obtained by the usual 
 * binding-specific method such as casting or by using the DOM Level 3 
 * getInterface method. In this case the implementation obtained from the 
 * Document supports the XPath DOM module and is compatible with the XPath 
 * 1.0 specification. 
 * <p>Evaluation of expressions with specialized extension functions or 
 * variables may not work in all implementations and is, therefore, not 
 * portable. <code>XPathEvaluator</code> implementations may be available 
 * from other sources that could provide specific support for specialized 
 * extension functions or variables as would be defined by other 
 * specifications. 
 * <p>See also the <a href='http://www.w3.org/2002/08/WD-DOM-Level-3-XPath-20020820'>Document Object Model (DOM) Level 3 XPath Specification</a>.
 */
public interface XPathEvaluator {
    /**
     * Creates a parsed XPath expression with resolved namespaces. This is 
     * useful when an expression will be reused in an application since it 
     * makes it possible to compile the expression string into a more 
     * efficient internal form and preresolve all namespace prefixes which 
     * occur within the expression.
     * @param expression The XPath expression string to be parsed.
     * @param resolver The <code>resolver</code> permits translation of 
     *   prefixes within the XPath expression into appropriate namespace URIs
     *   . If this is specified as <code>null</code>, any namespace prefix 
     *   within the expression will result in <code>DOMException</code> 
     *   being thrown with the code <code>NAMESPACE_ERR</code>.
     * @return The compiled form of the XPath expression.
     * @exception XPathException
     *   INVALID_EXPRESSION_ERR: Raised if the expression is not legal 
     *   according to the rules of the <code>XPathEvaluator</code>i
     * @exception DOMException
     *   NAMESPACE_ERR: Raised if the expression contains namespace prefixes 
     *   which cannot be resolved by the specified 
     *   <code>XPathNSResolver</code>.
     */
    public XPathExpression createExpression(String expression, 
                                            XPathNSResolver resolver)
                                            throws XPathException, DOMException;

    /**
     * Adapts any DOM node to resolve namespaces so that an XPath expression 
     * can be easily evaluated relative to the context of the node where it 
     * appeared within the document. This adapter works like the DOM Level 3 
     * method <code>lookupNamespaceURI</code> on nodes in resolving the 
     * namespaceURI from a given prefix using the current information 
     * available in the node's hierarchy at the time lookupNamespaceURI is 
     * called. also correctly resolving the implicit xml prefix.
     * @param nodeResolver The node to be used as a context for namespace 
     *   resolution.
     * @return <code>XPathNSResolver</code> which resolves namespaces with 
     *   respect to the definitions in scope for a specified node.
     */
    public XPathNSResolver createNSResolver(Node nodeResolver);

    /**
     * Evaluates an XPath expression string and returns a result of the 
     * specified type if possible.
     * @param expression The XPath expression string to be parsed and 
     *   evaluated.
     * @param contextNode The <code>context</code> is context node for the 
     *   evaluation of this XPath expression. If the XPathEvaluator was 
     *   obtained by casting the <code>Document</code> then this must be 
     *   owned by the same document and must be a <code>Document</code>, 
     *   <code>Element</code>, <code>Attribute</code>, <code>Text</code>, 
     *   <code>CDATASection</code>, <code>Comment</code>, 
     *   <code>ProcessingInstruction</code>, or <code>XPathNamespace</code> 
     *   node. If the context node is a <code>Text</code> or a 
     *   <code>CDATASection</code>, then the context is interpreted as the 
     *   whole logical text node as seen by XPath, unless the node is empty 
     *   in which case it may not serve as the XPath context.
     * @param resolver The <code>resolver</code> permits translation of 
     *   prefixes within the XPath expression into appropriate namespace URIs
     *   . If this is specified as <code>null</code>, any namespace prefix 
     *   within the expression will result in <code>DOMException</code> 
     *   being thrown with the code <code>NAMESPACE_ERR</code>.
     * @param type If a specific <code>type</code> is specified, then the 
     *   result will be returned as the corresponding type.For XPath 1.0 
     *   results, this must be one of the codes of the 
     *   <code>XPathResult</code> interface.
     * @param result The <code>result</code> specifies a specific result 
     *   object which may be reused and returned by this method. If this is 
     *   specified as <code>null</code>or the implementation does not reuse 
     *   the specified result, a new result object will be constructed and 
     *   returned.For XPath 1.0 results, this object will be of type 
     *   <code>XPathResult</code>.
     * @return The result of the evaluation of the XPath expression.For XPath 
     *   1.0 results, this object will be of type <code>XPathResult</code>.
     * @exception XPathException
     *   INVALID_EXPRESSION_ERR: Raised if the expression is not legal 
     *   according to the rules of the <code>XPathEvaluator</code>i
     *   <br>TYPE_ERR: Raised if the result cannot be converted to return the 
     *   specified type.
     * @exception DOMException
     *   NAMESPACE_ERR: Raised if the expression contains namespace prefixes 
     *   which cannot be resolved by the specified 
     *   <code>XPathNSResolver</code>.
     *   <br>WRONG_DOCUMENT_ERR: The Node is from a document that is not 
     *   supported by this <code>XPathEvaluator</code>.
     *   <br>NOT_SUPPORTED_ERR: The Node is not a type permitted as an XPath 
     *   context node or the request type is not permitted by this 
     *   <code>XPathEvaluator</code>.
     */
    public Object evaluate(String expression, 
                           Node contextNode, 
                           XPathNSResolver resolver, 
                           short type, 
                           Object result)
                           throws XPathException, DOMException;

}