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* Copyright (c) 2002 World Wide Web Consortium,
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* (Massachusetts Institute of Technology, Institut National de
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* Recherche en Informatique et en Automatique, Keio University). All
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* Rights Reserved. This program is distributed under the W3C's Software
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* Intellectual Property License. This program is distributed in the
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* hope that it will be useful, but WITHOUT ANY WARRANTY; without even
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* the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* See W3C License http://www.w3.org/Consortium/Legal/ for more details.
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package org.w3c.dom.xpath;
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import org.w3c.dom.Node;
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import org.w3c.dom.DOMException;
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* <strong>DOM Level 3 WD Experimental:
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* The DOM Level 3 specification is at the stage
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* of Working Draft, which represents work in
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* progress and thus may be updated, replaced,
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* or obsoleted by other documents at any time.</strong> <p>
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* <code>XPathEvaluator</code>, which will provide evaluation of XPath 1.0
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* expressions with no specialized extension functions or variables. It is
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* expected that the <code>XPathEvaluator</code> interface will be
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* implemented on the same object which implements the <code>Document</code>
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* interface in an implementation which supports the XPath DOM module.
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* <code>XPathEvaluator</code> implementations may be available from other
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* sources that may provide support for special extension functions or
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* variables which are not defined in this specification. The methods of
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* XPathExpression should be named with more-XPath- specific names because
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* the interface will often be implemented by the same object which
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* implements document.No change.The point of interfaces is to localize the
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* implementing namespace. This would make the method names unnecessarily
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* long and complex even though there are no conflicts in the interface
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* itself. The new core method getInterface is designed for discovering
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* interfaces of additional modules that may not be directly implemented on
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* the objects to which they are attached. This could be used to implement
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* XPath on a separate object. The user only refers to the separate
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* interfaces and not the proprietary aggregate implementation.Should entity
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* refs be supported so that queries can be made on them?No change.We will
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* not do this now. They are not part of the XPath data model. Note that
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* they may be present in the hierarchy of returned nodes, but may not
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* directly be requested or returned in the node set.What does createResult
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* create when one wants to reuse the XPath?It is not useful.Removed method.
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* Should ordering be a separate flag, or a type of result that can be
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* requested. As a type of result, it can be better optimized in
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* implementations.It makes sense as a type of result. Changed.Removed
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* method.Implementing XPathEvaluator on Document can be a problem due to
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* conflicts in the names of the methods.The working group finds no better
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* solution. GetInterface in Level 3 permits the object to be implemented
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* separately. We should be committed to this. We will leave this issue open
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* to see if we get more feedback on it.How does this interface adapt to
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* XPath 2.0 and other query languages.No change.This interface is not
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* intended to adapt to XPath 2.0 or other languages. The models of these
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* are likely to be incompatible enough to require new APIs.For alternate
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* implementations that can use this API, it can be obtained from different
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* sources.Support for custom variables and functions would be very useful.
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* No change.It is possible for an implementation to supply alternative
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* sources of an XPathEvaluator that can be customized with a custom
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* variable and function context. We do not specify how this is
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* accomplished. It is too complex to address in this version of the XPath
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* <p>See also the <a href='http://www.w3.org/TR/2002/WD-DOM-Level-3-XPath-20020328'>Document Object Model (DOM) Level 3 XPath Specification</a>.
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public interface XPathEvaluator {
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* Creates a parsed XPath expression with resolved namespaces. This is
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* useful when an expression will be reused in an application since it
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* makes it possible to compile the expression string into a more
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* efficient internal form and preresolve all namespace prefixes which
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* occur within the expression.createExpression should not raise
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* exceptions about type coercion.This was already fixed in the public
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* @param expression The XPath expression string to be parsed.
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* @param resolver The <code>resolver</code> permits translation of
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* prefixes within the XPath expression into appropriate namespace URIs
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* . If this is specified as <code>null</code>, any namespace prefix
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* within the expression will result in <code>DOMException</code>
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* being thrown with the code <code>NAMESPACE_ERR</code>.
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* @return The compiled form of the XPath expression.
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* @exception XPathException
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* INVALID_EXPRESSION_ERR: Raised if the expression is not legal
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* according to the rules of the <code>XPathEvaluator</code>i
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* @exception DOMException
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* NAMESPACE_ERR: Raised if the expression contains namespace prefixes
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* which cannot be resolved by the specified
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* <code>XPathNSResolver</code>.
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public XPathExpression createExpression(String expression,
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XPathNSResolver resolver)
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throws XPathException, DOMException;
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* Adapts any DOM node to resolve namespaces so that an XPath expression
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* can be easily evaluated relative to the context of the node where it
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* appeared within the document. This adapter works by calling the
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* method <code>lookupNamespacePrefix</code> on <code>Node</code>.It
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* should be possible to create an XPathNSResolver that does not rely on
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* a node, but which implements a map of resolutions that can be added
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* to by the application.No change.The application can easily create
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* this, which was why the interface was designed as it is. The
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* specification will not require a specific factory at this time for
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* application populated maps.There should be type restrictions on which
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* types of nodes may be adapted by createNSResolver.No change.The
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* namespace methods on the Node interface of the Level 3 core may be
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* called without exception on all node types. In some cases no non-null
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* namespace resolution will ever be returned. That is what may also be
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* expected of this adapter.
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* @param nodeResolver The node to be used as a context for namespace
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* @return <code>XPathNSResolver</code> which resolves namespaces with
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* respect to the definitions in scope for a specified node.
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public XPathNSResolver createNSResolver(Node nodeResolver);
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* Evaluates an XPath expression string and returns a result of the
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* specified type if possible.An exception needs to be raised when an
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* XPath expression is evaluated on a node such as an EntityReference
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* which cannot serve as an XPath context node.Done: NOT_SUPPORTED_ERR.A
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* description is needed of what happens when the node passed to the
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* evaluation function is a Text or CDATASection in the DOM case where
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* the text may be fragmented between text nodes.Done.Eliminate the
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* evaluate method from XPathEvaluator, forcing everyone to create
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* expressions.No change.Any implementor can easily implement it by
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* creating an expression. Having it available as a separate routine is
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* a convenience and may be an optimization as well in some cases.Revert
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* to multiple evaluateAs methods instead of passing a type code.No
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* change.This is an alternative which eliminates a method argument
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* while adding methods, but the type code is used to designate the type
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* on returns anyway and using it as an argument to specify any coercion
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* seems natural to many.Error exceptions are needed when there is a
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* mismatch between the implementation of XPathEvaluator and the context
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* node being evaluated.Done: WRONG_DOCUMENT_ERRConcern that the XPath
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* API should only support natural results of XPath expression, without
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* convenience coercion or alternative representations. Any special
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* thing such as ordering should be added later to resultNo change.We
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* have significant use cases for returning alternative types and
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* representations by explicit request in advance.Eliminate the reusable
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* result argument.No change.No. We have use cases for it, and there is
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* already an implementation showing there is nothing wrong with it.
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* State that the XPathNSResolver argument may be a function in
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* Javascript.Yes.There is an exception when there is a problem parsing
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* the expression, but none when there is a problem evaluating the
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* expression.No change.If the expression parsing was OK, then the worst
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* that can happen is an empty result is returned.When requesting any
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* type, the implementation should be permitted to return any type of
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* node set, i.e. ordered or unordered, it finds convenient.No change.
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* The iterator it returns may contain ordered results, but identifying
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* it as such produces undesirable results, because it would create
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* complexity for the user -- requiring checking two types to see if the
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* result was a node set -- or incompatibility caused by assuming it was
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* always the one returned by a particular implementation the developer
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* was using.NAMESPACE_ERR description is not appropriate to the way it
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* is being used here.Make the description of NAMESPACE_ERR in the core
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* specification more general.Should the INVALID_EXPRESSION_ERR be
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* INVALID_SYNTAX_ERR?No change.We can improve the description of the
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* error, but the name is appropriate as-is. It covers not only syntax
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* errors but expression errors, such as when the implementation has no
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* custom functions or variables but the expression specifies custom
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* functions or variables.
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* @param expression The XPath expression string to be parsed and
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* @param contextNode The <code>context</code> is context node for the
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* evaluation of this XPath expression. If the XPathEvaluator was
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* obtained by casting the <code>Document</code> then this must be
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* owned by the same document and must be a <code>Document</code>,
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* <code>Element</code>, <code>Attribute</code>, <code>Text</code>,
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* <code>CDATASection</code>, <code>Comment</code>,
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* <code>ProcessingInstruction</code>, or <code>XPathNamespace</code>
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* node. If the context node is a <code>Text</code> or a
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* <code>CDATASection</code>, then the context is interpreted as the
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* whole logical text node as seen by XPath, unless the node is empty
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* in which case it may not serve as the XPath context.
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* @param resolver The <code>resolver</code> permits translation of
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* prefixes within the XPath expression into appropriate namespace URIs
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* . If this is specified as <code>null</code>, any namespace prefix
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* within the expression will result in <code>DOMException</code>
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* being thrown with the code <code>NAMESPACE_ERR</code>.
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* @param type If a specific <code>type</code> is specified, then the
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* result will be coerced to return the specified type relying on
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* XPath type conversions and fail if the desired coercion is not
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* possible. This must be one of the type codes of
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* <code>XPathResult</code>.
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* @param result The <code>result</code> specifies a specific
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* <code>XPathResult</code> which may be reused and returned by this
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* method. If this is specified as <code>null</code>or the
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* implementation cannot reuse the specified result, a new
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* <code>XPathResult</code> will be constructed and returned.
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* @return The result of the evaluation of the XPath expression.
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* @exception XPathException
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* INVALID_EXPRESSION_ERR: Raised if the expression is not legal
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* according to the rules of the <code>XPathEvaluator</code>i
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* <br>TYPE_ERR: Raised if the result cannot be converted to return the
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* @exception DOMException
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* NAMESPACE_ERR: Raised if the expression contains namespace prefixes
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* which cannot be resolved by the specified
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* <code>XPathNSResolver</code>.
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* <br>WRONG_DOCUMENT_ERR: The Node is from a document that is not
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* supported by this XPathEvaluator.
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* <br>NOT_SUPPORTED_ERR: The Node is not a type permitted as an XPath
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public Object evaluate(String expression,
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XPathNSResolver resolver,
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throws XPathException, DOMException;
added
removed
src/org/w3c/dom/xpath/XPathEvaluator.java
