| /* |
| * 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>, which will provide evaluation of XPath 1.0 |
| * expressions with no specialized extension functions or variables. It is |
| * expected that the <code>XPathEvaluator</code> interface will be |
| * implemented on the same object which implements the <code>Document</code> |
| * interface in an implementation which supports the XPath DOM module. |
| * <code>XPathEvaluator</code> implementations may be available from other |
| * sources that may provide support for special extension functions or |
| * variables which are not defined in this specification. The methods of |
| * XPathExpression should be named with more-XPath- specific names because |
| * the interface will often be implemented by the same object which |
| * implements document.No change.The point of interfaces is to localize the |
| * implementing namespace. This would make the method names unnecessarily |
| * long and complex even though there are no conflicts in the interface |
| * itself. The new core method getInterface is designed for discovering |
| * interfaces of additional modules that may not be directly implemented on |
| * the objects to which they are attached. This could be used to implement |
| * XPath on a separate object. The user only refers to the separate |
| * interfaces and not the proprietary aggregate implementation.Should entity |
| * refs be supported so that queries can be made on them?No change.We will |
| * not do this now. They are not part of the XPath data model. Note that |
| * they may be present in the hierarchy of returned nodes, but may not |
| * directly be requested or returned in the node set.What does createResult |
| * create when one wants to reuse the XPath?It is not useful.Removed method. |
| * Should ordering be a separate flag, or a type of result that can be |
| * requested. As a type of result, it can be better optimized in |
| * implementations.It makes sense as a type of result. Changed.Removed |
| * method.Implementing XPathEvaluator on Document can be a problem due to |
| * conflicts in the names of the methods.The working group finds no better |
| * solution. GetInterface in Level 3 permits the object to be implemented |
| * separately. We should be committed to this. We will leave this issue open |
| * to see if we get more feedback on it.How does this interface adapt to |
| * XPath 2.0 and other query languages.No change.This interface is not |
| * intended to adapt to XPath 2.0 or other languages. The models of these |
| * are likely to be incompatible enough to require new APIs.For alternate |
| * implementations that can use this API, it can be obtained from different |
| * sources.Support for custom variables and functions would be very useful. |
| * No change.It is possible for an implementation to supply alternative |
| * sources of an XPathEvaluator that can be customized with a custom |
| * variable and function context. We do not specify how this is |
| * accomplished. It is too complex to address in this version of the XPath |
| * DOM. |
| * <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>. |
| */ |
| 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.createExpression should not raise |
| * exceptions about type coercion.This was already fixed in the public |
| * draft. |
| * @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 by calling the |
| * method <code>lookupNamespacePrefix</code> on <code>Node</code>.It |
| * should be possible to create an XPathNSResolver that does not rely on |
| * a node, but which implements a map of resolutions that can be added |
| * to by the application.No change.The application can easily create |
| * this, which was why the interface was designed as it is. The |
| * specification will not require a specific factory at this time for |
| * application populated maps.There should be type restrictions on which |
| * types of nodes may be adapted by createNSResolver.No change.The |
| * namespace methods on the Node interface of the Level 3 core may be |
| * called without exception on all node types. In some cases no non-null |
| * namespace resolution will ever be returned. That is what may also be |
| * expected of this adapter. |
| * @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.An exception needs to be raised when an |
| * XPath expression is evaluated on a node such as an EntityReference |
| * which cannot serve as an XPath context node.Done: NOT_SUPPORTED_ERR.A |
| * description is needed of what happens when the node passed to the |
| * evaluation function is a Text or CDATASection in the DOM case where |
| * the text may be fragmented between text nodes.Done.Eliminate the |
| * evaluate method from XPathEvaluator, forcing everyone to create |
| * expressions.No change.Any implementor can easily implement it by |
| * creating an expression. Having it available as a separate routine is |
| * a convenience and may be an optimization as well in some cases.Revert |
| * to multiple evaluateAs methods instead of passing a type code.No |
| * change.This is an alternative which eliminates a method argument |
| * while adding methods, but the type code is used to designate the type |
| * on returns anyway and using it as an argument to specify any coercion |
| * seems natural to many.Error exceptions are needed when there is a |
| * mismatch between the implementation of XPathEvaluator and the context |
| * node being evaluated.Done: WRONG_DOCUMENT_ERRConcern that the XPath |
| * API should only support natural results of XPath expression, without |
| * convenience coercion or alternative representations. Any special |
| * thing such as ordering should be added later to resultNo change.We |
| * have significant use cases for returning alternative types and |
| * representations by explicit request in advance.Eliminate the reusable |
| * result argument.No change.No. We have use cases for it, and there is |
| * already an implementation showing there is nothing wrong with it. |
| * State that the XPathNSResolver argument may be a function in |
| * Javascript.Yes.There is an exception when there is a problem parsing |
| * the expression, but none when there is a problem evaluating the |
| * expression.No change.If the expression parsing was OK, then the worst |
| * that can happen is an empty result is returned.When requesting any |
| * type, the implementation should be permitted to return any type of |
| * node set, i.e. ordered or unordered, it finds convenient.No change. |
| * The iterator it returns may contain ordered results, but identifying |
| * it as such produces undesirable results, because it would create |
| * complexity for the user -- requiring checking two types to see if the |
| * result was a node set -- or incompatibility caused by assuming it was |
| * always the one returned by a particular implementation the developer |
| * was using.NAMESPACE_ERR description is not appropriate to the way it |
| * is being used here.Make the description of NAMESPACE_ERR in the core |
| * specification more general.Should the INVALID_EXPRESSION_ERR be |
| * INVALID_SYNTAX_ERR?No change.We can improve the description of the |
| * error, but the name is appropriate as-is. It covers not only syntax |
| * errors but expression errors, such as when the implementation has no |
| * custom functions or variables but the expression specifies custom |
| * functions or variables. |
| * @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 coerced to return the specified type relying on |
| * XPath type conversions and fail if the desired coercion is not |
| * possible. This must be one of the type codes of |
| * <code>XPathResult</code>. |
| * @param result The <code>result</code> specifies a specific |
| * <code>XPathResult</code> which may be reused and returned by this |
| * method. If this is specified as <code>null</code>or the |
| * implementation cannot reuse the specified result, a new |
| * <code>XPathResult</code> will be constructed and returned. |
| * @return The result of the evaluation 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 |
| * <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 XPathEvaluator. |
| * <br>NOT_SUPPORTED_ERR: The Node is not a type permitted as an XPath |
| * context node. |
| */ |
| public XPathResult evaluate(String expression, |
| Node contextNode, |
| XPathNSResolver resolver, |
| short type, |
| XPathResult result) |
| throws XPathException, DOMException; |
| |
| } |
