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      1 /*
      2  * Licensed to the Apache Software Foundation (ASF) under one
      3  * or more contributor license agreements. See the NOTICE file
      4  * distributed with this work for additional information
      5  * regarding copyright ownership. The ASF licenses this file
      6  * to you under the Apache License, Version 2.0 (the  "License");
      7  * you may not use this file except in compliance with the License.
      8  * You may obtain a copy of the License at
      9  *
     10  *     http://www.apache.org/licenses/LICENSE-2.0
     11  *
     12  * Unless required by applicable law or agreed to in writing, software
     13  * distributed under the License is distributed on an "AS IS" BASIS,
     14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     15  * See the License for the specific language governing permissions and
     16  * limitations under the License.
     17  */
     18 /*
     19  * $Id: ExpressionContext.java 468637 2006-10-28 06:51:02Z minchau $
     20  */
     21 package org.apache.xalan.extensions;
     22 
     23 import javax.xml.transform.ErrorListener;
     24 
     25 import org.apache.xpath.objects.XObject;
     26 import org.w3c.dom.Node;
     27 import org.w3c.dom.traversal.NodeIterator;
     28 
     29 /**
     30  * An object that implements this interface can supply
     31  * information about the current XPath expression context.
     32  */
     33 public interface ExpressionContext
     34 {
     35 
     36   /**
     37    * Get the current context node.
     38    * @return The current context node.
     39    */
     40   public Node getContextNode();
     41 
     42   /**
     43    * Get the current context node list.
     44    * @return An iterator for the current context list, as
     45    * defined in XSLT.
     46    */
     47   public NodeIterator getContextNodes();
     48 
     49   /**
     50    * Get the error listener.
     51    * @return The registered error listener.
     52    */
     53   public ErrorListener getErrorListener();
     54 
     55   /**
     56    * Get the value of a node as a number.
     57    * @param n Node to be converted to a number.  May be null.
     58    * @return value of n as a number.
     59    */
     60   public double toNumber(Node n);
     61 
     62   /**
     63    * Get the value of a node as a string.
     64    * @param n Node to be converted to a string.  May be null.
     65    * @return value of n as a string, or an empty string if n is null.
     66    */
     67   public String toString(Node n);
     68 
     69   /**
     70    * Get a variable based on it's qualified name.
     71    *
     72    * @param qname The qualified name of the variable.
     73    *
     74    * @return The evaluated value of the variable.
     75    *
     76    * @throws javax.xml.transform.TransformerException
     77    */
     78   public XObject getVariableOrParam(org.apache.xml.utils.QName qname)
     79             throws javax.xml.transform.TransformerException;
     80 
     81   /**
     82    * Get the XPathContext that owns this ExpressionContext.
     83    *
     84    * Note: exslt:function requires the XPathContext to access
     85    * the variable stack and TransformerImpl.
     86    *
     87    * @return The current XPathContext.
     88    * @throws javax.xml.transform.TransformerException
     89    */
     90   public org.apache.xpath.XPathContext getXPathContext()
     91             throws javax.xml.transform.TransformerException;
     92 
     93 }
     94