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 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

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package com.sun.org.apache.xalan.internal.extensions;

import javax.xml.transform.ErrorListener;

import com.sun.org.apache.xpath.internal.objects.XObject;

import org.w3c.dom.Node;

import org.w3c.dom.traversal.NodeIterator;

/**

 * An object that implements this interface can supply

 * information about the current XPath expression context.

 */

public interface ExpressionContext

{

  /**

   * Get the current context node.

   * @return The current context node.

   */

  public Node getContextNode();

  /**

   * Get the current context node list.

   * @return An iterator for the current context list, as

   * defined in XSLT.

   */

  public NodeIterator getContextNodes();

  /**

   * Get the error listener.

   * @return The registered error listener.

   */

  public ErrorListener getErrorListener();

  /**

   * Get the value of a node as a number.

   * @param n Node to be converted to a number.  May be null.

   * @return value of n as a number.

   */

  public double toNumber(Node n);

  /**

   * Get the value of a node as a string.

   * @param n Node to be converted to a string.  May be null.

   * @return value of n as a string, or an empty string if n is null.

   */

  public String toString(Node n);

  /**

   * Get a variable based on it's qualified name.

   *

   * @param qname The qualified name of the variable.

   *

   * @return The evaluated value of the variable.

   *

   * @throws javax.xml.transform.TransformerException

   */

  public XObject getVariableOrParam(com.sun.org.apache.xml.internal.utils.QName qname)

            throws javax.xml.transform.TransformerException;

  /**

   * Get the XPathContext that owns this ExpressionContext.

   *

   * Note: exslt:function requires the XPathContext to access

   * the variable stack and TransformerImpl.

   *

   * @return The current XPathContext.

   * @throws javax.xml.transform.TransformerException

   */

  public com.sun.org.apache.xpath.internal.XPathContext getXPathContext()

            throws javax.xml.transform.TransformerException;

}