1/*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5/*
6 * Licensed to the Apache Software Foundation (ASF) under one or more
7 * contributor license agreements.  See the NOTICE file distributed with
8 * this work for additional information regarding copyright ownership.
9 * The ASF licenses this file to You under the Apache License, Version 2.0
10 * (the "License"); you may not use this file except in compliance with
11 * the License.  You may obtain a copy of the License at
12 *
13 *      http://www.apache.org/licenses/LICENSE-2.0
14 *
15 * Unless required by applicable law or agreed to in writing, software
16 * distributed under the License is distributed on an "AS IS" BASIS,
17 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18 * See the License for the specific language governing permissions and
19 * limitations under the License.
20 */
21
22package com.sun.org.apache.xalan.internal.extensions;
23
24import javax.xml.transform.ErrorListener;
25
26import com.sun.org.apache.xpath.internal.objects.XObject;
27import org.w3c.dom.Node;
28import org.w3c.dom.traversal.NodeIterator;
29
30/**
31 * An object that implements this interface can supply
32 * information about the current XPath expression context.
33 */
34public interface ExpressionContext
35{
36
37  /**
38   * Get the current context node.
39   * @return The current context node.
40   */
41  public Node getContextNode();
42
43  /**
44   * Get the current context node list.
45   * @return An iterator for the current context list, as
46   * defined in XSLT.
47   */
48  public NodeIterator getContextNodes();
49
50  /**
51   * Get the error listener.
52   * @return The registered error listener.
53   */
54  public ErrorListener getErrorListener();
55
56  /**
57   * Get the value of a node as a number.
58   * @param n Node to be converted to a number.  May be null.
59   * @return value of n as a number.
60   */
61  public double toNumber(Node n);
62
63  /**
64   * Get the value of a node as a string.
65   * @param n Node to be converted to a string.  May be null.
66   * @return value of n as a string, or an empty string if n is null.
67   */
68  public String toString(Node n);
69
70  /**
71   * Get a variable based on it's qualified name.
72   *
73   * @param qname The qualified name of the variable.
74   *
75   * @return The evaluated value of the variable.
76   *
77   * @throws javax.xml.transform.TransformerException
78   */
79  public XObject getVariableOrParam(com.sun.org.apache.xml.internal.utils.QName qname)
80            throws javax.xml.transform.TransformerException;
81
82  /**
83   * Get the XPathContext that owns this ExpressionContext.
84   *
85   * Note: exslt:function requires the XPathContext to access
86   * the variable stack and TransformerImpl.
87   *
88   * @return The current XPathContext.
89   * @throws javax.xml.transform.TransformerException
90   */
91  public com.sun.org.apache.xpath.internal.XPathContext getXPathContext()
92            throws javax.xml.transform.TransformerException;
93
94}
95