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: ExtensionsTable.java 469672 2006-10-31 21:56:19Z minchau $
20 */
21package org.apache.xalan.extensions;
22
23import java.util.Hashtable;
24import java.util.Vector;
25
26import org.apache.xalan.res.XSLMessages;
27import org.apache.xalan.res.XSLTErrorResources;
28import org.apache.xalan.templates.StylesheetRoot;
29import org.apache.xpath.XPathProcessorException;
30import org.apache.xpath.functions.FuncExtFunction;
31
32/**
33 * Class holding a table registered extension namespace handlers
34 * @xsl.usage internal
35 */
36public class ExtensionsTable
37{
38  /**
39   * Table of extensions that may be called from the expression language
40   * via the call(name, ...) function.  Objects are keyed on the call
41   * name.
42   * @xsl.usage internal
43   */
44  public Hashtable m_extensionFunctionNamespaces = new Hashtable();
45
46  /**
47   * The StylesheetRoot associated with this extensions table.
48   */
49  private StylesheetRoot m_sroot;
50
51  /**
52   * The constructor (called from TransformerImpl) registers the
53   * StylesheetRoot for the transformation and instantiates an
54   * ExtensionHandler for each extension namespace.
55   * @xsl.usage advanced
56   */
57  public ExtensionsTable(StylesheetRoot sroot)
58    throws javax.xml.transform.TransformerException
59  {
60    m_sroot = sroot;
61    Vector extensions = m_sroot.getExtensions();
62    for (int i = 0; i < extensions.size(); i++)
63    {
64      ExtensionNamespaceSupport extNamespaceSpt =
65                 (ExtensionNamespaceSupport)extensions.get(i);
66      ExtensionHandler extHandler = extNamespaceSpt.launch();
67        if (extHandler != null)
68          addExtensionNamespace(extNamespaceSpt.getNamespace(), extHandler);
69      }
70    }
71
72  /**
73   * Get an ExtensionHandler object that represents the
74   * given namespace.
75   * @param extns A valid extension namespace.
76   *
77   * @return ExtensionHandler object that represents the
78   * given namespace.
79   */
80  public ExtensionHandler get(String extns)
81  {
82    return (ExtensionHandler) m_extensionFunctionNamespaces.get(extns);
83  }
84
85  /**
86   * Register an extension namespace handler. This handler provides
87   * functions for testing whether a function is known within the
88   * namespace and also for invoking the functions.
89   *
90   * @param uri the URI for the extension.
91   * @param extNS the extension handler.
92   * @xsl.usage advanced
93   */
94  public void addExtensionNamespace(String uri, ExtensionHandler extNS)
95  {
96    m_extensionFunctionNamespaces.put(uri, extNS);
97  }
98
99  /**
100   * Execute the function-available() function.
101   * @param ns       the URI of namespace in which the function is needed
102   * @param funcName the function name being tested
103   *
104   * @return whether the given function is available or not.
105   *
106   * @throws javax.xml.transform.TransformerException
107   */
108  public boolean functionAvailable(String ns, String funcName)
109          throws javax.xml.transform.TransformerException
110  {
111    boolean isAvailable = false;
112
113    if (null != ns)
114    {
115      ExtensionHandler extNS =
116           (ExtensionHandler) m_extensionFunctionNamespaces.get(ns);
117      if (extNS != null)
118        isAvailable = extNS.isFunctionAvailable(funcName);
119    }
120    return isAvailable;
121  }
122
123  /**
124   * Execute the element-available() function.
125   * @param ns       the URI of namespace in which the function is needed
126   * @param elemName name of element being tested
127   *
128   * @return whether the given element is available or not.
129   *
130   * @throws javax.xml.transform.TransformerException
131   */
132  public boolean elementAvailable(String ns, String elemName)
133          throws javax.xml.transform.TransformerException
134  {
135    boolean isAvailable = false;
136    if (null != ns)
137    {
138      ExtensionHandler extNS =
139               (ExtensionHandler) m_extensionFunctionNamespaces.get(ns);
140      if (extNS != null) // defensive
141        isAvailable = extNS.isElementAvailable(elemName);
142    }
143    return isAvailable;
144  }
145
146  /**
147   * Handle an extension function.
148   * @param ns        the URI of namespace in which the function is needed
149   * @param funcName  the function name being called
150   * @param argVec    arguments to the function in a vector
151   * @param methodKey a unique key identifying this function instance in the
152   *                  stylesheet
153   * @param exprContext a context which may be passed to an extension function
154   *                  and provides callback functions to access various
155   *                  areas in the environment
156   *
157   * @return result of executing the function
158   *
159   * @throws javax.xml.transform.TransformerException
160   */
161  public Object extFunction(String ns, String funcName,
162                            Vector argVec, Object methodKey,
163                            ExpressionContext exprContext)
164            throws javax.xml.transform.TransformerException
165  {
166    Object result = null;
167    if (null != ns)
168    {
169      ExtensionHandler extNS =
170        (ExtensionHandler) m_extensionFunctionNamespaces.get(ns);
171      if (null != extNS)
172      {
173        try
174        {
175          result = extNS.callFunction(funcName, argVec, methodKey,
176                                      exprContext);
177        }
178        catch (javax.xml.transform.TransformerException e)
179        {
180          throw e;
181        }
182        catch (Exception e)
183        {
184          throw new javax.xml.transform.TransformerException(e);
185        }
186      }
187      else
188      {
189        throw new XPathProcessorException(XSLMessages.createMessage(XSLTErrorResources.ER_EXTENSION_FUNC_UNKNOWN, new Object[]{ns, funcName }));
190        //"Extension function '" + ns + ":" + funcName + "' is unknown");
191      }
192    }
193    return result;
194  }
195
196  /**
197   * Handle an extension function.
198   * @param extFunction  the extension function
199   * @param argVec    arguments to the function in a vector
200   * @param exprContext a context which may be passed to an extension function
201   *                  and provides callback functions to access various
202   *                  areas in the environment
203   *
204   * @return result of executing the function
205   *
206   * @throws javax.xml.transform.TransformerException
207   */
208  public Object extFunction(FuncExtFunction extFunction, Vector argVec,
209                            ExpressionContext exprContext)
210         throws javax.xml.transform.TransformerException
211  {
212    Object result = null;
213    String ns = extFunction.getNamespace();
214    if (null != ns)
215    {
216      ExtensionHandler extNS =
217        (ExtensionHandler) m_extensionFunctionNamespaces.get(ns);
218      if (null != extNS)
219      {
220        try
221        {
222          result = extNS.callFunction(extFunction, argVec, exprContext);
223        }
224        catch (javax.xml.transform.TransformerException e)
225        {
226          throw e;
227        }
228        catch (Exception e)
229        {
230          throw new javax.xml.transform.TransformerException(e);
231        }
232      }
233      else
234      {
235        throw new XPathProcessorException(XSLMessages.createMessage(XSLTErrorResources.ER_EXTENSION_FUNC_UNKNOWN,
236                                          new Object[]{ns, extFunction.getFunctionName()}));
237      }
238    }
239    return result;
240  }
241}
242