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: FuncExtFunction.java 468655 2006-10-28 07:12:06Z minchau $
20 */
21package org.apache.xpath.functions;
22
23import java.util.Vector;
24
25import org.apache.xalan.res.XSLMessages;
26import org.apache.xpath.Expression;
27import org.apache.xpath.ExpressionNode;
28import org.apache.xpath.ExpressionOwner;
29import org.apache.xpath.ExtensionsProvider;
30import org.apache.xpath.XPathContext;
31import org.apache.xpath.XPathVisitor;
32import org.apache.xpath.objects.XNull;
33import org.apache.xpath.objects.XObject;
34import org.apache.xpath.res.XPATHErrorResources;
35import org.apache.xpath.res.XPATHMessages;
36
37/**
38 * An object of this class represents an extension call expression.  When
39 * the expression executes, it calls ExtensionsTable#extFunction, and then
40 * converts the result to the appropriate XObject.
41 * @xsl.usage advanced
42 */
43public class FuncExtFunction extends Function
44{
45    static final long serialVersionUID = 5196115554693708718L;
46
47  /**
48   * The namespace for the extension function, which should not normally
49   *  be null or empty.
50   *  @serial
51   */
52  String m_namespace;
53
54  /**
55   * The local name of the extension.
56   *  @serial
57   */
58  String m_extensionName;
59
60  /**
61   * Unique method key, which is passed to ExtensionsTable#extFunction in
62   *  order to allow caching of the method.
63   *  @serial
64   */
65  Object m_methodKey;
66
67  /**
68   * Array of static expressions which represent the parameters to the
69   *  function.
70   *  @serial
71   */
72  Vector m_argVec = new Vector();
73
74  /**
75   * This function is used to fixup variables from QNames to stack frame
76   * indexes at stylesheet build time.
77   * @param vars List of QNames that correspond to variables.  This list
78   * should be searched backwards for the first qualified name that
79   * corresponds to the variable reference qname.  The position of the
80   * QName in the vector from the start of the vector will be its position
81   * in the stack frame (but variables above the globalsTop value will need
82   * to be offset to the current stack frame).
83   * NEEDSDOC @param globalsSize
84   */
85  public void fixupVariables(java.util.Vector vars, int globalsSize)
86  {
87
88    if (null != m_argVec)
89    {
90      int nArgs = m_argVec.size();
91
92      for (int i = 0; i < nArgs; i++)
93      {
94        Expression arg = (Expression) m_argVec.elementAt(i);
95
96        arg.fixupVariables(vars, globalsSize);
97      }
98    }
99  }
100
101  /**
102   * Return the namespace of the extension function.
103   *
104   * @return The namespace of the extension function.
105   */
106  public String getNamespace()
107  {
108    return m_namespace;
109  }
110
111  /**
112   * Return the name of the extension function.
113   *
114   * @return The name of the extension function.
115   */
116  public String getFunctionName()
117  {
118    return m_extensionName;
119  }
120
121  /**
122   * Return the method key of the extension function.
123   *
124   * @return The method key of the extension function.
125   */
126  public Object getMethodKey()
127  {
128    return m_methodKey;
129  }
130
131  /**
132   * Return the nth argument passed to the extension function.
133   *
134   * @param n The argument number index.
135   * @return The Expression object at the given index.
136   */
137  public Expression getArg(int n) {
138    if (n >= 0 && n < m_argVec.size())
139      return (Expression) m_argVec.elementAt(n);
140    else
141      return null;
142  }
143
144  /**
145   * Return the number of arguments that were passed
146   * into this extension function.
147   *
148   * @return The number of arguments.
149   */
150  public int getArgCount() {
151    return m_argVec.size();
152  }
153
154  /**
155   * Create a new FuncExtFunction based on the qualified name of the extension,
156   * and a unique method key.
157   *
158   * @param namespace The namespace for the extension function, which should
159   *                  not normally be null or empty.
160   * @param extensionName The local name of the extension.
161   * @param methodKey Unique method key, which is passed to
162   *                  ExtensionsTable#extFunction in order to allow caching
163   *                  of the method.
164   */
165  public FuncExtFunction(java.lang.String namespace,
166                         java.lang.String extensionName, Object methodKey)
167  {
168    //try{throw new Exception("FuncExtFunction() " + namespace + " " + extensionName);} catch (Exception e){e.printStackTrace();}
169    m_namespace = namespace;
170    m_extensionName = extensionName;
171    m_methodKey = methodKey;
172  }
173
174  /**
175   * Execute the function.  The function must return
176   * a valid object.
177   * @param xctxt The current execution context.
178   * @return A valid XObject.
179   *
180   * @throws javax.xml.transform.TransformerException
181   */
182  public XObject execute(XPathContext xctxt)
183          throws javax.xml.transform.TransformerException
184  {
185    if (xctxt.isSecureProcessing())
186      throw new javax.xml.transform.TransformerException(
187        XPATHMessages.createXPATHMessage(
188          XPATHErrorResources.ER_EXTENSION_FUNCTION_CANNOT_BE_INVOKED,
189          new Object[] {toString()}));
190
191    XObject result;
192    Vector argVec = new Vector();
193    int nArgs = m_argVec.size();
194
195    for (int i = 0; i < nArgs; i++)
196    {
197      Expression arg = (Expression) m_argVec.elementAt(i);
198
199      XObject xobj = arg.execute(xctxt);
200      /*
201       * Should cache the arguments for func:function
202       */
203      xobj.allowDetachToRelease(false);
204      argVec.addElement(xobj);
205    }
206    //dml
207    ExtensionsProvider extProvider = (ExtensionsProvider)xctxt.getOwnerObject();
208    Object val = extProvider.extFunction(this, argVec);
209
210    if (null != val)
211    {
212      result = XObject.create(val, xctxt);
213    }
214    else
215    {
216      result = new XNull();
217    }
218
219    return result;
220  }
221
222  /**
223   * Set an argument expression for a function.  This method is called by the
224   * XPath compiler.
225   *
226   * @param arg non-null expression that represents the argument.
227   * @param argNum The argument number index.
228   *
229   * @throws WrongNumberArgsException If the argNum parameter is beyond what
230   * is specified for this function.
231   */
232  public void setArg(Expression arg, int argNum)
233          throws WrongNumberArgsException
234  {
235    m_argVec.addElement(arg);
236    arg.exprSetParent(this);
237  }
238
239  /**
240   * Check that the number of arguments passed to this function is correct.
241   *
242   *
243   * @param argNum The number of arguments that is being passed to the function.
244   *
245   * @throws WrongNumberArgsException
246   */
247  public void checkNumberArgs(int argNum) throws WrongNumberArgsException{}
248
249
250  class ArgExtOwner implements ExpressionOwner
251  {
252
253    Expression m_exp;
254
255  	ArgExtOwner(Expression exp)
256  	{
257  		m_exp = exp;
258  	}
259
260    /**
261     * @see ExpressionOwner#getExpression()
262     */
263    public Expression getExpression()
264    {
265      return m_exp;
266    }
267
268
269    /**
270     * @see ExpressionOwner#setExpression(Expression)
271     */
272    public void setExpression(Expression exp)
273    {
274    	exp.exprSetParent(FuncExtFunction.this);
275    	m_exp = exp;
276    }
277  }
278
279
280  /**
281   * Call the visitors for the function arguments.
282   */
283  public void callArgVisitors(XPathVisitor visitor)
284  {
285      for (int i = 0; i < m_argVec.size(); i++)
286      {
287         Expression exp = (Expression)m_argVec.elementAt(i);
288         exp.callVisitors(new ArgExtOwner(exp), visitor);
289      }
290
291  }
292
293  /**
294   * Set the parent node.
295   * For an extension function, we also need to set the parent
296   * node for all argument expressions.
297   *
298   * @param n The parent node
299   */
300  public void exprSetParent(ExpressionNode n)
301  {
302
303    super.exprSetParent(n);
304
305    int nArgs = m_argVec.size();
306
307    for (int i = 0; i < nArgs; i++)
308    {
309      Expression arg = (Expression) m_argVec.elementAt(i);
310
311      arg.exprSetParent(n);
312    }
313  }
314
315  /**
316   * Constructs and throws a WrongNumberArgException with the appropriate
317   * message for this function object.  This class supports an arbitrary
318   * number of arguments, so this method must never be called.
319   *
320   * @throws WrongNumberArgsException
321   */
322  protected void reportWrongNumberArgs() throws WrongNumberArgsException {
323    String fMsg = XSLMessages.createXPATHMessage(
324        XPATHErrorResources.ER_INCORRECT_PROGRAMMER_ASSERTION,
325        new Object[]{ "Programmer's assertion:  the method FunctionMultiArgs.reportWrongNumberArgs() should never be called." });
326
327    throw new RuntimeException(fMsg);
328  }
329
330  /**
331   * Return the name of the extesion function in string format
332   */
333  public String toString()
334  {
335    if (m_namespace != null && m_namespace.length() > 0)
336      return "{" + m_namespace + "}" + m_extensionName;
337    else
338      return m_extensionName;
339  }
340}
341