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.xpath.internal.operations;
23
24import javax.xml.transform.TransformerException;
25
26import com.sun.org.apache.xalan.internal.res.XSLMessages;
27import com.sun.org.apache.xml.internal.utils.QName;
28import com.sun.org.apache.xpath.internal.Expression;
29import com.sun.org.apache.xpath.internal.ExpressionOwner;
30import com.sun.org.apache.xpath.internal.XPath;
31import com.sun.org.apache.xpath.internal.XPathContext;
32import com.sun.org.apache.xpath.internal.XPathVisitor;
33import com.sun.org.apache.xpath.internal.axes.PathComponent;
34import com.sun.org.apache.xpath.internal.axes.WalkerFactory;
35import com.sun.org.apache.xpath.internal.objects.XNodeSet;
36import com.sun.org.apache.xpath.internal.objects.XObject;
37import com.sun.org.apache.xpath.internal.res.XPATHErrorResources;
38
39
40/**
41 * The variable reference expression executer.
42 */
43public class Variable extends Expression implements PathComponent
44{
45    static final long serialVersionUID = -4334975375609297049L;
46  /** Tell if fixupVariables was called.
47   *  @serial   */
48  private boolean m_fixUpWasCalled = false;
49
50  /** The qualified name of the variable.
51   *  @serial   */
52  protected QName m_qname;
53
54  /**
55   * The index of the variable, which is either an absolute index to a
56   * global, or, if higher than the globals area, must be adjusted by adding
57   * the offset to the current stack frame.
58   */
59  protected int m_index;
60
61  /**
62   * Set the index for the variable into the stack.  For advanced use only. You
63   * must know what you are doing to use this.
64   *
65   * @param index a global or local index.
66   */
67  public void setIndex(int index)
68  {
69        m_index = index;
70  }
71
72  /**
73   * Set the index for the variable into the stack.  For advanced use only.
74   *
75   * @return index a global or local index.
76   */
77  public int getIndex()
78  {
79        return m_index;
80  }
81
82  /**
83   * Set whether or not this is a global reference.  For advanced use only.
84   *
85   * @param isGlobal true if this should be a global variable reference.
86   */
87  public void setIsGlobal(boolean isGlobal)
88  {
89        m_isGlobal = isGlobal;
90  }
91
92  /**
93   * Set the index for the variable into the stack.  For advanced use only.
94   *
95   * @return true if this should be a global variable reference.
96   */
97  public boolean getGlobal()
98  {
99        return m_isGlobal;
100  }
101
102
103
104
105
106  protected boolean m_isGlobal = false;
107
108  /**
109   * This function is used to fixup variables from QNames to stack frame
110   * indexes at stylesheet build time.
111   * @param vars List of QNames that correspond to variables.  This list
112   * should be searched backwards for the first qualified name that
113   * corresponds to the variable reference qname.  The position of the
114   * QName in the vector from the start of the vector will be its position
115   * in the stack frame (but variables above the globalsTop value will need
116   * to be offset to the current stack frame).
117   */
118  public void fixupVariables(java.util.Vector vars, int globalsSize)
119  {
120    m_fixUpWasCalled = true;
121    int sz = vars.size();
122
123    for (int i = vars.size()-1; i >= 0; i--)
124    {
125      QName qn = (QName)vars.elementAt(i);
126      // System.out.println("qn: "+qn);
127      if(qn.equals(m_qname))
128      {
129
130        if(i < globalsSize)
131        {
132          m_isGlobal = true;
133          m_index = i;
134        }
135        else
136        {
137          m_index = i-globalsSize;
138        }
139
140        return;
141      }
142    }
143
144    java.lang.String msg = XSLMessages.createXPATHMessage(XPATHErrorResources.ER_COULD_NOT_FIND_VAR,
145                                             new Object[]{m_qname.toString()});
146
147    TransformerException te = new TransformerException(msg, this);
148
149    throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(te);
150
151  }
152
153
154  /**
155   * Set the qualified name of the variable.
156   *
157   * @param qname Must be a non-null reference to a qualified name.
158   */
159  public void setQName(QName qname)
160  {
161    m_qname = qname;
162  }
163
164  /**
165   * Get the qualified name of the variable.
166   *
167   * @return A non-null reference to a qualified name.
168   */
169  public QName getQName()
170  {
171    return m_qname;
172  }
173
174  /**
175   * Execute an expression in the XPath runtime context, and return the
176   * result of the expression.
177   *
178   *
179   * @param xctxt The XPath runtime context.
180   *
181   * @return The result of the expression in the form of a <code>XObject</code>.
182   *
183   * @throws javax.xml.transform.TransformerException if a runtime exception
184   *         occurs.
185   */
186  public XObject execute(XPathContext xctxt)
187    throws javax.xml.transform.TransformerException
188  {
189        return execute(xctxt, false);
190  }
191
192
193  /**
194   * Dereference the variable, and return the reference value.  Note that lazy
195   * evaluation will occur.  If a variable within scope is not found, a warning
196   * will be sent to the error listener, and an empty nodeset will be returned.
197   *
198   *
199   * @param xctxt The runtime execution context.
200   *
201   * @return The evaluated variable, or an empty nodeset if not found.
202   *
203   * @throws javax.xml.transform.TransformerException
204   */
205  public XObject execute(XPathContext xctxt, boolean destructiveOK) throws javax.xml.transform.TransformerException
206  {
207    com.sun.org.apache.xml.internal.utils.PrefixResolver xprefixResolver = xctxt.getNamespaceContext();
208
209    XObject result;
210    // Is the variable fetched always the same?
211    // XObject result = xctxt.getVariable(m_qname);
212    if(m_fixUpWasCalled)
213    {
214      if(m_isGlobal)
215        result = xctxt.getVarStack().getGlobalVariable(xctxt, m_index, destructiveOK);
216      else
217        result = xctxt.getVarStack().getLocalVariable(xctxt, m_index, destructiveOK);
218    }
219    else {
220        result = xctxt.getVarStack().getVariableOrParam(xctxt,m_qname);
221    }
222
223      if (null == result)
224      {
225        // This should now never happen...
226        warn(xctxt, XPATHErrorResources.WG_ILLEGAL_VARIABLE_REFERENCE,
227             new Object[]{ m_qname.getLocalPart() });  //"VariableReference given for variable out "+
228  //      (new RuntimeException()).printStackTrace();
229  //      error(xctxt, XPATHErrorResources.ER_COULDNOT_GET_VAR_NAMED,
230  //            new Object[]{ m_qname.getLocalPart() });  //"Could not get variable named "+varName);
231
232        result = new XNodeSet(xctxt.getDTMManager());
233      }
234
235      return result;
236//    }
237//    else
238//    {
239//      // Hack city... big time.  This is needed to evaluate xpaths from extensions,
240//      // pending some bright light going off in my head.  Some sort of callback?
241//      synchronized(this)
242//      {
243//              com.sun.org.apache.xalan.internal.templates.ElemVariable vvar= getElemVariable();
244//              if(null != vvar)
245//              {
246//          m_index = vvar.getIndex();
247//          m_isGlobal = vvar.getIsTopLevel();
248//          m_fixUpWasCalled = true;
249//          return execute(xctxt);
250//              }
251//      }
252//      throw new javax.xml.transform.TransformerException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_VAR_NOT_RESOLVABLE, new Object[]{m_qname.toString()})); //"Variable not resolvable: "+m_qname);
253//    }
254  }
255
256  /**
257   * Get the XSLT ElemVariable that this sub-expression references.  In order for
258   * this to work, the SourceLocator must be the owning ElemTemplateElement.
259   * @return The dereference to the ElemVariable, or null if not found.
260   */
261  // J2SE does not support Xalan interpretive
262  /*
263  public com.sun.org.apache.xalan.internal.templates.ElemVariable getElemVariable()
264  {
265
266    // Get the current ElemTemplateElement, and then walk backwards in
267    // document order, searching
268    // for an xsl:param element or xsl:variable element that matches our
269    // qname.  If we reach the top level, use the StylesheetRoot's composed
270    // list of top level variables and parameters.
271
272    com.sun.org.apache.xalan.internal.templates.ElemVariable vvar = null;
273    com.sun.org.apache.xpath.internal.ExpressionNode owner = getExpressionOwner();
274
275    if (null != owner && owner instanceof com.sun.org.apache.xalan.internal.templates.ElemTemplateElement)
276    {
277
278      com.sun.org.apache.xalan.internal.templates.ElemTemplateElement prev =
279        (com.sun.org.apache.xalan.internal.templates.ElemTemplateElement) owner;
280
281      if (!(prev instanceof com.sun.org.apache.xalan.internal.templates.Stylesheet))
282      {
283        while ( prev != null && !(prev.getParentNode() instanceof com.sun.org.apache.xalan.internal.templates.Stylesheet) )
284        {
285          com.sun.org.apache.xalan.internal.templates.ElemTemplateElement savedprev = prev;
286
287          while (null != (prev = prev.getPreviousSiblingElem()))
288          {
289            if(prev instanceof com.sun.org.apache.xalan.internal.templates.ElemVariable)
290            {
291              vvar = (com.sun.org.apache.xalan.internal.templates.ElemVariable) prev;
292
293              if (vvar.getName().equals(m_qname))
294              {
295                return vvar;
296              }
297              vvar = null;
298            }
299          }
300          prev = savedprev.getParentElem();
301        }
302      }
303      if (prev != null)
304        vvar = prev.getStylesheetRoot().getVariableOrParamComposed(m_qname);
305    }
306    return vvar;
307
308  }
309  */
310  /**
311   * Tell if this expression returns a stable number that will not change during
312   * iterations within the expression.  This is used to determine if a proximity
313   * position predicate can indicate that no more searching has to occur.
314   *
315   *
316   * @return true if the expression represents a stable number.
317   */
318  public boolean isStableNumber()
319  {
320    return true;
321  }
322
323  /**
324   * Get the analysis bits for this walker, as defined in the WalkerFactory.
325   * @return One of WalkerFactory#BIT_DESCENDANT, etc.
326   */
327  public int getAnalysisBits()
328  {
329
330    // J2SE does not support Xalan interpretive
331    /*
332        com.sun.org.apache.xalan.internal.templates.ElemVariable vvar = getElemVariable();
333        if(null != vvar)
334        {
335                XPath xpath = vvar.getSelect();
336                if(null != xpath)
337                {
338                        Expression expr = xpath.getExpression();
339                        if(null != expr && expr instanceof PathComponent)
340                        {
341                                return ((PathComponent)expr).getAnalysisBits();
342                        }
343                }
344        }
345    */
346
347    return WalkerFactory.BIT_FILTER;
348  }
349
350
351  /**
352   * @see com.sun.org.apache.xpath.internal.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)
353   */
354  public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
355  {
356        visitor.visitVariableRef(owner, this);
357  }
358  /**
359   * @see Expression#deepEquals(Expression)
360   */
361  public boolean deepEquals(Expression expr)
362  {
363        if(!isSameClass(expr))
364                return false;
365
366        if(!m_qname.equals(((Variable)expr).m_qname))
367                return false;
368
369    // J2SE does not support Xalan interpretive
370    /*
371        // We have to make sure that the qname really references
372        // the same variable element.
373    if(getElemVariable() != ((Variable)expr).getElemVariable())
374        return false;
375        */
376
377        return true;
378  }
379
380  static final java.lang.String PSUEDOVARNAMESPACE = "http://xml.apache.org/xalan/psuedovar";
381
382  /**
383   * Tell if this is a psuedo variable reference, declared by Xalan instead
384   * of by the user.
385   */
386  public boolean isPsuedoVarRef()
387  {
388        java.lang.String ns = m_qname.getNamespaceURI();
389        if((null != ns) && ns.equals(PSUEDOVARNAMESPACE))
390        {
391                if(m_qname.getLocalName().startsWith("#"))
392                        return true;
393        }
394        return false;
395  }
396
397
398}
399