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.axes;
23
24import com.sun.org.apache.xml.internal.dtm.Axis;
25import com.sun.org.apache.xml.internal.dtm.DTM;
26import com.sun.org.apache.xml.internal.utils.PrefixResolver;
27import com.sun.org.apache.xpath.internal.Expression;
28import com.sun.org.apache.xpath.internal.ExpressionOwner;
29import com.sun.org.apache.xpath.internal.VariableStack;
30import com.sun.org.apache.xpath.internal.XPathContext;
31import com.sun.org.apache.xpath.internal.XPathVisitor;
32import com.sun.org.apache.xpath.internal.objects.XNodeSet;
33
34/**
35 * Class to use for one-step iteration that doesn't have a predicate, and
36 * doesn't need to set the context.
37 */
38public class FilterExprIteratorSimple extends LocPathIterator
39{
40    static final long serialVersionUID = -6978977187025375579L;
41  /** The contained expression. Should be non-null.
42   *  @serial   */
43  private Expression m_expr;
44
45  /** The result of executing m_expr.  Needs to be deep cloned on clone op.  */
46  transient private XNodeSet m_exprObj;
47
48  private boolean m_mustHardReset = false;
49  private boolean m_canDetachNodeset = true;
50
51  /**
52   * Create a FilterExprIteratorSimple object.
53   *
54   */
55  public FilterExprIteratorSimple()
56  {
57    super(null);
58  }
59
60  /**
61   * Create a FilterExprIteratorSimple object.
62   *
63   */
64  public FilterExprIteratorSimple(Expression expr)
65  {
66    super(null);
67    m_expr = expr;
68  }
69
70  /**
71   * Initialize the context values for this expression
72   * after it is cloned.
73   *
74   * @param context The XPath runtime context for this
75   * transformation.
76   */
77  public void setRoot(int context, Object environment)
78  {
79        super.setRoot(context, environment);
80        m_exprObj = executeFilterExpr(context, m_execContext, getPrefixResolver(),
81                          getIsTopLevel(), m_stackFrame, m_expr);
82  }
83
84  /**
85   * Execute the expression.  Meant for reuse by other FilterExpr iterators
86   * that are not derived from this object.
87   */
88  public static XNodeSet executeFilterExpr(int context, XPathContext xctxt,
89                                                                                                PrefixResolver prefixResolver,
90                                                                                                boolean isTopLevel,
91                                                                                                int stackFrame,
92                                                                                                Expression expr )
93    throws com.sun.org.apache.xml.internal.utils.WrappedRuntimeException
94  {
95    PrefixResolver savedResolver = xctxt.getNamespaceContext();
96    XNodeSet result = null;
97
98    try
99    {
100      xctxt.pushCurrentNode(context);
101      xctxt.setNamespaceContext(prefixResolver);
102
103      // The setRoot operation can take place with a reset operation,
104      // and so we may not be in the context of LocPathIterator#nextNode,
105      // so we have to set up the variable context, execute the expression,
106      // and then restore the variable context.
107
108      if (isTopLevel)
109      {
110        // System.out.println("calling m_expr.execute(getXPathContext())");
111        VariableStack vars = xctxt.getVarStack();
112
113        // These three statements need to be combined into one operation.
114        int savedStart = vars.getStackFrame();
115        vars.setStackFrame(stackFrame);
116
117        result = (com.sun.org.apache.xpath.internal.objects.XNodeSet) expr.execute(xctxt);
118        result.setShouldCacheNodes(true);
119
120        // These two statements need to be combined into one operation.
121        vars.setStackFrame(savedStart);
122      }
123      else
124          result = (com.sun.org.apache.xpath.internal.objects.XNodeSet) expr.execute(xctxt);
125
126    }
127    catch (javax.xml.transform.TransformerException se)
128    {
129
130      // TODO: Fix...
131      throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(se);
132    }
133    finally
134    {
135      xctxt.popCurrentNode();
136      xctxt.setNamespaceContext(savedResolver);
137    }
138    return result;
139  }
140
141  /**
142   *  Returns the next node in the set and advances the position of the
143   * iterator in the set. After a NodeIterator is created, the first call
144   * to nextNode() returns the first node in the set.
145   *
146   * @return  The next <code>Node</code> in the set being iterated over, or
147   *   <code>null</code> if there are no more members in that set.
148   */
149  public int nextNode()
150  {
151        if(m_foundLast)
152                return DTM.NULL;
153
154    int next;
155
156    if (null != m_exprObj)
157    {
158      m_lastFetched = next = m_exprObj.nextNode();
159    }
160    else
161      m_lastFetched = next = DTM.NULL;
162
163    // m_lastFetched = next;
164    if (DTM.NULL != next)
165    {
166      m_pos++;
167      return next;
168    }
169    else
170    {
171      m_foundLast = true;
172
173      return DTM.NULL;
174    }
175  }
176
177  /**
178   * Detaches the walker from the set which it iterated over, releasing
179   * any computational resources and placing the iterator in the INVALID
180   * state.
181   */
182  public void detach()
183  {
184    if(m_allowDetach)
185    {
186                super.detach();
187                m_exprObj.detach();
188                m_exprObj = null;
189    }
190  }
191
192  /**
193   * This function is used to fixup variables from QNames to stack frame
194   * indexes at stylesheet build time.
195   * @param vars List of QNames that correspond to variables.  This list
196   * should be searched backwards for the first qualified name that
197   * corresponds to the variable reference qname.  The position of the
198   * QName in the vector from the start of the vector will be its position
199   * in the stack frame (but variables above the globalsTop value will need
200   * to be offset to the current stack frame).
201   */
202  public void fixupVariables(java.util.Vector vars, int globalsSize)
203  {
204    super.fixupVariables(vars, globalsSize);
205    m_expr.fixupVariables(vars, globalsSize);
206  }
207
208  /**
209   * Get the inner contained expression of this filter.
210   */
211  public Expression getInnerExpression()
212  {
213    return m_expr;
214  }
215
216  /**
217   * Set the inner contained expression of this filter.
218   */
219  public void setInnerExpression(Expression expr)
220  {
221    expr.exprSetParent(this);
222    m_expr = expr;
223  }
224
225  /**
226   * Get the analysis bits for this walker, as defined in the WalkerFactory.
227   * @return One of WalkerFactory#BIT_DESCENDANT, etc.
228   */
229  public int getAnalysisBits()
230  {
231    if (null != m_expr && m_expr instanceof PathComponent)
232    {
233      return ((PathComponent) m_expr).getAnalysisBits();
234    }
235    return WalkerFactory.BIT_FILTER;
236  }
237
238  /**
239   * Returns true if all the nodes in the iteration well be returned in document
240   * order.
241   * Warning: This can only be called after setRoot has been called!
242   *
243   * @return true as a default.
244   */
245  public boolean isDocOrdered()
246  {
247    return m_exprObj.isDocOrdered();
248  }
249
250  class filterExprOwner implements ExpressionOwner
251  {
252    /**
253    * @see ExpressionOwner#getExpression()
254    */
255    public Expression getExpression()
256    {
257      return m_expr;
258    }
259
260    /**
261     * @see ExpressionOwner#setExpression(Expression)
262     */
263    public void setExpression(Expression exp)
264    {
265      exp.exprSetParent(FilterExprIteratorSimple.this);
266      m_expr = exp;
267    }
268
269  }
270
271  /**
272   * This will traverse the heararchy, calling the visitor for
273   * each member.  If the called visitor method returns
274   * false, the subtree should not be called.
275   *
276   * @param visitor The visitor whose appropriate method will be called.
277   */
278  public void callPredicateVisitors(XPathVisitor visitor)
279  {
280    m_expr.callVisitors(new filterExprOwner(), visitor);
281
282    super.callPredicateVisitors(visitor);
283  }
284
285  /**
286   * @see Expression#deepEquals(Expression)
287   */
288  public boolean deepEquals(Expression expr)
289  {
290    if (!super.deepEquals(expr))
291      return false;
292
293    FilterExprIteratorSimple fet = (FilterExprIteratorSimple) expr;
294    if (!m_expr.deepEquals(fet.m_expr))
295      return false;
296
297    return true;
298  }
299
300  /**
301   * Returns the axis being iterated, if it is known.
302   *
303   * @return Axis.CHILD, etc., or -1 if the axis is not known or is of multiple
304   * types.
305   */
306  public int getAxis()
307  {
308        if(null != m_exprObj)
309        return m_exprObj.getAxis();
310    else
311        return Axis.FILTEREDLIST;
312  }
313
314
315}
316