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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* $Id: FilterExprWalker.java 469367 2006-10-31 04:41:08Z minchau $
*/
package org.apache.xpath.axes;
import org.apache.xml.dtm.Axis;
import org.apache.xml.dtm.DTM;
import org.apache.xml.dtm.DTMIterator;
import org.apache.xpath.Expression;
import org.apache.xpath.ExpressionOwner;
import org.apache.xpath.XPathContext;
import org.apache.xpath.XPathVisitor;
import org.apache.xpath.compiler.Compiler;
import org.apache.xpath.compiler.OpCodes;
import org.apache.xpath.objects.XNodeSet;
/**
* Walker for the OP_VARIABLE, or OP_EXTFUNCTION, or OP_FUNCTION, or OP_GROUP,
* op codes.
* @see XPath FilterExpr descriptions
*/
public class FilterExprWalker extends AxesWalker
{
static final long serialVersionUID = 5457182471424488375L;
/**
* Construct a FilterExprWalker using a LocPathIterator.
*
* @param locPathIterator non-null reference to the parent iterator.
*/
public FilterExprWalker(WalkingIterator locPathIterator)
{
super(locPathIterator, Axis.FILTEREDLIST);
}
/**
* Init a FilterExprWalker.
*
* @param compiler non-null reference to the Compiler that is constructing.
* @param opPos positive opcode position for this step.
* @param stepType The type of step.
*
* @throws javax.xml.transform.TransformerException
*/
public void init(Compiler compiler, int opPos, int stepType)
throws javax.xml.transform.TransformerException
{
super.init(compiler, opPos, stepType);
// Smooth over an anomily in the opcode map...
switch (stepType)
{
case OpCodes.OP_FUNCTION :
case OpCodes.OP_EXTFUNCTION :
m_mustHardReset = true;
case OpCodes.OP_GROUP :
case OpCodes.OP_VARIABLE :
m_expr = compiler.compile(opPos);
m_expr.exprSetParent(this);
//if((OpCodes.OP_FUNCTION == stepType) && (m_expr instanceof org.apache.xalan.templates.FuncKey))
if(m_expr instanceof org.apache.xpath.operations.Variable)
{
// hack/temp workaround
m_canDetachNodeset = false;
}
break;
default :
m_expr = compiler.compile(opPos + 2);
m_expr.exprSetParent(this);
}
// if(m_expr instanceof WalkingIterator)
// {
// WalkingIterator wi = (WalkingIterator)m_expr;
// if(wi.getFirstWalker() instanceof FilterExprWalker)
// {
// FilterExprWalker fw = (FilterExprWalker)wi.getFirstWalker();
// if(null == fw.getNextWalker())
// {
// m_expr = fw.m_expr;
// m_expr.exprSetParent(this);
// }
// }
//
// }
}
/**
* Detaches the walker from the set which it iterated over, releasing
* any computational resources and placing the iterator in the INVALID
* state.
*/
public void detach()
{
super.detach();
if (m_canDetachNodeset)
{
m_exprObj.detach();
}
m_exprObj = null;
}
/**
* Set the root node of the TreeWalker.
*
* @param root non-null reference to the root, or starting point of
* the query.
*/
public void setRoot(int root)
{
super.setRoot(root);
m_exprObj = FilterExprIteratorSimple.executeFilterExpr(root,
m_lpi.getXPathContext(), m_lpi.getPrefixResolver(),
m_lpi.getIsTopLevel(), m_lpi.m_stackFrame, m_expr);
}
/**
* Get a cloned FilterExprWalker.
*
* @return A new FilterExprWalker that can be used without mutating this one.
*
* @throws CloneNotSupportedException
*/
public Object clone() throws CloneNotSupportedException
{
FilterExprWalker clone = (FilterExprWalker) super.clone();
if (null != m_exprObj)
clone.m_exprObj = (XNodeSet) m_exprObj.clone();
return clone;
}
/**
* This method needs to override AxesWalker.acceptNode because FilterExprWalkers
* don't need to, and shouldn't, do a node test.
* @param n The node to check to see if it passes the filter or not.
* @return a constant to determine whether the node is accepted,
* rejected, or skipped, as defined above .
*/
public short acceptNode(int n)
{
try
{
if (getPredicateCount() > 0)
{
countProximityPosition(0);
if (!executePredicates(n, m_lpi.getXPathContext()))
return DTMIterator.FILTER_SKIP;
}
return DTMIterator.FILTER_ACCEPT;
}
catch (javax.xml.transform.TransformerException se)
{
throw new RuntimeException(se.getMessage());
}
}
/**
* Moves the TreeWalker to the next visible node in document
* order relative to the current node, and returns the new node. If the
* current node has no next node, or if the search for nextNode attempts
* to step upward from the TreeWalker's root node, returns
* null , and retains the current node.
* @return The new node, or null if the current node has no
* next node in the TreeWalker's logical view.
*/
public int getNextNode()
{
if (null != m_exprObj)
{
int next = m_exprObj.nextNode();
return next;
}
else
return DTM.NULL;
}
/**
* Get the index of the last node that can be itterated to.
*
*
* @param xctxt XPath runtime context.
*
* @return the index of the last node that can be itterated to.
*/
public int getLastPos(XPathContext xctxt)
{
return m_exprObj.getLength();
}
/** The contained expression. Should be non-null.
* @serial */
private Expression m_expr;
/** The result of executing m_expr. Needs to be deep cloned on clone op. */
transient private XNodeSet m_exprObj;
private boolean m_mustHardReset = false;
private boolean m_canDetachNodeset = true;
/**
* This function is used to fixup variables from QNames to stack frame
* indexes at stylesheet build time.
* @param vars List of QNames that correspond to variables. This list
* should be searched backwards for the first qualified name that
* corresponds to the variable reference qname. The position of the
* QName in the vector from the start of the vector will be its position
* in the stack frame (but variables above the globalsTop value will need
* to be offset to the current stack frame).
*/
public void fixupVariables(java.util.Vector vars, int globalsSize)
{
super.fixupVariables(vars, globalsSize);
m_expr.fixupVariables(vars, globalsSize);
}
/**
* Get the inner contained expression of this filter.
*/
public Expression getInnerExpression()
{
return m_expr;
}
/**
* Set the inner contained expression of this filter.
*/
public void setInnerExpression(Expression expr)
{
expr.exprSetParent(this);
m_expr = expr;
}
/**
* Get the analysis bits for this walker, as defined in the WalkerFactory.
* @return One of WalkerFactory#BIT_DESCENDANT, etc.
*/
public int getAnalysisBits()
{
if (null != m_expr && m_expr instanceof PathComponent)
{
return ((PathComponent) m_expr).getAnalysisBits();
}
return WalkerFactory.BIT_FILTER;
}
/**
* Returns true if all the nodes in the iteration well be returned in document
* order.
* Warning: This can only be called after setRoot has been called!
*
* @return true as a default.
*/
public boolean isDocOrdered()
{
return m_exprObj.isDocOrdered();
}
/**
* Returns the axis being iterated, if it is known.
*
* @return Axis.CHILD, etc., or -1 if the axis is not known or is of multiple
* types.
*/
public int getAxis()
{
return m_exprObj.getAxis();
}
class filterExprOwner implements ExpressionOwner
{
/**
* @see ExpressionOwner#getExpression()
*/
public Expression getExpression()
{
return m_expr;
}
/**
* @see ExpressionOwner#setExpression(Expression)
*/
public void setExpression(Expression exp)
{
exp.exprSetParent(FilterExprWalker.this);
m_expr = exp;
}
}
/**
* This will traverse the heararchy, calling the visitor for
* each member. If the called visitor method returns
* false, the subtree should not be called.
*
* @param visitor The visitor whose appropriate method will be called.
*/
public void callPredicateVisitors(XPathVisitor visitor)
{
m_expr.callVisitors(new filterExprOwner(), visitor);
super.callPredicateVisitors(visitor);
}
/**
* @see Expression#deepEquals(Expression)
*/
public boolean deepEquals(Expression expr)
{
if (!super.deepEquals(expr))
return false;
FilterExprWalker walker = (FilterExprWalker)expr;
if(!m_expr.deepEquals(walker.m_expr))
return false;
return true;
}
}
