/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed 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: XRTreeFrag.java,v 1.30 2004/02/17 04:34:38 minchau Exp $
*/
package org.apache.xpath.objects;
import org.apache.xml.dtm.DTM;
import org.apache.xml.dtm.DTMIterator;
import org.apache.xml.utils.XMLString;
import org.apache.xpath.Expression;
import org.apache.xpath.ExpressionNode;
import org.apache.xpath.XPathContext;
import org.apache.xpath.axes.RTFIterator;
import org.w3c.dom.NodeList;
/**
* This class represents an XPath result tree fragment object, and is capable of
* converting the RTF to other types, such as a string.
* @xsl.usage general
*/
public class XRTreeFrag extends XObject implements Cloneable
{
DTM m_dtm;
int m_dtmRoot;
XPathContext m_xctxt;
boolean m_allowRelease = false;
// /**
// * Create an XRTreeFrag Object.
// *
// * @param frag Document fragment this will wrap
// */
// public XRTreeFrag(DTMIterator frag)
// {
// super(frag);
//
// // Obviously, this constructor should be avoided when possible.
// m_dtmRoot = frag.cloneWithReset().nextNode();
// }
/**
* Create an XRTreeFrag Object.
*
* @param frag Document fragment this will wrap
*/
public XRTreeFrag(int root, XPathContext xctxt, ExpressionNode parent)
{
super(null);
// Obviously, this constructor should be avoided when possible.
exprSetParent(parent);
m_dtmRoot = root;
m_xctxt = xctxt;
m_dtm = xctxt.getDTM(root);
}
/**
* Create an XRTreeFrag Object.
*
* @param frag Document fragment this will wrap
*/
public XRTreeFrag(int root, XPathContext xctxt)
{
super(null);
// Obviously, this constructor should be avoided when possible.
m_dtmRoot = root;
m_xctxt = xctxt;
m_dtm = xctxt.getDTM(root);
}
/**
* Return a java object that's closest to the representation
* that should be handed to an extension.
*
* @return The object that this class wraps
*/
public Object object()
{
if (m_xctxt != null)
return new org.apache.xml.dtm.ref.DTMNodeIterator((DTMIterator)(new org.apache.xpath.NodeSetDTM(m_dtmRoot, m_xctxt.getDTMManager())));
else
return super.object();
}
/**
* Create an XRTreeFrag Object.
*
* @param frag Document fragment this will wrap
*/
public XRTreeFrag(Expression expr)
{
super(expr);
}
/**
* Release any resources this object may have by calling destruct().
* %ISSUE% This release will occur asynchronously. Resources it manipulates
* MUST be thread-safe!
*
* @throws Throwable
*/
protected void finalize() throws Throwable
{
try
{
destruct();
}
finally
{
super.finalize(); // Always use this.
}
}
/**
* Specify if it's OK for detach to release the iterator for reuse.
*
* @param allowRelease true if it is OK for detach to release this iterator
* for pooling.
*/
public void allowDetachToRelease(boolean allowRelease)
{
m_allowRelease = allowRelease;
}
/**
* Detaches the <code>DTMIterator</code> from the set which it iterated
* over, releasing any computational resources and placing the iterator
* in the INVALID state. After <code>detach</code> has been invoked,
* calls to <code>nextNode</code> or <code>previousNode</code> will
* raise a runtime exception.
*
* In general, detach should only be called once on the object.
*/
public void detach()
{
if(m_allowRelease)
{
// %REVIEW% Do we actually _need_ detach, now that DTM RTF
// storage is managed as a stack?
// See #destruct() for a comment about this next check.
int ident = m_xctxt.getDTMIdentity(m_dtm);
DTM foundDTM = m_xctxt.getDTM(ident);
if(foundDTM == m_dtm)
{
m_xctxt.release(m_dtm, true);
m_dtm = null;
m_xctxt = null;
}
m_obj = null;
}
}
/**
* Forces the object to release it's resources. This is more harsh than
* detach(). You can call destruct as many times as you want.
*/
public void destruct()
{
if(null != m_dtm)
{
// For this next check, see http://nagoya.apache.org/bugzilla/show_bug.cgi?id=7622.
// What happens if you don't do this this check:
// 1) Transform#1 creates an XRTreeFrag. This has a reference to a DTM, that in turn
// is registered with a DTMManager. The DTM will need to be deleted from the
// DTMManager when the XRTreeFrag is deleted. The XRTreeFrag also contains a
// reference to the XPathContext.
// 2) Transform#1 completes. The XPathContext is reset... namely the a bunch
// of structures are reset or rebuilt, including DTMManagerDefault#m_dtms.
// BUT, the XRTreeFrags are still hanging around, waiting to unregister themselves.
// 3) Transform#2 starts humming along. It builds a XRTreeFrag and installs that
// RTF DTM into DTMManagerDefault#m_dtms[2].
// 4) The finalizer thread wakes and decides to delete some of those old XRTreeFrags
// from Transform#1.
// 5) The XRTreeFrag#finalize() method references through the XPathContext, and
// deletes what it thinks is it's DTM from DTMManagerDefault#m_dtms[2] (via
// getDTMIdentity(dtm)).
// 6) Transform#2 tries to reference DTMManagerDefault#m_dtms[2], finds it is
// null, and chaos results.
int ident = m_xctxt.getDTMIdentity(m_dtm);
DTM foundDTM = m_xctxt.getDTM(ident);
if(foundDTM == m_dtm)
{
m_xctxt.release(m_dtm, true);
m_dtm = null;
m_xctxt = null;
}
}
m_obj = null;
}
/**
* Tell what kind of class this is.
*
* @return type CLASS_RTREEFRAG
*/
public int getType()
{
return CLASS_RTREEFRAG;
}
/**
* Given a request type, return the equivalent string.
* For diagnostic purposes.
*
* @return type string "#RTREEFRAG"
*/
public String getTypeString()
{
return "#RTREEFRAG";
}
/**
* Cast result object to a number.
*
* @return The result tree fragment as a number or NaN
*/
public double num()
throws javax.xml.transform.TransformerException
{
XMLString s = xstr();
return s.toDouble();
}
/**
* Cast result object to a boolean. This always returns true for a RTreeFrag
* because it is treated like a node-set with a single root node.
*
* @return true
*/
public boolean bool()
{
return true;
}
private XMLString m_xmlStr = null;
/**
* Cast result object to an XMLString.
*
* @return The document fragment node data or the empty string.
*/
public XMLString xstr()
{
if(null == m_xmlStr)
m_xmlStr = m_dtm.getStringValue(m_dtmRoot);
return m_xmlStr;
}
/**
* Cast result object to a string.
*
* @return The string this wraps or the empty string if null
*/
public void appendToFsb(org.apache.xml.utils.FastStringBuffer fsb)
{
XString xstring = (XString)xstr();
xstring.appendToFsb(fsb);
}
/**
* Cast result object to a string.
*
* @return The document fragment node data or the empty string.
*/
public String str()
{
String str = m_dtm.getStringValue(m_dtmRoot).toString();
return (null == str) ? "" : str;
}
/**
* Cast result object to a result tree fragment.
*
* @return The document fragment this wraps
*/
public int rtf()
{
return m_dtmRoot;
}
/**
* Cast result object to a DTMIterator.
* dml - modified to return an RTFIterator for
* benefit of EXSLT object-type function in
* {@link org.apache.xalan.lib.ExsltCommon}.
* @return The document fragment as a DTMIterator
*/
public DTMIterator asNodeIterator()
{
return new RTFIterator(m_dtmRoot, m_xctxt.getDTMManager());
}
/**
* Cast result object to a nodelist. (special function).
*
* @return The document fragment as a nodelist
*/
public NodeList convertToNodeset()
{
if (m_obj instanceof NodeList)
return (NodeList) m_obj;
else
return new org.apache.xml.dtm.ref.DTMNodeList(asNodeIterator());
}
/**
* Tell if two objects are functionally equal.
*
* @param obj2 Object to compare this to
*
* @return True if the two objects are equal
*
* @throws javax.xml.transform.TransformerException
*/
public boolean equals(XObject obj2)
{
try
{
if (XObject.CLASS_NODESET == obj2.getType())
{
// In order to handle the 'all' semantics of
// nodeset comparisons, we always call the
// nodeset function.
return obj2.equals(this);
}
else if (XObject.CLASS_BOOLEAN == obj2.getType())
{
return bool() == obj2.bool();
}
else if (XObject.CLASS_NUMBER == obj2.getType())
{
return num() == obj2.num();
}
else if (XObject.CLASS_NODESET == obj2.getType())
{
return xstr().equals(obj2.xstr());
}
else if (XObject.CLASS_STRING == obj2.getType())
{
return xstr().equals(obj2.xstr());
}
else if (XObject.CLASS_RTREEFRAG == obj2.getType())
{
// Probably not so good. Think about this.
return xstr().equals(obj2.xstr());
}
else
{
return super.equals(obj2);
}
}
catch(javax.xml.transform.TransformerException te)
{
throw new org.apache.xml.utils.WrappedRuntimeException(te);
}
}
}