/*
* 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: ElemVariable.java,v 1.29 2005/01/23 00:27:29 mcnamara Exp $
*/
package org.apache.xalan.templates;
import javax.xml.transform.TransformerException;
import org.apache.xalan.transformer.TransformerImpl;
import org.apache.xml.utils.QName;
import org.apache.xpath.XPath;
import org.apache.xpath.XPathContext;
import org.apache.xpath.objects.XObject;
import org.apache.xpath.objects.XRTreeFrag;
import org.apache.xpath.objects.XRTreeFragSelectWrapper;
import org.apache.xpath.objects.XString;
import org.apache.xalan.res.XSLTErrorResources;
/**
* Implement xsl:variable.
* <pre>
* <!ELEMENT xsl:variable %template;>
* <!ATTLIST xsl:variable
* name %qname; #REQUIRED
* select %expr; #IMPLIED
* >
* </pre>
* @see <a href="http://www.w3.org/TR/xslt#variables">variables in XSLT Specification</a>
* @xsl.usage advanced
*/
public class ElemVariable extends ElemTemplateElement
{
static final long serialVersionUID = 9111131075322790061L;
/**
* Constructor ElemVariable
*
*/
public ElemVariable(){}
/**
* This is the index into the stack frame.
*/
protected int m_index;
/**
* The stack frame size for this variable if it is a global variable
* that declares an RTF, which is equal to the maximum number
* of variables that can be declared in the variable at one time.
*/
int m_frameSize = -1;
/**
* Sets the relative position of this variable within the stack frame (if local)
* or the global area (if global). Note that this should be called only for
* global variables since the local position is computed in the compose() method.
*/
public void setIndex(int index)
{
m_index = index;
}
/**
* If this element is not at the top-level, get the relative position of the
* variable into the stack frame. If this variable is at the top-level, get
* the relative position within the global area.
*/
public int getIndex()
{
return m_index;
}
/**
* The value of the "select" attribute.
* @serial
*/
private XPath m_selectPattern;
/**
* Set the "select" attribute.
* If the variable-binding element has a select attribute,
* then the value of the attribute must be an expression and
* the value of the variable is the object that results from
* evaluating the expression. In this case, the content
* of the variable must be empty.
*
* @param v Value to set for the "select" attribute.
*/
public void setSelect(XPath v)
{
m_selectPattern = v;
}
/**
* Get the "select" attribute.
* If the variable-binding element has a select attribute,
* then the value of the attribute must be an expression and
* the value of the variable is the object that results from
* evaluating the expression. In this case, the content
* of the variable must be empty.
*
* @return Value of the "select" attribute.
*/
public XPath getSelect()
{
return m_selectPattern;
}
/**
* The value of the "name" attribute.
* @serial
*/
protected QName m_qname;
/**
* Set the "name" attribute.
* Both xsl:variable and xsl:param have a required name
* attribute, which specifies the name of the variable. The
* value of the name attribute is a QName, which is expanded
* as described in [2.4 Qualified Names].
* @see <a href="http://www.w3.org/TR/xslt#qname">qname in XSLT Specification</a>
*
* @param v Value to set for the "name" attribute.
*/
public void setName(QName v)
{
m_qname = v;
}
/**
* Get the "name" attribute.
* Both xsl:variable and xsl:param have a required name
* attribute, which specifies the name of the variable. The
* value of the name attribute is a QName, which is expanded
* as described in [2.4 Qualified Names].
* @see <a href="http://www.w3.org/TR/xslt#qname">qname in XSLT Specification</a>
*
* @return Value of the "name" attribute.
*/
public QName getName()
{
return m_qname;
}
/**
* Tells if this is a top-level variable or param, or not.
* @serial
*/
private boolean m_isTopLevel = false;
/**
* Set if this is a top-level variable or param, or not.
* @see <a href="http://www.w3.org/TR/xslt#top-level-variables">top-level-variables in XSLT Specification</a>
*
* @param v Boolean indicating whether this is a top-level variable
* or param, or not.
*/
public void setIsTopLevel(boolean v)
{
m_isTopLevel = v;
}
/**
* Get if this is a top-level variable or param, or not.
* @see <a href="http://www.w3.org/TR/xslt#top-level-variables">top-level-variables in XSLT Specification</a>
*
* @return Boolean indicating whether this is a top-level variable
* or param, or not.
*/
public boolean getIsTopLevel()
{
return m_isTopLevel;
}
/**
* Get an integer representation of the element type.
*
* @return An integer representation of the element, defined in the
* Constants class.
* @see org.apache.xalan.templates.Constants
*/
public int getXSLToken()
{
return Constants.ELEMNAME_VARIABLE;
}
/**
* Return the node name.
*
* @return The node name
*/
public String getNodeName()
{
return Constants.ELEMNAME_VARIABLE_STRING;
}
/**
* Copy constructor.
*
* @param param An element created from an xsl:variable
*
* @throws TransformerException
*/
public ElemVariable(ElemVariable param) throws TransformerException
{
m_selectPattern = param.m_selectPattern;
m_qname = param.m_qname;
m_isTopLevel = param.m_isTopLevel;
// m_value = param.m_value;
// m_varContext = param.m_varContext;
}
/**
* Execute a variable declaration and push it onto the variable stack.
* @see <a href="http://www.w3.org/TR/xslt#variables">variables in XSLT Specification</a>
*
* @param transformer non-null reference to the the current transform-time state.
*
* @throws TransformerException
*/
public void execute(TransformerImpl transformer) throws TransformerException
{
if (transformer.getDebug())
transformer.getTraceManager().fireTraceEvent(this);
int sourceNode = transformer.getXPathContext().getCurrentNode();
XObject var = getValue(transformer, sourceNode);
// transformer.getXPathContext().getVarStack().pushVariable(m_qname, var);
transformer.getXPathContext().getVarStack().setLocalVariable(m_index, var);
if (transformer.getDebug())
transformer.getTraceManager().fireTraceEndEvent(this);
}
/**
* Get the XObject representation of the variable.
*
* @param transformer non-null reference to the the current transform-time state.
* @param sourceNode non-null reference to the <a href="http://www.w3.org/TR/xslt#dt-current-node">current source node</a>.
*
* @return the XObject representation of the variable.
*
* @throws TransformerException
*/
public XObject getValue(TransformerImpl transformer, int sourceNode)
throws TransformerException
{
XObject var;
XPathContext xctxt = transformer.getXPathContext();
xctxt.pushCurrentNode(sourceNode);
try
{
if (null != m_selectPattern)
{
var = m_selectPattern.execute(xctxt, sourceNode, this);
var.allowDetachToRelease(false);
if (transformer.getDebug())
transformer.getTraceManager().fireSelectedEvent(sourceNode, this,
"select", m_selectPattern, var);
}
else if (null == getFirstChildElem())
{
var = XString.EMPTYSTRING;
}
else
{
// Use result tree fragment.
// Global variables may be deferred (see XUnresolvedVariable) and hence
// need to be assigned to a different set of DTMs than local variables
// so they aren't popped off the stack on return from a template.
int df;
// Bugzilla 7118: A variable set via an RTF may create local
// variables during that computation. To keep them from overwriting
// variables at this level, push a new variable stack.
////// PROBLEM: This is provoking a variable-used-before-set
////// problem in parameters. Needs more study.
try
{
//////////xctxt.getVarStack().link(0);
if(m_parentNode instanceof Stylesheet) // Global variable
df = transformer.transformToGlobalRTF(this);
else
df = transformer.transformToRTF(this);
}
finally{
//////////////xctxt.getVarStack().unlink();
}
var = new XRTreeFrag(df, xctxt, this);
}
}
finally
{
xctxt.popCurrentNode();
}
return var;
}
/**
* This function is called after everything else has been
* recomposed, and allows the template to set remaining
* values that may be based on some other property that
* depends on recomposition.
*/
public void compose(StylesheetRoot sroot) throws TransformerException
{
// See if we can reduce an RTF to a select with a string expression.
if(null == m_selectPattern
&& sroot.getOptimizer())
{
XPath newSelect = rewriteChildToExpression(this);
if(null != newSelect)
m_selectPattern = newSelect;
}
StylesheetRoot.ComposeState cstate = sroot.getComposeState();
// This should be done before addVariableName, so we don't have visibility
// to the variable now being defined.
java.util.Vector vnames = cstate.getVariableNames();
if(null != m_selectPattern)
m_selectPattern.fixupVariables(vnames, cstate.getGlobalsSize());
// Only add the variable if this is not a global. If it is a global,
// it was already added by stylesheet root.
if(!(m_parentNode instanceof Stylesheet) && m_qname != null)
{
m_index = cstate.addVariableName(m_qname) - cstate.getGlobalsSize();
}
else if (m_parentNode instanceof Stylesheet)
{
// If this is a global, then we need to treat it as if it's a xsl:template,
// and count the number of variables it contains. So we set the count to
// zero here.
cstate.resetStackFrameSize();
}
// This has to be done after the addVariableName, so that the variable
// pushed won't be immediately popped again in endCompose.
super.compose(sroot);
}
/**
* This after the template's children have been composed. We have to get
* the count of how many variables have been declared, so we can do a link
* and unlink.
*/
public void endCompose(StylesheetRoot sroot) throws TransformerException
{
super.endCompose(sroot);
if(m_parentNode instanceof Stylesheet)
{
StylesheetRoot.ComposeState cstate = sroot.getComposeState();
m_frameSize = cstate.getFrameSize();
cstate.resetStackFrameSize();
}
}
// /**
// * This after the template's children have been composed.
// */
// public void endCompose() throws TransformerException
// {
// super.endCompose();
// }
/**
* If the children of a variable is a single xsl:value-of or text literal,
* it is cheaper to evaluate this as an expression, so try and adapt the
* child an an expression.
*
* @param varElem Should be a ElemParam, ElemVariable, or ElemWithParam.
*
* @return An XPath if rewrite is possible, else null.
*
* @throws TransformerException
*/
static XPath rewriteChildToExpression(ElemTemplateElement varElem)
throws TransformerException
{
ElemTemplateElement t = varElem.getFirstChildElem();
// Down the line this can be done with multiple string objects using
// the concat function.
if (null != t && null == t.getNextSiblingElem())
{
int etype = t.getXSLToken();
if (Constants.ELEMNAME_VALUEOF == etype)
{
ElemValueOf valueof = (ElemValueOf) t;
// %TBD% I'm worried about extended attributes here.
if (valueof.getDisableOutputEscaping() == false
&& valueof.getDOMBackPointer() == null)
{
varElem.m_firstChild = null;
return new XPath(new XRTreeFragSelectWrapper(valueof.getSelect().getExpression()));
}
}
else if (Constants.ELEMNAME_TEXTLITERALRESULT == etype)
{
ElemTextLiteral lit = (ElemTextLiteral) t;
if (lit.getDisableOutputEscaping() == false
&& lit.getDOMBackPointer() == null)
{
String str = lit.getNodeValue();
XString xstr = new XString(str);
varElem.m_firstChild = null;
return new XPath(new XRTreeFragSelectWrapper(xstr));
}
}
}
return null;
}
/**
* This function is called during recomposition to
* control how this element is composed.
* @param root The root stylesheet for this transformation.
*/
public void recompose(StylesheetRoot root)
{
root.recomposeVariables(this);
}
/**
* Set the parent as an ElemTemplateElement.
*
* @param p This node's parent as an ElemTemplateElement
*/
public void setParentElem(ElemTemplateElement p)
{
super.setParentElem(p);
p.m_hasVariableDecl = true;
}
/**
* Accept a visitor and call the appropriate method
* for this class.
*
* @param visitor The visitor whose appropriate method will be called.
* @return true if the children of the object should be visited.
*/
protected boolean accept(XSLTVisitor visitor)
{
return visitor.visitVariableOrParamDecl(this);
}
/**
* Call the children visitors.
* @param visitor The visitor whose appropriate method will be called.
*/
protected void callChildVisitors(XSLTVisitor visitor, boolean callAttrs)
{
if(null != m_selectPattern)
m_selectPattern.getExpression().callVisitors(m_selectPattern, visitor);
super.callChildVisitors(visitor, callAttrs);
}
/**
* Tell if this is a psuedo variable reference, declared by Xalan instead
* of by the user.
*/
public boolean isPsuedoVar()
{
java.lang.String ns = m_qname.getNamespaceURI();
if((null != ns) && ns.equals(RedundentExprEliminator.PSUEDOVARNAMESPACE))
{
if(m_qname.getLocalName().startsWith("#"))
return true;
}
return false;
}
/**
* Add a child to the child list. If the select attribute
* is present, an error will be raised.
*
* @param elem New element to append to this element's children list
*
* @return null if the select attribute was present, otherwise the
* child just added to the child list
*/
public ElemTemplateElement appendChild(ElemTemplateElement elem)
{
// cannot have content and select
if (m_selectPattern != null)
{
error(XSLTErrorResources.ER_CANT_HAVE_CONTENT_AND_SELECT,
new Object[]{"xsl:" + this.getNodeName()});
return null;
}
return super.appendChild(elem);
}
}