org.apache.xpath.operations

Class Variable

public class Variable extends Expression implements PathComponent

The variable reference expression executer.
Method Summary
voidcallVisitors(ExpressionOwner owner, XPathVisitor visitor)
booleandeepEquals(Expression expr)
XObjectexecute(XPathContext xctxt)
Execute an expression in the XPath runtime context, and return the result of the expression.
XObjectexecute(XPathContext xctxt, boolean destructiveOK)
Dereference the variable, and return the reference value.
voidfixupVariables(Vector vars, int globalsSize)
This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.
intgetAnalysisBits()
Get the analysis bits for this walker, as defined in the WalkerFactory.
ElemVariablegetElemVariable()
Get the XSLT ElemVariable that this sub-expression references.
booleangetGlobal()
Set the index for the variable into the stack.
intgetIndex()
Set the index for the variable into the stack.
QNamegetQName()
Get the qualified name of the variable.
booleanisPsuedoVarRef()
Tell if this is a psuedo variable reference, declared by Xalan instead of by the user.
booleanisStableNumber()
Tell if this expression returns a stable number that will not change during iterations within the expression.
voidsetIndex(int index)
Set the index for the variable into the stack.
voidsetIsGlobal(boolean isGlobal)
Set whether or not this is a global reference.
voidsetQName(QName qname)
Set the qualified name of the variable.

Method Detail

callVisitors

public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)

See Also: XPathVisitable

deepEquals

public boolean deepEquals(Expression expr)

See Also: deepEquals

execute

public XObject execute(XPathContext xctxt)
Execute an expression in the XPath runtime context, and return the result of the expression.

Parameters: xctxt The XPath runtime context.

Returns: The result of the expression in the form of a XObject.

Throws: javax.xml.transform.TransformerException if a runtime exception occurs.

execute

public XObject execute(XPathContext xctxt, boolean destructiveOK)
Dereference the variable, and return the reference value. Note that lazy evaluation will occur. If a variable within scope is not found, a warning will be sent to the error listener, and an empty nodeset will be returned.

Parameters: xctxt The runtime execution context.

Returns: The evaluated variable, or an empty nodeset if not found.

Throws: javax.xml.transform.TransformerException

fixupVariables

public void fixupVariables(Vector vars, int globalsSize)
This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.

Parameters: 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).

getAnalysisBits

public int getAnalysisBits()
Get the analysis bits for this walker, as defined in the WalkerFactory.

Returns: One of WalkerFactory#BIT_DESCENDANT, etc.

getElemVariable

public ElemVariable getElemVariable()
Get the XSLT ElemVariable that this sub-expression references. In order for this to work, the SourceLocator must be the owning ElemTemplateElement.

Returns: The dereference to the ElemVariable, or null if not found.

getGlobal

public boolean getGlobal()
Set the index for the variable into the stack. For advanced use only.

Returns: true if this should be a global variable reference.

getIndex

public int getIndex()
Set the index for the variable into the stack. For advanced use only.

Returns: index a global or local index.

getQName

public QName getQName()
Get the qualified name of the variable.

Returns: A non-null reference to a qualified name.

isPsuedoVarRef

public boolean isPsuedoVarRef()
Tell if this is a psuedo variable reference, declared by Xalan instead of by the user.

isStableNumber

public boolean isStableNumber()
Tell if this expression returns a stable number that will not change during iterations within the expression. This is used to determine if a proximity position predicate can indicate that no more searching has to occur.

Returns: true if the expression represents a stable number.

setIndex

public void setIndex(int index)
Set the index for the variable into the stack. For advanced use only. You must know what you are doing to use this.

Parameters: index a global or local index.

setIsGlobal

public void setIsGlobal(boolean isGlobal)
Set whether or not this is a global reference. For advanced use only.

Parameters: isGlobal true if this should be a global variable reference.

setQName

public void setQName(QName qname)
Set the qualified name of the variable.

Parameters: qname Must be a non-null reference to a qualified name.

Copyright B) 2006 Apache XML Project. All Rights Reserved.