org.apache.xpath.operations

Class Variable

Implemented Interfaces:
ExpressionNode, PathComponent, Serializable, SourceLocator, XPathVisitable
Known Direct Subclasses:
VariableSafeAbsRef

public class Variable
extends Expression
implements PathComponent

The variable reference expression executer.
See Also:
Serialized Form

Method Summary

void
callVisitors(ExpressionOwner owner, XPathVisitor visitor)
boolean
deepEquals(Expression expr)
XObject
execute(XPathContext xctxt)
Execute an expression in the XPath runtime context, and return the result of the expression.
XObject
execute(XPathContext xctxt, boolean destructiveOK)
Dereference the variable, and return the reference value.
void
fixupVariables(Vector vars, int globalsSize)
This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.
int
getAnalysisBits()
Get the analysis bits for this walker, as defined in the WalkerFactory.
ElemVariable
getElemVariable()
Get the XSLT ElemVariable that this sub-expression references.
boolean
getGlobal()
Set the index for the variable into the stack.
int
getIndex()
Set the index for the variable into the stack.
QName
getQName()
Get the qualified name of the variable.
boolean
isPsuedoVarRef()
Tell if this is a psuedo variable reference, declared by Xalan instead of by the user.
boolean
isStableNumber()
Tell if this expression returns a stable number that will not change during iterations within the expression.
void
setIndex(int index)
Set the index for the variable into the stack.
void
setIsGlobal(boolean isGlobal)
Set whether or not this is a global reference.
void
setQName(QName qname)
Set the qualified name of the variable.

Methods inherited from class org.apache.xpath.Expression

asIterator, asIteratorRaw, asNode, assertion, bool, canTraverseOutsideSubtree, deepEquals, error, execute, execute, execute, execute, executeCharsToContentHandler, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, fixupVariables, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isNodesetExpr, isStableNumber, num, warn, xstr

Method Details

callVisitors

public void callVisitors(ExpressionOwner owner,
                         XPathVisitor visitor)
Specified by:
callVisitors in interface XPathVisitable
See Also:
XPathVisitable.callVisitors(ExpressionOwner, XPathVisitor)

deepEquals

public boolean deepEquals(Expression expr)
Overrides:
deepEquals in interface Expression

execute

public XObject execute(XPathContext xctxt)
            throws TransformerException
Execute an expression in the XPath runtime context, and return the result of the expression.
Overrides:
execute in interface Expression
Parameters:
xctxt - The XPath runtime context.
Returns:
The result of the expression in the form of a XObject.

execute

public XObject execute(XPathContext xctxt,
                       boolean destructiveOK)
            throws TransformerException
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.
Overrides:
execute in interface Expression
Parameters:
xctxt - The runtime execution context.
Returns:
The evaluated variable, or an empty nodeset if not found.

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.
Overrides:
fixupVariables in interface Expression
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.
Specified by:
getAnalysisBits in interface PathComponent
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.
Overrides:
isStableNumber in interface Expression
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) 2004 Apache XML Project. All Rights Reserved.