org.apache.xpath.operations

Class Variable

java.lang.Object

org.apache.xpath.Expression

org.apache.xpath.operations.Variable

All Implemented Interfaces:

Serializable, SourceLocator, PathComponent, ExpressionNode, XPathVisitable

Direct Known Subclasses:

VariableSafeAbsRef

public class Variable
extends Expression
implements PathComponent

The variable reference expression executer.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected int	m_index The index of the variable, which is either an absolute index to a global, or, if higher than the globals area, must be adjusted by adding the offset to the current stack frame.
protected boolean	m_isGlobal
protected QName	m_qname The qualified name of the variable.

Constructor Summary

Constructors

Constructor and Description
Variable()

Method Summary

Methods

Modifier and Type	Method and Description
void	callVisitors(ExpressionOwner owner, XPathVisitor visitor) This will traverse the heararchy, calling the visitor for each member.
boolean	deepEquals(Expression expr) Compare this object with another object and see if they are equal, include the sub heararchy.
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, error, execute, execute, executeCharsToContentHandler, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isNodesetExpr, isSameClass, num, warn, xstr

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

m_qname

protected QName m_qname

The qualified name of the variable.

m_index

protected int m_index

The index of the variable, which is either an absolute index to a global, or, if higher than the globals area, must be adjusted by adding the offset to the current stack frame.

m_isGlobal

protected boolean m_isGlobal

Constructor Detail

Variable

public Variable()

Method Detail

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.

getIndex

public int getIndex()

Set the index for the variable into the stack. For advanced use only.

Returns:

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.

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.

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.

Specified by:

fixupVariables in class 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).

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.

getQName

public QName getQName()

Get the qualified name of the variable.

Returns:

A non-null reference to a qualified name.

execute

public XObject execute(XPathContext xctxt)
                throws TransformerException

Execute an expression in the XPath runtime context, and return the result of the expression.

Specified by:

execute in class Expression

Parameters:

xctxt - The XPath runtime context.

Returns:

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

Throws:

TransformerException - if a runtime exception occurs.

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 class Expression

Parameters:

xctxt - The runtime execution context.

destructiveOK - true if a "safe" object doesn't need to be returned.

Returns:

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

Throws:

TransformerException

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.

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 class Expression

Returns:

true if the expression represents a stable number.

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.

callVisitors

public void callVisitors(ExpressionOwner owner,
                XPathVisitor visitor)

Description copied from interface: XPathVisitable

This will traverse the heararchy, calling the visitor for each member. If the called visitor method returns false, the subtree should not be called.

Specified by:

callVisitors in interface XPathVisitable

Parameters:

owner - The owner of the visitor, where that path may be rewritten if needed.

visitor - The visitor whose appropriate method will be called.

See Also:

XPathVisitable.callVisitors(ExpressionOwner, XPathVisitor)

deepEquals

public boolean deepEquals(Expression expr)

Description copied from class: Expression

Compare this object with another object and see if they are equal, include the sub heararchy.

Specified by:

deepEquals in class Expression

Parameters:

expr - Another expression object.

Returns:

true if this objects class and the expr object's class are the same, and the data contained within both objects are considered equal.

See Also:

Expression.deepEquals(Expression)

isPsuedoVarRef

public boolean isPsuedoVarRef()

Tell if this is a psuedo variable reference, declared by Xalan instead of by the user.