org.apache.xpath.operations
Class Variable

java.lang.Object
  extended byorg.apache.xpath.Expression
      extended byorg.apache.xpath.operations.Variable
All Implemented Interfaces:
ExpressionNode, PathComponent, Serializable, javax.xml.transform.SourceLocator, XPathVisitable
Direct Known Subclasses:
VariableSafeAbsRef

public class Variable
extends Expression
implements PathComponent

The variable reference expression executer.

See Also:
Serialized Form

Field Summary
private  boolean m_fixUpWasCalled
          Tell if fixupVariables was called.
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.
(package private) static String PSUEDOVARNAMESPACE
           
 
Fields inherited from class org.apache.xpath.Expression
 
Constructor Summary
Variable()
           
 
Method Summary
 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_fixUpWasCalled

private boolean m_fixUpWasCalled
Tell if fixupVariables was called.


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

PSUEDOVARNAMESPACE

static final String PSUEDOVARNAMESPACE
See Also:
Constant Field Values
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 javax.xml.transform.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:
javax.xml.transform.TransformerException - if a runtime exception occurs.

execute

public XObject execute(XPathContext xctxt,
                       boolean destructiveOK)
                throws javax.xml.transform.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:
javax.xml.transform.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.