org.apache.xpath.operations
Class Variable

java.lang.Object
  |
  +--org.apache.xpath.Expression
        |
        +--org.apache.xpath.operations.Variable
Direct Known Subclasses:
VariableSafeAbsRef

public class Variable
extends Expression
implements PathComponent

The variable reference expression executer.

See Also:
Serialized Form

Constructor Summary
Variable()
           
 
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(java.util.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, num, warn, xstr
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

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(java.util.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).
Overrides:
fixupVariables in class Expression

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.
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.
Overrides:
execute in class Expression

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.
Parameters:
xctxt - The runtime execution context.
Returns:
The evaluated variable, or an empty nodeset if not found.
Throws:
TransformerException -  
Overrides:
execute in class Expression

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.
Returns:
true if the expression represents a stable number.
Overrides:
isStableNumber in class Expression

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)
See Also:
XPathVisitable.callVisitors(ExpressionOwner, XPathVisitor)

deepEquals

public boolean deepEquals(Expression expr)
Overrides:
deepEquals in class Expression
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.


Copyright 2006 Apache XML Project. All Rights Reserved.