net.sf.saxon.sxpath

Class XPathVariable

public final class XPathVariable extends Object implements VariableDeclaration, Binding, Serializable

An object representing an XPath variable for use in the standalone XPath API. The object can only be created by calling the declareVariable method of class IndependentContext. Note that once declared, this object is thread-safe: it does not hold the actual variable value, which means it can be used with any number of evaluations of a given XPath expression, in series or in parallel.

A variable can be given a value by calling XPathDynamicContext. Note that the value of the variable is not held in the XPathVariable object, but in the XPathDynamicContext, which means that the XPathVariable itself can be used in multiple threads.

Method Summary
ValueRepresentationevaluateVariable(XPathContext context)
Get the value of the variable.
intgetLocalSlotNumber()
If this is a local variable held on the local stack frame, return the corresponding slot number.
SequenceTypegetRequiredType()
Get the required type of this variable.
StructuredQNamegetVariableQName()
Get the name of the variable as a QNameValue.
booleanisAssignable()
Test whether it is permitted to assign to the variable using the saxon:assign extension element.
booleanisGlobal()
Ask whether the binding is local or global.
protected static XPathVariablemake(StructuredQName name)
Factory method, for use by the declareVariable method of class IndependentContext
voidregisterReference(BindingReference ref)
Method called by the XPath expression parser to register a reference to this variable.
voidsetRequiredType(SequenceType requiredType)
Set the required type of this variable.
voidsetSlotNumber(int slotNumber)
Set the slot number allocated to this variable.

Method Detail

evaluateVariable

public ValueRepresentation evaluateVariable(XPathContext context)
Get the value of the variable. This method is used by the XPath execution engine to retrieve the value. Note that the value is not held within the variable itself, but within the dunamic context.

Parameters: context The dynamic evaluation context

Returns: The value of the variable

getLocalSlotNumber

public int getLocalSlotNumber()
If this is a local variable held on the local stack frame, return the corresponding slot number. In other cases, return -1.

getRequiredType

public SequenceType getRequiredType()
Get the required type of this variable. If no required type has been specified, the type item()* is returned.

Returns: the required type of the variable

getVariableQName

public StructuredQName getVariableQName()
Get the name of the variable as a QNameValue.

Returns: the name of the variable, as a QNameValue

isAssignable

public final boolean isAssignable()
Test whether it is permitted to assign to the variable using the saxon:assign extension element. This will only be for an XSLT global variable where the extra attribute saxon:assignable="yes" is present.

Returns: false (always)

isGlobal

public boolean isGlobal()
Ask whether the binding is local or global. A global binding is one that has a fixed value for the life of a query or transformation; any other binding is local. An XPath variable is treated as a local variable (largely because it is held on the stack frame)

Returns: false (always)

make

protected static XPathVariable make(StructuredQName name)
Factory method, for use by the declareVariable method of class IndependentContext

Parameters: name the name of the variable to create

Returns: the constructed XPathVariable

registerReference

public void registerReference(BindingReference ref)
Method called by the XPath expression parser to register a reference to this variable. This method should not be called by users of the API.

setRequiredType

public void setRequiredType(SequenceType requiredType)
Set the required type of this variable. If no required type is specified, the type item()* is assumed.

Parameters: requiredType the required type

setSlotNumber

public void setSlotNumber(int slotNumber)
Set the slot number allocated to this variable. This method is for internal use.

Parameters: slotNumber the slot number to be allocated