Package net.sf.saxon.sxpath

Class XPathVariable

java.lang.Object
net.sf.saxon.sxpath.XPathVariable
All Implemented Interfaces:
Binding, LocalBinding
public final class XPathVariable extends Object implements LocalBinding
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.setVariable(XPathVariable, net.sf.saxon.om.Sequence). 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 Details

    • make

      public 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

    • 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)
      Specified by:
      isGlobal in interface Binding
      Returns:
      false (always)

    • 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.
      Specified by:
      isAssignable in interface Binding
      Returns:
      false (always)

    • 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

    • getRequiredType

      public SequenceType getRequiredType()
      Get the required type of this variable. If no required type has been specified, the type item()* is returned.
      Specified by:
      getRequiredType in interface Binding
      Returns:
      the required type of the variable

    • getIntegerBoundsForVariable

      public IntegerValue[] getIntegerBoundsForVariable()
      If the variable is bound to an integer, get the minimum and maximum possible values. Return null if unknown or not applicable
      Specified by:
      getIntegerBoundsForVariable in interface Binding
      Returns:
      a pair of integers containing the minimum and maximum values for the integer value; or null if the value is not an integer or the range is unknown

    • 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

    • 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.
      Specified by:
      getLocalSlotNumber in interface LocalBinding
      Returns:
      the slot number on the local stack frame

    • getVariableQName

      public StructuredQName getVariableQName()
      Get the name of the variable as a QNameValue.
      Specified by:
      getVariableQName in interface Binding
      Returns:
      the name of the variable, as a QNameValue

    • addReference

      public void addReference(VariableReference ref, boolean isLoopingReference)
      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.
      Specified by:
      addReference in interface Binding
      Parameters:
      ref - the variable reference
      isLoopingReference - - true if the reference occurs within a loop, such as the predicate of a filter expression

    • setDefaultValue

      public void setDefaultValue(Sequence defaultValue)
      Set a default value for the variable, to be used if no specific value is supplied when the expression is evaluated
      Parameters:
      defaultValue - the default value for the variable

    • getDefaultValue

      public Sequence getDefaultValue()
      Get the default value of the variable
      Returns:
      the default value if one has been registered, or null otherwise

    • evaluateVariable

      public Sequence 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 dynamic context.
      Specified by:
      evaluateVariable in interface Binding
      Parameters:
      context - The dynamic evaluation context
      Returns:
      The value of the variable

    • setIndexedVariable

      public void setIndexedVariable()
      Say that the bound value has the potential to be indexed
      Specified by:
      setIndexedVariable in interface LocalBinding

    • isIndexedVariable

      public boolean isIndexedVariable()
      Ask whether the binding is to be indexed
      Specified by:
      isIndexedVariable in interface LocalBinding
      Returns:
      true if the variable value can be indexed