Class JAXPVariable

  • All Implemented Interfaces:
    Binding, VariableDeclaration

    public final class JAXPVariable
    extends java.lang.Object
    implements VariableDeclaration, Binding
    An object representing an XPath variable for use in the JAXP XPath API. The object is created at compile time when the parser tries to bind a variable reference; the value is fetched at run-time from the XPathVariableResolver. With this interface, there is no way of reporting a static error if the variable has not been declared.

    In Saxon terms, this class is both a VariableDeclaration and a Binding. Unlike a normal VariableDeclaration, it isn't created in advance, but is created on demand when the parser encounters a variable reference. This actually means that if the XPath expression contains two references to the same variable, two VariableDeclarations will be created; however, they will be indistinguishable to the VariableResolver. Acting as a VariableDeclaration, the object goes through the motions of fixing up a binding to a variable reference (in practice, of course, there is exactly one reference to the variable). Acting as a run-time binding, it then evaluates the variable by calling the XPathVariableResolver supplied by the API caller. If no XPathVariableResolver was supplied, an error is reported when a variable is encountered; but if the variable resolver doesn't recognize the variable name, it returns null, which is treated as an empty sequence.

    • Constructor Summary

      Constructors 
      Constructor Description
      JAXPVariable​(QNameValue name, javax.xml.xpath.XPathVariableResolver resolver)
      Private constructor: for use only be the protected factory method make()
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      ValueRepresentation evaluateVariable​(XPathContext context)
      Get the value of the variable.
      int getLocalSlotNumber()
      If this is a local variable held on the local stack frame, return the corresponding slot number.
      int getNameCode()
      Establish the fingerprint of the name of this variable.
      java.lang.String getVariableName()
      Get the name of the variable.
      boolean isAssignable()
      Test whether it is permitted to assign to the variable using the saxon:assign extension element.
      boolean isGlobal()
      Indicate whether the binding is local or global.
      (package private) javax.xml.namespace.QName makeQName​(QNameValue in)  
      void registerReference​(BindingReference ref)
      Method called by the XPath expression parser to register a reference to this variable.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • JAXPVariable

        public JAXPVariable​(QNameValue name,
                            javax.xml.xpath.XPathVariableResolver resolver)
        Private constructor: for use only be the protected factory method make()
    • Method Detail

      • isGlobal

        public boolean isGlobal()
        Indicate 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.
        Specified by:
        isGlobal in interface Binding
      • 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
      • 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 Binding
      • getVariableName

        public java.lang.String getVariableName()
        Get the name of the variable. Used for diagnostic purposes only.
        Specified by:
        getVariableName in interface VariableDeclaration
        Returns:
        the name of the variable, as a string (containing the raw QName)
      • getNameCode

        public int getNameCode()
        Establish the fingerprint of the name of this variable. Dummy implementation, not used.
        Specified by:
        getNameCode in interface VariableDeclaration
        Returns:
        -1, always
      • 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.
        Specified by:
        registerReference in interface VariableDeclaration
      • makeQName

        javax.xml.namespace.QName makeQName​(QNameValue in)