Class ItemChecker

    • Constructor Detail

      • ItemChecker

        public ItemChecker​(Expression sequence,
                           ItemType itemType,
                           RoleLocator role)
        Constructor
        Parameters:
        sequence - the expression whose value we are checking
        itemType - the required type of the items in the sequence
        role - information used in constructing an error message
    • Method Detail

      • getRequiredType

        public ItemType getRequiredType()
        Get the required type
        Returns:
        the required type of the items in the sequence
      • getRoleLocator

        public RoleLocator getRoleLocator()
        Get the RoleLocator (used to construct error messages)
        Returns:
        the RoleLocator
      • typeCheck

        public Expression typeCheck​(ExpressionVisitor visitor,
                                    ItemType contextItemType)
                             throws XPathException
        Type-check the expression
        Overrides:
        typeCheck in class UnaryExpression
        Parameters:
        visitor - an expression visitor
        contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE
        Returns:
        the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
        Throws:
        XPathException - if an error is discovered during this phase (typically a type error)
      • evaluateItem

        public Item evaluateItem​(XPathContext context)
                          throws XPathException
        Evaluate as an Item.
        Specified by:
        evaluateItem in interface EvaluableItem
        Overrides:
        evaluateItem in class Expression
        Parameters:
        context - The context in which the expression is to be evaluated
        Returns:
        the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression
      • process

        public void process​(XPathContext context)
                     throws XPathException
        Process the instruction, without returning any tail calls
        Overrides:
        process in class Expression
        Parameters:
        context - The dynamic context, giving access to the current node, the current variables, etc.
        Throws:
        XPathException
      • copy

        public Expression copy()
        Copy an expression. This makes a deep copy.
        Specified by:
        copy in class Expression
        Returns:
        the copy of the original expression
      • getItemType

        public ItemType getItemType​(TypeHierarchy th)
        Determine the data type of the items returned by the expression
        Overrides:
        getItemType in class UnaryExpression
        Parameters:
        th - the type hierarchy cache
        Returns:
        the item type of the items in the result sequence, insofar as this is known statically.
      • equals

        public boolean equals​(java.lang.Object other)
        Is this expression the same as another expression?
        Overrides:
        equals in class UnaryExpression
      • explain

        public void explain​(ExpressionPresenter out)
        Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
        Overrides:
        explain in class UnaryExpression
        Parameters:
        out - the expression presenter used to display the structure