Class CastableExpression

    • Field Detail

      • allowEmpty

        boolean allowEmpty
    • Constructor Detail

      • CastableExpression

        public CastableExpression​(Expression source,
                                  AtomicType target,
                                  boolean allowEmpty)
    • Method Detail

      • typeCheck

        public Expression typeCheck​(StaticContext env,
                                    ItemType contextItemType)
                             throws XPathException
        Type-check the expression
        Specified by:
        typeCheck in interface Expression
        Overrides:
        typeCheck in class UnaryExpression
        Parameters:
        env - the static context of the expression
        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:
        StaticError - if an error is discovered during this phase (typically a type error)
        XPathException
      • optimize

        public Expression optimize​(Optimizer opt,
                                   StaticContext env,
                                   ItemType contextItemType)
                            throws XPathException
        Optimize the expression
        Specified by:
        optimize in interface Expression
        Overrides:
        optimize in class UnaryExpression
        Parameters:
        opt - the optimizer in use. This provides access to supporting functions; it also allows different optimization strategies to be used in different circumstances.
        env - the static context of the expression
        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 if appropriate to optimize execution
        Throws:
        net.sf.saxon.trans.StaticError - if an error is discovered during this phase (typically a type error)
        XPathException
      • equals

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

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

        public int computeCardinality()
        Description copied from class: UnaryExpression
        Determine the static cardinality. Default implementation returns the cardinality of the operand
        Overrides:
        computeCardinality in class UnaryExpression
      • evaluateItem

        public Item evaluateItem​(XPathContext context)
        Evaluate the expression
        Specified by:
        evaluateItem in interface Expression
        Overrides:
        evaluateItem in class ComputedExpression
        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
      • effectiveBooleanValue

        public boolean effectiveBooleanValue​(XPathContext context)
        Description copied from class: ComputedExpression
        Get the effective boolean value of the expression. This returns false if the value is the empty sequence, a zero-length string, a number equal to zero, or the boolean false. Otherwise it returns true.
        Specified by:
        effectiveBooleanValue in interface Expression
        Overrides:
        effectiveBooleanValue in class ComputedExpression
        Parameters:
        context - The context in which the expression is to be evaluated
        Returns:
        the effective boolean value
      • displayOperator

        protected java.lang.String displayOperator​(Configuration config)
        Give a string representation of the operator for use in diagnostics
        Specified by:
        displayOperator in class UnaryExpression
        Parameters:
        config -
        Returns:
        the operator, as a string