Class Evaluate

    • Constructor Detail

      • Evaluate

        public Evaluate()
    • Method Detail

      • getRequiredType

        protected SequenceType getRequiredType​(int arg)
        Get the required type of the nth argument
        Overrides:
        getRequiredType in class SystemFunction
        Parameters:
        arg - the number of the argument whose type is requested, zero-based
        Returns:
        the required type of the argument as defined in the function signature
      • preEvaluate

        public Expression preEvaluate​(ExpressionVisitor visitor)
                               throws XPathException
        preEvaluate: for saxon:expression, if the expression is known at compile time, then it is compiled at compile time. In other cases this method suppresses compile-time evaluation by doing nothing (because the value of the expression depends on the runtime context).
        Overrides:
        preEvaluate in class FunctionCall
        Parameters:
        visitor - an expression visitor
        Returns:
        the result of the early evaluation, or the original expression, or potentially a simplified expression
        Throws:
        XPathException
      • addToPathMap

        public PathMap.PathMapNodeSet addToPathMap​(PathMap pathMap,
                                                   PathMap.PathMapNodeSet pathMapNodeSet)
        Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited by an expression in a source tree.

        The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.

        This particular implementation has to deal with the fact that saxon:evaluate() and related functions can navigate anywhere in the tree.

        Overrides:
        addToPathMap in class Expression
        Parameters:
        pathMap - the PathMap to which the expression should be added
        pathMapNodeSet - the PathMapNodeSet to which the paths embodied in this expression should be added
        Returns:
        the pathMapNodeSet representing the points in the source document that are both reachable by this expression, and that represent possible results of this expression. For an expression that does navigation, it represents the end of the arc in the path map that describes the navigation route. For other expressions, it is the same as the input pathMapNode.
      • evaluateItem

        public Item evaluateItem​(XPathContext c)
                          throws XPathException
        Evaluate in a general context
        Specified by:
        evaluateItem in interface EvaluableItem
        Overrides:
        evaluateItem in class Expression
        Parameters:
        c - 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
      • getIntrinsicDependencies

        public int getIntrinsicDependencies()
        Determine the dependencies
        Overrides:
        getIntrinsicDependencies in class Expression
        Returns:
        a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty