Class FirstItemExpression.FirstItemExprElaborator

  • Enclosing class:

    public static class FirstItemExpression.FirstItemExprElaborator
    extends ItemElaborator
    An elaborator for a "first-item" expression, typically written as X[1] or as head(X).
    • Constructor Detail

      • FirstItemExprElaborator

        public FirstItemExprElaborator()
    • Method Detail

      • elaborateForItem

        public ItemEvaluator elaborateForItem()
        Description copied from class: Elaborator
        Get a function that evaluates the underlying expression in the form of a Item. This must only be called for expressions whose result has cardinality zero or one.
        Specified by:
        elaborateForItem in class ItemElaborator
        an evaluator for the expression that returns an Item, or null to represent an empty sequence.