/// <summary>
/// Visits a <see cref="FirstPredicateOperator" /> node.
/// </summary>
/// <param name="op">Node to visit.</param>
/// <returns>Result of visiting the node.</returns>
protected internal override QueryOperator VisitFirstPredicate(FirstPredicateOperator op)
{
var src = VisitAndConvert <MonadMember>(op.Source);
var pred = Visit(op.Predicate);
if (src != op.Source || pred != op.Predicate)
{
return(MakeFirstPredicate(op, src, pred));
}
return(op);
}
/// <summary>
/// Makes a <see cref="FirstPredicateOperator" /> with the given children.
/// </summary>
/// <param name="node">Original query expression.</param>
/// <param name="source">Source query expression.</param>
/// <param name="predicate">Predicate query expression.</param>
/// <returns>Representation of the original query expression.</returns>
protected sealed override QueryOperator MakeFirstPredicate(FirstPredicateOperator node, MonadMember source, QueryTree predicate)
{
return(node.QueryExpressionFactory.First(node.ElementType, source, predicate));
}
/// <summary>
/// Creates a textual representation of the FirstPredicateOperator with the given children.
/// </summary>
/// <param name="node">Original query expression.</param>
/// <param name="source">Source query expression.</param>
/// <param name="predicate">Predicate query expression.</param>
/// <returns>Representation of the original query expression.</returns>
protected override string MakeFirstPredicate(FirstPredicateOperator node, string source, string predicate)
{
return(string.Format(CultureInfo.InvariantCulture, "@First({0}, {1})", source, predicate));
}
/// <summary>
/// Makes a <see cref="FirstPredicateOperator" /> with the given children.
/// </summary>
/// <param name="node">Original query expression.</param>
/// <param name="source">Source query expression.</param>
/// <param name="elementType">Element type for the resulting operator.</param>
/// <param name="predicate">Predicate query expression.</param>
/// <returns>Representation of the original query expression.</returns>
protected virtual QueryOperator MakeFirstPredicate(FirstPredicateOperator node, Type elementType, MonadMember source, QueryTree predicate)
{
return(node.QueryExpressionFactory.First(elementType, source, predicate));
}