public static IEnumerable <SearchItem> Last(SearchExpressionContext c)
{
var argIndex = 0;
var takeNumber = 1;
if (c.args[0].types.HasFlag(SearchExpressionType.Number))
{
++argIndex;
takeNumber = Math.Max((int)(c.args[0].GetNumberValue(takeNumber)), 0);
}
var queue = new Queue <SearchItem>(takeNumber);
return(c.ForEachArgument((context, e) =>
{
queue.Clear();
if (takeNumber == 0)
{
context.Break();
}
}, argIndex).AggregateResults(queue, (context, item, aggregator) =>
{
if (queue.Count == takeNumber)
{
queue.Dequeue();
}
queue.Enqueue(item);
}));
}
public static IEnumerable <SearchItem> First(SearchExpressionContext c)
{
var argIndex = 0;
var takeNumber = 1;
if (c.args[0].types.HasFlag(SearchExpressionType.Number))
{
++argIndex;
takeNumber = Math.Max((int)(c.args[0].GetNumberValue(takeNumber)), 0);
}
var taken = 0;
return(c.ForEachArgument((context, e) =>
{
taken = 0;
if (takeNumber == 0)
{
context.Break();
}
}, argIndex).ForEachResult((context, item) =>
{
if (taken >= takeNumber)
{
context.Break();
return null;
}
++taken;
return item;
}));
}
public static IEnumerable <SearchItem> Avg(SearchExpressionContext c)
{
var skipCount = 0;
string selector = null;
if (c.args[0].types.HasFlag(SearchExpressionType.Selector))
{
skipCount++;
selector = c.args[0].innerText.ToString();
}
return(c.ForEachArgument(skipCount).AggregateResults(Average.Zero,
(context, item, avg) => Aggregate(item, selector, avg, (d, _avg) => _avg.Add(d)),
(context, avg) => EvaluatorUtils.CreateItem(avg.result, context.ResolveAlias("Average"))));
}
public static IEnumerable <SearchItem> Max(SearchExpressionContext c)
{
var skipCount = 0;
string selector = null;
if (c.args[0].types.HasFlag(SearchExpressionType.Selector))
{
skipCount++;
selector = c.args[0].innerText.ToString();
}
return(c.ForEachArgument(skipCount).AggregateResults(double.MinValue,
(context, item, max) => Aggregate(item, selector, max, (d, _max) => d > _max),
(context, max) => EvaluatorUtils.CreateItem(max, context.ResolveAlias("Max"))));
}
public static IEnumerable <SearchItem> Sum(SearchExpressionContext c)
{
var skipCount = 0;
string selector = null;
if (c.args[0].types.HasFlag(SearchExpressionType.Selector))
{
skipCount++;
selector = c.args[0].innerText.ToString();
}
return(c.ForEachArgument(skipCount).AggregateResults(0d,
(context, item, sum) => Aggregate(item, selector, sum, (d, _sum) => _sum + d),
(context, sum) => EvaluatorUtils.CreateItem(sum, context.ResolveAlias("Sum"))));
}