/// <summary>
/// Safely returns the <see cref="Layout{T}"/> from a layout object.
/// </summary>
/// <param name="source"></param>
/// <param name="getter"></param>
/// <typeparam name="TLayout"></typeparam>
/// <typeparam name="T"></typeparam>
/// <returns></returns>
public static LayoutList <T> Select <TLayout, T>(this Layout <TLayout> source, Func <TLayout, LayoutList <T> > getter)
where TLayout : Layout
where T : Layout
{
if (source == null || !source.IsPresent)
{
return(LayoutList.Missing <T>());
}
return(getter(source.Value) ?? LayoutList.Missing <T>());
}
/// <summary>
/// Safely returns the <see cref="LayoutList{TValue}"/> from the parsed result.
/// </summary>
/// <param name="result"></param>
/// <param name="getter"></param>
/// <typeparam name="TCursor"></typeparam>
/// <typeparam name="TLayout"></typeparam>
/// <typeparam name="T"></typeparam>
/// <returns></returns>
public static LayoutList <T> Select <TCursor, TLayout, T>(this Result <Cursor <TCursor>, TLayout> result, Func <TLayout, LayoutList <T> > getter)
where TLayout : Layout
where T : Layout
{
if (result == null || !result.HasResult)
{
return(LayoutList.Missing <T>());
}
return(getter(result.Result) ?? LayoutList.Missing <T>());
}
/// <summary>
/// Safely returns the <see cref="Layout{T}"/> from a layout object.
/// </summary>
/// <param name="source"></param>
/// <param name="getter"></param>
/// <typeparam name="TLayout"></typeparam>
/// <typeparam name="T"></typeparam>
/// <returns></returns>
public static LayoutList <T> Select <TLayout, T>(this Layout <TLayout> source, Func <TLayout, LayoutList <T> > getter)
where TLayout : Layout
where T : Layout
{
Debug.Assert(source != null);
if (source == null || !source.HasValue)
{
return(LayoutList.Missing <T>());
}
return(getter(source.Value) ?? LayoutList.Missing <T>());
}