/// WARNING: Use only if T is a value type.
///
/// Returns the List's underlying array. Modifications made to it will
/// be reflected in the list.
///
/// The reflection version of this function is not especially fast; with
/// the added overhead, the break-even point for iterating over a []
/// instead of a List<> while doing a tiny amount of work (eg a vector
/// dot + multiply) is about about 40 elements.
/// TODO: investigate https://mattwarren.org/2016/12/14/Why-is-Reflection-slow/
///
/// The real win is getting to use Array.Copy, pointers, etc.
public static T[] GetBackingArray <T>(this List <T> list)
{
var pub = ConvertHelper <List <T>, PublicList <T> > .Convert(list);
if (pub != null)
{
return(pub.BackingArray);
}
else
{
return((T[])sm_items.Get(typeof(List <T>)).GetValue(list));
}
}
public static void SetBackingArray <T>(this List <T> list, T[] value)
{
var pub = ConvertHelper <List <T>, PublicList <T> > .Convert(list);
if (pub != null)
{
pub.BackingArray = value;
}
else
{
if (value == null)
{
throw new ArgumentNullException("value");
}
sm_items.Get(typeof(List <T>)).SetValue(list, value);
sm_size.Get(typeof(List <T>)).SetValue(list, value.Length);
}
}