public static Span <T> Flatten <T>(this ISpanSequence <T> sequence)
{
var position = Position.First;
Span <T> firstSpan;
// if sequence length == 0
if (!sequence.TryGet(ref position, out firstSpan, advance: true))
{
return(Span <T> .Empty);
}
Span <T> secondSpan;
// if sequence length == 1
if (!sequence.TryGet(ref position, out secondSpan, advance: true))
{
return(firstSpan);
}
// allocate and copy
Span <T> result;
// if we know the total size of the sequence
if (sequence.TotalLength != null)
{
result = new T[sequence.TotalLength.Value];
result.Set(firstSpan);
result.Slice(firstSpan.Length).Set(secondSpan);
int copied = firstSpan.Length + secondSpan.Length;
Span <T> nextSpan;
while (sequence.TryGet(ref position, out nextSpan, advance: true))
{
nextSpan.CopyTo(result.Slice(copied));
copied += nextSpan.Length;
}
return(result);
}
else
{
var capacity = (firstSpan.Length + secondSpan.Length) * 2;
var resizableArray = new ResizableArray <T>(capacity);
firstSpan.CopyTo(ref resizableArray);
secondSpan.CopyTo(ref resizableArray);
Span <T> nextSpan;
int copied = firstSpan.Length + secondSpan.Length;
while (sequence.TryGet(ref position, out nextSpan, advance: true))
{
while (copied + nextSpan.Length > resizableArray.Capacity)
{
var newLength = resizableArray.Capacity * 2;
resizableArray.Resize(newLength);
}
nextSpan.CopyTo(ref resizableArray);
copied += nextSpan.Length;
}
return(resizableArray._array.Slice(0, copied));
}
}
/// <summary>
///
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="sequence"></param>
/// <param name="destination">The parameter is updated if it's longer than the items in the sequence</param>
/// <param name="skip">number of items from the begining of sequence to skip, i.e. not copy.</param>
/// <returns>True if all items did fit in the destination, false otherwise.</returns>
/// <remarks>If the destination is too short, up to destination.Length items are copied in, even if the function returns false.</remarks>
public static bool TryCopyTo <T>(this ISpanSequence <T> sequence, ref Span <T> destination, int skip = 0)
{
var position = Position.First;
Span <T> next;
int copied = 0;
while (sequence.TryGet(ref position, out next, advance: true))
{
var free = destination.Slice(copied);
if (skip > next.Length)
{
skip -= next.Length;
continue;
}
if (skip > 0)
{
next = next.Slice(skip);
}
if (free.Length > next.Length)
{
free.Set(next);
copied += next.Length;
}
else
{
free.Set(next.Slice(0, free.Length));
return(false);
}
}
destination = destination.Slice(0, copied);
return(true);
}
public static Span <T> First <T>(this ISpanSequence <T> sequence)
{
Span <T> result;
var first = Position.First;
if (!sequence.TryGet(ref first, out result))
{
ThrowHelper.ThrowInvalidOperationException();
}
return(result);
}
public bool MoveNext()
{
Span <T> span;
var result = _sequence.TryGet(ref _position, out span, advance: true);
if (_position == Position.First)
{
return(true);
}
if (_position == Position.AfterLast)
{
return(false);
}
return(result);
}
void IOutput.Enlarge(int desiredBufferLength)
{
if (NeedShift)
{
throw new NotImplementedException("need to allocate temp array");
}
_previousPosition = _currentPosition;
_previousWrittenBytes = _currentWrittenBytes;
Span <byte> span;
if (!_buffers.TryGet(ref _currentPosition, out span, advance: true))
{
throw new InvalidOperationException();
}
_currentWrittenBytes = 0;
}