/// <summary>
/// Combines one or more ReadOnlySequences into a single ReadOnlySequence
/// </summary>
/// <typeparam name="T">The element type in the sequence</typeparam>
/// <param name="source">An enumeration of ReadOnlySequences</param>
/// <returns>The concatenation of the given ReadOnlySequences</returns>
public static ReadOnlySequence<T> Combine<T>(this IEnumerable<ReadOnlySequence<T>> source)
{
if (source == null)
throw new ArgumentNullException(nameof(source));
ReadOnlySequence<T>? FirstSequence = null;
CombinedSegment<T>? StartSegment = null, CurrentSegment = null;
// Merge all the sequences into one
foreach (var Sequence in source)
{
if (Sequence.IsEmpty)
continue;
if (CurrentSegment == null)
{
// Cache the first sequence. If there are no others, we can just return it as-is
if (FirstSequence == null)
{
FirstSequence = Sequence;
continue;
}
// Found a second sequence
// Create the first segment of the linked list
StartSegment = CurrentSegment = new CombinedSegment<T>(FirstSequence.Value.First);
// Append any subsequent segments
foreach (var ChildSegment in FirstSequence.Value.Slice(StartSegment.Memory.Length))
CurrentSegment = new CombinedSegment<T>(CurrentSegment, ChildSegment);
}
// Append the segments of this sequence to the linked list as well
foreach (var ChildSegment in Sequence)
CurrentSegment = new CombinedSegment<T>(CurrentSegment, ChildSegment);
}
if (CurrentSegment == null)
{
// Only found one non-empty sequence
if (FirstSequence != null)
return FirstSequence.Value;
// Found no non-empty sequences
return ReadOnlySequence<T>.Empty;
}
return new ReadOnlySequence<T>(StartSegment!, 0, CurrentSegment, CurrentSegment.Memory.Length);
}
/// <summary>
/// Encodes a char sequence as a byte sequence
/// </summary>
/// <param name="sequence">The char sequence to decode</param>
/// <param name="encoding">The encoding to use</param>
/// <returns>The encoded contents of the sequence</returns>
public static ReadOnlySequence<byte> Encode(this ReadOnlySequence<char> sequence, Encoding encoding)
{
if (encoding == null)
throw new ArgumentNullException(nameof(encoding));
if (sequence.IsSingleSegment)
return new ReadOnlySequence<byte>(encoding.GetBytes(sequence.First.Span));
var Encoder = encoding.GetEncoder();
CombinedSegment<byte>? StartSegment = null, CurrentSegment = null;
foreach (var MySegment in sequence)
{
var InBuffer = MySegment.Span;
var OutBuffer = new byte[Encoder.GetByteCount(InBuffer, false)];
var WrittenChars = Encoder.GetBytes(InBuffer, OutBuffer, false);
var OutSegment = new ReadOnlyMemory<byte>(OutBuffer, 0, WrittenChars);
if (StartSegment == null)
StartSegment = CurrentSegment = new CombinedSegment<byte>(OutSegment);
else
CurrentSegment = new CombinedSegment<byte>(CurrentSegment!, OutSegment);
}
// Flush the encoder
var RemainingBytes = Encoder.GetByteCount(Array.Empty<char>(), true);
if (RemainingBytes > 0)
{
var OutBuffer = new byte[RemainingBytes];
var WrittenChars = Encoder.GetBytes(Array.Empty<char>(), OutBuffer, true);
var OutSegment = new ReadOnlyMemory<byte>(OutBuffer, 0, WrittenChars);
if (StartSegment == null)
StartSegment = CurrentSegment = new CombinedSegment<byte>(OutSegment);
else
CurrentSegment = new CombinedSegment<byte>(CurrentSegment!, OutSegment);
}
if (CurrentSegment == null)
return ReadOnlySequence<byte>.Empty;
return new ReadOnlySequence<byte>(StartSegment!, 0, CurrentSegment, CurrentSegment.Memory.Length);
}
/// <summary>
/// Combines one or more ReadOnlyMemory blocks into a single ReadOnlySequence
/// </summary>
/// <typeparam name="T">The element type in the sequence</typeparam>
/// <param name="source">An enumeration of ReadOnlyMemory blocks</param>
/// <returns>A ReadOnlySequence from the given blocks</returns>
public static ReadOnlySequence<T> Combine<T>(this IEnumerable<ReadOnlyMemory<T>> source)
{
if (source == null)
throw new ArgumentNullException(nameof(source));
ReadOnlyMemory<T>? FirstSegment = null;
CombinedSegment<T>? StartSegment = null, CurrentSegment = null;
foreach (var Segment in source)
{
if (Segment.IsEmpty)
continue;
if (CurrentSegment == null)
{
// Cache the first segment. If there are no others, we can just wrap it as-is
if (FirstSegment == null)
{
FirstSegment = Segment;
continue;
}
// Found a second segment
// Create the first segment of the linked list
StartSegment = CurrentSegment = new CombinedSegment<T>(FirstSegment.Value);
}
CurrentSegment = new CombinedSegment<T>(CurrentSegment, Segment);
}
if (CurrentSegment == null)
{
// Only found one non-empty sequence
if (FirstSegment != null)
return new ReadOnlySequence<T>(FirstSegment.Value);
// Found no non-empty sequences
return ReadOnlySequence<T>.Empty;
}
return new ReadOnlySequence<T>(StartSegment!, 0, CurrentSegment, CurrentSegment.Memory.Length);
}
