public static bool TryReadUntill(ref BufferReader reader, out ReadOnlySequence <byte> bytes, byte delimiter)
{
var copy = reader;
var start = reader.Position;
while (!reader.End)
{
SequencePosition end = reader.Position;
if (reader.Read() == delimiter)
{
bytes = reader.Sequence.Slice(start, end);
return(true);
}
}
reader = copy;
bytes = default;
return(false);
}
private bool TryReadToAnyInternal(out ReadOnlySequence <T> sequence, ReadOnlySpan <T> delimiters, bool advancePastDelimiter, int skip = 0)
{
BufferReader <T> copy = this;
if (skip > 0)
{
Advance(skip);
}
ReadOnlySpan <T> remaining = CurrentSpanIndex == 0 ? CurrentSpan : UnreadSpan;
while (!End)
{
int index = delimiters.Length == 2
? remaining.IndexOfAny(delimiters[0], delimiters[1])
: remaining.IndexOfAny(delimiters);
if (index != -1)
{
// Found one of the delimiters. Move to it, slice, then move past it.
if (index > 0)
{
Advance(index);
}
sequence = Sequence.Slice(copy.Position, Position);
if (advancePastDelimiter)
{
Advance(1);
}
return(true);
}
Advance(remaining.Length);
remaining = CurrentSpan;
}
// Didn't find anything, reset our original state.
this = copy;
sequence = default;
return(false);
}
public static bool TryRead(ref BufferReader reader, out int value, bool littleEndian = false)
{
var unread = reader.UnreadSegment;
if (littleEndian)
{
if (BinaryPrimitives.TryReadInt32LittleEndian(unread, out value))
{
reader.Advance(sizeof(int));
return(true);
}
}
else if (BinaryPrimitives.TryReadInt32BigEndian(unread, out value))
{
reader.Advance(sizeof(int));
return(true);
}
Span <byte> tempSpan = stackalloc byte[4];
var copied = Peek(reader, tempSpan);
if (copied < 4)
{
value = default;
return(false);
}
if (littleEndian)
{
value = BinaryPrimitives.ReadInt32LittleEndian(tempSpan);
}
else
{
value = BinaryPrimitives.ReadInt32BigEndian(tempSpan);
}
reader.Advance(sizeof(int));
return(true);
}
internal static int Peek(BufferReader bytes, Span <byte> destination)
{
var first = bytes.UnreadSegment;
if (first.Length > destination.Length)
{
first.Slice(0, destination.Length).CopyTo(destination);
return(destination.Length);
}
else if (first.Length == destination.Length)
{
first.CopyTo(destination);
return(destination.Length);
}
else
{
first.CopyTo(destination);
int copied = first.Length;
var next = bytes._nextSequencePosition;
while (bytes.Sequence.TryGet(ref next, out ReadOnlyMemory <byte> nextSegment, true))
{
var nextSpan = nextSegment.Span;
if (nextSpan.Length > 0)
{
var toCopy = Math.Min(nextSpan.Length, destination.Length - copied);
nextSpan.Slice(0, toCopy).CopyTo(destination.Slice(copied));
copied += toCopy;
if (copied >= destination.Length)
{
break;
}
}
}
return(copied);
}
}
public static bool TryParse(ref BufferReader reader, out bool value)
{
var unread = reader.UnreadSegment;
if (Utf8Parser.TryParse(unread, out value, out int consumed))
{
if (unread.Length > consumed)
{
reader.Advance(consumed);
return(true);
}
}
Span <byte> tempSpan = stackalloc byte[5];
var copied = BufferReaderExtensions.Peek(reader, tempSpan);
if (Utf8Parser.TryParse(tempSpan.Slice(0, copied), out value, out consumed))
{
reader.Advance(consumed);
return(true);
}
return(false);
}
private bool TryReadToSlow(out ReadOnlySequence <T> sequence, T delimiter, T delimiterEscape, int index, bool advancePastDelimiter)
{
BufferReader <T> copy = this;
ReadOnlySpan <T> remaining = UnreadSpan;
bool priorEscape = false;
do
{
if (index >= 0)
{
if (index == 0 && priorEscape)
{
// We were in the escaped state, so skip this delimiter
priorEscape = false;
Advance(index + 1);
remaining = UnreadSpan;
goto Continue;
}
else if (index > 0 && remaining[index - 1].Equals(delimiterEscape))
{
// This delimiter might be skipped
// Count our escapes
int escapeCount = 1;
int i = index - 2;
for (; i >= 0; i--)
{
if (!remaining[i].Equals(delimiterEscape))
{
break;
}
}
if (i < 0 && priorEscape)
{
// Started and ended with escape, increment once more
escapeCount++;
}
escapeCount += index - 2 - i;
if ((escapeCount & 1) != 0)
{
priorEscape = false;
// We're in the escaped state, so skip this delimiter
Advance(index + 1);
remaining = UnreadSpan;
goto Continue;
}
}
// Found the delimiter. Move to it, slice, then move past it.
Advance(index);
sequence = Sequence.Slice(copy.Position, Position);
if (advancePastDelimiter)
{
Advance(1);
}
return(true);
}
else
{
// No delimiter, need to check the end of the span for odd number of escapes then advance
if (remaining.Length > 0 && remaining[remaining.Length - 1].Equals(delimiterEscape))
{
int escapeCount = 1;
int i = remaining.Length - 2;
for (; i >= 0; i--)
{
if (!remaining[i].Equals(delimiterEscape))
{
break;
}
}
escapeCount += remaining.Length - 2 - i;
if (i < 0 && priorEscape)
{
priorEscape = (escapeCount & 1) == 0; // equivalent to incrementing escapeCount before setting priorEscape
}
else
{
priorEscape = (escapeCount & 1) != 0;
}
}
else
{
priorEscape = false;
}
}
// Nothing in the current span, move to the end, checking for the skip delimiter
Advance(remaining.Length);
remaining = CurrentSpan;
Continue:
index = remaining.IndexOf(delimiter);
} while (!End);
// Didn't find anything, reset our original state.
this = copy;
sequence = default;
return(false);
}
/// <summary>
/// Try to read everything up to the given <paramref name="delimiter"/>, ignoring delimiters that are
/// preceeded by <paramref name="delimiterEscape"/>.
/// </summary>
/// <param name="sequence">The read data, if any.</param>
/// <param name="delimiter">The delimiter to look for.</param>
/// <param name="delimiterEscape">If found prior to <paramref name="delimiter"/> it will skip that occurence.</param>
/// <param name="advancePastDelimiter">True to move past the <paramref name="delimiter"/> if found.</param>
/// <returns>True if the <paramref name="delimiter"/> was found.</returns>
public bool TryReadTo(out ReadOnlySequence <T> sequence, T delimiter, T delimiterEscape, bool advancePastDelimiter = true)
{
BufferReader <T> copy = this;
ReadOnlySpan <T> remaining = UnreadSpan;
bool priorEscape = false;
while (!End)
{
int index = remaining.IndexOf(delimiter);
if (index != -1)
{
if (index == 0 && priorEscape)
{
// We were in the escaped state, so skip this delimiter
priorEscape = false;
Advance(index + 1);
remaining = UnreadSpan;
continue;
}
else if (index > 0 && remaining[index - 1].Equals(delimiterEscape))
{
// This delimiter might be skipped
// Count our escapes
int escapeCount = 0;
for (int i = index; i > 0 && remaining[i - 1].Equals(delimiterEscape); i--, escapeCount++)
{
;
}
if (escapeCount == index && priorEscape)
{
// Started and ended with escape, increment once more
escapeCount++;
}
priorEscape = false;
if (escapeCount % 2 != 0)
{
// We're in the escaped state, so skip this delimiter
Advance(index + 1);
remaining = UnreadSpan;
continue;
}
}
// Found the delimiter. Move to it, slice, then move past it.
if (index > 0)
{
Advance(index);
}
sequence = Sequence.Slice(copy.Position, Position);
if (advancePastDelimiter)
{
Advance(1);
}
return(true);
}
// No delimiter, need to check the end of the span for odd number of escapes then advance
{
int escapeCount = 0;
for (int i = remaining.Length; i > 0 && remaining[i - 1].Equals(delimiterEscape); i--, escapeCount++)
{
;
}
if (priorEscape && escapeCount == remaining.Length)
{
escapeCount++;
}
priorEscape = escapeCount % 2 != 0;
}
// Nothing in the current span, move to the end, checking for the skip delimiter
Advance(remaining.Length);
remaining = CurrentSpan;
}
// Didn't find anything, reset our original state.
this = copy;
sequence = default;
return(false);
}
