private bool TryReadToAnyInternal(out ReadOnlySequence <T> sequence, ReadOnlySpan <T> delimiters, bool advancePastDelimiter, int skip = 0)
{
SequenceReader <T> copy = this;
if (skip > 0)
{
Advance(skip);
}
ReadOnlySpan <T> remaining = 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)
{
AdvanceCurrentSpan(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);
}
private bool TryReadToInternal(out ReadOnlySequence <T> sequence, T delimiter, bool advancePastDelimiter, int skip = 0)
{
Debug.Assert(skip >= 0);
SequenceReader <T> copy = this;
if (skip > 0)
{
Advance(skip);
}
ReadOnlySpan <T> remaining = UnreadSpan;
while (_moreData)
{
int index = remaining.IndexOf(delimiter);
if (index != -1)
{
// Found the delimiter. Move to it, slice, then move past it.
if (index > 0)
{
AdvanceCurrentSpan(index);
}
sequence = Sequence.Slice(copy.Position, Position);
if (advancePastDelimiter)
{
Advance(1);
}
return(true);
}
AdvanceCurrentSpan(remaining.Length);
remaining = CurrentSpan;
}
// Didn't find anything, reset our original state.
this = copy;
sequence = default;
return(false);
}
private bool TryReadToSlow(out ReadOnlySequence <T> sequence, T delimiter, T delimiterEscape, int index, bool advancePastDelimiter)
{
SequenceReader <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)
{
// An odd escape count means we're currently escaped,
// skip the delimiter and reset escaped state.
Advance(index + 1);
priorEscape = false;
remaining = UnreadSpan;
goto Continue;
}
}
// Found the delimiter. Move to it, slice, then move past it.
AdvanceCurrentSpan(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
AdvanceCurrentSpan(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
/// preceded 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 occurrence.</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)
{
SequenceReader <T> copy = this;
ReadOnlySpan <T> remaining = UnreadSpan;
bool priorEscape = false;
while (_moreData)
{
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 & 1) != 0)
{
// Odd escape count means 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);
}