// TODO: Hide this ctor and force users to pass Positions. This will let us hide Position.Object
public ReadOnlyBytes(IBufferList first, IBufferList last)
{
_start = first;
_startIndex = 0;
_end = last;
_endIndex = last.Memory.Length;
Validate();
}
public ReadWriteBytes(IBufferList <byte> first, IBufferList <byte> last)
{
_start = first;
_startIndex = 0;
_end = last;
_endIndex = last.Memory.Length;
Validate();
}
public ReadOnlyBuffer(IBufferList startSegment, int offset, IBufferList endSegment, int endIndex)
{
Debug.Assert(startSegment != null);
Debug.Assert(endSegment != null);
Debug.Assert(startSegment.Memory.Length >= offset);
Debug.Assert(endSegment.Memory.Length >= endIndex);
BufferStart = new Position(startSegment, offset);
BufferEnd = new Position(endSegment, endIndex);
}
public static Position?PositionOf(this IBufferList list, byte value)
{
while (list != null)
{
var current = list.Memory.Span;
var index = current.IndexOf(value);
if (index != -1)
{
return(new Position(list, index));
}
list = list.Next;
}
return(null);
}
public static long IndexOf(this IBufferList list, ReadOnlySpan <byte> value)
{
var first = list.Memory.Span;
var index = first.IndexOf(value);
if (index != -1)
{
return(index);
}
var rest = list.Next;
if (rest == null)
{
return(-1);
}
return(IndexOfStraddling(first, list.Next, value));
}
public static int CopyTo(this IBufferList list, Span <byte> destination)
{
var current = list.Memory.Span;
int copied = 0;
while (destination.Length > 0)
{
if (current.Length >= destination.Length)
{
current.Slice(0, destination.Length).CopyTo(destination);
copied += destination.Length;
return(copied);
}
else
{
current.CopyTo(destination);
copied += current.Length;
destination = destination.Slice(current.Length);
}
}
return(copied);
}
public ReadWriteBytes(IBufferList <byte> segments) :
this(segments.First, segments.Rest, Unspecified)
{
}
public ReadWriteBytes(IBufferList <byte> segments, int length) :
this(segments.First, segments.Rest, length)
{
}
public ReadWriteBytes(Buffer <byte> first, IBufferList <byte> rest) :
this(first, rest, Unspecified)
{
}
public ReadWriteBytes(Buffer <byte> first, IBufferList <byte> rest, int length)
{
_rest = rest;
_first = first;
_length = length;
}
// TODO (pri 3): I am pretty sure this whole routine can be written much better
// searches values that potentially straddle between first and rest
internal static long IndexOfStraddling(this ReadOnlySpan <byte> first, IBufferList rest, ReadOnlySpan <byte> value)
{
Debug.Assert(first.IndexOf(value) == -1);
if (rest == null)
{
return(-1);
}
// we only need to search the end of the first buffer. More precisely, only up to value.Length - 1 bytes in the first buffer
// The other bytes in first, were already search and presumably did not match
int bytesToSkipFromFirst = 0;
if (first.Length > value.Length - 1)
{
bytesToSkipFromFirst = first.Length - value.Length - 1;
}
// now that we know how many bytes we need to skip, create slice of first buffer with bytes that need to be searched.
ReadOnlySpan <byte> bytesToSearchAgain;
if (bytesToSkipFromFirst > 0)
{
bytesToSearchAgain = first.Slice(bytesToSkipFromFirst);
}
else
{
bytesToSearchAgain = first;
}
long index;
// now combine the bytes from the end of the first buffer with bytes in the rest, and serarch the combined buffer
// this check is a small optimization: if the first byte from the value does not exist in the bytesToSearchAgain, there is no reason to combine
if (bytesToSearchAgain.IndexOf(value[0]) != -1)
{
var combinedBufferLength = value.Length << 1;
var combined = combinedBufferLength < 128 ?
stackalloc byte[combinedBufferLength] :
// TODO (pri 3): I think this could be eliminated by chunking values
new byte[combinedBufferLength];
bytesToSearchAgain.CopyTo(combined);
int combinedLength = bytesToSearchAgain.Length + rest.CopyTo(combined.Slice(bytesToSearchAgain.Length));
combined = combined.Slice(0, combinedLength);
if (combined.Length < value.Length)
{
return(-1);
}
index = combined.IndexOf(value);
if (index != -1)
{
return(index + bytesToSkipFromFirst);
}
}
// try to find the bytes in _rest
index = rest.IndexOf(value);
if (index != -1)
{
return(first.Length + index);
}
return(-1);
}
