public ReaderEnumerator(IPersistentStorage storage, PostingListAddress address)
{
this.persistentStorage = storage;
this.address = address;
this.buffer = new byte[ReadBufferSize];
this.selectors = new int[4];
this.data = null;
this.dataIndex = 0;
Reset();
}
private int NextInteger()
{
if (data == null || dataIndex >= data.Length)
{
data = ReadPacked();
dataIndex = 0;
}
return(data.Get(dataIndex++));
}
public void Reset()
{
state = 0;
dataInBuffer = 0;
indxInBuffer = 0;
readOffset = address.Offset;
isEof = false;
listEndOffset = 0;
continuationOffset = 0;
data = null;
dataIndex = 0;
}
public bool MoveNext()
{
while (true)
{
if (state == 0)
{
if (continuationOffset > 0)
{
readOffset = continuationOffset;
isEof = false;
dataInBuffer = 0;
indxInBuffer = 0;
}
if (isEof)
{
return(false);
}
var headerBuffer = new byte[HeaderLength];
persistentStorage.ReadAll(readOffset, headerBuffer, 0, headerBuffer.Length);
continuationOffset = BitConverter.ToInt64(headerBuffer, 0);
listEndOffset = readOffset + HeaderLength + BitConverter.ToInt32(headerBuffer, sizeof(long));
readOffset += headerBuffer.Length;
state = 1;
data = null;
dataIndex = 0;
}
if (state == 1)
{
current = Occurrence.O((ulong)NextInteger(),
(ulong)NextInteger(),
(ulong)NextInteger());
state = 2;
return(true);
}
if (state == 2)
{
if (isEof && indxInBuffer >= dataInBuffer && (data == null || dataIndex >= data.Length))
{
state = 0;
}
else
{
deltaSelector = (uint)NextInteger();
if (deltaSelector == 0)
{
state = 0;
}
else
{
state = 3;
}
}
}
if (state == 3)
{
int delta = (int)(deltaSelector & 0b00000011);
deltaSelector >>= 2;
switch (delta)
{
case 0:
{
throw new Exception("Zero delta is not used, see comments in DeltaWriter");
}
case 1:
{
var deltaToken = (ulong)NextInteger();
current = Occurrence.O(current.DocumentId,
current.FieldId,
current.TokenId + deltaToken);
break;
}
case 2:
{
var deltaFieldId = (ulong)NextInteger();
var token = (ulong)NextInteger();
current = Occurrence.O(current.DocumentId,
current.FieldId + deltaFieldId,
token);
break;
}
case 3:
{
var deltaDocId = (ulong)NextInteger();
var fieldId = (ulong)NextInteger();
var token = (ulong)NextInteger();
current = Occurrence.O(current.DocumentId + deltaDocId,
fieldId,
token);
break;
}
default:
{
throw new Exception("Something wrong");
}
}
if (deltaSelector == 0)
{
state = 2;
}
return(true);
}
}
}
