/// <summary>
/// It is way to find needed block if we don't cache it yet. This method have O(n) complexity.
/// In fact we just get last cached block and move next until we find block we need. Also we cache all new blocks until needed.
/// </summary>
/// <param name="index">Index to find information about block, which containes it.</param>
/// <param name="searchBlockRange"><see cref="Range"/> to find index in it. It use to get better performance.</param>
/// <returns>Information about block, which contain specified index.</returns>
private BlockInfo LinearBlockInfo(int index, Range searchBlockRange)
{
lock (_locker)
{
Debug.Assert(index >= GetCachedElementCount());
if (!_blockCollection.IsValidRange(searchBlockRange))
{
throw new ArgumentOutOfRangeException("searchBlockRange");
}
//Move to start
var startBlock = GetStartBlockInfoForLinear();
if (startBlock.Compare(index) == 0)
{
return(startBlock);
}
int commonStartIndex = startBlock.CommonStartIndex + startBlock.Count;
Debug.Assert(startBlock.CommonStartIndex + startBlock.Count <= index);
//Start block must be last cached block info
Debug.Assert(startBlock.IndexOfBlock + 1 == _blocksInfoList.Count);
//Add new blocks while we try to find needed block
for (int i = startBlock.IndexOfBlock + 1; i < searchBlockRange.Index + searchBlockRange.Count; i++)
{
var elementCount = _blockCollection[i].Count;
var newBlock = new BlockInfo(i, commonStartIndex, elementCount);
_blocksInfoList.Add(newBlock);
//If there is needed block
if (index >= commonStartIndex && index < commonStartIndex + elementCount)
{
if (i + 1 == _blockCollection.Count)
{
_indexOfFirstChangedBlock = NoBlockChanges;
}
else
{
_indexOfFirstChangedBlock = i + 1;
}
return(newBlock);
}
commonStartIndex += elementCount;
}
throw new ArgumentOutOfRangeException("index");
}
}