public static List <byte[]> ReadVariableSizeItems(IPage page)
{
PageType pageType = PageHeaderBase.GetPageType(page);
if (pageType != PageType.RadixTree)
{
throw new PageFormatException("Page is not dedicated to variable size items.");
}
short headerLength = BitConverter.ToInt16(page.Content, OnPageOffsets.HeaderLength);
var result = new List <byte[]>();
var lengthMarkers = ReadMarkers(page, headerLength);
int offset = 0;
foreach (var length in lengthMarkers)
{
offset += Math.Abs(length);
var bytes = new byte[length];
Buffer.BlockCopy(page.Content, page.Content.Length - offset, bytes, 0, length);
result.Add(bytes);
}
return(result);
}
public static ushort GetFreeSpace(IPage page)
{
PageType pageType = PageHeaderBase.GetPageType(page);
if (pageType != PageType.RadixTree)
{
throw new PageFormatException("Page is not dedicated to variable size items.");
}
return(RadixTreeNodesPageHeader.ReadFreeSpace(page));
}
public static short ReadItemMarkersLength(IPage page)
{
PageType pageType = PageHeaderBase.GetPageType(page);
if (pageType != PageType.RadixTree)
{
throw new PageFormatException("Page is not dedicated to variable size items.");
}
short headerLength = BitConverter.ToInt16(page.Content, OnPageOffsets.HeaderLength);
return(BitConverter.ToInt16(page.Content, headerLength));
}
public static byte[] ReadVariableSizeItem(IPage page, short itemIndex)
{
PageType pageType = PageHeaderBase.GetPageType(page);
if (pageType != PageType.RadixTree)
{
throw new PageFormatException("Page is not dedicated to variable size items.");
}
short headerLength = BitConverter.ToInt16(page.Content, OnPageOffsets.HeaderLength);
var lengthMarkers = ReadMarkers(page, headerLength);
if (itemIndex >= lengthMarkers.Length)
{
throw new PageFormatException("Wrong item index.");
}
int offset = 0;
int length = 0;
for (int i = 0; i <= itemIndex; i++)
{
length = lengthMarkers[i];
offset += Math.Abs(length);
}
if (length <= 0)
{
throw new PageFormatException("Item has been deleted.");
}
var result = new byte[length];
Buffer.BlockCopy(page.Content, page.Content.Length - offset, result, 0, length);
return(result);
}
public static PageHeaderBase GetPageHeader(IPage page)
{
PageHeaderBase ph;
PageType pt = PageHeaderBase.GetPageType(page);
switch (pt)
{
case PageType.FreeSpaceMap:
ph = new FreeSpaceMapPageHeader();
ph.Read(page);
return(ph);
case PageType.Heading:
ph = new HeadingPageHeader();
ph.Read(page);
return(ph);
case PageType.MultipageItem:
ph = new MultipageItemPageHeader();
ph.Read(page);
return(ph);
case PageType.FixedSizeItem:
ph = new FixedSizeItemsPageHeader();
ph.Read(page);
return(ph);
case PageType.BPlusTree:
ph = new BPlusTreeNodePageHeader();
ph.Read(page);
return(ph);
case PageType.RadixTree:
ph = new RadixTreeNodesPageHeader();
ph.Read(page);
return(ph);
}
return(null);
}