public int GetPrevKey()
{
int RecordPointer = int.MaxValue;
#region
try
{
CurrentKey--;
if (CurrentKey < 0)
{
CurrentKey = 0;
return(-1);
}
RecordPointer = RecordOffset + CurrentKey * RecordSize;
FileStreamData.Seek(RecordPointer, 0);
Key = BinaryReaderData.ReadString();
Flag = BinaryReaderData.ReadBoolean();
Value = BinaryReaderData.ReadString();
return(RecordPointer);
}
catch (Exception e)
{
StringLastError = e.Message;
return(-3);
}
#endregion
}
public int GetNextKey()
{
int RecordPointer = int.MaxValue;
#region
try
{
CurrentKey++;
if (CurrentKey == NumberOfKeys)
{
CurrentKey = (int)NumberOfKeys - 1;
return(-2);
}
RecordPointer = RecordOffset + CurrentKey * RecordSize;
FileStreamData.Seek(RecordPointer, 0);
Key = BinaryReaderData.ReadString();
Flag = BinaryReaderData.ReadBoolean();
Value = BinaryReaderData.ReadString();
return(RecordPointer);
}
catch (Exception e)
{
StringLastError = e.Message;
return(-3);
}
#endregion
}
public uint DeleteKey(string P_key)
{
uint RecordPointer = uint.MaxValue, IndexPointer = uint.MaxValue;
KeyBytes = ASCIIEncoding.UTF8.GetBytes(P_key);
ByteIndex = 0;
IndexOffset = 0;
for (ByteIndex = 0; ByteIndex < KeyBytes.Length; ByteIndex++)
{
#region
count++;
IndexPosition = (uint)(IndexOffset + (KeyBytes[ByteIndex] - 32) * 8);
try
{
FileStreamIdx.Seek(IndexPosition, 0);
RecordPointer = BinaryReaderIdx.ReadUInt32();
IndexPointer = BinaryReaderIdx.ReadUInt32();
if (IndexPointer == uint.MaxValue)
{
return(uint.MaxValue);
}
FileStreamData.Seek(RecordPointer, 0);
Key = BinaryReaderData.ReadString();
if (Key.Equals(P_key))
{
if (BinaryReaderData.PeekChar() == 0)
{
BinaryWriterData.Write(true);
}
return(RecordPointer);
}
else
{
IndexOffset = IndexPointer;
}
}
catch (Exception e)
{
StringLastError = e.Message;
return(uint.MaxValue);;
}
#endregion
}
return(uint.MaxValue);
}
public int CreateIndex(string P_key, string P_value)
{
// Key Should contain ASCII 32-122 only
KeyBytes = ASCIIEncoding.UTF8.GetBytes(P_key);
uint RecordPointer = uint.MaxValue, NewRecordPointer = uint.MaxValue, IndexPointer = uint.MaxValue, NewIndexOffset = 0;
String LastKey = "";
NewRecordPointer = (uint)LastPosition; /// Start of Next Key
IndexOffset = 0;
ByteIndex = 0;
do
{
IndexPosition = (uint)(IndexOffset + (KeyBytes[ByteIndex] - 32) * 8);
count++;
try // Read next Branch (ASCII 32-122)
{
if (KeyBytes[ByteIndex] < 32 || KeyBytes[ByteIndex] > 122)
{
return(-52); // Validate Character Range
}
FileStreamIdx.Seek(IndexPosition, 0);
RecordPointer = BinaryReaderIdx.ReadUInt32();
IndexPointer = BinaryReaderIdx.ReadUInt32();
}
catch (Exception e)
{
StringLastError = e.Message;
return(-1);
}
if (IndexPointer == uint.MaxValue)
{
try
{
FileStreamIdx.Seek(IndexPosition, 0);
BinaryWriterIdx.Write(NewRecordPointer);
BinaryWriterIdx.Write(IndexPosition);
FileStreamIdx.Flush();
return(1); // Inserted new Branch successfully
}
catch (Exception e)
{
StringLastError = e.Message;
return(-1);
}
}
else
{
try
{
FileStreamData.Seek(RecordPointer, 0);
LastKey = BinaryReaderData.ReadString();
LastKeyBytes = ASCIIEncoding.UTF8.GetBytes(LastKey);
}
catch (Exception e)
{
StringLastError = e.Message;
return(-10);
}
Difference = GetDif(ref LastKeyBytes, ref KeyBytes);
if (Difference == 0)
{
if (BinaryReaderData.PeekChar() == 0)
{
return(-3);
}
else
{
FileStreamData.Seek(RecordPointer, 0);
BinaryWriterData.Write(P_key);
BinaryWriterData.Write(false);
BinaryWriterData.Write(P_value);
BinaryWriterData.Flush();
return(-4); /// if the record flag is deleted, update record.
}
}
else
{
if (Difference > 0)
{
if (IndexPointer == IndexPosition)
{
try
{
NewIndexOffset = (uint)FileStreamIdx.Length;
FileStreamIdx.Seek(IndexPosition + 4, 0);
BinaryWriterIdx.Write(NewIndexOffset);
ADDIndexBlock();
IndexPosition = (uint)(NewIndexOffset + (KeyBytes[ByteIndex + 1] - 32) * 8);
FileStreamIdx.Seek(IndexPosition, 0);
BinaryWriterIdx.Write(NewRecordPointer);
BinaryWriterIdx.Write(IndexPosition);
FileStreamIdx.Flush();
return(1); // Inserted new key successfully
}
catch (Exception e)
{
StringLastError = e.Message;
return(-16);
}
}
else
{
IndexOffset = IndexPointer;
}
}
else
{
if (IndexPointer == IndexPosition)
{
try
{
NewIndexOffset = (uint)FileStreamIdx.Length;
FileStreamIdx.Seek(IndexPosition, 0);
BinaryWriterIdx.Write(NewRecordPointer);
BinaryWriterIdx.Write(NewIndexOffset);
ADDIndexBlock();
NewRecordPointer = RecordPointer;
KeyBytes = ASCIIEncoding.UTF8.GetBytes(LastKey);
P_key = LastKey;
IndexOffset = NewIndexOffset;
IndexPosition = (uint)(NewIndexOffset + (KeyBytes[ByteIndex + 1] - 32) * 8);
FileStreamIdx.Seek(IndexPosition, 0);
BinaryWriterIdx.Write(NewRecordPointer);
BinaryWriterIdx.Write(IndexPosition);
FileStreamIdx.Flush();
return(1); // Inserted new key successfully
}
catch (Exception e)
{
StringLastError = e.Message;
return(-17);
}
}
else
{
try
{
FileStreamIdx.Seek(IndexPosition, 0);
BinaryWriterIdx.Write(NewRecordPointer);
NewRecordPointer = RecordPointer;
KeyBytes = ASCIIEncoding.UTF8.GetBytes(LastKey);
P_key = LastKey;
FileStreamIdx.Flush();
IndexOffset = IndexPointer;
}
catch (Exception e)
{
StringLastError = e.Message;
return(-18);
}
}
}
}
}
ByteIndex++;
} while (ByteIndex < KeyBytes.Length);
return(-20);
}
