private FileAccess GetFileStreamAccess(AlgFileAccess access)
{
if (access == AlgFileAccess.Read)
{
return(System.IO.FileAccess.Read);
}
else
{
return(System.IO.FileAccess.ReadWrite);
}
}
/// <summary>
/// Creates an algorithm file
/// </summary>
/// <param name="path">The file location of the file</param>
/// <param name="fileMode">Creating a new file or Opening an exising file</param>
/// <param name="fileAccess">Read or ReadWrite</param>
/// <param name="numAlgs">The number of algorithms in the file. Required if creating a new file, ignored if opening a file</param>
public AlgFile(string path, AlgFileMode fileMode, AlgFileAccess fileAccess, int numAlgs = -1)
{
FileAccess = fileAccess;
if (string.IsNullOrEmpty(path))
{
throw new ArgumentException("path is not a valid string");
}
if (!Path.GetExtension(path).Equals(".alg"))
{
throw new ArgumentException("path is not the correct type of file");
}
if (fileMode == AlgFileMode.Create && FileAccess == AlgFileAccess.Read)
{
throw new ArgumentException("Cannot create file with only read access");
}
if (fileMode == AlgFileMode.Create && numAlgs <= 0)
{
throw new ArgumentException("number of algs is not positive");
}
_stream = new FileStream(path, GetFileStreamMode(fileMode), System.IO.FileAccess.ReadWrite);
if (fileMode == AlgFileMode.Create)
{
NumAlgs = numAlgs;
_stream.SetLength((numAlgs + 1) * 32);
_stream.Position = 0;
byte[] header = Encoding.Unicode.GetBytes(headerString);
_stream.Write(header, 0, 28);
_stream.Write(BitConverter.GetBytes(numAlgs), 0, 4);
}
else
{
_stream.Position = 0;
byte[] header = new byte[32];
_stream.Read(header, 0, 32);
for (int k = 0; k < 14; k++)
{
char c = BitConverter.ToChar(header, 2 * k);
if (c != headerString[k])
{
throw new IOException("The file is not in the correct format");
}
}
NumAlgs = BitConverter.ToInt32(header, 28);
}
_isClosed = false;
}
