/// <summary>
/// Разбивает указанный файл на два вспомогательных
/// </summary>
/// <param name="fileName"></param>
/// <param name="maxSeriesLenght"></param>
/// <param name="comparer"></param>
private void SplitFile(string fileName, int maxSeriesLenght, IComparer <T> comparer,
WriteTypeToFile <T> write, ReadTypeFromFile <T> read)
{
T currentNode;
StreamReader reader = new StreamReader(fileName);
StreamWriter firstWriter = new StreamWriter("f1.txt");
StreamWriter secondWriter = new StreamWriter("f2.txt");
StreamWriter currentWriter = firstWriter;
currentNode = read(reader);
T tmpNode;
int currentSeriesLenght = 0;
while (currentNode != null)
{
currentSeriesLenght++;
write(currentWriter, currentNode);
tmpNode = read(reader);
if (tmpNode != null)
{
if (comparer.Compare(tmpNode, currentNode) < 0 /*|| currentSeriesLenght >= maxSeriesLenght*/) // tmpNode < currentNode
{
currentWriter.WriteLine("`");
currentSeriesLenght = 0;
currentWriter = SetOppositeWriter(firstWriter, secondWriter, currentWriter);
}
}
currentNode = tmpNode;
}
secondWriter.Close();
firstWriter.Close();
reader.Close();
}
public int ExternalNaturalMergeSort(string externalFile, int maxSeriesLenght, IComparer <T> comparer,
WriteTypeToFile <T> write, ReadTypeFromFile <T> read)
{
Random random = new Random();
bool isSorted = false;
int iterations = 0;
int currentSeriesMaxLenght;
while (!isSorted)
{
currentSeriesMaxLenght = random.Next(1, maxSeriesLenght);
SplitFile(externalFile, currentSeriesMaxLenght, comparer, write, read);
if (IsEmpty("f1.txt", read) || IsEmpty("f2.txt", read))
{
isSorted = true;
}
MergeAuxiliaryFiles(externalFile, "f1.txt", "f2.txt", comparer, write, read);
iterations++;
}
return(iterations);
}
/// <summary>
/// Сливает вспомогательные файлы в один, используя слияние
/// </summary>
/// <param name="firstFileName"></param>
/// <param name="secondFileName"></param>
/// <param name="comparer"></param>
private void MergeAuxiliaryFiles(string fileWhereToMerge, string firstFileName, string secondFileName, IComparer <T> comparer,
WriteTypeToFile <T> write, ReadTypeFromFile <T> read)
{
T firstNode;
T secondNode;
StreamWriter writer = new StreamWriter(fileWhereToMerge);
StreamReader firstReader = new StreamReader(firstFileName);
StreamReader secondReader = new StreamReader(secondFileName);
firstNode = read(firstReader);
secondNode = read(secondReader);
while (firstNode != null && secondNode != null)
{
if (comparer.Compare(firstNode, secondNode) < 0)
{
write(writer, firstNode);
firstNode = read(firstReader);
}
else
{
write(writer, secondNode);
secondNode = read(secondReader);
}
}
while (firstNode != null)
{
write(writer, firstNode);
firstNode = read(firstReader);
}
while (secondNode != null)
{
write(writer, secondNode);
secondNode = read(secondReader);
}
secondReader.Close();
firstReader.Close();
writer.Close();
}
