public void ConstructorSetsPublicPropertiesAsExpected()
{
const int limit = 300;
const OnFullDictionaryOption onFullDictionaryOption = OnFullDictionaryOption.Empty;
var lzWDictionary = new LzWDictionary(limit, onFullDictionaryOption);
Assert.AreEqual(limit, lzWDictionary.Limit);
Assert.AreEqual(onFullDictionaryOption, lzWDictionary.OnFullDictionaryOption);
}
public void Setup()
{
lzWEncoder = new LzWEncoder();
fileReaderMock = new Mock <IFileReader>();
fileWriterMock = new Mock <IFileWriter>();
onFullDictionaryOption = OnFullDictionaryOption.Empty;
numberOfBitsForIndex = 12;
}
public LzWDictionary(int limit, OnFullDictionaryOption onFullDictionaryOption)
{
if (limit < 256)
{
throw new ArgumentException($"{nameof(limit)} must be at least 256");
}
Limit = limit;
OnFullDictionaryOption = onFullDictionaryOption;
dictionary = new Dictionary <string, uint>();
for (uint key = 0; key < 256; key++)
{
dictionary.Add(((char)key).ToString(), key);
}
dictionaryLastIndex = 255;
}
private void WriteHeader(IFileWriter fileWriter, OnFullDictionaryOption onFullDictionaryOption, int numberOfBitsIndex)
{
fileWriter.WriteValueOnBits((uint)numberOfBitsIndex, 4);
fileWriter.WriteValueOnBits((uint)onFullDictionaryOption, 1);
}
public void EncodeFile(IFileReader fileReader, IFileWriter fileWriter, OnFullDictionaryOption onFullDictionaryOption, int numberOfBitsIndex)
{
if (fileReader == null)
{
throw new ArgumentNullException(nameof(fileReader));
}
if (fileWriter == null)
{
throw new ArgumentNullException(nameof(fileWriter));
}
if (numberOfBitsIndex < 9 || numberOfBitsIndex > 15)
{
throw new ArgumentException($"{nameof(numberOfBitsIndex)} must be at least 9, and at most 15");
}
WriteHeader(fileWriter, onFullDictionaryOption, numberOfBitsIndex);
IndexesFromLastRun.Clear();
LzWDictionary = new LzWDictionary((int)Math.Pow(2, numberOfBitsIndex) - 1, onFullDictionaryOption);
var lastCharacter = (char)fileReader.ReadBits(8);
var shouldStop = false;
while (true)
{
var currentString = lastCharacter.ToString();
uint lastIndex = 0;
if (shouldStop)
{
break;
}
while (true)
{
if (LzWDictionary.ContainsString(currentString))
{
lastIndex = LzWDictionary.GetIndexByString(currentString);
if (shouldStop)
{
fileWriter.WriteValueOnBits(lastIndex, (byte)numberOfBitsIndex);
IndexesFromLastRun.Add(lastIndex);
break;
}
}
else
{
LzWDictionary.Add(currentString);
fileWriter.WriteValueOnBits(lastIndex, (byte)numberOfBitsIndex);
IndexesFromLastRun.Add(lastIndex);
break;
}
if (!fileReader.ReachedEndOfFile)
{
var readByte = (byte)fileReader.ReadBits(8);
currentString += (char)readByte;
lastCharacter = (char)readByte;
}
else
{
shouldStop = true;
}
}
}
fileWriter.Flush();
}