private string TextDecode(BitArray code, int index, Dictionary <char, int> frequencyDictionary, int textLength)
{
var res = new StringBuilder();
var probabilities = new List <RationalNumber> {
0
};
var mapNumberInSymbols = new Dictionary <int, char>();
foreach (var pair in frequencyDictionary)
{
mapNumberInSymbols.Add(probabilities.Count, pair.Key);
probabilities.Add(new RationalNumber(pair.Value, textLength) + probabilities[probabilities.Count - 1]);
}
RationalNumber a = 0;
RationalNumber b = 1;
var c = (RationalNumber)BitArrayConverter.ConvertToBigInteger(code, ref index, code.Length - index, out var digitCnt);
c /= BigInteger.Pow(10, digitCnt);
for (var i = 0; i < textLength; i++)
{
var length = b - a;
var ind = LowerBound(probabilities, (c - a) / length);
res.Append(mapNumberInSymbols[ind]);
b = probabilities[ind] * length + a;
a = probabilities[ind - 1] * length + a;
}
return(res.ToString());
}
private BitArray TextCode(string text, Dictionary <char, int> frequencyDictionary)
{
var res = new BigInteger(0);
var digitCnt = 0;
var probabilities = new List <RationalNumber>();
var mapSymbolsInNumber = new Dictionary <char, int>();
probabilities.Add(0);
foreach (var pair in frequencyDictionary)
{
mapSymbolsInNumber.Add(pair.Key, probabilities.Count);
probabilities.Add(new RationalNumber(pair.Value, text.Length) + probabilities[probabilities.Count - 1]);
}
RationalNumber a = 0;
RationalNumber b = 1;
foreach (var c in text)
{
var index = mapSymbolsInNumber[c];
var length = b - a;
b = probabilities[index] * length + a;
a = probabilities[index - 1] * length + a;
while (RetrieveCode(ref a, ref b, ref res, ref digitCnt))
{
}
}
res = res * 10 + a.FirstDigitAfterDot() + 1;
digitCnt++;
return(BitArrayConverter.ConvertToBitArray(res, digitCnt));
}
public string Decode(BitArray code, out int codeLength)
{
var index = 0;
var length = BitArrayConverter.ConvertToInt(code, ref index, 32);
var dict = FrequencyDictionaryCoder.GetDictionary(code, ref index);
codeLength = code.Length - index;
return(TextDecode(code, index, dict, length));
}
private BitArray TextCode(string text, Dictionary <char, BitArray> codesDictionary)
{
var bitArrays = new List <BitArray>();
foreach (var c in text)
{
bitArrays.Add(codesDictionary[c]);
}
return(BitArrayConverter.ConvertToBitArray(bitArrays));
}
private BitArray GetCode(string text, Dictionary <char, BitArray> codesDictionary, out int codeLength)
{
var dictionaryCode = CodesDictionaryCoder.GetCode(codesDictionary);
var textCode = TextCode(text, codesDictionary);
codeLength = textCode.Length;
return(BitArrayConverter.ConvertToBitArray(new List <BitArray>()
{
dictionaryCode, textCode
}));
}
private BitArray ListOfPairsToBitArray(List <Pair <char, int> > listOfPairs)
{
var arrays = new List <BitArray>();
foreach (var pair in listOfPairs)
{
arrays.Add(BitArrayConverter.ConvertToBitArray(pair.First));
arrays.Add(BitArrayConverter.ConvertToBitArray(pair.Second, LengthOfNumber));
}
return(BitArrayConverter.ConvertToBitArray(arrays));
}
private BitArray GetCode(string text, Dictionary <char, int> frequencyDictionary, out int codeLength)
{
var length = BitArrayConverter.ConvertToBitArray(text.Length, 32);
var dictionaryCode = FrequencyDictionaryCoder.GetCode(frequencyDictionary);
var textCode = TextCode(text, frequencyDictionary);
codeLength = textCode.Length;
return(BitArrayConverter.ConvertToBitArray(new List <BitArray>()
{
length, dictionaryCode, textCode
}));
}
private List <Pair <char, int> > BitArrayToListOfPairs(BitArray code)
{
var res = new List <Pair <char, int> >();
var index = 0;
while (index < code.Length)
{
var symbol = BitArrayConverter.ConvertToChar(code, ref index);
var number = BitArrayConverter.ConvertToInt(code, ref index, LengthOfNumber);
res.Add(new Pair <char, int>(symbol, number));
}
return(res);
}
public static Dictionary <char, int> GetDictionary(BitArray code, ref int index)
{
var res = new Dictionary <char, int>();
var cnt = BitArrayConverter.ConvertToInt(code, ref index, 8);
for (var _ = 0; _ < cnt; _++)
{
var symbol = BitArrayConverter.ConvertToInt(code, ref index, 16);
var newCode = BitArrayConverter.ConvertToInt(code, ref index, 32);
res.Add((char)symbol, newCode);
}
return(res);
}
public static BitArray GetCode(Dictionary <char, int> frequencyDictionary)
{
var bitArrays = new List <BitArray>();
var cnt = BitArrayConverter.ConvertToBitArray(frequencyDictionary.Count, 8);
bitArrays.Add(cnt);
foreach (var pair in frequencyDictionary)
{
var symbol = BitArrayConverter.ConvertToBitArray(pair.Key, 16);
var code = BitArrayConverter.ConvertToBitArray(pair.Value, 32);
bitArrays.Add(symbol);
bitArrays.Add(code);
}
return(BitArrayConverter.ConvertToBitArray(bitArrays));
}
public static BitArray GetCode(Dictionary <char, BitArray> codesDictionary)
{
var bitArrays = new List <BitArray>();
var cnt = BitArrayConverter.ConvertToBitArray(codesDictionary.Count, 8);
bitArrays.Add(cnt);
foreach (var pair in codesDictionary)
{
var symbol = BitArrayConverter.ConvertToBitArray(pair.Key, 16);
var length = BitArrayConverter.ConvertToBitArray(pair.Value.Length, 5);
var code = pair.Value;
bitArrays.Add(symbol);
bitArrays.Add(length);
bitArrays.Add(code);
}
return(BitArrayConverter.ConvertToBitArray(bitArrays));
}
public static Dictionary <BitArray, char> GetDictionary(BitArray code, ref int index)
{
var res = new Dictionary <BitArray, char>(new BitArrayComparer());
var cnt = BitArrayConverter.ConvertToInt(code, ref index, 8);
for (var _ = 0; _ < cnt; _++)
{
var symbol = BitArrayConverter.ConvertToInt(code, ref index, 16);
var length = BitArrayConverter.ConvertToInt(code, ref index, 5);
var newCode = new BitArray(length);
for (var i = 0; i < length; i++)
{
newCode[i] = code[index];
index++;
}
res.Add(newCode, (char)symbol);
}
return(res);
}
