/// <summary>
/// Save the gram data into stream.
/// </summary>
/// <param name="stream">Binary stream.</param>
public void SaveToBinary(Stream stream)
{
if (stream == null)
{
throw new ArgumentNullException("stream");
}
if (_grammarCount == 0)
{
throw new InvalidDataException("There is no nGram data");
}
using (TrieTree graphemeTrieTree = new TrieTree(_graphemeDictionary))
{
byte[] graphemeDictData = graphemeTrieTree.GetTrieData();
int graphemeDictLength = graphemeDictData.Length;
// Keep data alignment as 2 bytes
if (graphemeDictLength % 2 != 0)
{
graphemeDictLength++;
}
// Save NGramData
GrammarState[] grammarStates = new GrammarState[_grammarCount + 2];
grammarStates[0] = new GrammarState();
grammarStates[0].ReferenceIndex = 1;
Dictionary<string, int> grammarIndex = new Dictionary<string, int>();
int stateIndex = 1;
int finalGramStateIndex = 0;
for (int gram = 1; gram <= _maxNgram; gram++)
{
string lastReferredGrammar = string.Empty;
if (gram == _maxNgram)
{
finalGramStateIndex = stateIndex;
grammarStates[stateIndex++] = new GrammarState();
}
foreach (string grammar in _nGramData[gram].Keys)
{
string[] graphemes = grammar.Split(GrammarSeparator, StringSplitOptions.RemoveEmptyEntries);
// last grapheme
string lastGrapheme = graphemes[graphemes.Length - 1];
int len = 0;
int graphemeId = graphemeTrieTree.FindLongest(lastGrapheme, out len);
Debug.Assert(graphemeId != -1);
Debug.Assert(!grammarIndex.ContainsKey(grammar));
// Save the state index for easily query
grammarIndex.Add(grammar, stateIndex);
grammarStates[stateIndex] = new GrammarState();
grammarStates[stateIndex].GraphId = (GrapId)graphemeId;
// Convert the probability into ProbabilityInt type with amplifier
if (_nGramData[gram][grammar].Probability * _probabilityAmplifier < ProbabilityInt.MinValue)
{
grammarStates[stateIndex].Prob = ProbabilityInt.MinValue;
}
else
{
grammarStates[stateIndex].Prob = (ProbabilityInt)(_nGramData[gram][grammar].Probability * _probabilityAmplifier);
}
if (_nGramData[gram][grammar].Backoff * _probabilityAmplifier < short.MinValue)
{
grammarStates[stateIndex].Backoff = ProbabilityInt.MinValue;
}
else
{
grammarStates[stateIndex].Backoff = (ProbabilityInt)(_nGramData[gram][grammar].Backoff * _probabilityAmplifier);
}
// set the reference index for lower level gram data
if (gram != 1)
{
string referredGrammar = graphemes[0];
for (int i = 1; i < graphemes.Length - 1; i++)
{
referredGrammar = referredGrammar + " " + graphemes[i];
}
if (!referredGrammar.Equals(lastReferredGrammar, StringComparison.Ordinal))
{
// Update the reference index for the lower level gram
lastReferredGrammar = referredGrammar;
Debug.Assert(grammarIndex.ContainsKey(lastReferredGrammar));
int referredIndex = grammarIndex[lastReferredGrammar];
Debug.Assert(grammarStates[referredIndex] != null);
if (gram != _maxNgram)
{
grammarStates[referredIndex].ReferenceIndex = (ReferenceIndex)stateIndex;
}
else
{
grammarStates[referredIndex].ReferenceIndex = (ReferenceIndex)(stateIndex - finalGramStateIndex);
}
}
}
stateIndex++;
}
}
// Save the model into binary stream
BinaryWriter bw = new BinaryWriter(stream);
{
// Write the language ID
bw.Write((ushort)_language);
// Write the Gram Count
bw.Write((ushort)this._maxNgram);
// Write the Probability Amplifier
bw.Write((int)_probabilityAmplifier);
// Write the grammar state number
bw.Write((uint)finalGramStateIndex);
// Write the Final grammar state number
bw.Write((uint)(_grammarCount + 2 - finalGramStateIndex));
int headerSize = sizeof(ushort) + sizeof(ushort) + sizeof(int) +
sizeof(uint) + sizeof(uint) +
sizeof(uint) + sizeof(uint) + sizeof(uint);
// Write the offset of Dictionary
bw.Write((uint)headerSize);
// Write the offset of Grammar State
bw.Write((uint)(headerSize + graphemeDictLength));
// Write the offset of Final Grammar State
bw.Write((uint)(headerSize + graphemeDictLength + (finalGramStateIndex *
(sizeof(GrapId) + sizeof(ProbabilityInt) + sizeof(ProbabilityInt) + sizeof(ReferenceIndex)))));
// Write the grapheme Trie Dictionary
bw.Write(graphemeDictData, 0, graphemeDictData.Length);
// Add the data alignment for grapheme Trie Dictionary
for (int i = graphemeDictData.Length; i < graphemeDictLength; i++)
{
bw.Write((byte)0);
}
// Write the grammar states for low level gram
for (int i = 0; i < finalGramStateIndex; i++)
{
bw.Write(grammarStates[i].GraphId);
bw.Write(grammarStates[i].Prob);
bw.Write(grammarStates[i].Backoff);
bw.Write(grammarStates[i].ReferenceIndex);
}
// Write the grammar state for final level gram
for (int i = finalGramStateIndex; i < _grammarCount + 2; i++)
{
bw.Write(grammarStates[i].GraphId);
bw.Write(grammarStates[i].Prob);
}
}
}
}
