protected static void read_header_and_symbols(IGenericFst fst, BinaryReader reader)
{
if (read_int32_LE(reader) != OPENFST_MAGIC)
throw new Exception("invalid magic number");
read_magic_string(reader, "vector");
read_magic_string(reader, "standard");
int version = read_int32_LE(reader);
if (version < MIN_VERSION)
throw new Exception("file has too old version");
int flags = read_int32_LE(reader);
read_int64_LE(reader); // properties
Int64 start = read_int64_LE(reader);
Int64 nstates = read_int64_LE(reader);
if (nstates < 0)
return; // to prevent creating 2^31 nodes in case of sudden EOF
fst.Clear();
for (int i = 0; i < nstates; i++)
fst.NewState();
fst.SetStart((int)start);
read_int64_LE(reader); // narcs
if ((flags & FLAG_HAS_ISYMBOLS) > 0)
skip_symbol_table(reader);
if ((flags & FLAG_HAS_OSYMBOLS) > 0)
skip_symbol_table(reader);
}
/// <summary>
/// Copy one FST to another, preserving only lowest-cost arcs.
/// This is useful for visualization.
/// </summary>
/// <param name="dst">The destination. Will be cleared before copying.</param>
/// <param name="src">The FST to copy.</param>
public static void fst_copy_best_arcs_only(IGenericFst dst, IGenericFst src)
{
dst.Clear();
int n = src.nStates();
for (int i = 0; i < n; i++)
dst.NewState();
dst.SetStart(src.GetStart());
for(int i = 0; i < n; i++)
{
dst.SetAccept(i, src.GetAcceptCost(i));
Intarray targets = new Intarray(), outputs = new Intarray(), inputs = new Intarray();
Floatarray costs = new Floatarray();
src.Arcs(inputs, targets, outputs, costs, i);
int inlen = inputs.Length();
if (inlen != targets.Length())
throw new Exception("ASSERT: inputs.length() == targets.length()");
if (inlen != outputs.Length())
throw new Exception("ASSERT: inputs.length() == outputs.length()");
if (inlen != costs.Length())
throw new Exception("ASSERT: inputs.length() == costs.length()");
Dictionary< int, int > hash = new Dictionary<int,int>();
for(int j = 0; j < n; j++) {
int t = targets[j];
int best_so_far = -1;
if (hash.ContainsKey(t))
best_so_far = hash[t];
if(best_so_far == -1 || costs[j] < costs[best_so_far])
hash[t] = j;
}
Intarray keys = new Intarray();
//hash.keys(keys);
keys.Clear();
foreach (int key in hash.Keys)
{
keys.Push(key);
}
for(int k = 0; k < keys.Length(); k++) {
int j = hash[keys[k]];
dst.AddTransition(i, targets[j], outputs[j], costs[j], inputs[j]);
}
}
}
/// <summary>
/// Copy one FST to another.
/// </summary>
/// <param name="dst">The destination. Will be cleared before copying.</param>
/// <param name="src">The FST to copy.</param>
public static void fst_copy(IGenericFst dst, IGenericFst src)
{
dst.Clear();
int n = src.nStates();
for (int i = 0; i < n; i++)
dst.NewState();
dst.SetStart(src.GetStart());
for (int i = 0; i < n; i++)
{
dst.SetAccept(i, src.GetAcceptCost(i));
Intarray targets = new Intarray(), outputs = new Intarray(), inputs = new Intarray();
Floatarray costs = new Floatarray();
src.Arcs(inputs, targets, outputs, costs, i);
int inlen = inputs.Length();
if (inlen != targets.Length())
throw new Exception("ASSERT: inputs.length() == targets.length()");
if (inlen != outputs.Length())
throw new Exception("ASSERT: inputs.length() == outputs.length()");
if (inlen != costs.Length())
throw new Exception("ASSERT: inputs.length() == costs.length()");
for (int j = 0; j < inputs.Length(); j++)
dst.AddTransition(i, targets.At1d(j), outputs.At1d(j), costs.At1d(j), inputs.At1d(j));
}
}
/// <summary>
/// Reverse the FST's arcs, adding a new start vertex (former accept).
/// </summary>
public static void fst_copy_reverse(IGenericFst dst, IGenericFst src, bool no_accept = false)
{
dst.Clear();
int n = src.nStates();
for (int i = 0; i <= n; i++)
dst.NewState();
if (!no_accept)
dst.SetAccept(src.GetStart());
dst.SetStart(n);
for (int i = 0; i < n; i++)
{
dst.AddTransition(n, i, 0, src.GetAcceptCost(i), 0);
Intarray targets = new Intarray(), outputs = new Intarray(), inputs = new Intarray();
Floatarray costs = new Floatarray();
src.Arcs(inputs, targets, outputs, costs, i);
if (inputs.Length() != targets.Length())
throw new Exception("ASSERT: inputs.length() == targets.length()");
if (inputs.Length() != outputs.Length())
throw new Exception("ASSERT: inputs.length() == outputs.length()");
if (inputs.Length() != costs.Length())
throw new Exception("ASSERT: inputs.length() == costs.length()");
for (int j = 0; j < inputs.Length(); j++)
dst.AddTransition(targets.At1d(j), i, outputs.At1d(j), costs.At1d(j), inputs.At1d(j));
}
}
