/**
* /// given edges e1 and e2 from node n to nodes n1 and n2
* /// <p/>
* /// merge e1 and e2, that is, merge the scores of e1 and e2 create n' that is a merge of n1 and n2 add n' add edge e'
* /// from n to n'
* /// <p/>
* /// remove n1 and n2 and all associated edges
*
* /// @param n
* /// @param e1
* /// @param e2
*/
protected void mergeNodesAndEdgesForward(Node n, Edge e1, Edge e2)
{
Trace.Assert(lattice.hasNode(n));
Trace.Assert(lattice.hasEdge(e1));
Trace.Assert(lattice.hasEdge(e2));
Trace.Assert(e1.getFromNode() == n);
Trace.Assert(e2.getFromNode() == n);
Node n1 = e1.getToNode();
Node n2 = e2.getToNode();
Trace.Assert(n1.hasEquivalentEnteringEdges(n1));
Trace.Assert(n1.getWord().Equals(n2.getWord()));
// merge the scores of e1 and e2 into e1
e1.setAcousticScore(mergeAcousticScores
(e1.getAcousticScore(), e2.getAcousticScore()));
e1.setLMScore(mergeLanguageScores(e1.getLMScore(),
e2.getLMScore()));
// add n2's edges to n1
foreach (Edge e in n2.getLeavingEdges())
{
e2 = n1.getEdgeToNode(e.getToNode());
if (e2 == null)
{
lattice.addEdge(n1, e.getToNode(),
e.getAcousticScore(), e.getLMScore());
}
else
{
// if we got here then n1 and n2 had edges to the same node
// choose the edge with best score
e2.setAcousticScore
(mergeAcousticScores
(e.getAcousticScore(), e2.getAcousticScore()));
e2.setLMScore(mergeLanguageScores(e.getLMScore(),
e2.getLMScore()));
}
}
// remove n2 and all associated edges
lattice.removeNodeAndEdges(n2);
}
/**
* /// Internal routine used when creating a Lattice from a .LAT file
*
* /// @param lattice
* /// @param tokens
*/
public static void load(Lattice lattice, StringTokenizer tokens)
{
String from = tokens.nextToken();
String to = tokens.nextToken();
int score = int.Parse(tokens.nextToken());
Node fromNode = lattice.getNode(from);
if (fromNode == null)
{
throw new Exception("Edge fromNode \"" + from + "\" does not exist");
}
Node toNode = lattice.getNode(to);
if (toNode == null)
{
throw new Exception("Edge toNode \"" + to + "\" does not exist");
}
lattice.addEdge(fromNode, toNode, score, 0.0);
}