/**
* Creates the grammar from the language model. This Grammar contains one word per grammar node.
* Each word (and grammar node) is connected to all other words with the given probability
*
* @return the initial grammar node
*/
@Override
protected GrammarNode createGrammar() throws IOException {
if (lattice == null) {
return createGrammarNode("<s>");
}
lattice.removeFillers();
GrammarNode firstNode = null;
HashMap<Node, GrammarNode> nodeMap = new HashMap<Node, GrammarNode>();
for (Node n : lattice.getNodes()) {
String word = n.getWord().toString();
GrammarNode node = createGrammarNode(word);
if (n.equals(lattice.getInitialNode())) firstNode = node;
if (n.equals(lattice.getTerminalNode())) node.setFinalNode(true);
nodeMap.put(n, node);
}
if (firstNode == null) {
throw new Error("No lattice start found");
}
for (Edge e : lattice.getEdges()) {
float logProbability = (float) e.getLMScore();
GrammarNode prevNode = nodeMap.get(e.getFromNode());
GrammarNode toNode = nodeMap.get(e.getToNode());
prevNode.add(toNode, logProbability);
}
return firstNode;
}
