/**
* 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;
}
/**
* Test if a Node has all Edges to the same Nodes and another Node.
*
* @param n the node of interest
* @return true if this Node has all Edges to the sames Nodes as n
*/
public boolean hasEquivalentLeavingEdges(Node n) {
if (leavingEdges.size() != n.getLeavingEdges().size()) {
return false;
}
for (Edge e : leavingEdges) {
Node toNode = e.getToNode();
if (!n.hasEdgeToNode(toNode)) {
return false;
}
}
return true;
}
/**
* Test if a Node has all Edges from the same Nodes and another Node.
*
* @param n node to check
* @return true if this Node has Edges from the same Nodes as n
*/
protected boolean hasEquivalentEnteringEdges(Node n) {
if (enteringEdges.size() != n.getEnteringEdges().size()) {
return false;
}
for (Edge e : enteringEdges) {
Node fromNode = e.getFromNode();
if (!n.hasEdgeFromNode(fromNode)) {
return false;
}
}
return true;
}
protected boolean isAncestorHelper(List<Node> children, Node node, Set<Node> seenNodes) {
for (Node n : children) {
if (seenNodes.contains(n)) {
continue;
}
seenNodes.add(n);
if (n.equals(node)) {
return true;
}
if (isAncestorHelper(n.getChildNodes(), node, seenNodes)) {
return true;
}
}
return false;
}
protected void cacheDescendantsHelper(Node n) {
for (Node child : n.getChildNodes()) {
if (descendants.contains(child)) {
continue;
}
descendants.add(child);
cacheDescendantsHelper(child);
}
}
/**
* Returns true if the given node is equivalent to this node. Two nodes are equivalent only if
* they have the same word, the same number of entering and leaving edges, and that their begin
* and end times are the same.
*
* @param other the Node we're comparing to
* @return true if the Node is equivalent; false otherwise
*/
public boolean isEquivalent(Node other) {
return ((word.getSpelling().equals(other.getWord().getSpelling())
&& (getEnteringEdges().size() == other.getEnteringEdges().size()
&& getLeavingEdges().size() == other.getLeavingEdges().size()))
&& (getBeginTime() == other.getBeginTime() && endTime == other.getEndTime()));
}
/**
* Check whether this node has an ancestral relationship with another node (i.e. either this node
* is an ancestor of the other node, or vice versa)
*
* @param node the Node to check for a relationship
* @return whether a relationship exists
*/
public boolean hasAncestralRelationship(Node node) {
return this.isAncestorOf(node) || node.isAncestorOf(this);
}