/**
* Constructs a new dot chart from a specified input lattice, a translation grammar, and a parse
* chart.
*
* @param input A lattice which represents an input sentence.
* @param grammar A translation grammar.
* @param chart A CKY+ style chart in which completed span entries are stored.
*/
public DotChart(Lattice<Integer> input, Grammar grammar, Chart chart) {
this.pChart = chart;
this.pGrammar = grammar;
this.input = input;
this.sentLen = input.size();
this.dotbins = new DotCell[sentLen][sentLen + 1];
// seeding the dotChart
seed();
}
/**
* two kinds of symbols in the foreign side: (1) non-terminal (e.g., X or NP); (2) CN-side
* terminal therefore, two ways to extend the dot postion.
*/
void expandDotCell(int i, int j) {
// if (logger.isLoggable(Level.FINEST)) logger.finest("Expanding dot cell ("+i+","+j+")");
// (1) if the dot is just to the left of a non-terminal variable,
// looking for theorems or axioms in the Chart that may apply and
// extend the dot pos
for (int k = i + 1; k < j; k++) { // varying middle point k
extendDotItemsWithProvedItems(i, k, j, false);
}
// (2) the dot-item is looking for a CN-side terminal symbol:
// so we just need a CN-side terminal symbol to advance the dot in
// seeding case: j=i+1, therefore, it will look for l_dot_bins[i][i]
Node<Integer> node = input.getNode(j - 1);
for (Arc<Integer> arc : node.getOutgoingArcs()) {
int last_word = arc.getLabel();
// Tail and Head are backward! FIX names!
int arc_len = arc.getTail().getNumber() - arc.getHead().getNumber();
// int last_word=foreign_sent[j-1]; // input.getNode(j-1).getNumber(); //
if (null != dotbins[i][j - 1]) {
// dotitem in dot_bins[i][k]: looking for an item in the right to the dot
for (DotNode dt : dotbins[i][j - 1].dotNodes) {
if (null == dt.trieNode) {
// We'll get one anyways in the else branch
// TODO: better debugging.
throw new NullPointerException(
"DotChart.expand_cell(" + i + "," + j + "): " + "Null tnode for DotItem");
} else {
// match the terminal
Trie child_tnode = dt.trieNode.matchOne(last_word);
if (null != child_tnode) {
// we do not have an ant for the terminal
addDotItem(
child_tnode, i, j - 1 + arc_len, dt.antSuperNodes, null, dt.srcPath.extend(arc));
}
}
} // end foreach DotItem
}
}
}