/** Called by determineHead and may be overridden in subclasses
* if special treatment is necessary for particular categories.
*/
protected Tree determineNonTrivialHead(Tree t, Tree parent) {
Tree theHead = null;
String motherCat = basicCategory(t.label().value());
if (DEBUG) {
System.err.println("Looking for head of " + t.label() +
"; value is |" + t.label().value() + "|, " +
" baseCat is |" + motherCat + "|");
}
// We know we have nonterminals underneath
// (a bit of a Penn Treebank assumption, but).
// Look at label.
String[][] how = nonTerminalInfo.get(motherCat);
if (how == null) {
if (DEBUG) {
System.err.println("Warning: No rule found for " + motherCat +
" (first char: " + motherCat.charAt(0) + ")");
System.err.println("Known nonterms are: " + nonTerminalInfo.keySet());
}
if (defaultRule != null) {
if (DEBUG) {
System.err.println(" Using defaultRule");
}
return traverseLocate(t.children(), defaultRule, true);
} else {
return null;
}
}
for (int i = 0; i < how.length; i++) {
boolean deflt = (i == how.length - 1);
theHead = traverseLocate(t.children(), how[i], deflt);
if (theHead != null) {
break;
}
}
if (DEBUG) {
System.err.println(" Chose " + theHead.label());
}
return theHead;
}