@Override
public List<LookupResult> lookup(CharSequence key, boolean onlyMorePopular, int num) {
assert num > 0;
BytesRef scratch = new BytesRef(key);
int prefixLength = scratch.length;
Arc<Long> arc = new Arc<Long>();
// match the prefix portion exactly
Long prefixOutput = null;
try {
prefixOutput = lookupPrefix(scratch, arc);
} catch (IOException bogus) {
throw new RuntimeException(bogus);
}
if (prefixOutput == null) {
return Collections.<LookupResult>emptyList();
}
List<LookupResult> results = new ArrayList<LookupResult>(num);
CharsRef spare = new CharsRef();
if (exactFirst && arc.isFinal()) {
spare.grow(scratch.length);
UnicodeUtil.UTF8toUTF16(scratch, spare);
results.add(
new LookupResult(spare.toString(), decodeWeight(prefixOutput + arc.nextFinalOutput)));
if (--num == 0) {
return results; // that was quick
}
}
// complete top-N
MinResult<Long> completions[] = null;
try {
completions = Util.shortestPaths(fst, arc, weightComparator, num);
} catch (IOException bogus) {
throw new RuntimeException(bogus);
}
BytesRef suffix = new BytesRef(8);
for (MinResult<Long> completion : completions) {
scratch.length = prefixLength;
// append suffix
Util.toBytesRef(completion.input, suffix);
scratch.append(suffix);
spare.grow(scratch.length);
UnicodeUtil.UTF8toUTF16(scratch, spare);
results.add(
new LookupResult(spare.toString(), decodeWeight(prefixOutput + completion.output)));
}
return results;
}
@Override
public void seekExact(long ord) throws IOException {
// TODO: would be better to make this simpler and faster.
// but we dont want to introduce a bug that corrupts our enum state!
bytesReader.setPosition(0);
fst.getFirstArc(firstArc);
IntsRef output = Util.getByOutput(fst, ord, bytesReader, firstArc, scratchArc, scratchInts);
BytesRefBuilder scratchBytes = new BytesRefBuilder();
scratchBytes.clear();
Util.toBytesRef(output, scratchBytes);
// TODO: we could do this lazily, better to try to push into FSTEnum though?
in.seekExact(scratchBytes.get());
}
