/** Creates a new iterator, buffering entries from the specified iterator */
public BufferingTermFreqIteratorWrapper(TermFreqIterator source) throws IOException {
this.comp = source.getComparator();
BytesRef spare;
int freqIndex = 0;
while ((spare = source.next()) != null) {
entries.append(spare);
if (freqIndex >= freqs.length) {
freqs = ArrayUtil.grow(freqs, freqs.length + 1);
}
freqs[freqIndex++] = source.weight();
}
}
@Override
public void build(TermFreqIterator iterator) throws IOException {
BytesRef scratch = new BytesRef();
TermFreqIterator iter =
new WFSTTermFreqIteratorWrapper(iterator, BytesRef.getUTF8SortedAsUnicodeComparator());
IntsRef scratchInts = new IntsRef();
BytesRef previous = null;
PositiveIntOutputs outputs = PositiveIntOutputs.getSingleton(true);
Builder<Long> builder = new Builder<Long>(FST.INPUT_TYPE.BYTE1, outputs);
while ((scratch = iter.next()) != null) {
long cost = iter.weight();
if (previous == null) {
previous = new BytesRef();
} else if (scratch.equals(previous)) {
continue; // for duplicate suggestions, the best weight is actually
// added
}
Util.toIntsRef(scratch, scratchInts);
builder.add(scratchInts, cost);
previous.copyBytes(scratch);
}
fst = builder.finish();
}
@Override
public void build(TermFreqIterator tfit) throws IOException {
if (tfit instanceof TermFreqPayloadIterator) {
throw new IllegalArgumentException("this suggester doesn't support payloads");
}
File tempInput =
File.createTempFile(
FSTCompletionLookup.class.getSimpleName(), ".input", Sort.defaultTempDir());
File tempSorted =
File.createTempFile(
FSTCompletionLookup.class.getSimpleName(), ".sorted", Sort.defaultTempDir());
Sort.ByteSequencesWriter writer = new Sort.ByteSequencesWriter(tempInput);
Sort.ByteSequencesReader reader = null;
ExternalRefSorter sorter = null;
// Push floats up front before sequences to sort them. For now, assume they are non-negative.
// If negative floats are allowed some trickery needs to be done to find their byte order.
boolean success = false;
try {
byte[] buffer = new byte[0];
ByteArrayDataOutput output = new ByteArrayDataOutput(buffer);
BytesRef spare;
while ((spare = tfit.next()) != null) {
if (spare.length + 4 >= buffer.length) {
buffer = ArrayUtil.grow(buffer, spare.length + 4);
}
output.reset(buffer);
output.writeInt(encodeWeight(tfit.weight()));
output.writeBytes(spare.bytes, spare.offset, spare.length);
writer.write(buffer, 0, output.getPosition());
}
writer.close();
// We don't know the distribution of scores and we need to bucket them, so we'll sort
// and divide into equal buckets.
SortInfo info = new Sort().sort(tempInput, tempSorted);
tempInput.delete();
FSTCompletionBuilder builder =
new FSTCompletionBuilder(
buckets, sorter = new ExternalRefSorter(new Sort()), sharedTailLength);
final int inputLines = info.lines;
reader = new Sort.ByteSequencesReader(tempSorted);
long line = 0;
int previousBucket = 0;
int previousScore = 0;
ByteArrayDataInput input = new ByteArrayDataInput();
BytesRef tmp1 = new BytesRef();
BytesRef tmp2 = new BytesRef();
while (reader.read(tmp1)) {
input.reset(tmp1.bytes);
int currentScore = input.readInt();
int bucket;
if (line > 0 && currentScore == previousScore) {
bucket = previousBucket;
} else {
bucket = (int) (line * buckets / inputLines);
}
previousScore = currentScore;
previousBucket = bucket;
// Only append the input, discard the weight.
tmp2.bytes = tmp1.bytes;
tmp2.offset = input.getPosition();
tmp2.length = tmp1.length - input.getPosition();
builder.add(tmp2, bucket);
line++;
}
// The two FSTCompletions share the same automaton.
this.higherWeightsCompletion = builder.build();
this.normalCompletion =
new FSTCompletion(higherWeightsCompletion.getFST(), false, exactMatchFirst);
success = true;
} finally {
if (success) IOUtils.close(reader, writer, sorter);
else IOUtils.closeWhileHandlingException(reader, writer, sorter);
tempInput.delete();
tempSorted.delete();
}
}