TokenStream ts = queryAnalyzer.tokenStream("", key.toString());
try {
TermToBytesRefAttribute termBytesAtt = ts.addAttribute(TermToBytesRefAttribute.class);
OffsetAttribute offsetAtt = ts.addAttribute(OffsetAttribute.class);
PositionLengthAttribute posLenAtt = ts.addAttribute(PositionLengthAttribute.class);
PositionIncrementAttribute posIncAtt = ts.addAttribute(PositionIncrementAttribute.class);
ts.reset();
BytesRef[] lastTokens = new BytesRef[grams];
//System.out.println("lookup: key='" + key + "'");
// Run full analysis, but save only the
// last 1gram, last 2gram, etc.:
BytesRef tokenBytes = termBytesAtt.getBytesRef();
int maxEndOffset = -1;
boolean sawRealToken = false;
while(ts.incrementToken()) {
termBytesAtt.fillBytesRef();
sawRealToken |= tokenBytes.length > 0;
// TODO: this is somewhat iffy; today, ShingleFilter
// sets posLen to the gram count; maybe we should make
// a separate dedicated att for this?
int gramCount = posLenAtt.getPositionLength();
assert gramCount <= grams;
// Safety: make sure the recalculated count "agrees":
if (countGrams(tokenBytes) != gramCount) {
throw new IllegalArgumentException("tokens must not contain separator byte; got token=" + tokenBytes + " but gramCount=" + gramCount + " does not match recalculated count=" + countGrams(tokenBytes));
}
maxEndOffset = Math.max(maxEndOffset, offsetAtt.endOffset());
lastTokens[gramCount-1] = BytesRef.deepCopyOf(tokenBytes);
}
ts.end();
if (!sawRealToken) {
throw new IllegalArgumentException("no tokens produced by analyzer, or the only tokens were empty strings");
}
// Carefully fill last tokens with _ tokens;
// ShingleFilter appraently won't emit "only hole"
// tokens:
int endPosInc = posIncAtt.getPositionIncrement();
// Note this will also be true if input is the empty
// string (in which case we saw no tokens and
// maxEndOffset is still -1), which in fact works out OK
// because we fill the unigram with an empty BytesRef