// returns true if multigroup
private boolean openDocumentIndex(int docID) throws Exception {
// The data is only the data for this document id. Thus the base is set
// to zero.
_data = _env.getPositions(docID);
_base = 0;
_startingIndex = 0;
int kk = _data[_base] & 0xFF, k2;
switch (kk >> 6) // get type
{
case 0: // single group, no extents
k2 = _data[_base + 1];
_firstGenerator.init(_data, _base += 2, k2);
// decode concept table
_nConcepts = _firstGenerator.decodeConcepts(kk & 0x3F, 0, _concepts);
return false;
case 2: // multi group, no extents
_kTable.clear();
_offsets.clear();
_maxConcepts.clear();
ByteArrayDecompressor compr = new ByteArrayDecompressor(_data, _base + 1);
compr.decode(kk & 0x3F, _kTable);
compr.ascDecode(_kTable.popLast(), _offsets);
compr.ascDecode(_kTable.popLast(), _maxConcepts);
_base += 1 + compr.bytesRead();
_limit = _maxConcepts.cardinality();
return true;
case 1: // single group, extents
case 3: // multi group, extents
throw new Exception("extents not yet implemented\n");
}
return false;
}
private ConceptGroupGenerator makeGenerator(int group) throws Exception {
int shift, index;
if (group > 0) {
index = _base + _offsets.at(group - 1);
shift = _maxConcepts.at(group - 1);
} else {
index = _base;
shift = 0;
}
// initialize generator
ConceptGroupGenerator gen = new ConceptGroupGenerator(_data, index, _kTable.at(2 * group + 1));
// decode concept table
_nConcepts = gen.decodeConcepts(_kTable.at(2 * group), shift, _concepts);
if (group < _limit) _max = _concepts[_nConcepts] = _maxConcepts.at(group);
else _max = _concepts[_nConcepts - 1];
_genHeap.addGenerator(gen);
_startingIndex = 0; // in _concepts; lower search index
return gen;
}
