/**
* Constructor, initializing the index structure.
*
* @param data data reference
* @throws IOException I/O Exception
*/
public FTIndex(final Data data) throws IOException {
super(data, true);
// cache token length index
inY = new DataAccess(data.meta.dbfile(DATAFTX + 'y'));
inZ = new DataAccess(data.meta.dbfile(DATAFTX + 'z'));
inX = new DataAccess(data.meta.dbfile(DATAFTX + 'x'));
tp = new int[data.meta.maxlen + 3];
final int tl = tp.length;
for (int i = 0; i < tl; ++i) tp[i] = -1;
int is = inX.readNum();
while (--is >= 0) {
int p = inX.readNum();
final int r;
if (p < tl) {
r = inX.read4();
} else {
// legacy issue (7.0.2 -> 7.1)
r = p << 24 | (inX.read1() & 0xFF) << 16 | (inX.read1() & 0xFF) << 8 | inX.read1() & 0xFF;
p = p >> 8 | 0x40;
}
tp[p] = r;
}
tp[tl - 1] = (int) inY.length();
}
/**
* Performs a wildcard search for the specified token.
*
* @param token token to look for
* @return iterator
*/
private synchronized IndexIterator wc(final byte[] token) {
final FTIndexIterator it = FTIndexIterator.FTEMPTY;
final FTWildcard wc = new FTWildcard(token);
if (!wc.parse()) return it;
final IntList pr = new IntList();
final IntList ps = new IntList();
final byte[] pref = wc.prefix();
final int pl = pref.length, tl = tp.length;
final int l = Math.min(tl - 1, wc.max());
for (int ti = pl; ti <= l; ti++) {
int i = tp[ti];
if (i == -1) continue;
int c = ti + 1;
int e = -1;
while (c < tl && e == -1) e = tp[c++];
i = find(pref, i, e, ti);
while (i < e) {
final byte[] t = inY.readBytes(i, ti);
if (!startsWith(t, pref)) break;
if (wc.match(t)) {
inZ.cursor(pointer(i, ti));
final int s = size(i, ti);
for (int d = 0; d < s; d++) {
pr.add(inZ.readNum());
ps.add(inZ.readNum());
}
}
i += ti + ENTRY;
}
}
return iter(new FTCache(pr, ps), token);
}
/**
* Returns an iterator for an index entry.
*
* @param off offset on entries
* @param size number of id/pos entries
* @param da data source
* @param token index token
* @return iterator
*/
private static FTIndexIterator iter(
final long off, final int size, final DataAccess da, final byte[] token) {
da.cursor(off);
final IntList pr = new IntList(size);
final IntList ps = new IntList(size);
for (int c = 0; c < size; c++) {
pr.add(da.readNum());
ps.add(da.readNum());
}
return iter(new FTCache(pr, ps), token);
}