@Override
protected Expr opt(final QueryContext qc, final VarScope scp) {
final Expr e = exprs[0];
final SeqType st = e.seqType();
if (!st.mayBeZero()) return e;
seqType = SeqType.get(st.type, seqType.occ);
return this;
}
@Override
public GroupBy optimize(final QueryContext qc, final VarScope scp) throws QueryException {
final int pl = preExpr.length;
for (int p = 0; p < pl; p++) {
final SeqType it = preExpr[p].seqType();
post[p].refineType(it.withOcc(it.mayBeZero() ? Occ.ZERO_MORE : Occ.ONE_MORE), qc);
}
return this;
}
@Override
public Expr compile(final QueryContext ctx) throws QueryException {
for (int e = 0; e < expr.length; e++) expr[e] = expr[e].compile(ctx);
// compute number of results
size = 0;
for (final Expr e : expr) {
final long c = e.size();
if (c == -1) {
size = c;
break;
}
size += c;
}
// evaluate sequence type
type = SeqType.EMP;
Value[] val = new Value[expr.length];
for (int v = 0; v < expr.length; v++) {
final Expr e = expr[v];
// check if all expressions are values
if (val != null) {
if (e.isValue()) val[v] = (Value) e;
else val = null;
}
// skip expression that will not add any results
if (e.isEmpty()) continue;
// evaluate sequence type
final SeqType et = e.type();
type =
type == SeqType.EMP
? et
: SeqType.get(
et.type == type.type ? et.type : AtomType.ITEM,
et.mayBeZero() && type.mayBeZero() ? Occ.ZERO_MORE : Occ.ONE_MORE);
}
// return cached integer sequence, cached values or self reference
Expr e = this;
final int s = (int) size;
if (val != null && size <= Integer.MAX_VALUE) {
if (type.type == AtomType.STR) e = StrSeq.get(val, s);
else if (type.type == AtomType.BLN) e = BlnSeq.get(val, s);
else if (type.type == AtomType.FLT) e = FltSeq.get(val, s);
else if (type.type == AtomType.DBL) e = DblSeq.get(val, s);
else if (type.type == AtomType.DEC) e = DecSeq.get(val, s);
else if (type.type == AtomType.BYT) e = BytSeq.get(val, s);
else if (type.type.instanceOf(AtomType.ITR)) e = IntSeq.get(val, s, type.type);
else {
final ValueBuilder vb = new ValueBuilder(s);
for (final Value v : val) vb.add(v);
e = vb.value();
}
}
return optPre(e, ctx);
}