@Override
public final Expr compile(final QueryContext ctx, final VarScope scp) throws QueryException {
// invalidate current context value (will be overwritten by filter)
final Value cv = ctx.value;
try {
root = root.compile(ctx, scp);
// return empty root
if (root.isEmpty()) return optPre(null, ctx);
// convert filters without numeric predicates to axis paths
if (root instanceof AxisPath && !super.has(Flag.FCS))
return ((AxisPath) root.copy(ctx, scp)).addPreds(ctx, scp, preds).compile(ctx, scp);
// optimize filter expressions
ctx.value = null;
final Expr e = super.compile(ctx, scp);
if (e != this) return e;
// no predicates.. return root; otherwise, do some advanced compilations
return preds.length == 0 ? root : opt(ctx);
} finally {
ctx.value = cv;
}
}
