As a user of QStringBuilder, I would like to be able to express repetition and conditionals in expressions

For conditionals, we currently work around the lack of this feature by using the ternary operator nested within the QStringBuilder expression:

QStringView foo = ~~~;
QString s = str1 % ~~~~ % (shouldIncludeFoo ? foo : u"") % ~~~~ ;

But this requires the LHS and RHS of the ternary to have a reasonably-identical type. I cannot add a QL1S in one and a QStringView in the other, let alone QStringBuilder<T,S> for differing T, S.

I'm not sure whether one could just overload the ternary operator for QStringBuilder<>, but that would probably mean that at least one of the legs has to be a QStringBuilder expression itself, so maybe something more explicit is needed, like QStringBuilder::Conditional(cond, lhs, rhs)?

For repetition we don't have any work-around, except storing a subexpression in QString and then using QString::repeated().