Support for ordered insert/erase on json::object #748
Description
I have a json that needs to be manipulated and maintaining the order of the keys in the object is really imported (even though it is supposed to be unordered key-value map).
Currently insertions are ordered so creating a json::object and inserting at the end will preserve the order. A work around I have now is something like this:
template<class K, class P> void ordered_insert_before(boost::json::object& o, K&& key, P&& p) { auto x = boost::json::object(o.storage()); x.reserve(o.size() + 1); bool added = false; for (auto&& [k, v] : o) { if (k == key && !added) { x.insert(std::forward<P>(p)); added = true; } x.insert(boost::json::object::value_type{std::move(k), std::move(v)}); } if (!added) { x.insert(std::forward<P>(p)); } o.swap(x); } template<class K> void ordered_erase(boost::json::object& o, K&& key) { auto x = boost::json::object(o.storage()); x.reserve(o.size()); for (auto&& [k, v] : o) { if (k != key) { x.insert(boost::json::object::value_type{std::move(k), std::move(v)}); } } o.swap(x); }There are of course O(N). Is there interest for adding these as member functions or free functions with stronger ordering guarantees but worse O(N) complexity + allocations?