BloombergLP::ball::CategoryManager_RadixTree::EmplaceResult

The return type of adding a value to the tree with emplace(). It is not the usual insert return type, because this data structure does not provide an iterator. The .first boolean is true if an element was inserted, and the .second data member is a reference to the (possibly newly created) value. Notice that if the value existed (.first == false) the reference wrapper will still give access to the value of that node; the .second is always a valid mutable reference to the value belonging to the key used in the emplace call.