- non static and non namespaced global variable EMOJIS (should be inside the emojize method or at least in the namespace)
- lack of STL use, that std::string replacing code doesn't look very "modern" at all
- complete lack of unit tests
- README has unsupported emojis under the "supported" header
This is the sort of thing that turns me off C++ completely. It used to be a pragmatic extension to C, now it's about trend-chasing.
The code could be simpler (the extra "index" which is essentially a state variable is odd), but IMHO it is otherwise perfectly fine. Useless superficial criticism like this is just another form of cargo-culting.
no, it's about maximizing performance, because C++ libs are what countless software build upon. Maybe someone will want to use this to display a 4*4k mural screen with 2000000 of those displayed and changing in real-time. Just using a <map> instead of a hash-container (there's a compile-time one just on top of HN right now which would fit the bill perfectly since these are known at compile time) is already a fairly big smell.
The implementation honestly should be put in .cpp file, not a header. Currently it will define both the gigantic statically-initialized map and a function in each module where it's used. Compared to consequences of this lack of unit tests looks like nit-picking.
And yeah, the logic of the function is easy to follow, so it's definitely not modern C++.
It isn't easy to follow at all, count how many "+1" had to be added just to get indices working right, it's a mine field of off by one errors.
You can't be serious.