What is the best way to compile JavaScript-like structures to static, fast C++?

Question

On the development of a compiler from a language very similar to JavaScript to C++, I need a way to represent data structures. JavaScript's main data structures are Arrays and Hash-Tables. Arrays are more straighforward: I can use a vector of untyped pointers . It needs to be a vector because JS arrays are dynamic, and of pointers because JS arrays can hold any kind of object, for example:

var array = [1,2,[3,4],"test"];

I can't see a way to represent this other than that (is there?). For the hashes, I could use something similar, except including the string hashing step on access.

The problem is: JavaScript hashes are JIT-compiled into actual C++ objects which probably are much faster than hashes . This way, I'm afraid my attempt to generate C++ like that will actually result in slower code than the JavaScript version!

1. Does that make sense?
2. What would be the best approach to my compiler?

Answer 1

If this is an AOT compiler you can only process the hash keys that you see at compile-time, obviously. In this case you can change hash accesses to known keys to array accesses, giving each known key a small integer as index.