Hash function which preserves orders for a stream of keys

I would like to have hashing function that has the following property

if A < B ==>  HASH(A) < HASH(B)

If the keys (e,g., {A, B, ...}) are present, the solution becomes fairly straight-forward. However, I receive the codes in a stream, which means that only one code is available at a given time.

I am using C++11.

Any solution or advice is greatly appreciated.