The question is about the puzzle pieces needed to make a functioning autocomplete in the context of C text editing. An example of autocomplete can be seen in VSCode, Geany, and even vim. The latter would interest me more, but differences might be worth noting.

Mainly, I want to know if the computer re-calculates all the words each time, or whether it has a database of the words, or at least some rudimentary alphabet array that has pointers to the words beginning with a certain letter.

Also, some autocompletes react only to the specific letters you type in order (like “ba”, will give you “banana”, “baloon”), but some others (Like VSCode) will give things like “beaver” (just because it contains the two letters anywhere). I think the first approach looks less intensive, but the second might help with typos and whatnot.

Also, a big concern is how to possibly be able to make extern and MACROS from other #include-d files available to the droplist, without going overboard and wasting resources cascading throughout the whole glibc.