optparse VS fst

Between -std=c99 and removing these headers, you're missing time definitions (struct timeval, gettimeofday) and option parsing definitions (struct option, getopt_long). Mingw-w64 provides all this for compatibility, but MSVC has none of these, so you'll need to write replacements. I've written embeddable, public domain implementations of getopt and something like getopt_long, in case that helps. These are how I deal with option parsing portability.

getopt_long is a GNU extension, common across unix-like systems, for parsing long options. You can find libraries for functionality as well.

When I need something more sophisticated, where long options would be nice, I reach for my own Optparse.

https://github.com/skeeto/optparse (short and long)

This is bug-free and feature complete so it never needs to be updated. When I need argument parsing in a C program, I just copy-paste that into my source and massage it into place. Sometimes I cut the fprintf() stuff, or replace the isalnum, or otherwise adapt it to fit the program's needs. The point is that it becomes wholly owned by the project using it. It's a similar story for long option parsing.

I'd point you towards BurntSushi's fst crate: https://github.com/BurntSushi/fst

The fst crate effectively relies on mmap for it to work right. The folks here suggesting you just use the heap might be right, but only if using the heap is actually plausible. If your dictionary is GBs big (an FST might be bigger than available memory), then copying it the heap first would be disastrous.

You'll love what we're working on if you're interested in the implementation of:- Tantivy- Meilisearch- Finite State Transducers

Here's an example of longest prefix matching using a FST which I based my approach on: https://github.com/BurntSushi/fst/pull/104/files

Finite State Transducers

As a result, I have a plan to implement a desktop version from then and I finished today with a beta version. The desktop is based on tauri, and the dictionary index algorithm is FST (it is an awesome index algorithm).

WordBueno’s data is currently derived from Wiktionary. The backend is using Rust’s warp with fst for indexing.

No you don't. I've written multiple programs that load things instantly off the file system via memory maps. See the fst crate[1], for example, which is designed to work with memory maps.

Rust "works badly with memory mapped files" doesn't mean, "Rust can't use memory mapped files." It means, "it is difficult to reconcile Rust's safety story with memory maps." ripgrep for example uses memory maps because they are faster sometimes, and its safety contract[2] is a bit strained. But it works.

[1] - https://github.com/BurntSushi/fst/

[2] - https://docs.rs/grep-searcher/0.1.7/grep_searcher/struct.Mma...