BTreeMap range test for woodpecker

btreemap-range-test.rs

use std::collections::BTreeMap;
use std::collections::Bound::Included;

static mut INC: i32 = 0;

fn inc() -> i32 {
    unsafe {
        INC += 1;
        INC
    }
}

fn find(map: &BTreeMap<&str, i32>, module: &str) -> Option<String> {
    let top = module.split("::").nth(0).or(Some(module)).unwrap();
    let mut range = map.range::<str, _>((Included(top), Included(module)));

    let last = range.next_back();
    if last.is_none() {
        return None;
    }
    let (last, _) = last.unwrap();
    if module.starts_with(last) {
        return Some(last.to_string());
    }

    let first = range.next();
    if first.is_none() {
        return None;
    }
    let (first, _) = first.unwrap();
    Some(first.to_string())
}

fn main() {
    let mut map = BTreeMap::new();
    let keys = vec![
        "a",
        "a::b",
        "a::b::c",
        "a::c::c",

        "b",
        "b::b",
        "b::c::c",

        "c",
        "c::b",
        "c::b::c",
        "c::c::c",
    ];

    for key in keys {
        map.insert(key, inc());
    }

    println!("{:#?}", map);
    println!("");

    for module in &["b", "b::b", "b::b::c", "b::a", "b::c", "b::c::c", "d"] {
        println!(">> Looking for '{}', found {:?}", module, find(&map, module));
    }
}