collect-once-hashmap

This crate provides a type CollectOnceHashMap (and the same for BTreeMap that can be collected from an iterator just like a normal std::collections::HashMap, but it makes sure that a duplicated key results in an error.

Example:

```rust

use collectoncehashmap::{CollectOnceHashMap, Error};

let hm = vec![(1, 1), (1, 2)] .intoiter() .collect::>() .intoinner();

assert!(hm.is_err()); assert!(std::matches!(hm, Err(Error::DuplicatedKey(1))));

let bm = vec![(1, 1), (1, 2)] .intoiter() .collect::>() .intoinner();

assert!(bm.is_err()); assert!(std::matches!(bm, Err(Error::DuplicatedKey(1)))); ```

License

MPL-2.0 (c) Matthias Beyer