entry_put_ext

Map entry extension for put operations.

The author of this crate is not good at English.
Forgive me if the document is hard to read.

What is this?

This crate extends result type of the entry methods of the maps (HashMap and BTreeMap) by adding an put methods. These put methods are helper method to set a value of an entry and get a reference to it. This makes common code about setting and getting shortened a little.

use std::collections::HashMap;
use entry_put_ext::hash_map::EntryPutExt;

let mut map = HashMap::from([("X", false)]);
let x = *map.entry("X").put(true);
let y = *map.entry("Y").put(true);

assert_eq!(x, map["X"]);
assert_eq!(y, map["Y"]);

Other options

Without this crate.

insert and get (Simple, but little slow and not one-liner).

use std::collections::HashMap;

let mut map = HashMap::from([("X", false)]);
map.insert("X", true);
map.insert("Y", true);
let x = *map.get("X").unwrap();
let y = *map.get("Y").unwrap();

assert_eq!(x, map["X"]);
assert_eq!(y, map["Y"]);

and_modify and or_insert (required Copy trait for value type).

use std::collections::HashMap;

let mut map = HashMap::from([("X", false)]);
let (xv, yv) = (true, true);
let x = *map.entry("X").and_modify(|x| *x = xv).or_insert(xv);
let y = *map.entry("Y").and_modify(|x| *x = yv).or_insert(yv);

assert_eq!(x, map["X"]);
assert_eq!(y, map["Y"]);