std.hashmap

APIs documented for this release.

use std.hashmap;

Use std.hashmap.HashMap<V> to look up values by string keys. Save this as hashmap.xen:

use std.hashmap as hashmap;

#![explc]
fn main() {
    let mut prices = hashmap.new<Int>();
    prices.insert("tea", 3);
    prices.insert("coffee", 4);
    let key = "tea";
    println(match prices.get_cloned(&key) {
        Option.Some(price) => price,
        Option.None => 0,
    });
    println(prices.len());
}

$ xen run hashmap.xen
3
2

Task	API
Create	std.hashmap.new<V>()
Count or check emptiness	map.len(), map.is_empty()
Insert or replace	map.insert(key, value); returns the previous value as Some if present
Look up	map.get_cloned(&key); returns a copy in an Option
Check presence	map.contains_key(&key)
Remove	map.remove(&key); returns the removed value in an Option
List keys	map.keys(); an independent Vec<String>
Empty	map.clear()
Consume and iterate	map.into_iter(); (String, V) items

The map itself is move-only. get_cloned cannot retrieve noncopyable values such as Box or File. Take them out with remove, or inspect them through std.hashmap.with_value<V, R>(&map, &key, inspect) using a named fn(&V) -> R callback. Explicit reference arguments require explc. Key lists and iteration have unspecified order. Use the APIs rather than changing map fields directly.