Crate map_of_indexes
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Map-of-indexes
A small utility crate when you have a list of unique but not dense indexes for which to each you want to associates a value.
In the documentation the indexes are referred as key. Not an indexed map!
It can be considered a slower but more compact version of BTreeMap.
Examples
A brief example of the crate’s capacities
use map_of_indexes::{MapOfIndexes, MapOfIndexesError, KeyValue};
let v = vec![(3, 4), (1, 2), (5, 6)];
let mut map: MapOfIndexes::<(u8, u16)> = v.try_into()?;
map.push((7,8));
let push_res = map.push_checked((0,9));
assert_eq!(push_res, Err(MapOfIndexesError::SmallerKey));
let old_key_value = map.set((1,9))?;
assert_eq!(old_key_value.key(), &1);
assert_eq!(old_key_value.value(), &2);CombinedKeyValue is a compact representation when you need to save space.
use map_of_indexes::{CombinedKeyValue};
// We have keys that take up to 40 bits, and value up to 24;
// Using (u64, u64) would have wasted 8 byte per entry.
type CombinedU64 = CombinedKeyValue<u64, 40, 24>;
CombinedU64::safety_check(); // ensure that key and value size fit on the unsigned integer.
let v = vec![CombinedU64::new(3u64, 4u32), CombinedU64::new(1u64, 2u32), CombinedU64::new(5u64, 6u32)];
let map: MapOfIndexes<_> = v.try_into()?;
let inner_raw: Vec<u64> = Vec::from_iter(map.iter().map(|x| *x.as_ref()));
assert_eq!(inner_raw, vec![2199023255553, 4398046511107, 6597069766661]);For an even more compact representation, consider using the bitvec crate.
Structs
A compact struct that implement KeyValue
Basically a sorted vec
Enums
Different kind of errors generated by the library
Traits
Trait that T must implement to be able to work with MapOfIndexes of T.