Crate double_map

Double map

This crate is an attempt to provide Rust hash map with double key to single data/value.

Sometimes during development, it may be necessary to have a data structure like a HashMaps but with two different keys referring to the same data. For example, if you have some data with a unique ID and a name, then you create a structure that contains the name, and store it in a normal HashMap using the unique ID as the key. However, finding the element throughout the name will be performed with O(n) time. The same is true for the reverse case.

This crate try to resolve this contradiction by providing a DHashMap structure - a map where you can add, look up and remove elements using either the first key of type K1 or the second key of type K2. Internally, it uses two HashMaps: the first is of type HashMap<K1, (K2, V)> and the second is of type HashMap<K2, K1>. Using two HashMap’s insides instead one brings to the performance and memory penalty.

It is recommended to use the first key of type K1 for quick access to the data, because indexing by the second key of type K2 requires two HashMap lookups.

Modules

dhash_map

A hash map with double keys implemented as wrapper above two HashMaps.

Macros

dhashmap

Create a DHashMap<K1, K2, V, RandomState> from a list of sequentially given keys and values.

Structs

DHashMap

A hash map with double keys implemented as wrapper above two HashMaps.