Awesome

StableHashMap

Stable HashMaps in Motoko.

Motivation

Inspiration taken from this back and forth in the Dfinity developer forums.

API Documentation

API documentation for this library can be found at https://canscale.github.io/StableHashMap

Implementation

Two different StableHashMap implementations are accessible via this module.

FunctionalStableHashMap (Recommended)

This module is a direct deconstruction of the object oriented [HashMap.mo class in motoko-base] (https://github.com/dfinity/motoko-base/blob/master/src/HashMap.mo) into a series of functions and is meant to be persistent across updates, with the tradeoff being larger function signatures.

One of the main additions/difference between the two modules at this time besides class deconstruction is the differing initialization methods if an initialCapacity is known (to prevent array doubling slowdown during map initialization)

ClassStableHashMap

Note: If using this module the exportProps() and importProps() class methods must be used in conjunction with the system pre/post-upgrade methods to assure stability.

This module is nearly identical to https://github.com/dfinity/motoko-base/blob/master/src/HashMap.mo, except public exportProps() and importProps() class methods were added to the original implementation in order to allow the hashtable and it's item count to be retrievable and therefore persistable across upgrades.

License

StableHashMap is distributed under the terms of the Apache License (Version 2.0).

See LICENSE for details.