https://github.com/wolgemoth/cpp-hashmap
Concurrent multiplatform hashmap with simple API, exception safety, and sequential collision resolution.
https://github.com/wolgemoth/cpp-hashmap
concurrency concurrent cpp cpp17 dictionary exception-safety hashmap initializer-list modern-cpp multiplatform multithreading sequential-chain templates
Last synced: about 2 months ago
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Concurrent multiplatform hashmap with simple API, exception safety, and sequential collision resolution.
- Host: GitHub
- URL: https://github.com/wolgemoth/cpp-hashmap
- Owner: wolgemoth
- License: mit
- Created: 2024-01-10T19:34:34.000Z (over 1 year ago)
- Default Branch: master
- Last Pushed: 2024-07-27T22:03:33.000Z (10 months ago)
- Last Synced: 2025-02-06T00:31:48.783Z (4 months ago)
- Topics: concurrency, concurrent, cpp, cpp17, dictionary, exception-safety, hashmap, initializer-list, modern-cpp, multiplatform, multithreading, sequential-chain, templates
- Language: C++
- Homepage:
- Size: 69.3 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# C++ Hashmap (2.3.0)
## Table of Contents
- [About](#About)
- [Instructions](#Instructions)
- [Dependencies](#Dependencies)
- [References](#References)
### About
This is a hashmap written in C++.
It has a similar API to C#'s [Dictionary](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2?view=net-8.0) and self-initializes like an [std::vector](https://en.cppreference.com/w/cpp/container/vector). Currently, it uses [sequential chaining](https://en.wikipedia.org/wiki/Hash_table#Separate_chaining) for collision resolution. More collision resolution techniques may be added in the future.
This structure provides robust exception safety, and is suitable for use in a concurrent environment. Furthermore, it supports move semantics and initialiser lists.
Explicit finalization of the hashmap is not necessary. However, if you are storing manually-managed memory, then remember to free any elements before removal.
If you find a bug or have a feature-request, please raise an issue.
Like hashsets? Check out my other project: [cpp-hashset](https://github.com/wolgemoth/cpp-hashset)!
### Instructions
The implementation is header-only and written in templated C++17. You should not need to make any adjustments to your project settings or compiler flags.
Simply include it in your project and you are ready to start!
#### Example:
#include
#include "Hashmap.hpp"
LouiEriksson::Hashmap hashmap {
{ "key1", 1.0f },
{ "key2", 2.0f },
{ "key3", 3.0f },
}
int main() {
if (const auto item = hashmap.Get("key3")) {
std::cout << "Value: " << item.value() << '\n';
}
else {
std::cout << "Key not in Hashmap!\n";
}
return 0;
}
### Dependencies
The hashmap was written in C++17 and utilises the following standard headers:
#### <algorithm>
#### <cstddef>
#### <functional>
#### <initializer_list>
#### <iostream>
#### <mutex>
#### <optional>
#### <stdexcept>
#### <vector>
### Why not use <unordered_map>?
I find unordered_map to be way too verbose for most situations.
In this implementation, key existence and value retrieval are merged into a single conditional expression. This allows for simpler, cleaner code that affords better exception handling.
### Note
Please note that while the hashmap is capable of being used in a concurrent environment, it does not provide a mechanism for synchronising changes to the hashmap which are made in between operations.
Therefore, if you need to perform a synchronous series of operations on the Hashmap while it is being used in a concurrent context, you should lock access to the hashmap to one thread while doing so, otherwise you may encounter race conditions.
### References
- Wang, Q. (Harry) (2020). Implementing Your Own HashMap (Explanation + Code). YouTube. Available at: https://www.youtube.com/watch?v=_Q-eNqTOxlE [Accessed 2021].