https://github.com/wertzui123/hashmap

A generic hashmap implementation written in V that allows any kind of key-value-pairs
https://github.com/wertzui123/hashmap

hashmap v vlang

Last synced: 19 days ago
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A generic hashmap implementation written in V that allows any kind of key-value-pairs

• Host: GitHub
• URL: https://github.com/wertzui123/hashmap
• Owner: Wertzui123
• License: mit
• Created: 2022-04-10T15:12:49.000Z (almost 3 years ago)
• Default Branch: main
• Last Pushed: 2023-11-24T15:09:24.000Z (about 1 year ago)
• Last Synced: 2024-11-08T18:19:06.413Z (2 months ago)
• Topics: hashmap, v, vlang
• Language: V
• Homepage:
• Size: 21.5 KB
• Stars: 8
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# HashMap

This is a hashmap/hashtable implementation written in V.


Since the standard `map` type in V does not allow for arbitrary key types, you can use this library when you need keys of different types than `string`, `integer`, `float`, `rune`, `enum` or `voidptr`[^1].


Note that both your key and value types must define an `equals` as well as a `hash` method.

[^1]: Those types are allowed in the default V `map` datatype, see https://github.com/vlang/v/blob/a0e7a46be4d468ecf61b0e6cd7c81f11ddbd4233/vlib/v/parser/parse_type.v#L131

## Example

```v

import wertzui123.hashmap

struct Str {

	str string

}

pub fn (s1 Str) equals(s2 Str) bool {

	return s1.str == s2.str

}

pub fn (s Str) hash() int {

	return s.str.hash()

}

fn main() {

	mut m := hashmap.new_hashmap[Str, Str]()!

	m.set(Str{'Hello'}, Str{'World'})

	assert m.contains_key(Str{'Hello'})

	assert m.contains_value(Str{'World'})

	assert m.get_value(Str{'Hello'})? == Str{'World'}

	assert m.get_key(Str{'World'})? == Str{'Hello'}

	m.remove(Str{'Hello'})

	assert m.len == 0

}

```

## Performance

Since this is my first attempt at writing a hashmap, the performance is probably pretty poor; in particular, removing elements is really slow.


Furthermore, the array under the hoods is scaled by only one element each time it is enlarged, which is very bad if many elements are added (you can provide an `initial_capacity` when creating a hashmap though).


Of course the performance also depends a lot on what hashing algorithm you use for your keys.

## License

This library is licensed under the MIT license (see [LICENSE](LICENSE)).