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 voidptr¹.
Note that both your key and value types must define an equals as well as a hash method.

Example

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).

Footnotes

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 ↩