HashSet¶

Module: Std::HashSet

An open-addressing hash set of unique integer keys.

Summary¶

struct HashSet {
    data: *uint8;
    cap: uint;
    count: uint;
}

func Init(setPtr: *HashSet)
func InitWithCap(setPtr: *HashSet, capacity: uint)

extend HashSet {
    func Insert(self, key: int)
    func Contains(self, key: int) -> bool
    func Remove(self, key: int) -> bool
    func Clear(self)
    func Free(self)
    func Len(self) -> uint
    func Cap(self) -> uint
    func Keys(self) -> *int
}

Description¶

HashSet is an open-addressing hash set using linear probing. Keys are signed int values. The set automatically resizes when the load factor exceeds ⅞.

The hash function uses a splitmix64-derived mixing step for good distribution.

Initialization¶

A set must be initialized before use. Use Init for the default capacity (16) or InitWithCap for a custom minimum capacity. Sets should be freed with Free when no longer needed.

import Std::HashSet;

func Main() {
    var set: HashSet;
    HashSet::Init(&set);
    set.Insert(42);
    set.Free();
}

Functions¶

Insert¶

func Insert(self, key: int)

Inserts key into the set. Duplicate insertions are idempotent. Triggers a resize if the load factor exceeds ⅞.

Contains¶

func Contains(self, key: int) -> bool

Returns true if key exists in the set.

Example¶

var set: HashSet;
HashSet::Init(&set);
set.Insert(42);
var found = set.Contains(42); // true

Remove¶

func Remove(self, key: int) -> bool

Removes key from the set. Rehashes subsequent entries in the same probe chain to maintain correctness. Returns true if the key was found.

Clear¶

func Clear(self)

Removes all entries without deallocating the backing array — capacity is preserved.

Free¶

func Free(self)

Frees the backing array and resets the set to zero capacity.

Keys¶

func Keys(self) -> *int

Returns a heap-allocated array of all keys. The caller must free it with Std::Memory::Free. Returns null if the set is empty.

Example¶

import Std::HashSet;

func Main() {
    var set: HashSet;
    HashSet::Init(&set);

    set.Insert(10);
    set.Insert(20);
    set.Insert(30);

    var found = set.Contains(20); // true
    var missing = set.Contains(99); // false

    set.Remove(10);
    // set.Len() == 2

    set.Free();
}