HashMap¶

Module: Std::HashMap

An open-addressing hash map from integer keys to opaque pointer values.

Summary¶

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

func Init(mapPtr: *HashMap)
func InitWithCap(mapPtr: *HashMap, capacity: uint)

extend HashMap {
    func Len(self) -> uint
    func Cap(self) -> uint
    func Set(self, key: int, value: *opaque)
    func Get(self, key: int) -> *opaque
    func Contains(self, key: int) -> bool
    func Remove(self, key: int) -> bool
    func Clear(self)
    func Free(self)
    func Keys(self) -> *int
    func Values(self) -> **opaque
}

Description¶

HashMap is an open-addressing hash table using linear probing. Keys are signed int values, values are *opaque pointers. The map automatically resizes when the load factor exceeds ⅞.

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

Initialization¶

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

import Std::HashMap;

func Main() {
    var map: HashMap;
    HashMap::Init(&map);
    map.Set(1, 42 as *opaque);
    map.Free();
}

Functions¶

Set¶

func Set(self, key: int, value: *opaque)

Inserts or updates the value for key. Triggers a resize if the load factor exceeds ⅞.

Get¶

func Get(self, key: int) -> *opaque

Returns the value for key, or null if not found.

Example¶

var map: HashMap;
HashMap::Init(&map);
map.Set(1, 42 as *opaque);
var val = map.Get(1); // 42 as *opaque

Contains¶

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

Returns true if key exists in the map.

Remove¶

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

Removes key from the map. 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 map 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 map is empty.

Values¶

func Values(self) -> **opaque

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

Example¶

import Std::HashMap;

func Main() {
    var map: HashMap;
    HashMap::Init(&map);

    map.Set(10, "ten" as *opaque);
    map.Set(20, "twenty" as *opaque);

    var val = map.Get(10);
    // val points to "ten"

    map.Remove(20);
    // map.Len() == 1

    map.Free();
}