Hashmap

This project implements a hashmap with the Robin Hood hashing algorithm (see paper).

The default key hash function is Go's standard library implementation. It is extracted at run time using an unsafe pointer to the native map. Refer to the source source of hasher.go for more details.

Usage

// Init
m := hashmap.New[string, int]() // Equivalent to make(map[string]int)

// Write
m.Set("key", 123)

// Read
value := m.Get("key") // value == 123

// Try read
value, found := m.TryGet("key") // value == 123, found == true
value, found := m.TryGet("key2") // value == 0, found == false

// Get stored entries count
length := m.Len() // length == 1

// Get all stored key-value pairs
entries := m.GetEntries() // entries == []KeyValue[string, int]{{Key: "key", Value: 123}}

// Delete a specific entry
m.Delete("key")

// Clear the entire map
m.Clear()

Configuration

The hashmap is pre-configured with the following values, but they can be configured:

• Key hasher: Go's native implementation.
• Initial capacity: 128 entries.
• Load factor: 50%. The load factor is the maximum hashmap load at which point it will resize itself at double its size.

// Custom key hasher
hasher := func(keyPtr, seed uintptr) uintptr {
    // [...]
    return generatedHash
}

// Specify initial capacity (must be a power of 2)
initialCap := 256

// With an increased load factor
loadFactor := 70

// Create configured map
m := hashmap.New[string, int](
    hashmap.WithHashFunc[string, int](hasher),
    hashmap.WithInitialCapacity[string, int](initialCap),
    hashmap.WithMaxLoadPercentage[string, int](loadFactor),
)