chore: move from tools/dsa (#1)

Moved the implementation of this hash table from `tools/dsa` #1.

Reviewed-on: #1
Co-authored-by: M.V. Hutz <git@maximhutz.me>
Co-committed-by: M.V. Hutz <git@maximhutz.me>

bucket.go

@@ -0,0 +1,73 @@
+package cuckoo
+
+type entry[K, V any] struct {
+	key   K
+	value V
+}
+
+type slot[K, V any] struct {
+	entry[K, V]
+	occupied bool
+}
+
+type bucket[K, V any] struct {
+	hash           Hash[K]
+	slots          []slot[K, V]
+	capacity, size uint64
+	compare        EqualFunc[K]
+}
+
+func (b bucket[K, V]) location(key K) uint64 {
+	return b.hash(key) % b.capacity
+}
+
+func (b bucket[K, V]) get(key K) (value V, found bool) {
+	slot := b.slots[b.location(key)]
+	return slot.value, slot.occupied && b.compare(slot.key, key)
+}
+
+func (b *bucket[K, V]) resize(capacity uint64) {
+	b.slots = make([]slot[K, V], capacity)
+	b.capacity = capacity
+	b.size = 0
+}
+
+func (b bucket[K, V]) update(key K, value V) (updated bool) {
+	slot := &b.slots[b.location(key)]
+
+	if slot.occupied && b.compare(slot.key, key) {
+		slot.value = value
+		return true
+	}
+
+	return false
+}
+
+func (b *bucket[K, V]) evict(insertion entry[K, V]) (evicted entry[K, V], eviction bool) {
+	slot := &b.slots[b.location(insertion.key)]
+
+	if !slot.occupied {
+		slot.entry = insertion
+		slot.occupied = true
+		b.size++
+		return
+	}
+
+	if b.compare(slot.key, insertion.key) {
+		slot.value = insertion.value
+		return
+	}
+
+	insertion, slot.entry = slot.entry, insertion
+	return insertion, true
+}
+
+func newBucket[K, V any](capacity uint64, hash Hash[K], compare EqualFunc[K]) bucket[K, V] {
+	return bucket[K, V]{
+		hash:     hash,
+		capacity: capacity,
+		compare:  compare,
+		size:     0,
+		slots:    make([]slot[K, V], capacity),
+	}
+}