bucket.go

@@ -1,103 +0,0 @@
-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]
-}
-
-// location determines where in the bucket a certain key would be placed. If the
-// capacity is 0, this will panic.
-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) {
-	if b.capacity == 0 {
-		return
-	}
-
-	slot := b.slots[b.location(key)]
-	return slot.value, slot.occupied && b.compare(slot.key, key)
-}
-
-func (b *bucket[K, V]) drop(key K) (occupied bool) {
-	if b.capacity == 0 {
-		return
-	}
-
-	slot := &b.slots[b.location(key)]
-
-	if slot.occupied && b.compare(slot.key, key) {
-		slot.occupied = false
-		b.size--
-		return true
-	}
-
-	return false
-}
-
-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) {
-	if b.capacity == 0 {
-		return
-	}
-
-	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) {
-	if b.capacity == 0 {
-		return insertion, true
-	}
-
-	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),
-	}
-}

hash_table.go

@@ -0,0 +1,237 @@
+package cuckoo
+
+import (
+	"fmt"
+	"iter"
+	"math/bits"
+	"strings"
+)
+
+// A HashTable is hash table that uses cuckoo hashing to resolve collision. Create
+// one with [NewTable]. Or if you want more granularity, use [NewTableBy] or
+// [NewCustomTable].
+type HashTable[K, V any] struct {
+	tableA, tableB table[K, V]
+	growthFactor   uint64
+	minLoadFactor  float64
+}
+
+// TotalCapacity returns the number of slots allocated for the [HashTable]. To get the
+// number of slots filled, look at [HashTable.Size].
+func (t *HashTable[K, V]) TotalCapacity() uint64 {
+	return t.tableA.capacity + t.tableB.capacity
+}
+
+// Size returns how many slots are filled in the [HashTable].
+func (t *HashTable[K, V]) Size() int {
+	return int(t.tableA.size + t.tableB.size)
+}
+
+func log2(n uint64) (m int) {
+	return max(0, bits.Len64(n)-1)
+}
+
+func (t *HashTable[K, V]) maxEvictions() int {
+	return 3 * log2(t.TotalCapacity())
+}
+
+func (t *HashTable[K, V]) load() float64 {
+	// When there are no slots in the table, we still treat the load as 100%.
+	// Every slot in the table is full.
+	if t.TotalCapacity() == 0 {
+		return 1.0
+	}
+
+	return float64(t.Size()) / float64(t.TotalCapacity())
+}
+
+// resize clears all buckets, changes the sizes of them to a specific capacity,
+// and fills them back up again. It is a helper function for [HashTable.grow] and
+// [HashTable.shrink]; use them instead.
+func (t *HashTable[K, V]) resize(capacity uint64) error {
+	entries := make([]entry[K, V], 0, t.Size())
+	for k, v := range t.Entries() {
+		entries = append(entries, entry[K, V]{k, v})
+	}
+
+	t.tableA.resize(capacity)
+	t.tableB.resize(capacity)
+
+	for _, entry := range entries {
+		if err := t.Put(entry.key, entry.value); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// grow increases the table's capacity by the [HashTable.growthFactor]. If the
+// capacity is 0, it increases it to 1.
+func (t *HashTable[K, V]) grow() error {
+	var newCapacity uint64
+
+	if t.TotalCapacity() == 0 {
+		newCapacity = 1
+	} else {
+		newCapacity = t.tableA.capacity * t.growthFactor
+	}
+
+	return t.resize(newCapacity)
+}
+
+// shrink reduces the table's capacity by the [HashTable.growthFactor]. It may
+// reduce it down to 0.
+func (t *HashTable[K, V]) shrink() error {
+	return t.resize(t.tableA.capacity / t.growthFactor)
+}
+
+// Get fetches the value for a key in the [HashTable]. Returns an error if no value
+// is found.
+func (t *HashTable[K, V]) Get(key K) (value V, err error) {
+	if item, ok := t.tableA.get(key); ok {
+		return item, nil
+	}
+
+	if item, ok := t.tableB.get(key); ok {
+		return item, nil
+	}
+
+	return value, fmt.Errorf("key '%v' not found", key)
+}
+
+// Has returns true if a key has a value in the table.
+func (t *HashTable[K, V]) Has(key K) (exists bool) {
+	_, err := t.Get(key)
+	return err == nil
+}
+
+// Put sets the value for a key. Returns error if its value cannot be set.
+func (t *HashTable[K, V]) Put(key K, value V) (err error) {
+	if t.tableA.update(key, value) {
+		return nil
+	}
+
+	if t.tableB.update(key, value) {
+		return nil
+	}
+
+	entry, eviction := entry[K, V]{key, value}, false
+	for range t.maxEvictions() {
+		if entry, eviction = t.tableA.evict(entry); !eviction {
+			return nil
+		}
+
+		if entry, eviction = t.tableB.evict(entry); !eviction {
+			return nil
+		}
+	}
+
+	if t.load() < t.minLoadFactor {
+		return fmt.Errorf("bad hash: resize on load %d/%d = %f", t.Size(), t.TotalCapacity(), t.load())
+	}
+
+	if err := t.grow(); err != nil {
+		return err
+	}
+
+	return t.Put(entry.key, entry.value)
+}
+
+// Drop removes a value for a key in the table. Returns an error if its value
+// cannot be removed.
+func (t *HashTable[K, V]) Drop(key K) (err error) {
+	t.tableA.drop(key)
+	t.tableB.drop(key)
+
+	if t.load() < t.minLoadFactor {
+		return t.shrink()
+	}
+
+	return nil
+}
+
+// Entries returns an unordered sequence of all key-value pairs in the table.
+func (t *HashTable[K, V]) Entries() iter.Seq2[K, V] {
+	return func(yield func(K, V) bool) {
+		for _, slot := range t.tableA.slots {
+			if slot.occupied {
+				if !yield(slot.key, slot.value) {
+					return
+				}
+			}
+		}
+
+		for _, slot := range t.tableB.slots {
+			if slot.occupied {
+				if !yield(slot.key, slot.value) {
+					return
+				}
+			}
+		}
+	}
+}
+
+// String returns the entries of the table as a string in the format:
+// "table[k1:v1 h2:v2 ...]".
+func (t *HashTable[K, V]) String() string {
+	var sb strings.Builder
+	sb.WriteString("table[")
+
+	first := true
+	for k, v := range t.Entries() {
+		if !first {
+			sb.WriteString(" ")
+		}
+
+		fmt.Fprintf(&sb, "%v:%v", k, v)
+		first = false
+	}
+
+	sb.WriteString("]")
+	return sb.String()
+}
+
+// NewCustomTable creates a [HashTable] with custom [Hash] and [EqualFunc]
+// functions, along with any [Option] the user provides.
+func NewCustomTable[K, V any](hashA, hashB Hash[K], compare EqualFunc[K], options ...Option) *HashTable[K, V] {
+	settings := &settings{
+		growthFactor:  DefaultGrowthFactor,
+		bucketSize:    DefaultCapacity,
+		minLoadFactor: defaultMinimumLoad,
+	}
+
+	for _, option := range options {
+		option(settings)
+	}
+
+	return &HashTable[K, V]{
+		growthFactor:  settings.growthFactor,
+		minLoadFactor: settings.minLoadFactor,
+		tableA:        newTable[K, V](settings.bucketSize, hashA, compare),
+		tableB:        newTable[K, V](settings.bucketSize, hashB, compare),
+	}
+}
+
+func pipe[X, Y, Z any](a func(X) Y, b func(Y) Z) func(X) Z {
+	return func(x X) Z { return b(a(x)) }
+}
+
+// NewTableBy creates a [HashTable] for any key type by using keyFunc to derive a
+// comparable key. Two keys with the same derived key are treated as equal.
+func NewTableBy[K, V any, C comparable](keyFunc func(K) C, options ...Option) *HashTable[K, V] {
+	return NewCustomTable[K, V](
+		pipe(keyFunc, NewDefaultHash[C]()),
+		pipe(keyFunc, NewDefaultHash[C]()),
+		func(a, b K) bool { return keyFunc(a) == keyFunc(b) },
+		options...,
+	)
+}
+
+// NewTable creates a [HashTable] using the default [Hash] and [EqualFunc]. Use
+// the [Option] functions to configure its behavior. Note that this constructor
+// is only provided for comparable keys. For arbitrary keys, consider
+// [NewTableBy] or [NewCustomTable].
+func NewTable[K comparable, V any](options ...Option) *HashTable[K, V] {
+	return NewCustomTable[K, V](NewDefaultHash[K](), NewDefaultHash[K](), DefaultEqualFunc[K], options...)
+}

table.go

@@ -1,237 +1,103 @@
 package cuckoo
 
-import (
+type entry[K, V any] struct {
-	"fmt"
+	key   K
-	"iter"
+	value V
-	"math/bits"
-	"strings"
-)
-
-// A Table is hash table that uses cuckoo hashing to resolve collision. Create
-// one with [NewTable]. Or if you want more granularity, use [NewTableBy] or
-// [NewCustomTable].
-type Table[K, V any] struct {
-	bucketA, bucketB bucket[K, V]
-	growthFactor     uint64
-	minLoadFactor    float64
 }
 
-// TotalCapacity returns the number of slots allocated for the [Table]. To get the
+type slot[K, V any] struct {
-// number of slots filled, look at [Table.Size].
+	entry[K, V]
-func (t Table[K, V]) TotalCapacity() uint64 {
+	occupied bool
-	return t.bucketA.capacity + t.bucketB.capacity
 }
 
-// Size returns how many slots are filled in the [Table].
+type table[K, V any] struct {
-func (t Table[K, V]) Size() int {
+	hash           Hash[K]
-	return int(t.bucketA.size + t.bucketB.size)
+	slots          []slot[K, V]
+	capacity, size uint64
+	compare        EqualFunc[K]
 }
 
-func log2(n uint64) (m int) {
+// location determines where in the bucket a certain key would be placed. If the
-	return max(0, bits.Len64(n)-1)
+// capacity is 0, this will panic.
+func (t table[K, V]) location(key K) uint64 {
+	return t.hash(key) % t.capacity
 }
 
-func (t Table[K, V]) maxEvictions() int {
+func (t table[K, V]) get(key K) (value V, found bool) {
-	return 3 * log2(t.TotalCapacity())
+	if t.capacity == 0 {
-}
-
-func (t Table[K, V]) load() float64 {
-	// When there are no slots in the table, we still treat the load as 100%.
-	// Every slot in the table is full.
-	if t.TotalCapacity() == 0 {
-		return 1.0
-	}
-
-	return float64(t.Size()) / float64(t.TotalCapacity())
-}
-
-// resize clears all buckets, changes the sizes of them to a specific capacity,
-// and fills them back up again. It is a helper function for [Table.grow] and
-// [Table.shrink]; use them instead.
-func (t *Table[K, V]) resize(capacity uint64) error {
-	entries := make([]entry[K, V], 0, t.Size())
-	for k, v := range t.Entries() {
-		entries = append(entries, entry[K, V]{k, v})
-	}
-
-	t.bucketA.resize(capacity)
-	t.bucketB.resize(capacity)
-
-	for _, entry := range entries {
-		if err := t.Put(entry.key, entry.value); err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-// grow increases the table's capacity by the [Table.growthFactor]. If the
-// capacity is 0, it increases it to 1.
-func (t *Table[K, V]) grow() error {
-	var newCapacity uint64
-
-	if t.TotalCapacity() == 0 {
-		newCapacity = 1
-	} else {
-		newCapacity = t.bucketA.capacity * t.growthFactor
-	}
-
-	return t.resize(newCapacity)
-}
-
-// shrink reduces the table's capacity by the [Table.growthFactor]. It may
-// reduce it down to 0.
-func (t *Table[K, V]) shrink() error {
-	return t.resize(t.bucketA.capacity / t.growthFactor)
-}
-
-// Get fetches the value for a key in the [Table]. Returns an error if no value
-// is found.
-func (t Table[K, V]) Get(key K) (value V, err error) {
-	if item, ok := t.bucketA.get(key); ok {
-		return item, nil
-	}
-
-	if item, ok := t.bucketB.get(key); ok {
-		return item, nil
-	}
-
-	return value, fmt.Errorf("key '%v' not found", key)
-}
-
-// Has returns true if a key has a value in the table.
-func (t Table[K, V]) Has(key K) (exists bool) {
-	_, err := t.Get(key)
-	return err == nil
-}
-
-// Put sets the value for a key. Returns error if its value cannot be set.
-func (t *Table[K, V]) Put(key K, value V) (err error) {
-	if t.bucketA.update(key, value) {
-		return nil
-	}
-
-	if t.bucketB.update(key, value) {
-		return nil
-	}
-
-	entry, eviction := entry[K, V]{key, value}, false
-	for range t.maxEvictions() {
-		if entry, eviction = t.bucketA.evict(entry); !eviction {
-			return nil
-		}
-
-		if entry, eviction = t.bucketB.evict(entry); !eviction {
-			return nil
-		}
-	}
-
-	if t.load() < t.minLoadFactor {
-		return fmt.Errorf("bad hash: resize on load %d/%d = %f", t.Size(), t.TotalCapacity(), t.load())
-	}
-
-	if err := t.grow(); err != nil {
-		return err
-	}
-
-	return t.Put(entry.key, entry.value)
-}
-
-// Drop removes a value for a key in the table. Returns an error if its value
-// cannot be removed.
-func (t *Table[K, V]) Drop(key K) (err error) {
-	t.bucketA.drop(key)
-	t.bucketB.drop(key)
-
-	if t.load() < t.minLoadFactor {
-		return t.shrink()
-	}
-
-	return nil
-}
-
-// Entries returns an unordered sequence of all key-value pairs in the table.
-func (t Table[K, V]) Entries() iter.Seq2[K, V] {
-	return func(yield func(K, V) bool) {
-		for _, slot := range t.bucketA.slots {
-			if slot.occupied {
-				if !yield(slot.key, slot.value) {
 		return
 	}
-			}
+
+	slot := t.slots[t.location(key)]
+	return slot.value, slot.occupied && t.compare(slot.key, key)
 }
 
-		for _, slot := range t.bucketB.slots {
+func (t *table[K, V]) drop(key K) (occupied bool) {
-			if slot.occupied {
+	if t.capacity == 0 {
-				if !yield(slot.key, slot.value) {
 		return
 	}
-			}
+
-		}
+	slot := &t.slots[t.location(key)]
-	}
+
+	if slot.occupied && t.compare(slot.key, key) {
+		slot.occupied = false
+		t.size--
+		return true
 	}
 
-// String returns the entries of the table as a string in the format:
+	return false
-// "table[k1:v1 h2:v2 ...]".
-func (t Table[K, V]) String() string {
-	var sb strings.Builder
-	sb.WriteString("table[")
-
-	first := true
-	for k, v := range t.Entries() {
-		if !first {
-			sb.WriteString(" ")
 }
 
-		fmt.Fprintf(&sb, "%v:%v", k, v)
+func (t *table[K, V]) resize(capacity uint64) {
-		first = false
+	t.slots = make([]slot[K, V], capacity)
+	t.capacity = capacity
+	t.size = 0
 }
 
-	sb.WriteString("]")
+func (t table[K, V]) update(key K, value V) (updated bool) {
-	return sb.String()
+	if t.capacity == 0 {
+		return
 	}
 
-// NewCustomTable creates a [Table] with custom [Hash] and [EqualFunc]
+	slot := &t.slots[t.location(key)]
-// functions, along with any [Option] the user provides.
+
-func NewCustomTable[K, V any](hashA, hashB Hash[K], compare EqualFunc[K], options ...Option) *Table[K, V] {
+	if slot.occupied && t.compare(slot.key, key) {
-	settings := &settings{
+		slot.value = value
-		growthFactor:  DefaultGrowthFactor,
+		return true
-		bucketSize:    DefaultCapacity,
-		minLoadFactor: defaultMinimumLoad,
 	}
 
-	for _, option := range options {
+	return false
-		option(settings)
 }
 
-	return &Table[K, V]{
+func (t *table[K, V]) evict(insertion entry[K, V]) (evicted entry[K, V], eviction bool) {
-		growthFactor:  settings.growthFactor,
+	if t.capacity == 0 {
-		minLoadFactor: settings.minLoadFactor,
+		return insertion, true
-		bucketA:       newBucket[K, V](settings.bucketSize, hashA, compare),
-		bucketB:       newBucket[K, V](settings.bucketSize, hashB, compare),
-	}
 	}
 
-func pipe[X, Y, Z any](a func(X) Y, b func(Y) Z) func(X) Z {
+	slot := &t.slots[t.location(insertion.key)]
-	return func(x X) Z { return b(a(x)) }
+
+	if !slot.occupied {
+		slot.entry = insertion
+		slot.occupied = true
+		t.size++
+		return
 	}
 
-// NewTableBy creates a [Table] for any key type by using keyFunc to derive a
+	if t.compare(slot.key, insertion.key) {
-// comparable key. Two keys with the same derived key are treated as equal.
+		slot.value = insertion.value
-func NewTableBy[K, V any, C comparable](keyFunc func(K) C, options ...Option) *Table[K, V] {
+		return
-	return NewCustomTable[K, V](
-		pipe(keyFunc, NewDefaultHash[C]()),
-		pipe(keyFunc, NewDefaultHash[C]()),
-		func(a, b K) bool { return keyFunc(a) == keyFunc(b) },
-		options...,
-	)
 	}
 
-// NewTable creates a [Table] using the default [Hash] and [EqualFunc]. Use
+	insertion, slot.entry = slot.entry, insertion
-// the [Option] functions to configure its behavior. Note that this constructor
+	return insertion, true
-// is only provided for comparable keys. For arbitrary keys, consider
+}
-// [NewTableBy] or [NewCustomTable].
+
-func NewTable[K comparable, V any](options ...Option) *Table[K, V] {
+func newTable[K, V any](capacity uint64, hash Hash[K], compare EqualFunc[K]) table[K, V] {
-	return NewCustomTable[K, V](NewDefaultHash[K](), NewDefaultHash[K](), DefaultEqualFunc[K], options...)
+	return table[K, V]{
+		hash:     hash,
+		capacity: capacity,
+		compare:  compare,
+		size:     0,
+		slots:    make([]slot[K, V], capacity),
+	}
 }