docs: replaced instances of "bucket" with "table"

- Removed instances of `growthFactor`, as it is unexported.
- Typo in `HashTable.String()`.

.claude/settings.json

@@ -1,7 +0,0 @@
-{
-  "permissions": {
-    "allow": [
-      "Bash(curl -s -w \"\\\\n---HTTP_STATUS:%{http_code}---\" https://raw.githubusercontent.com/kubernetes/kubernetes/master/.markdownlint.yaml)"
-    ]
-  }
-}

.gitea/ISSUE_TEMPLATE/BUG_REPORT.yml

@@ -0,0 +1,26 @@
+# yaml-language-server: $schema=https://www.schemastore.org/gitea-issue-forms.json
+name: 🐛 Bug Report
+about: Report a bug in this project
+title: "[BUG]: "
+body:
+  - type: textarea
+    id: context
+    attributes:
+      label: Context
+      placeholder: What circumstances led to the bug?
+    validations:
+      required: true
+  - type: textarea
+    id: expected-behavior
+    attributes:
+      label: Expected Behavior
+      placeholder: What did you expect would happen?
+    validations:
+      required: true
+  - type: textarea
+    id: actual-behavior
+    attributes:
+      label: Actual Behavior
+      placeholder: What happened, and why was it unexpected?
+    validations:
+      required: true

.gitea/ISSUE_TEMPLATE/FEATURE_REQUEST.yml

@@ -0,0 +1,37 @@
+# 'Feature Request Template' By @cheehwatang
+# https://github.com/cheehwatang/.github/blob/master/.github/ISSUE_TEMPLATE/feature_request.yml
+#
+# yaml-language-server: $schema=https://www.schemastore.org/gitea-issue-forms.json
+name: ✨ Feature Request
+about: Suggest an idea for this project
+title: "[FEATURE]: "
+body:
+  - type: dropdown
+    attributes:
+      multiple: false
+      label: Feature Type
+      options:
+        - "✨ New Feature"
+        - "📝 Documentation"
+        - "🎨 Style and UI"
+        - "🔨 Code Refactor"
+        - "⚡ Performance Improvements"
+        - "✅ New Test"
+    validations:
+      required: true
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      placeholder: |
+        Give us a brief description of the feature or enhancement you would
+        like!
+    validations:
+      required: true
+  - type: textarea
+    id: additional-information
+    attributes:
+      label: Additional Information
+      placeholder: |
+        Give us some additional information on the feature request like proposed
+        solutions, links, screenshots, etc.

.gitea/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,2 @@
+# yaml-language-server: $schema=https://www.schemastore.org/gitea-issue-config.json
+blank_issues_enabled: false

.gitea/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,17 @@
+---
+name: "New Pull Request"
+about: "Standard PR template"
+title: ""
+ref: "main"
+---
+
+## Description
+
+## Changes
+
+### Design Decisions
+
+## Checklist
+
+- [ ] Tests pass
+- [ ] Docs updated

.gitea/workflows/ci.yml

@@ -6,6 +6,19 @@ on:
   pull_request:
 
 jobs:
+  check-pr-title:
+    name: Check PR Title
+    runs-on: ubuntu-latest
+    if: github.event_name == 'pull_request'
+    env:
+      TITLE: ${{ gitea.event.pull_request.title }}
+    steps:
+      - run: |
+          if ! echo "$TITLE" | grep -qE '^(WIP: )?(feat|fix|docs|chore|ci|test|refactor|perf|build|style|revert)(\(.+\))?(!)?: .+'; then
+            echo "::error::Pull Request title must follow conventional commits"
+            exit 1
+          fi
+
   lint-go:
     name: Go Lint
     runs-on: ubuntu-latest

.gitignore

@@ -24,4 +24,3 @@ go.work.sum
 
 # env file
 .env
-

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),
-	}
-}

compare.go

@@ -1,11 +1,11 @@
 package cuckoo
 
 // An EqualFunc determines whethers two keys are 'equal'. Keys that are 'equal'
-// are teated as the same by the [Table]. A good EqualFunc is pure,
-// deterministic, and fast. By default, [NewTable] uses [DefaultEqualFunc].
+// are teated as the same by the [HashTable]. A good EqualFunc is pure,
+// deterministic, and fast. By default, [New] uses [DefaultEqualFunc].
 //
 // This function MUST NOT return true if the [Hash] digest of two keys
-// are different: the [Table] will not work.
+// are different: the [HashTable] will not work.
 type EqualFunc[K any] = func(a, b K) bool
 
 // DefaultEqualFunc compares two keys by strict equality. Returns true if the

compare_example_test.go

@@ -28,7 +28,7 @@ func ExampleEqualFunc_badEqualFunc() {
 	// Two users with the same ID are equal.
 	isEqual := func(a, b User) bool { return a.ID == b.ID }
 
-	userbase := cuckoo.NewCustomTable[User, bool](makeHash(1), makeHash(2), isEqual)
+	userbase := cuckoo.NewCustom[User, bool](makeHash(1), makeHash(2), isEqual)
 
 	(userbase.Put(User{"1", "Robert Doe"}, true))
 

cuckoo_fuzz_test.go

@@ -1,7 +1,9 @@
 package cuckoo_test
 
 import (
+	"fmt"
 	"maps"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -25,8 +27,9 @@ type fuzzStep struct {
 }
 
 type fuzzScenario struct {
-	seedA, seedB uint32
-	steps        []fuzzStep
+	seedA, seedB           uint32
+	capacity, growthFactor uint8
+	steps                  []fuzzStep
 }
 
 func FuzzInsertLookup(f *testing.F) {
@@ -40,14 +43,25 @@ func FuzzInsertLookup(f *testing.F) {
 			return
 		}
 
-		if scenario.seedA == scenario.seedB {
-			return
+		seedA, seedB := scenario.seedA, scenario.seedB
+		growthFactor := max(2, int(scenario.growthFactor))
+		capacity := int(scenario.capacity)
+
+		// If they are the same number, the hashes will clash, always causing an
+		// error.
+		if seedA == seedB {
+			t.Skip()
 		}
 
-		actual := cuckoo.NewCustomTable[uint32, uint32](
-			offsetHash(scenario.seedA),
-			offsetHash(scenario.seedB),
+		fmt.Fprintf(os.Stderr, "seedA=%d seedB=%d capacity=%d growthFactor=%d\n",
+			seedA, seedB, capacity, growthFactor)
+
+		actual := cuckoo.NewCustom[uint32, uint32](
+			offsetHash(seedA),
+			offsetHash(seedB),
 			func(a, b uint32) bool { return a == b },
+			cuckoo.Capacity(capacity),
+			cuckoo.GrowthFactor(growthFactor),
 		)
 
 		expected := map[uint32]uint32{}

cuckoo_internal_test.go

@@ -11,7 +11,7 @@ func TestMaxEvictions(t *testing.T) {
 	assert := assert.New(t)
 
 	for i := 16; i < 116; i++ {
-		table := NewTable[int, bool](Capacity(i / 2))
+		table := New[int, bool](Capacity(i / 2))
 		expectedEvictions := 3 * math.Floor(math.Log2(float64(i)))
 
 		assert.Equal(table.maxEvictions(), int(expectedEvictions))
@@ -20,7 +20,7 @@ func TestMaxEvictions(t *testing.T) {
 
 func TestLoad(t *testing.T) {
 	assert := assert.New(t)
-	table := NewTable[int, bool](Capacity(8))
+	table := New[int, bool](Capacity(8))
 
 	for i := range 16 {
 		err := table.Put(i, true)

cuckoo_test.go

@@ -14,7 +14,7 @@ import (
 func TestNewTable(t *testing.T) {
 	assert := assert.New(t)
 
-	table := cuckoo.NewTable[int, bool]()
+	table := cuckoo.New[int, bool]()
 
 	assert.NotNil(table)
 	assert.Zero(table.Size())
@@ -23,7 +23,7 @@ func TestNewTable(t *testing.T) {
 func TestAddItem(t *testing.T) {
 	assert := assert.New(t)
 	key, value := 0, true
-	table := cuckoo.NewTable[int, bool]()
+	table := cuckoo.New[int, bool]()
 
 	err := table.Put(key, value)
 
@@ -35,7 +35,7 @@ func TestAddItem(t *testing.T) {
 func TestPutOverwrite(t *testing.T) {
 	assert := assert.New(t)
 	key, value, newValue := 0, 1, 2
-	table := cuckoo.NewTable[int, int]()
+	table := cuckoo.New[int, int]()
 	(table.Put(key, value))
 
 	err := table.Put(key, newValue)
@@ -50,7 +50,7 @@ func TestPutOverwrite(t *testing.T) {
 func TestSameHash(t *testing.T) {
 	assert := assert.New(t)
 	hash := func(int) uint64 { return 0 }
-	table := cuckoo.NewCustomTable[int, bool](hash, hash, cuckoo.DefaultEqualFunc[int])
+	table := cuckoo.NewCustom[int, bool](hash, hash, cuckoo.DefaultEqualFunc[int])
 
 	errA := table.Put(0, true)
 	errB := table.Put(1, true)
@@ -63,14 +63,14 @@ func TestSameHash(t *testing.T) {
 
 func TestStartingCapacity(t *testing.T) {
 	assert := assert.New(t)
-	table := cuckoo.NewTable[int, bool](cuckoo.Capacity(64))
+	table := cuckoo.New[int, bool](cuckoo.Capacity(64))
 
 	assert.Equal(uint64(128), table.TotalCapacity())
 }
 
 func TestResizeCapacity(t *testing.T) {
 	assert := assert.New(t)
-	table := cuckoo.NewTable[int, bool](
+	table := cuckoo.New[int, bool](
 		cuckoo.Capacity(8),
 		cuckoo.GrowthFactor(2),
 	)
@@ -85,7 +85,7 @@ func TestResizeCapacity(t *testing.T) {
 
 func TestPutMany(t *testing.T) {
 	assert := assert.New(t)
-	expected, actual := map[int]bool{}, cuckoo.NewTable[int, bool]()
+	expected, actual := map[int]bool{}, cuckoo.New[int, bool]()
 
 	for i := range 1_000 {
 		expected[i] = true
@@ -100,7 +100,7 @@ func TestPutMany(t *testing.T) {
 
 func TestGetMany(t *testing.T) {
 	assert := assert.New(t)
-	table := cuckoo.NewTable[int, bool]()
+	table := cuckoo.New[int, bool]()
 
 	for i := range 1_000 {
 		err := table.Put(i, true)
@@ -121,7 +121,7 @@ func TestGetMany(t *testing.T) {
 func TestDropExistingItem(t *testing.T) {
 	assert := assert.New(t)
 	key, value := 0, true
-	table := cuckoo.NewTable[int, bool]()
+	table := cuckoo.New[int, bool]()
 	(table.Put(key, value))
 
 	err := table.Drop(key)
@@ -134,7 +134,7 @@ func TestDropExistingItem(t *testing.T) {
 func TestDropNoItem(t *testing.T) {
 	assert := assert.New(t)
 	key := 0
-	table := cuckoo.NewTable[int, bool]()
+	table := cuckoo.New[int, bool]()
 
 	err := table.Drop(key)
 
@@ -146,7 +146,7 @@ func TestDropNoItem(t *testing.T) {
 func TestDropItemCapacity(t *testing.T) {
 	assert := assert.New(t)
 	key := 0
-	table := cuckoo.NewTable[int, bool](
+	table := cuckoo.New[int, bool](
 		cuckoo.Capacity(64),
 		cuckoo.GrowthFactor(2),
 	)
@@ -164,7 +164,7 @@ func TestDropItemCapacity(t *testing.T) {
 func TestPutNoCapacity(t *testing.T) {
 	assert := assert.New(t)
 	key, value := 0, true
-	table := cuckoo.NewTable[int, bool](
+	table := cuckoo.New[int, bool](
 		cuckoo.Capacity(0),
 	)
 
@@ -177,7 +177,7 @@ func TestPutNoCapacity(t *testing.T) {
 
 func TestBadHashCapacity(t *testing.T) {
 	assert := assert.New(t)
-	table := cuckoo.NewCustomTable[int, bool](
+	table := cuckoo.NewCustom[int, bool](
 		func(int) uint64 { return 0 },
 		func(int) uint64 { return 0 },
 		func(a, b int) bool { return a == b },
@@ -197,7 +197,7 @@ func TestBadHashCapacity(t *testing.T) {
 
 func TestDropResizeCapacity(t *testing.T) {
 	assert := assert.New(t)
-	table := cuckoo.NewTable[int, bool](
+	table := cuckoo.New[int, bool](
 		cuckoo.Capacity(10),
 	)
 
@@ -217,9 +217,7 @@ func TestNewTableBy(t *testing.T) {
 	}
 
 	assert := assert.New(t)
-	table := cuckoo.NewTableBy[User, bool](
-		func(u User) string { return u.id },
-	)
+	table := cuckoo.NewBy[User, bool](func(u User) string { return u.id })
 
 	err := table.Put(User{nil, "1", "Robert"}, true)
 

doc.go

@@ -1,8 +1,8 @@
 // Package cuckoo provides a hash table that uses cuckoo hashing to achieve
 // a worst-case O(1) lookup time.
 //
-// While a [NewTable] only supports comparable keys by default, you can create
-// a table with any key type using [NewCustomTable]. Custom [Hash] functions and
+// While a [New] only supports comparable keys by default, you can create
+// a table with any key type using [NewCustom]. Custom [Hash] functions and
 // key comparison are also supported.
 //
 // See more: https://en.wikipedia.org/wiki/Cuckoo_hashing

doc_example_test.go

@@ -8,7 +8,7 @@ import (
 )
 
 func Example_basic() {
-	table := cuckoo.NewTable[int, string]()
+	table := cuckoo.New[int, string]()
 
 	if err := table.Put(1, "Hello, World!"); err != nil {
 		fmt.Println("Put error:", err)

hash.go

@@ -7,9 +7,9 @@ import (
 // A Hash function maps any data to a fixed-length value (in this case, a
 // [uint64]).
 //
-// It is used by the [Table] to evenly distribute values
+// It is used by the [HashTable] to evenly distribute values
 // amongst its slots. A good hash function is uniform, [chaotic], and
-// deterministic. [Table] uses [NewDefaultHash] by default, which is built on
+// deterministic. [HashTable] uses [NewDefaultHash] by default, which is built on
 // [maphash.Comparable].
 //
 // [chaotic]: https://en.wikipedia.org/wiki/Avalanche_effect

hash_table.go

@@ -0,0 +1,237 @@
+package cuckoo
+
+import (
+	"fmt"
+	"iter"
+	"math/bits"
+	"strings"
+)
+
+// A HashTable which uses cuckoo hashing to resolve collision. Create
+// one with [New]. Or if you want more granularity, use [NewBy] or
+// [NewCustom].
+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 tables, 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 growth factor. 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 growth factor. 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 k2: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()
+}
+
+// NewCustom creates a [HashTable] with custom [Hash] and [EqualFunc]
+// functions, along with any [Option] the user provides.
+func NewCustom[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)) }
+}
+
+// NewBy 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 NewBy[K, V any, C comparable](keyFunc func(K) C, options ...Option) *HashTable[K, V] {
+	return NewCustom[K, V](
+		pipe(keyFunc, NewDefaultHash[C]()),
+		pipe(keyFunc, NewDefaultHash[C]()),
+		func(a, b K) bool { return keyFunc(a) == keyFunc(b) },
+		options...,
+	)
+}
+
+// New 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
+// [NewBy] or [NewCustom].
+func New[K comparable, V any](options ...Option) *HashTable[K, V] {
+	return NewCustom[K, V](NewDefaultHash[K](), NewDefaultHash[K](), DefaultEqualFunc[K], options...)
+}

settings.go

@@ -1,20 +1,23 @@
 package cuckoo
 
-// DefaultCapacity is the initial capacity of a [Table]. It is inspired from
+import "fmt"
+
+// DefaultCapacity is the initial capacity of a [HashTable]. It is inspired from
 // Java's [HashMap] implementation, which also uses 16.
 //
 // [HashMap]: https://docs.oracle.com/javase/8/docs/api/java/util/HashMap.html#HashMap--
 const DefaultCapacity uint64 = 16
 
-// DefaultGrowthFactor is the standard resize multiplier for a [Table]. Most
-// hash table implementations use 2.
+// DefaultGrowthFactor is the standard resize multiplier for a [HashTable]. Most
+// implementations use 2.
 const DefaultGrowthFactor uint64 = 2
 
-// DefaultMinimumLoad is the default lowest acceptable occupancy of a [Table].
-// The value of 5% is taken from [libcuckoo].
+// defaultMinimumLoad is the default lowest acceptable occupancy of a [HashTable].
+// The higher the minimum load, the more likely that a [HashTable.Put] will not
+// succeed. The value of 5% is taken from [libcuckoo].
 //
 // [libcuckoo]: https://github.com/efficient/libcuckoo/blob/656714705a055df2b7a605eb3c71586d9da1e119/libcuckoo/cuckoohash_config.hh#L21
-const DefaultMinimumLoad float64 = 0.05
+const defaultMinimumLoad float64 = 0.05
 
 type settings struct {
 	growthFactor  uint64
@@ -22,24 +25,26 @@ type settings struct {
 	bucketSize    uint64
 }
 
-// An Option modifies the settings of a [Table]. It is used in its constructors
-// like [NewTable], for example.
+// An Option modifies the settings of a [HashTable]. It is used in its constructors
+// like [New], for example.
 type Option func(*settings)
 
-// Capacity modifies the starting capacity of each bucket of the [Table]. The
-// value must be greater than 0.
+// Capacity modifies the starting capacity of each table of the [HashTable]. The
+// value must be non-negative.
 func Capacity(value int) Option {
+	if value < 0 {
+		panic(fmt.Sprintf("go-cuckoo: Capacity must be non-negative, got %d", value))
+	}
+
 	return func(s *settings) { s.bucketSize = uint64(value) }
 }
 
-// MinimumLoad modifies the [DefaultMinimumLoad] of the [Table]. The value must
-// be between 0.00 and 1.00.
-func MinimumLoad(value float64) Option {
-	return func(s *settings) { s.minLoadFactor = value }
-}
-
-// GrowthFactor controls how much the capacity of the [Table] multiplies when
+// GrowthFactor controls how much the capacity of the [HashTable] multiplies when
 // it must resize. The value must be greater than 1.
 func GrowthFactor(value int) Option {
+	if value < 2 {
+		panic(fmt.Sprintf("go-cuckoo: GrowthFactor must be greater than 1, got %d", value))
+	}
+
 	return func(s *settings) { s.growthFactor = uint64(value) }
 }

table.go

@@ -1,237 +1,103 @@
 package cuckoo
 
-import (
-	"fmt"
-	"iter"
-	"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
+type entry[K, V any] struct {
+	key   K
+	value V
 }
 
-// TotalCapacity returns the number of slots allocated for the [Table]. To get the
-// number of slots filled, look at [Table.Size].
-func (t Table[K, V]) TotalCapacity() uint64 {
-	return t.bucketA.capacity + t.bucketB.capacity
+type slot[K, V any] struct {
+	entry[K, V]
+	occupied bool
 }
 
-// Size returns how many slots are filled in the [Table].
-func (t Table[K, V]) Size() int {
-	return int(t.bucketA.size + t.bucketB.size)
+type table[K, V any] struct {
+	hash           Hash[K]
+	slots          []slot[K, V]
+	capacity, size uint64
+	compare        EqualFunc[K]
 }
 
-func log2(n uint64) (m int) {
-	return max(0, bits.Len64(n)-1)
+// location determines where in the table a certain key would be placed. If the
+// 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 {
-	return 3 * log2(t.TotalCapacity())
-}
-
-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
+func (t table[K, V]) get(key K) (value V, found bool) {
+	if t.capacity == 0 {
+		return
 	}
 
-	return float64(t.Size()) / float64(t.TotalCapacity())
+	slot := t.slots[t.location(key)]
+	return slot.value, slot.occupied && t.compare(slot.key, key)
 }
 
-// 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})
+func (t *table[K, V]) drop(key K) (occupied bool) {
+	if t.capacity == 0 {
+		return
 	}
 
-	t.bucketA.resize(capacity)
-	t.bucketB.resize(capacity)
+	slot := &t.slots[t.location(key)]
 
-	for _, entry := range entries {
-		if err := t.Put(entry.key, entry.value); err != nil {
-			return err
-		}
+	if slot.occupied && t.compare(slot.key, key) {
+		slot.occupied = false
+		t.size--
+		return true
 	}
 
-	return nil
+	return false
 }
 
-// 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)
+func (t *table[K, V]) resize(capacity uint64) {
+	t.slots = make([]slot[K, V], capacity)
+	t.capacity = capacity
+	t.size = 0
 }
 
-// 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)
+func (t table[K, V]) update(key K, value V) (updated bool) {
+	if t.capacity == 0 {
+		return
+	}
+
+	slot := &t.slots[t.location(key)]
+
+	if slot.occupied && t.compare(slot.key, key) {
+		slot.value = value
+		return true
+	}
+
+	return false
 }
 
-// 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
+func (t *table[K, V]) evict(insertion entry[K, V]) (evicted entry[K, V], eviction bool) {
+	if t.capacity == 0 {
+		return insertion, true
 	}
 
-	if item, ok := t.bucketB.get(key); ok {
-		return item, nil
+	slot := &t.slots[t.location(insertion.key)]
+
+	if !slot.occupied {
+		slot.entry = insertion
+		slot.occupied = true
+		t.size++
+		return
 	}
 
-	return value, fmt.Errorf("key '%v' not found", key)
+	if t.compare(slot.key, insertion.key) {
+		slot.value = insertion.value
+		return
+	}
+
+	insertion, slot.entry = slot.entry, insertion
+	return insertion, true
 }
 
-// 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
-				}
-			}
-		}
-
-		for _, slot := range t.bucketB.slots {
-			if slot.occupied {
-				if !yield(slot.key, slot.value) {
-					return
-				}
-			}
-		}
+func newTable[K, V any](capacity uint64, hash Hash[K], compare EqualFunc[K]) table[K, V] {
+	return table[K, V]{
+		hash:     hash,
+		capacity: capacity,
+		compare:  compare,
+		size:     0,
+		slots:    make([]slot[K, V], capacity),
 	}
 }
-
-// String returns the entries of the table as a string in the format:
-// "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)
-		first = false
-	}
-
-	sb.WriteString("]")
-	return sb.String()
-}
-
-// NewCustomTable creates a [Table] 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) *Table[K, V] {
-	settings := &settings{
-		growthFactor:  DefaultGrowthFactor,
-		bucketSize:    DefaultCapacity,
-		minLoadFactor: DefaultMinimumLoad,
-	}
-
-	for _, option := range options {
-		option(settings)
-	}
-
-	return &Table[K, V]{
-		growthFactor:  settings.growthFactor,
-		minLoadFactor: settings.minLoadFactor,
-		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 {
-	return func(x X) Z { return b(a(x)) }
-}
-
-// NewTableBy creates a [Table] 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) *Table[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 [Table] 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) *Table[K, V] {
-	return NewCustomTable[K, V](NewDefaultHash[K](), NewDefaultHash[K](), DefaultEqualFunc[K], options...)
-}