fix: allow 0 capacity for table

- Added guards at the bucket level, to ensure that getting an item in an empty bucket doesn't cause an error.
- Added grow() and shrink() functions to Table, to prevent a capacity of 0 from not being able to grow.
- Updated the fuzz test to use `go_fuzz-utils`.

.gitea/ISSUE_TEMPLATE/BUG_REPORT.yml

@@ -1,26 +0,0 @@
-# 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

@@ -1,37 +0,0 @@
-# '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

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

.gitea/PULL_REQUEST_TEMPLATE.md

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

.gitea/workflows/ci.yml

@@ -6,19 +6,6 @@ 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
@@ -52,14 +39,6 @@ jobs:
       - name: Run mutation tests
         run: make lint-makefile
 
-  lint-markdown:
-    name: Markdown Lint
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-
-      - uses: DavidAnson/markdownlint-cli2-action@v19
-
   test-unit:
     name: Unit Tests
     runs-on: ubuntu-latest

.gitignore

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

.golangci.yml

@@ -114,9 +114,6 @@ linters:
     # Reports uses of functions with replacement inside the testing package.
     - usetesting
 
-    # Reports mixed receiver types in structs/interfaces.
-    - recvcheck
-
   settings:
     revive:
       rules:
@@ -201,7 +198,7 @@ linters:
 
         # warns when initialism, variable or package naming conventions are not followed.
         - name: var-naming
-    
+
     misspell:
       # Correct spellings using locale preferences for US or UK.
       # Setting locale to US will correct the British spelling of 'colour' to 'color'.

.gremlins.yaml

@@ -4,6 +4,4 @@ unleash:
   timeout-coefficient: 50
   
   workers: 4
-  dry-run: false
+  dry-run: false
-  threshold:
-    efficacy: 1.0

.markdownlint.yml

@@ -1,17 +0,0 @@
-default: true
-heading-style:
-  style: atx
-ul-indent:
-  indent: 2
-line-length: false
-no-duplicate-heading:
-  siblings_only: true
-no-inline-html:
-  allowed_elements:
-    - br
-    - details
-    - summary
-    - img
-    - picture
-    - source
-first-line-heading: true

Makefile

@@ -1,4 +1,4 @@
-.PHONY: all help install clean test-unit test-mutation test-fuzz test docs lint-go lint-makefile lint-markdown lint
+.PHONY: all help install clean test-unit test-mutation test-fuzz test docs lint-go lint-makefile lint
 
 help: ## Show this help
 	@grep -E '^[a-zA-Z_-]+:.*##' $(MAKEFILE_LIST) | awk -F ':.*## ' '{printf "  %-15s %s\n", $$1, $$2}'
@@ -32,10 +32,7 @@ lint-go: ## Lint Go code
 lint-makefile: ## Lint the Makefile
 	checkmake Makefile
 
-lint-markdown: ## Lint Markdown files
+lint: lint-go lint-makefile ## Lint all code
-	docker run --rm -v $(CURDIR):/workdir davidanson/markdownlint-cli2 "**/*.md"
-
-lint: lint-go lint-makefile lint-markdown ## Lint all code
 
 docs: ## Serve godoc locally
 	@echo ">>> Visit: http://localhost:6060/pkg/$$(go list -m)"

README.md

@@ -1,3 +1,3 @@
-# <img height="30" src="assets/logo.svg" alt="Go Cuckoo, by `mvhutz`."> Go Cuckoo
+# go-cuckoo
 
-A hash table that uses cuckoo hashing to achieve a worst-case O(1) lookup time. Read more about it in [the package documentation](https://pkg.go.dev/git.maximhutz.com/tools/go-cuckoo).
+A hash table that uses cuckoo hashing to achieve a worst-case O(1) lookup time.

assets/logo.svg

@@ -1 +0,0 @@
-<svg width="16" height="16" xmlns="http://www.w3.org/2000/svg" shape-rendering="crispEdges"><path fill="#2a1512" d="M3,6h1v1h-1v-1M2,7h1v1h-1v-1M12,7h1v1h-1v-1M1,8h1v1h-1v-1M4,8h1v2h-1v-2M14,8h1v1h-1v-1M11,9h1v2h-2v-1h1v-1M5,10h1v1h-1v-1M1,13h2v1h1v1h-2v-1h-1v-1M13,13h2v1h-1v1h-1v1h-1v-2h1v-1M4,15h1v1h-1v-1"/><path fill="#38231f" d="M4,6h1v1h-1v-1M11,6h1v1h-1v-1M13,7h1v1h-1v-1M1,9h1v2h-1v-2M14,9h1v1h-1v-1M14,11h1v2h-1v-2M1,12h1v1h-1v-1M5,15h3v1h-3v-1M10,15h2v1h-2v-1"/><path fill="#3f3f74" d="M7,3h2v1h-2v-1M6,4h1v1h-1v-1M9,4h1v1h-1v-1M5,5h1v5h-1v-5M10,5h1v5h-1v-5M6,10h4v1h-4v-1"/><path fill="#6262ab" d="M9,5h1v1h-1v-1M6,9h1v1h-1v-1M9,9h1v1h-1v-1"/><path fill="#663931" d="M11,8h1v1h-1v-1M2,9h1v1h-1v-1M14,10h1v1h-1v-1M1,11h1v1h-1v-1M3,11h2v1h-2v-1M13,11h1v1h-1v-1M2,12h1v1h-1v-1M5,12h1v1h-1v-1M10,12h3v2h-1v-1h-2v-1M3,13h1v1h-1v-1M8,13h2v1h-2v-1M4,14h3v1h-3v-1M10,14h2v1h-2v-1M8,15h2v1h-2v-1"/><path fill="#8d8dcb" d="M9,6h1v3h-1v1h-2v-1h1v-1h1v-2M6,8h1v1h-1v-1"/><path fill="#8f563b" d="M2,8h1v1h-1v-1M12,9h1v1h-1v-1M2,10h1v1h-1v-1M13,10h1v1h-1v-1M7,11h1v1h-1v-1M11,11h2v1h-2v-1M4,12h1v1h1v-1h1v2h-3v-2M13,12h1v1h-1v-1M10,13h2v1h-2v-1M7,14h3v1h-3v-1"/><path fill="#a4a4d5" d="M8,4h1v4h-1v1h-1v-1h-1v-2h1v-1h1v-1"/><path fill="#ab764a" d="M4,7h1v1h-1v-1M3,8h1v2h-1v-2M12,10h1v1h-1v-1M2,11h1v1h-1v-1M8,11h1v1h-1v-1M3,12h1v1h-1v-1M7,12h1v2h-1v-2"/><path fill="#cacaea" d="M7,4h1v1h-1v-1M6,5h1v1h-1v-1"/><path fill="#d9a066" d="M3,7h1v1h-1v-1M11,7h1v1h-1v-1M12,8h2v2h-1v-1h-1v-1M3,10h2v1h-2v-1M5,11h2v1h-2v-1M9,11h2v1h-1v1h-2v-1h1v-1"/></svg>

bucket.go

@@ -0,0 +1,101 @@
+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) {
+	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

@@ -2,7 +2,7 @@ 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, [New] uses [DefaultEqualFunc].
+// deterministic, and fast. By default, [NewTable] uses [DefaultEqualFunc].
 //
 // This function MUST NOT return true if the [Hash] digest of two keys
 // are different: the [Table] will not work.

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.NewCustom[User, bool](makeHash(1), makeHash(2), isEqual)
+	userbase := cuckoo.NewCustomTable[User, bool](makeHash(1), makeHash(2), isEqual)
 
 	(userbase.Put(User{"1", "Robert Doe"}, true))
 

cuckoo_fuzz_test.go

@@ -1,9 +1,7 @@
 package cuckoo_test
 
 import (
-	"fmt"
 	"maps"
-	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -27,9 +25,8 @@ type fuzzStep struct {
 }
 
 type fuzzScenario struct {
-	seedA, seedB           uint32
+	seedA, seedB uint32
-	capacity, growthFactor uint8
+	steps        []fuzzStep
-	steps                  []fuzzStep
 }
 
 func FuzzInsertLookup(f *testing.F) {
@@ -43,25 +40,14 @@ func FuzzInsertLookup(f *testing.F) {
 			return
 		}
 
-		seedA, seedB := scenario.seedA, scenario.seedB
+		if scenario.seedA == scenario.seedB {
-		growthFactor := max(2, int(scenario.growthFactor))
+			return
-		capacity := int(scenario.capacity)
-
-		// If they are the same number, the hashes will clash, always causing an
-		// error.
-		if seedA == seedB {
-			t.Skip()
 		}
 
-		fmt.Fprintf(os.Stderr, "seedA=%d seedB=%d capacity=%d growthFactor=%d\n",
+		actual := cuckoo.NewCustomTable[uint32, uint32](
-			seedA, seedB, capacity, growthFactor)
+			offsetHash(scenario.seedA),
-
+			offsetHash(scenario.seedB),
-		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{}
@@ -73,16 +59,16 @@ func FuzzInsertLookup(f *testing.F) {
 
 				delete(expected, step.key)
 
-				_, ok := actual.Get(step.key)
+				_, err = actual.Get(step.key)
-				assert.False(ok)
+				assert.Error(err)
 			} else {
 				err := actual.Put(step.key, step.value)
 				assert.NoError(err)
 
 				expected[step.key] = step.value
 
-				found, ok := actual.Get(step.key)
+				found, err := actual.Get(step.key)
-				assert.True(ok)
+				assert.NoError(err)
 				assert.Equal(step.value, found)
 			}
 

cuckoo_internal_test.go

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

cuckoo_test.go

@@ -1,7 +1,6 @@
 package cuckoo_test
 
 import (
-	"errors"
 	"maps"
 	"math/rand/v2"
 	"testing"
@@ -14,7 +13,7 @@ import (
 func TestNewTable(t *testing.T) {
 	assert := assert.New(t)
 
-	table := cuckoo.New[int, bool]()
+	table := cuckoo.NewTable[int, bool]()
 
 	assert.NotNil(table)
 	assert.Zero(table.Size())
@@ -23,7 +22,7 @@ func TestNewTable(t *testing.T) {
 func TestAddItem(t *testing.T) {
 	assert := assert.New(t)
 	key, value := 0, true
-	table := cuckoo.New[int, bool]()
+	table := cuckoo.NewTable[int, bool]()
 
 	err := table.Put(key, value)
 
@@ -35,7 +34,7 @@ func TestAddItem(t *testing.T) {
 func TestPutOverwrite(t *testing.T) {
 	assert := assert.New(t)
 	key, value, newValue := 0, 1, 2
-	table := cuckoo.New[int, int]()
+	table := cuckoo.NewTable[int, int]()
 	(table.Put(key, value))
 
 	err := table.Put(key, newValue)
@@ -50,7 +49,7 @@ func TestPutOverwrite(t *testing.T) {
 func TestSameHash(t *testing.T) {
 	assert := assert.New(t)
 	hash := func(int) uint64 { return 0 }
-	table := cuckoo.NewCustom[int, bool](hash, hash, cuckoo.DefaultEqualFunc[int])
+	table := cuckoo.NewCustomTable[int, bool](hash, hash, cuckoo.DefaultEqualFunc[int])
 
 	errA := table.Put(0, true)
 	errB := table.Put(1, true)
@@ -63,14 +62,14 @@ func TestSameHash(t *testing.T) {
 
 func TestStartingCapacity(t *testing.T) {
 	assert := assert.New(t)
-	table := cuckoo.New[int, bool](cuckoo.Capacity(64))
+	table := cuckoo.NewTable[int, bool](cuckoo.Capacity(64))
 
 	assert.Equal(uint64(128), table.TotalCapacity())
 }
 
 func TestResizeCapacity(t *testing.T) {
 	assert := assert.New(t)
-	table := cuckoo.New[int, bool](
+	table := cuckoo.NewTable[int, bool](
 		cuckoo.Capacity(8),
 		cuckoo.GrowthFactor(2),
 	)
@@ -85,7 +84,7 @@ func TestResizeCapacity(t *testing.T) {
 
 func TestPutMany(t *testing.T) {
 	assert := assert.New(t)
-	expected, actual := map[int]bool{}, cuckoo.New[int, bool]()
+	expected, actual := map[int]bool{}, cuckoo.NewTable[int, bool]()
 
 	for i := range 1_000 {
 		expected[i] = true
@@ -100,7 +99,7 @@ func TestPutMany(t *testing.T) {
 
 func TestGetMany(t *testing.T) {
 	assert := assert.New(t)
-	table := cuckoo.New[int, bool]()
+	table := cuckoo.NewTable[int, bool]()
 
 	for i := range 1_000 {
 		err := table.Put(i, true)
@@ -108,20 +107,32 @@ func TestGetMany(t *testing.T) {
 	}
 
 	for i := range 2_000 {
-		value, ok := table.Get(i)
+		value, err := table.Get(i)
 		if i < 1_000 {
-			assert.True(ok)
+			assert.NoError(err)
 			assert.Equal(value, true)
 		} else {
-			assert.False(ok)
+			assert.Error(err)
 		}
 	}
 }
 
+func TestRemove(t *testing.T) {
+	assert := assert.New(t)
+	table := cuckoo.NewTable[int, bool]()
+
+	assert.False(table.Has(0))
+
+	err := table.Put(0, true)
+	assert.NoError(err)
+
+	assert.True(table.Has(0))
+}
+
 func TestDropExistingItem(t *testing.T) {
 	assert := assert.New(t)
 	key, value := 0, true
-	table := cuckoo.New[int, bool]()
+	table := cuckoo.NewTable[int, bool]()
 	(table.Put(key, value))
 
 	err := table.Drop(key)
@@ -134,7 +145,7 @@ func TestDropExistingItem(t *testing.T) {
 func TestDropNoItem(t *testing.T) {
 	assert := assert.New(t)
 	key := 0
-	table := cuckoo.New[int, bool]()
+	table := cuckoo.NewTable[int, bool]()
 
 	err := table.Drop(key)
 
@@ -142,86 +153,3 @@ func TestDropNoItem(t *testing.T) {
 	assert.Equal(0, table.Size())
 	assert.False(table.Has(key))
 }
-
-func TestDropItemCapacity(t *testing.T) {
-	assert := assert.New(t)
-	key := 0
-	table := cuckoo.New[int, bool](
-		cuckoo.Capacity(64),
-		cuckoo.GrowthFactor(2),
-	)
-
-	startingCapacity := table.TotalCapacity()
-	err := table.Drop(key)
-	endingCapacity := table.TotalCapacity()
-
-	assert.NoError(err)
-	assert.Equal(0, table.Size())
-	assert.Equal(uint64(128), startingCapacity)
-	assert.Equal(uint64(64), endingCapacity)
-}
-
-func TestPutNoCapacity(t *testing.T) {
-	assert := assert.New(t)
-	key, value := 0, true
-	table := cuckoo.New[int, bool](
-		cuckoo.Capacity(0),
-	)
-
-	err := table.Put(key, value)
-
-	assert.NoError(err)
-	assert.Equal(1, table.Size())
-	assert.True(table.Has(key))
-}
-
-func TestBadHashCapacity(t *testing.T) {
-	assert := assert.New(t)
-	table := cuckoo.NewCustom[int, bool](
-		func(int) uint64 { return 0 },
-		func(int) uint64 { return 0 },
-		func(a, b int) bool { return a == b },
-		cuckoo.Capacity(20),
-	)
-
-	err1 := table.Put(0, true)
-	err2 := table.Put(1, true)
-	err3 := table.Put(2, true)
-
-	assert.NoError(err1)
-	assert.NoError(err2)
-	assert.Error(err3)
-
-	assert.Equal(uint64(80), table.TotalCapacity())
-}
-
-func TestDropResizeCapacity(t *testing.T) {
-	assert := assert.New(t)
-	table := cuckoo.New[int, bool](
-		cuckoo.Capacity(10),
-	)
-
-	err1 := table.Put(0, true)
-	err2 := table.Put(1, true)
-	err3 := table.Drop(1)
-
-	assert.NoError(errors.Join(err1, err2, err3))
-	assert.Equal(uint64(20), table.TotalCapacity())
-}
-
-func TestNewTableBy(t *testing.T) {
-	type User struct {
-		_    func()
-		id   string
-		name string
-	}
-
-	assert := assert.New(t)
-	table := cuckoo.NewBy[User, bool](func(u User) string { return u.id })
-
-	err := table.Put(User{nil, "1", "Robert"}, true)
-
-	assert.NoError(err)
-	assert.Equal(1, table.Size())
-	assert.True(table.Has(User{nil, "1", "Robbie"}))
-}

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 [New] only supports comparable keys by default, you can create
+// While a [NewTable] only supports comparable keys by default, you can create
-// a table with any key type using [NewCustom]. Custom [Hash] functions and
+// a table with any key type using [NewCustomTable]. Custom [Hash] functions and
 // key comparison are also supported.
 //
 // See more: https://en.wikipedia.org/wiki/Cuckoo_hashing

doc_example_test.go

@@ -8,25 +8,25 @@ import (
 )
 
 func Example_basic() {
-	table := cuckoo.New[int, string]()
+	table := cuckoo.NewTable[int, string]()
 
 	if err := table.Put(1, "Hello, World!"); err != nil {
 		fmt.Println("Put error:", err)
 	}
 
-	if item, ok := table.Get(1); !ok {
+	if item, err := table.Get(1); err != nil {
-		fmt.Println("Not Found 1!")
+		fmt.Println("Error:", err)
 	} else {
 		fmt.Println("Found 1:", item)
 	}
 
-	if item, ok := table.Get(0); !ok {
+	if item, err := table.Get(0); err != nil {
-		fmt.Println("Not Found 0!")
+		fmt.Println("Error:", err)
 	} else {
 		fmt.Println("Found 0:", item)
 	}
 
 	// Output:
 	// Found 1: Hello, World!
-	// Not Found 0!
+	// Error: key '0' not found
 }

go.mod

@@ -4,8 +4,6 @@ go 1.25.6
 
 require github.com/stretchr/testify v1.11.1
 
-require github.com/kr/pretty v0.3.1 // indirect
-
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect

go.sum

@@ -1,21 +1,12 @@
-github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
-github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
-github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
-github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
-github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
-github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/trailofbits/go-fuzz-utils v0.0.0-20260318143407-0907cafe7589 h1:UmBZCTPdDYore2IEHN+U4eIqEaRq6METh9pKiPumkqc=
 github.com/trailofbits/go-fuzz-utils v0.0.0-20260318143407-0907cafe7589/go.mod h1:zh+T+w9XT/3o4E0WLEGCdmLJ8Yqx/zY3o538tQY3OjY=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
-gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

settings.go

@@ -1,7 +1,5 @@
 package cuckoo
 
-import "fmt"
-
 // DefaultCapacity is the initial capacity of a [Table]. It is inspired from
 // Java's [HashMap] implementation, which also uses 16.
 //
@@ -9,15 +7,14 @@ import "fmt"
 const DefaultCapacity uint64 = 16
 
 // DefaultGrowthFactor is the standard resize multiplier for a [Table]. Most
-// implementations use 2.
+// hash table implementations use 2.
 const DefaultGrowthFactor uint64 = 2
 
-// defaultMinimumLoad is the default lowest acceptable occupancy of a [Table].
+// DefaultMinimumLoad is the default lowest acceptable occupancy of a [Table].
-// The higher the minimum load, the more likely that a [Table.Put] will not
+// The value of 5% is taken from [libcuckoo].
-// 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
@@ -26,25 +23,23 @@ type settings struct {
 }
 
 // An Option modifies the settings of a [Table]. It is used in its constructors
-// like [New], for example.
+// like [NewTable], for example.
 type Option func(*settings)
 
-// Capacity modifies the starting capacity of each subtable of the [Table]. The
+// Capacity modifies the starting capacity of each bucket of the [Table]. The
-// value must be non-negative.
+// value must be greater than 0.
 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
 // 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) }
 }

subtable.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 subtable[K, V any] struct {
-	hash           Hash[K]
-	slots          []slot[K, V]
-	capacity, size uint64
-	compare        EqualFunc[K]
-}
-
-// location determines where in the subtable a certain key would be placed. If
-// the capacity is 0, this will panic.
-func (t *subtable[K, V]) location(key K) uint64 {
-	return t.hash(key) % t.capacity
-}
-
-func (t *subtable[K, V]) get(key K) (value V, found bool) {
-	if t.capacity == 0 {
-		return
-	}
-
-	slot := t.slots[t.location(key)]
-	return slot.value, slot.occupied && t.compare(slot.key, key)
-}
-
-func (t *subtable[K, V]) drop(key K) (occupied bool) {
-	if t.capacity == 0 {
-		return
-	}
-
-	slot := &t.slots[t.location(key)]
-
-	if slot.occupied && t.compare(slot.key, key) {
-		slot.occupied = false
-		t.size--
-		return true
-	}
-
-	return false
-}
-
-func (t *subtable[K, V]) resize(capacity uint64) {
-	t.slots = make([]slot[K, V], capacity)
-	t.capacity = capacity
-	t.size = 0
-}
-
-func (t *subtable[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
-}
-
-func (t *subtable[K, V]) evict(insertion entry[K, V]) (evicted entry[K, V], eviction bool) {
-	if t.capacity == 0 {
-		return insertion, true
-	}
-
-	slot := &t.slots[t.location(insertion.key)]
-
-	if !slot.occupied {
-		slot.entry = insertion
-		slot.occupied = true
-		t.size++
-		return
-	}
-
-	if t.compare(slot.key, insertion.key) {
-		slot.value = insertion.value
-		return
-	}
-
-	insertion, slot.entry = slot.entry, insertion
-	return insertion, true
-}
-
-func newSubtable[K, V any](capacity uint64, hash Hash[K], compare EqualFunc[K]) subtable[K, V] {
-	return subtable[K, V]{
-		hash:     hash,
-		capacity: capacity,
-		compare:  compare,
-		size:     0,
-		slots:    make([]slot[K, V], capacity),
-	}
-}

table.go

@@ -1,50 +1,41 @@
 package cuckoo
 
 import (
-	"errors"
 	"fmt"
 	"iter"
 	"math/bits"
 	"strings"
 )
 
-// ErrBadHash occurs when the hashes given to a [Table] cause too many key
+// A Table is hash table that uses cuckoo hashing to resolve collision. Create
-// collisions. Try rebuilding the table using:
+// one with [NewTable]. Or if you want more granularity, use [NewTableBy] or
-//
+// [NewCustomTable].
-//  1. Different hash seeds. Equal seeds produce equal hash functions, which
-//     always cycle.
-//  2. A different [Hash] algorithm.
-var ErrBadHash = errors.New("bad hash")
-
-// A Table which uses cuckoo hashing to resolve collision. Create
-// one with [New]. Or if you want more granularity, use [NewBy] or
-// [NewCustom].
 type Table[K, V any] struct {
-	tableA, tableB subtable[K, V]
+	bucketA, bucketB bucket[K, V]
-	growthFactor   uint64
+	growthFactor     uint64
-	minLoadFactor  float64
+	minLoadFactor    float64
 }
 
 // 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 {
+func (t Table[K, V]) TotalCapacity() uint64 {
-	return t.tableA.capacity + t.tableB.capacity
+	return t.bucketA.capacity + t.bucketB.capacity
 }
 
 // Size returns how many slots are filled in the [Table].
-func (t *Table[K, V]) Size() int {
+func (t Table[K, V]) Size() int {
-	return int(t.tableA.size + t.tableB.size)
+	return int(t.bucketA.size + t.bucketB.size)
 }
 
 func log2(n uint64) (m int) {
 	return max(0, bits.Len64(n)-1)
 }
 
-func (t *Table[K, V]) maxEvictions() int {
+func (t Table[K, V]) maxEvictions() int {
 	return 3 * log2(t.TotalCapacity())
 }
 
-func (t *Table[K, V]) load() float64 {
+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 {
@@ -54,17 +45,14 @@ func (t *Table[K, V]) load() float64 {
 	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 [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.tableA.resize(capacity)
+	t.bucketA.resize(capacity)
-	t.tableB.resize(capacity)
+	t.bucketB.resize(capacity)
 
 	for _, entry := range entries {
 		if err := t.Put(entry.key, entry.value); err != nil {
@@ -75,76 +63,65 @@ func (t *Table[K, V]) resize(capacity uint64) error {
 	return nil
 }
 
-// grow increases the table's capacity by the growth factor. 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.tableA.capacity * t.growthFactor
+		newCapacity = t.bucketA.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 *Table[K, V]) shrink() error {
-	return t.resize(t.tableA.capacity / t.growthFactor)
+	return t.resize(t.bucketA.capacity / t.growthFactor)
 }
 
-// Get fetches the value for a key in the [Table]. Matches the comma-ok pattern
+// Get fetches the value for a key in the [Table]. Returns an error if no value
-// of a builtin map; see [Table.Find] for plain indexing.
+// is found.
-func (t *Table[K, V]) Get(key K) (value V, ok bool) {
+func (t Table[K, V]) Get(key K) (value V, err error) {
-	if item, ok := t.tableA.get(key); ok {
+	if item, ok := t.bucketA.get(key); ok {
-		return item, true
+		return item, nil
 	}
 
-	if item, ok := t.tableB.get(key); ok {
+	if item, ok := t.bucketB.get(key); ok {
-		return item, true
+		return item, nil
 	}
 
-	return
+	return value, fmt.Errorf("key '%v' not found", key)
-}
-
-// Find fetches the value of a key. Matches direct indexing of a builtin map;
-// see [Table.Get] for a comma-ok pattern.
-func (t *Table[K, V]) Find(key K) (value V) {
-	value, _ = t.Get(key)
-	return
 }
 
 // Has returns true if a key has a value in the table.
-func (t *Table[K, V]) Has(key K) (exists bool) {
+func (t Table[K, V]) Has(key K) (exists bool) {
-	_, exists = t.Get(key)
+	_, err := t.Get(key)
-	return
+	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.tableA.update(key, value) {
+	if t.bucketA.update(key, value) {
 		return nil
 	}
 
-	if t.tableB.update(key, value) {
+	if t.bucketB.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 {
+		if entry, eviction = t.bucketA.evict(entry); !eviction {
 			return nil
 		}
 
-		if entry, eviction = t.tableB.evict(entry); !eviction {
+		if entry, eviction = t.bucketB.evict(entry); !eviction {
 			return nil
 		}
 	}
 
 	if t.load() < t.minLoadFactor {
-		return fmt.Errorf("hash functions produced a cycle at load %d/%d: %w", t.Size(), t.TotalCapacity(), ErrBadHash)
+		return fmt.Errorf("bad hash: resize on load %d/%d = %f", t.Size(), t.TotalCapacity(), t.load())
 	}
 
 	if err := t.grow(); err != nil {
@@ -157,8 +134,8 @@ func (t *Table[K, V]) Put(key K, value V) (err error) {
 // 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.tableA.drop(key)
+	t.bucketA.drop(key)
-	t.tableB.drop(key)
+	t.bucketB.drop(key)
 
 	if t.load() < t.minLoadFactor {
 		return t.shrink()
@@ -168,9 +145,9 @@ func (t *Table[K, V]) Drop(key K) (err error) {
 }
 
 // Entries returns an unordered sequence of all key-value pairs in the table.
-func (t *Table[K, V]) Entries() iter.Seq2[K, V] {
+func (t Table[K, V]) Entries() iter.Seq2[K, V] {
 	return func(yield func(K, V) bool) {
-		for _, slot := range t.tableA.slots {
+		for _, slot := range t.bucketA.slots {
 			if slot.occupied {
 				if !yield(slot.key, slot.value) {
 					return
@@ -178,7 +155,7 @@ func (t *Table[K, V]) Entries() iter.Seq2[K, V] {
 			}
 		}
 
-		for _, slot := range t.tableB.slots {
+		for _, slot := range t.bucketB.slots {
 			if slot.occupied {
 				if !yield(slot.key, slot.value) {
 					return
@@ -189,8 +166,8 @@ func (t *Table[K, V]) Entries() iter.Seq2[K, V] {
 }
 
 // String returns the entries of the table as a string in the format:
-// "table[k1:v1 k2:v2 ...]".
+// "table[k1:v1 h2:v2 ...]".
-func (t *Table[K, V]) String() string {
+func (t Table[K, V]) String() string {
 	var sb strings.Builder
 	sb.WriteString("table[")
 
@@ -208,13 +185,13 @@ func (t *Table[K, V]) String() string {
 	return sb.String()
 }
 
-// NewCustom creates a [Table] with custom [Hash] and [EqualFunc]
+// NewCustomTable creates a [Table] 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) *Table[K, V] {
+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,
+		minLoadFactor: DefaultMinimumLoad,
 	}
 
 	for _, option := range options {
@@ -224,8 +201,8 @@ func NewCustom[K, V any](hashA, hashB Hash[K], compare EqualFunc[K], options ...
 	return &Table[K, V]{
 		growthFactor:  settings.growthFactor,
 		minLoadFactor: settings.minLoadFactor,
-		tableA:        newSubtable[K, V](settings.bucketSize, hashA, compare),
+		bucketA:       newBucket[K, V](settings.bucketSize, hashA, compare),
-		tableB:        newSubtable[K, V](settings.bucketSize, hashB, compare),
+		bucketB:       newBucket[K, V](settings.bucketSize, hashB, compare),
 	}
 }
 
@@ -233,10 +210,10 @@ 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 [Table] for any key type by using keyFunc to derive a
+// 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 NewBy[K, V any, C comparable](keyFunc func(K) C, options ...Option) *Table[K, V] {
+func NewTableBy[K, V any, C comparable](keyFunc func(K) C, options ...Option) *Table[K, V] {
-	return NewCustom[K, V](
+	return NewCustomTable[K, V](
 		pipe(keyFunc, NewDefaultHash[C]()),
 		pipe(keyFunc, NewDefaultHash[C]()),
 		func(a, b K) bool { return keyFunc(a) == keyFunc(b) },
@@ -244,10 +221,10 @@ func NewBy[K, V any, C comparable](keyFunc func(K) C, options ...Option) *Table[
 	)
 }
 
-// New creates a [Table] using the default [Hash] and [EqualFunc]. Use
+// 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
-// [NewBy] or [NewCustom].
+// [NewTableBy] or [NewCustomTable].
-func New[K comparable, V any](options ...Option) *Table[K, V] {
+func NewTable[K comparable, V any](options ...Option) *Table[K, V] {
-	return NewCustom[K, V](NewDefaultHash[K](), NewDefaultHash[K](), DefaultEqualFunc[K], options...)
+	return NewCustomTable[K, V](NewDefaultHash[K](), NewDefaultHash[K](), DefaultEqualFunc[K], options...)
 }

testdata/fuzz/FuzzInsertLookup/663e746d1518e2f5

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("B000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000")