1 files changed, 69 insertions, 0 deletions
diff --git a/typedsync/map.go b/typedsync/map.go
new file mode 100644
index 0000000..6bb1170
--- /dev/null
+++ b/typedsync/map.go
@@ -0,0 +1,69 @@
+// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package typedsync
+
+import (
+	"sync"
+)
+
+// Map is a type-safe equivalent of the standard library's sync.Map.
+//
+// With versions of Go prior to Go 1.20, Map is specified too loosely,
+// as
+//
+//	Map[K any, V any]
+//
+// while with Go 1.20 and later, Map is specified as
+//
+//	Map[K comparable, V any]
+//
+// This is because with Go versions prior to 1.20, 'comparable' was
+// overly strict, disallowing many types that are valid map-keys (see
+// https://github.com/golang/go/issues/56548).  The type used as K in
+// a Map older versions of Go must be a valid map-key type, even
+// though the type specification of Map does not enforce that.
+type Map[K mapkey, V any] struct {
+	inner sync.Map
+}
+
+func (m *Map[K, V]) Delete(key K) {
+	m.inner.Delete(key)
+}
+
+func (m *Map[K, V]) Load(key K) (value V, ok bool) {
+	_value, ok := m.inner.Load(key)
+	if ok {
+		//nolint:forcetypeassert // Typed wrapper around untyped lib.
+		value = _value.(V)
+	}
+	return value, ok
+}
+
+func (m *Map[K, V]) LoadAndDelete(key K) (value V, loaded bool) {
+	_value, ok := m.inner.LoadAndDelete(key)
+	if ok {
+		//nolint:forcetypeassert // Typed wrapper around untyped lib.
+		value = _value.(V)
+	}
+	return value, ok
+}
+
+func (m *Map[K, V]) LoadOrStore(key K, value V) (actual V, loaded bool) {
+	_actual, loaded := m.inner.LoadOrStore(key, value)
+	//nolint:forcetypeassert // Typed wrapper around untyped lib.
+	actual = _actual.(V)
+	return actual, loaded
+}
+
+func (m *Map[K, V]) Range(f func(key K, value V) bool) {
+	m.inner.Range(func(key, value any) bool {
+		//nolint:forcetypeassert // Typed wrapper around untyped lib.
+		return f(key.(K), value.(V))
+	})
+}
+
+func (m *Map[K, V]) Store(key K, value V) {
+	m.inner.Store(key, value)
+}