feat: trie implementation

internal/utils/trie/any.go

@@ -0,0 +1,49 @@
+package trie
+
+import (
+	"sync/atomic"
+)
+
+// AnyValue is a wrapper of atomic.Value
+// It is used to store values in trie nodes
+// And allowed to assign to empty struct value when node
+// is not an end node anymore
+type AnyValue struct {
+	v atomic.Value
+}
+
+type zeroValue struct{}
+
+var zero zeroValue
+
+func (av *AnyValue) Store(v any) {
+	if v == nil {
+		av.v.Store(zero)
+		return
+	}
+	defer panicInvalidAssignment()
+	av.v.Store(v)
+}
+
+func (av *AnyValue) Swap(v any) any {
+	defer panicInvalidAssignment()
+	return av.v.Swap(v)
+}
+
+func (av *AnyValue) Load() any {
+	switch v := av.v.Load().(type) {
+	case zeroValue:
+		return nil
+	default:
+		return v
+	}
+}
+
+func (av *AnyValue) IsNil() bool {
+	switch v := av.v.Load().(type) {
+	case zeroValue:
+		return true // assigned nil manually
+	default:
+		return v == nil // uninitialized
+	}
+}