feat: add KeyByOperator and wordCounter for stateful processing

1 files changed, 13 insertions, 0 deletions

diff --git a/core/state_backend.go b/core/state_backend.go
index 219bb63..f8b83fb 100644
--- a/core/state_backend.go
+++ b/core/state_backend.go
@@ -11,3 +11,16 @@ type StateBackend interface {
 	// GetValueState will perform in disk
 	GetValueState(ctx context.Context, key string) (ValueState[any], error)
 }
+
+type stateBackendKeyType struct{}
+
+var stateBackendKey stateBackendKeyType
+
+func InjectStateBackend(ctx context.Context, state StateBackend) context.Context {
+	return context.WithValue(ctx, stateBackendKey, state)
+}
+
+func ExtractStateBackend(ctx context.Context) (StateBackend, bool) {
+	backend, ok := ctx.Value(stateBackendKey).(StateBackend)
+	return backend, ok
+}