1package backend
 2
 3import "context"
 4
 5var contextKey = &struct{ string }{"backend"}
 6
 7// FromContext returns the backend from a context.
 8func FromContext(ctx context.Context) Backend {
 9	if b, ok := ctx.Value(contextKey).(Backend); ok {
10		return b
11	}
12
13	return nil
14}
15
16// WithContext returns a new context with the backend attached.
17func WithContext(ctx context.Context, b Backend) context.Context {
18	return context.WithValue(ctx, contextKey, b)
19}