package util

import "io"

// Cycler stores a value and an accompanying io.Closer. When the value is set,
// the closer associated with the previous value is closed.
type Cycler[T any] struct {
	value  T
	closer io.Closer
}

// Value returns the cycler's value.
func (this *Cycler[T]) Value () T {
	return this.value
}

// Set sets the value and associated closer, closing the previous one.
func (this *Cycler[T]) Set (value T, closer io.Closer) (err error) {
	if this.closer != nil {
		err = this.closer.Close()
	}
	this.value  = value
	this.closer = closer
	return err
}

// Close closes the associated closer early.
func (this *Cycler[T]) Close () error {
	err := this.closer.Close()
	this.closer = nil
	return err
}