package parsekit

func (p *P) RouteRepeat() {
	p.nextState = p.state
	return
}

type RouteFollowup struct {
	p *P
}

func (p *P) RouteTo(state StateFn) *RouteFollowup {
	p.nextState = state
	return &RouteFollowup{p}
}

func (r *RouteFollowup) ThenTo(state StateFn) *RouteFollowup {
	r.p.PushState(state)
	return r
}

func (r *RouteFollowup) ThenReturnHere() {
	r.p.PushState(r.p.state)
}

func (p *P) RouteReturn() {
	p.nextState = p.PopState()
}

func (p *P) ToChildState(state StateFn) StateFn {
	p.PushState(p.state)
	return state
}

func (p *P) ToParentState() StateFn {
	state := p.PopState()
	return state
}

// PushState adds the state function to the state stack.
// This is used for implementing nested parsing.
func (p *P) PushState(state StateFn) {
	p.stack = append(p.stack, state)
}

// PopState pops the last pushed state from the state stack.
func (p *P) PopState() StateFn {
	last := len(p.stack) - 1
	head, tail := p.stack[:last], p.stack[last]
	p.stack = head
	return tail
}