leaderboard.go

package leaderboard

import ()

//Item is an interface for a leaderboard item. It only exposes a comparison method
type Item interface {
	LessThan(Item) bool
}

//Board implements a leaderboard
type Board []*Item

//Collect adds an item to a leaderboard, at the proper position
func (lb *Board) Collect(newItem Item) {
	if len(*lb) == cap(*lb) && newItem.LessThan(*(*lb)[len(*lb)-1]) {
		//if leaderboard is full and the new item is smaller than the last item in leaderboard, we can just discard it
		return
	}
	for i, item := range *lb {
		if (*item).LessThan(newItem) {
			if len(*lb) < cap(*lb) {
				*lb = append(*lb, nil)
			}
			copy((*lb)[i+1:], (*lb)[i:])
			(*lb)[i] = &newItem
			return
		}
	}

	if len(*lb) < cap(*lb) {
		*lb = append(*lb, &newItem)
		return
	}

}

//New creates a new leaderboard of a size
func New(size int) Board {
	lb := make([]*Item, 0, size)
	return lb
}