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package media
import (
"sort"
)
type Playlist []*Video
// By is the type of a "less" function that defines the ordering of its Playlist arguments.
type By func(p1, p2 *Video) bool
// Sort is a method on the function type, By, that sorts the argument slice according to the function.
func (by By) Sort(pl Playlist) {
ps := &playlistSorter{
pl: pl,
by: by, // The Sort method's receiver is the function (closure) that defines the sort order.
}
sort.Sort(ps)
}
// playlistSorter joins a By function and a slice of Playlist to be sorted.
type playlistSorter struct {
pl Playlist
by func(p1, p2 *Video) bool // Closure used in the Less method.
}
// Len is part of sort.Interface.
func (s *playlistSorter) Len() int {
return len(s.pl)
}
// Swap is part of sort.Interface.
func (s *playlistSorter) Swap(i, j int) {
s.pl[i], s.pl[j] = s.pl[j], s.pl[i]
}
// Less is part of sort.Interface. It is implemented by calling the "by" closure in the sorter.
func (s *playlistSorter) Less(i, j int) bool {
return s.by(s.pl[i], s.pl[j])
}
func SortByTimestamp(v1, v2 *Video) bool {
return v1.Timestamp.After(v2.Timestamp)
}
func SortByViews(v1, v2 *Video) bool {
return v1.Views < v2.Views
}
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