gotosocial/internal/timeline/postindex.go

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package timeline
import (
"container/list"
"errors"
)
type postIndex struct {
data *list.List
}
type postIndexEntry struct {
statusID string
boostOfID string
}
func (p *postIndex) insertIndexed(i *postIndexEntry) error {
if p.data == nil {
p.data = &list.List{}
}
// if we have no entries yet, this is both the newest and oldest entry, so just put it in the front
if p.data.Len() == 0 {
p.data.PushFront(i)
return nil
}
var insertMark *list.Element
var position int
// We need to iterate through the index to make sure we put this post in the appropriate place according to when it was created.
// We also need to make sure we're not inserting a duplicate post -- this can happen sometimes and it's not nice UX (*shudder*).
for e := p.data.Front(); e != nil; e = e.Next() {
position = position + 1
entry, ok := e.Value.(*postIndexEntry)
if !ok {
return errors.New("index: could not parse e as a postIndexEntry")
}
// don't insert this if it's a boost of a status we've seen recently
if i.boostOfID != "" {
if i.boostOfID == entry.boostOfID || i.boostOfID == entry.statusID {
if position < boostReinsertionDepth {
return nil
}
}
}
// if the post to index is newer than e, insert it before e in the list
if insertMark == nil {
if i.statusID > entry.statusID {
insertMark = e
}
}
// make sure we don't insert a duplicate
if entry.statusID == i.statusID {
return nil
}
}
if insertMark != nil {
p.data.InsertBefore(i, insertMark)
return nil
}
// if we reach this point it's the oldest post we've seen so put it at the back
p.data.PushBack(i)
return nil
}