Function applyEdits

internal/attachments/references.go:731–760

applyEdits rewrites the markdown back to front, so that an earlier edit cannot shift a later one, and reports which arguments were actually written. Edits overlap when a video embed alone in its paragraph is replaced by a bare URL and its alt text carries a reference of its own. The wider edit wins

(md string, edits []edit)

// wins, and the dropped one's argument is reported unwritten so the caller
// appends it.
func applyEdits(md string, edits []edit) (string, map[int]bool) {
	written := map[int]bool{}
	if len(edits) == 0 {
		return md, written
	}

	sort.SliceStable(edits, func(i, j int) bool {
		if edits[i].at.start != edits[j].at.start {
			return edits[i].at.start < edits[j].at.start
		}
		return edits[i].at.stop > edits[j].at.stop
	})

	var kept []edit
	end := 0
	for _, e := range edits {
		if e.at.start < end || e.at.start > e.at.stop || e.at.stop > len(md) {
			continue
		}
		kept = append(kept, e)
		written[e.a] = true
		end = e.at.stop
	}

	out := md
	for _, e := range slices.Backward(kept) {
		out = out[:e.at.start] + e.text + out[e.at.stop:]
	}
	return out, written
}

// standsAlone reports whether replacing a node with a bare URL will render as
// a player.