feat: Waku v2 bridge

Issue #12610

vendor/github.com/anacrolix/torrent/segments/index.go

@@ -0,0 +1,45 @@
+package segments
+
+import (
+	"sort"
+)
+
+func NewIndex(segments LengthIter) (ret Index) {
+	var start Length
+	for l, ok := segments(); ok; l, ok = segments() {
+		ret.segments = append(ret.segments, Extent{start, l})
+		start += l
+	}
+	return
+}
+
+type Index struct {
+	segments []Extent
+}
+
+func (me Index) iterSegments() func() (Length, bool) {
+	return func() (Length, bool) {
+		if len(me.segments) == 0 {
+			return 0, false
+		} else {
+			l := me.segments[0].Length
+			me.segments = me.segments[1:]
+			return l, true
+		}
+	}
+}
+
+func (me Index) Locate(e Extent, output Callback) bool {
+	first := sort.Search(len(me.segments), func(i int) bool {
+		_e := me.segments[i]
+		return _e.End() > e.Start
+	})
+	if first == len(me.segments) {
+		return false
+	}
+	e.Start -= me.segments[first].Start
+	me.segments = me.segments[first:]
+	return Scan(me.iterSegments(), e, func(i int, e Extent) bool {
+		return output(i+first, e)
+	})
+}

vendor/github.com/anacrolix/torrent/segments/segments.go

@@ -0,0 +1,63 @@
+package segments
+
+type Int = int64
+
+type Length = Int
+
+func min(i Int, rest ...Int) Int {
+	ret := i
+	for _, i := range rest {
+		if i < ret {
+			ret = i
+		}
+	}
+	return ret
+}
+
+type Extent struct {
+	Start, Length Int
+}
+
+func (e Extent) End() Int {
+	return e.Start + e.Length
+}
+
+type (
+	Callback   = func(int, Extent) bool
+	LengthIter = func() (Length, bool)
+)
+
+func Scan(haystack LengthIter, needle Extent, callback Callback) bool {
+	i := 0
+	for needle.Length != 0 {
+		l, ok := haystack()
+		if !ok {
+			return false
+		}
+		if needle.Start < l || needle.Start == l && l == 0 {
+			e1 := Extent{
+				Start:  needle.Start,
+				Length: min(l, needle.End()) - needle.Start,
+			}
+			if e1.Length >= 0 {
+				if !callback(i, e1) {
+					return true
+				}
+				needle.Start = 0
+				needle.Length -= e1.Length
+			}
+		} else {
+			needle.Start -= l
+		}
+		i++
+	}
+	return true
+}
+
+func LocaterFromLengthIter(li LengthIter) Locater {
+	return func(e Extent, c Callback) bool {
+		return Scan(li, e, c)
+	}
+}
+
+type Locater func(Extent, Callback) bool