create wantlist object

exchange/bitswap/wantlist/wantlist.go

@@ -0,0 +1,56 @@
+package wantlist
+
+import (
+	u "github.com/jbenet/go-ipfs/util"
+	"sort"
+)
+
+type Wantlist struct {
+	set map[u.Key]*Entry
+}
+
+func NewWantlist() *Wantlist {
+	return &Wantlist{
+		set: make(map[u.Key]*Entry),
+	}
+}
+
+type Entry struct {
+	Value    u.Key
+	Priority int
+}
+
+func (w *Wantlist) Add(k u.Key, priority int) {
+	if _, ok := w.set[k]; ok {
+		return
+	}
+	w.set[k] = &Entry{
+		Value:    k,
+		Priority: priority,
+	}
+}
+
+func (w *Wantlist) Remove(k u.Key) {
+	delete(w.set, k)
+}
+
+func (w *Wantlist) Contains(k u.Key) bool {
+	_, ok := w.set[k]
+	return ok
+}
+
+type entrySlice []*Entry
+
+func (es entrySlice) Len() int           { return len(es) }
+func (es entrySlice) Swap(i, j int)      { es[i], es[j] = es[j], es[i] }
+func (es entrySlice) Less(i, j int) bool { return es[i].Priority < es[j].Priority }
+
+func (w *Wantlist) Entries() []*Entry {
+	var es entrySlice
+
+	for _, e := range w.set {
+		es = append(es, e)
+	}
+	sort.Sort(es)
+	return es
+}