1 files changed, 80 insertions, 0 deletions
diff --git a/ui/util.go b/ui/util.go
index b17f106c..0cca0909 100644
--- a/ui/util.go
+++ b/ui/util.go
@@ -12,6 +12,86 @@ import (
 	"github.com/lxn/walk"
 )
 
+type orderedStringSet struct {
+	items      []string
+	item2index map[string]int
+}
+
+func orderedStringSetFromSlice(items []string) *orderedStringSet {
+	oss := newOrderedStringSet()
+	oss.AddMany(items)
+	return oss
+}
+
+func newOrderedStringSet() *orderedStringSet {
+	return &orderedStringSet{item2index: make(map[string]int)}
+}
+
+func (oss *orderedStringSet) Add(item string) bool {
+	if _, ok := oss.item2index[item]; ok {
+		return false
+	}
+
+	oss.item2index[item] = len(oss.items)
+	oss.items = append(oss.items, item)
+	return true
+}
+
+func (oss *orderedStringSet) AddMany(items []string) {
+	for _, item := range items {
+		oss.Add(item)
+	}
+}
+
+func (oss *orderedStringSet) UniteWith(other *orderedStringSet) {
+	if other == oss {
+		return
+	}
+
+	oss.AddMany(other.items)
+}
+
+func (oss *orderedStringSet) Remove(item string) bool {
+	if i, ok := oss.item2index[item]; ok {
+		oss.items = append(oss.items[:i], oss.items[i+1:]...)
+		delete(oss.item2index, item)
+		return true
+	}
+
+	return false
+}
+
+func (oss *orderedStringSet) Len() int {
+	return len(oss.items)
+}
+
+func (oss *orderedStringSet) ToSlice() []string {
+	return append(([]string)(nil), oss.items...)
+}
+
+func (oss *orderedStringSet) Contains(item string) bool {
+	_, ok := oss.item2index[item]
+	return ok
+}
+
+func (oss *orderedStringSet) IsSupersetOf(other *orderedStringSet) bool {
+	if oss.Len() < other.Len() {
+		return false
+	}
+
+	for _, item := range other.items {
+		if !oss.Contains(item) {
+			return false
+		}
+	}
+
+	return true
+}
+
+func (oss *orderedStringSet) String() string {
+	return fmt.Sprintf("%v", oss.items)
+}
+
 func writeFileWithOverwriteHandling(owner walk.Form, filePath string, write func(file *os.File) error) bool {
 	showError := func(err error) bool {
 		if err == nil {