Initial QSfera import

Server/vendor/github.com/sergi/go-diff/diffmatchpatch/index.go

@@ -0,0 +1,32 @@
+package diffmatchpatch
+
+type index uint32
+
+const runeSkipStart = 0xd800
+const runeSkipEnd = 0xdfff + 1
+const runeMax = 0x110000 // next invalid code point
+
+func stringToIndex(text string) []index {
+	runes := []rune(text)
+	indexes := make([]index, len(runes))
+	for i, r := range runes {
+		if r < runeSkipEnd {
+			indexes[i] = index(r)
+		} else {
+			indexes[i] = index(r) - (runeSkipEnd - runeSkipStart)
+		}
+	}
+	return indexes
+}
+
+func indexesToString(indexes []index) string {
+	runes := make([]rune, len(indexes))
+	for i, index := range indexes {
+		if index < runeSkipStart {
+			runes[i] = rune(index)
+		} else {
+			runes[i] = rune(index + (runeSkipEnd - runeSkipStart))
+		}
+	}
+	return string(runes)
+}