Implement stringutils.Ellipsis()

This patch implements an Ellipsis utility to
append an ellipsis (...)  when truncating
strings in output.

It also fixes the existing Truncate() utility
to be compatible with unicode/multibyte characters.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: 51dc35cf23a5418e93128854bedc2e59d8ca743a
Component: engine

components/engine/pkg/stringutils/stringutils.go

@@ -32,12 +32,26 @@ func GenerateRandomASCIIString(n int) string {
 	return string(res)
 }
 
-// Truncate truncates a string to maxlen.
-func Truncate(s string, maxlen int) string {
-	if len(s) <= maxlen {
+// Ellipsis truncates a string to fit within maxlen, and appends ellipsis (...).
+// For maxlen of 3 and lower, no ellipsis is appended.
+func Ellipsis(s string, maxlen int) string {
+	r := []rune(s)
+	if len(r) <= maxlen {
 		return s
 	}
-	return s[:maxlen]
+	if maxlen <= 3 {
+		return string(r[:maxlen])
+	}
+	return string(r[:maxlen-3]) + "..."
+}
+
+// Truncate truncates a string to maxlen.
+func Truncate(s string, maxlen int) string {
+	r := []rune(s)
+	if len(r) <= maxlen {
+		return s
+	}
+	return string(r[:maxlen])
 }
 
 // InSlice tests whether a string is contained in a slice of strings or not.