Added TrimStrIfAppropriate & docs for TrimStr2Runes.

helper.go

@@ -45,15 +45,39 @@ func str2runes(s string) []rune {
 	return []rune(s)
 }
 
+// Here for backwards-compatibility.
 func trimStr2Runes(s string, w int) []rune {
+	return TrimStr2Runes(s, w)
+}
+
+// TrimStr2Runes trims string to w[-1 rune], appends …, and returns the runes
+// of that string if string is grather then n. If string is small then w,
+// return the runes.
+func TrimStr2Runes(s string, w int) []rune {
 	if w <= 0 {
 		return []rune{}
 	}
+
 	sw := rw.StringWidth(s)
 	if sw > w {
 		return []rune(rw.Truncate(s, w, dot))
 	}
-	return str2runes(s) //[]rune(rw.Truncate(s, w, ""))
+	return str2runes(s)
+}
+
+// TrimStrIfAppropriate trim string to "s[:-1] + …"
+// if string > width otherwise return string
+func TrimStrIfAppropriate(s string, w int) string {
+	if w <= 0 {
+		return ""
+	}
+
+	sw := rw.StringWidth(s)
+	if sw > w {
+		return rw.Truncate(s, w, dot)
+	}
+
+	return s
 }
 
 func strWidth(s string) int {

helper_test.go

@@ -5,24 +5,21 @@
 package termui
 
 import (
+	"fmt"
 	"testing"
-
-	"github.com/davecgh/go-spew/spew"
 )
 
 func TestStr2Rune(t *testing.T) {
 	s := "你好,世界."
 	rs := str2runes(s)
 	if len(rs) != 6 {
-		t.Error()
+		t.Error(t)
 	}
 }
 
 func TestWidth(t *testing.T) {
 	s0 := "つのだ☆HIRO"
 	s1 := "11111111111"
-	spew.Dump(s0)
-	spew.Dump(s1)
 	// above not align for setting East Asian Ambiguous to wide!!
 
 	if strWidth(s0) != strWidth(s1) {
@@ -56,3 +53,21 @@ func TestTrim(t *testing.T) {
 		t.Error("avoid trim failed")
 	}
 }
+
+func assertEqual(t *testing.T, expected, got interface{}, msg ...interface{}) {
+	baseMsg := fmt.Sprintf("Got %v expected %v", got, expected)
+	msg = append([]interface{}{baseMsg}, msg...)
+
+	if expected != got {
+		t.Error(fmt.Sprint(msg...))
+	}
+}
+
+func TestTrimStrIfAppropriate_NoTrim(t *testing.T) {
+	assertEqual(t, "hello", TrimStrIfAppropriate("hello", 5))
+}
+
+func TestTrimStrIfAppropriate(t *testing.T) {
+	assertEqual(t, "hel…", TrimStrIfAppropriate("hello", 4))
+	assertEqual(t, "h…", TrimStrIfAppropriate("hello", 2))
+}