diff --git a/vendor/github.com/mattn/go-runewidth/runewidth_posix.go b/vendor/github.com/mattn/go-runewidth/runewidth_posix.go
new file mode 100644
index 0000000..480ad74
--- /dev/null
+++ b/vendor/github.com/mattn/go-runewidth/runewidth_posix.go
@@ -0,0 +1,82 @@
+// +build !windows
+// +build !js
+// +build !appengine
+
+package runewidth
+
+import (
+	"os"
+	"regexp"
+	"strings"
+)
+
+var reLoc = regexp.MustCompile(`^[a-z][a-z][a-z]?(?:_[A-Z][A-Z])?\.(.+)`)
+
+var mblenTable = map[string]int{
+	"utf-8":   6,
+	"utf8":    6,
+	"jis":     8,
+	"eucjp":   3,
+	"euckr":   2,
+	"euccn":   2,
+	"sjis":    2,
+	"cp932":   2,
+	"cp51932": 2,
+	"cp936":   2,
+	"cp949":   2,
+	"cp950":   2,
+	"big5":    2,
+	"gbk":     2,
+	"gb2312":  2,
+}
+
+func isEastAsian(locale string) bool {
+	charset := strings.ToLower(locale)
+	r := reLoc.FindStringSubmatch(locale)
+	if len(r) == 2 {
+		charset = strings.ToLower(r[1])
+	}
+
+	if strings.HasSuffix(charset, "@cjk_narrow") {
+		return false
+	}
+
+	for pos, b := range []byte(charset) {
+		if b == '@' {
+			charset = charset[:pos]
+			break
+		}
+	}
+	max := 1
+	if m, ok := mblenTable[charset]; ok {
+		max = m
+	}
+	if max > 1 && (charset[0] != 'u' ||
+		strings.HasPrefix(locale, "ja") ||
+		strings.HasPrefix(locale, "ko") ||
+		strings.HasPrefix(locale, "zh")) {
+		return true
+	}
+	return false
+}
+
+// IsEastAsian return true if the current locale is CJK
+func IsEastAsian() bool {
+	locale := os.Getenv("LC_ALL")
+	if locale == "" {
+		locale = os.Getenv("LC_CTYPE")
+	}
+	if locale == "" {
+		locale = os.Getenv("LANG")
+	}
+
+	// ignore C locale
+	if locale == "POSIX" || locale == "C" {
+		return false
+	}
+	if len(locale) > 1 && locale[0] == 'C' && (locale[1] == '.' || locale[1] == '-') {
+		return false
+	}
+
+	return isEastAsian(locale)
+}