1
2
3
4 package runewidth
5
6 import (
7 "os"
8 "regexp"
9 "strings"
10 )
11
12 var reLoc = regexp.MustCompile(`^[a-z][a-z][a-z]?(?:_[A-Z][A-Z])?\.(.+)`)
13
14 var mblenTable = map[string]int{
15 "utf-8": 6,
16 "utf8": 6,
17 "jis": 8,
18 "eucjp": 3,
19 "euckr": 2,
20 "euccn": 2,
21 "sjis": 2,
22 "cp932": 2,
23 "cp51932": 2,
24 "cp936": 2,
25 "cp949": 2,
26 "cp950": 2,
27 "big5": 2,
28 "gbk": 2,
29 "gb2312": 2,
30 }
31
32 func isEastAsian(locale string) bool {
33 charset := strings.ToLower(locale)
34 r := reLoc.FindStringSubmatch(locale)
35 if len(r) == 2 {
36 charset = strings.ToLower(r[1])
37 }
38
39 if strings.HasSuffix(charset, "@cjk_narrow") {
40 return false
41 }
42
43 for pos, b := range []byte(charset) {
44 if b == '@' {
45 charset = charset[:pos]
46 break
47 }
48 }
49 max := 1
50 if m, ok := mblenTable[charset]; ok {
51 max = m
52 }
53 if max > 1 && (charset[0] != 'u' ||
54 strings.HasPrefix(locale, "ja") ||
55 strings.HasPrefix(locale, "ko") ||
56 strings.HasPrefix(locale, "zh")) {
57 return true
58 }
59 return false
60 }
61
62
63 func IsEastAsian() bool {
64 locale := os.Getenv("LC_ALL")
65 if locale == "" {
66 locale = os.Getenv("LC_CTYPE")
67 }
68 if locale == "" {
69 locale = os.Getenv("LANG")
70 }
71
72
73 if locale == "POSIX" || locale == "C" {
74 return false
75 }
76 if len(locale) > 1 && locale[0] == 'C' && (locale[1] == '.' || locale[1] == '-') {
77 return false
78 }
79
80 return isEastAsian(locale)
81 }
82
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