golang grammar 代码
文件路径：/src/mime/grammar.go
/ Copyright 2010 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
package mime
import (
"strings"
)
/ isTSpecial reports whether rune is in 'tspecials' as defined by RFC
/ 1521 and RFC 2045.
func isTSpecial(r rune) bool {
return strings.ContainsRune(`()<>@,;:\"/[]?=`, r)
}
/ isTokenChar reports whether rune is in 'token' as defined by RFC
/ 1521 and RFC 2045.
func isTokenChar(r rune) bool {
/ token := 1*<any (US-ASCII) CHAR except SPACE, CTLs,
/ or tspecials>
return r > 0x20 && r < 0x7f && !isTSpecial(r)
}
/ isToken reports whether s is a 'token' as defined by RFC 1521
/ and RFC 2045.
func isToken(s string) bool {
if s == "" {
return false
}
return strings.IndexFunc(s, isNotTokenChar) < 0
}