libgo/go/mime/grammar.go

   1 // Copyright 2010 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package mime
   6
   7 import (
   8         "strings"
   9 )
  10
  11 // isTSpecial returns true if rune is in 'tspecials' as defined by RFC
  12 // 1521 and RFC 2045.
  13 func isTSpecial(r rune) bool {
  14         return strings.IndexRune(`()<>@,;:\"/[]?=`, r) != -1
  15 }
  16
  17 // isTokenChar returns true if rune is in 'token' as defined by RFC
  18 // 1521 and RFC 2045.
  19 func isTokenChar(r rune) bool {
  20         // token := 1*<any (US-ASCII) CHAR except SPACE, CTLs,
  21         //             or tspecials>
  22         return r > 0x20 && r < 0x7f && !isTSpecial(r)
  23 }
  24
  25 // isToken returns true if s is a 'token' as as defined by RFC 1521
  26 // and RFC 2045.
  27 func isToken(s string) bool {
  28         if s == "" {
  29                 return false
  30         }
  31         return strings.IndexFunc(s, isNotTokenChar) < 0
  32 }
  33
  34 // isQText returns true if rune is in 'qtext' as defined by RFC 822.
  35 func isQText(r int) bool {
  36         // CHAR        =  <any ASCII character>        ; (  0-177,  0.-127.)
  37         // qtext       =  <any CHAR excepting <">,     ; => may be folded
  38         //                "\" & CR, and including
  39         //                linear-white-space>
  40         switch r {
  41         case '"', '\\', '\r':
  42                 return false
  43         }
  44         return r < 0x80
  45 }