Source file src/pkg/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	}