1 files changed, 32 insertions, 0 deletions
diff --git a/src/mime/grammar.go b/src/mime/grammar.go
new file mode 100644
index 000000000..2347324aa
--- /dev/null
+++ b/src/mime/grammar.go
@@ -0,0 +1,32 @@
+// 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 returns true if rune is in 'tspecials' as defined by RFC
+// 1521 and RFC 2045.
+func isTSpecial(r rune) bool {
+	return strings.IndexRune(`()<>@,;:\"/[]?=`, r) != -1
+}
+
+// isTokenChar returns true if 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 returns true if 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
+}