1 files changed, 20 insertions, 0 deletions
diff --git a/borrowed_misc.go b/borrowed_misc.go
index 343c924..d5ace19 100644
--- a/borrowed_misc.go
+++ b/borrowed_misc.go
@@ -6,6 +6,8 @@ package lowmemjson
 
 import (
 	"reflect"
+	"strings"
+	"unicode"
 )
 
 // from encode.go
@@ -26,3 +28,21 @@ func isEmptyValue(v reflect.Value) bool {
 	}
 	return false
 }
+
+// from encode.go
+func isValidTag(s string) bool {
+	if s == "" {
+		return false
+	}
+	for _, c := range s {
+		switch {
+		case strings.ContainsRune("!#$%&()*+-./:;<=>?@[]^_{|}~ ", c):
+			// Backslash and quote chars are reserved, but
+			// otherwise any punctuation chars are allowed
+			// in a tag name.
+		case !unicode.IsLetter(c) && !unicode.IsDigit(c):
+			return false
+		}
+	}
+	return true
+}