1 files changed, 42 insertions, 0 deletions
diff --git a/modules/translation/i18n/format.go b/modules/translation/i18n/format.go
new file mode 100644
index 0000000000..3fb9e6d6d0
--- /dev/null
+++ b/modules/translation/i18n/format.go
@@ -0,0 +1,42 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package i18n
+
+import (
+	"fmt"
+	"reflect"
+)
+
+// Format formats provided arguments for a given translated message
+func Format(format string, args ...interface{}) (msg string, err error) {
+	if len(args) == 0 {
+		return format, nil
+	}
+
+	fmtArgs := make([]interface{}, 0, len(args))
+	for _, arg := range args {
+		val := reflect.ValueOf(arg)
+		if val.Kind() == reflect.Slice {
+			// Previously, we would accept Tr(lang, key, a, [b, c], d, [e, f]) as Sprintf(msg, a, b, c, d, e, f)
+			// but this is an unstable behavior.
+			//
+			// So we restrict the accepted arguments to either:
+			//
+			// 1. Tr(lang, key, [slice-items]) as Sprintf(msg, items...)
+			// 2. Tr(lang, key, args...) as Sprintf(msg, args...)
+			if len(args) == 1 {
+				for i := 0; i < val.Len(); i++ {
+					fmtArgs = append(fmtArgs, val.Index(i).Interface())
+				}
+			} else {
+				err = ErrUncertainArguments
+				break
+			}
+		} else {
+			fmtArgs = append(fmtArgs, arg)
+		}
+	}
+	return fmt.Sprintf(format, fmtArgs...), err
+}