Add fmt::bytes

include/fmt/core.h

@@ -1513,8 +1513,8 @@ FMT_API void vprint_mojibake(std::FILE*, string_view, format_args);
 
 /**
   \rst
-  Prints formatted data to the file *f*. For wide format strings *f* should be
-  in wide-oriented mode set via ``fwide(f, 1)``.
+  Prints formatted data to the file *f*. Strings are assumed to be
+  Unicode-encoded unless the ``FMT_UNICODE`` macro is set to 0.
 
   **Example**::
 
@@ -1535,8 +1535,9 @@ inline void print(std::FILE* f, const S& format_str, Args&&... args) {
 
 /**
   \rst
-  Formats ``args`` according to specifications in ``format_str`` and writes the
-  output to ``stdout``.
+  Formats ``args`` according to specifications in ``format_str`` and writes
+  the output to ``stdout``. Strings are assumed to be Unicode-encoded unless
+  the ``FMT_UNICODE`` macro is set to 0.
 
   **Example**::
 

include/fmt/format.h

@@ -3112,6 +3112,22 @@ template <typename T> inline const void* ptr(const std::shared_ptr<T>& p) {
   return p.get();
 }
 
+class bytes {
+ private:
+  string_view data_;
+  friend struct formatter<bytes>;
+
+ public:
+  explicit bytes(string_view data) : data_(data) {}
+};
+
+template <> struct formatter<bytes> : formatter<string_view> {
+  template <typename FormatContext>
+  auto format(bytes b, FormatContext& ctx) -> decltype(ctx.out()) {
+    return formatter<string_view>::format(b.data_, ctx);
+  }
+};
+
 template <typename It, typename Char> struct arg_join : internal::view {
   It begin;
   It end;

test/format-test.cc

@@ -1766,6 +1766,12 @@ TEST(FormatTest, Dynamic) {
   EXPECT_EQ("42 and abc1 and 1.5", result);
 }
 
+TEST(FormatTest, Bytes) {
+  auto s = fmt::format("{:10}", fmt::bytes("ёжик"));
+  EXPECT_EQ("ёжик  ", s);
+  EXPECT_EQ(10, s.size());
+}
+
 TEST(FormatTest, JoinArg) {
   using fmt::join;
   int v1[3] = {1, 2, 3};