Make buffer_range public and update custom formatting docs (#1281)

test/custom-formatter-test.cc

@@ -18,9 +18,9 @@
 // A custom argument formatter that doesn't print `-` for floating-point values
 // rounded to 0.
 class custom_arg_formatter
-    : public fmt::arg_formatter<fmt::internal::buffer_range<char>> {
+    : public fmt::arg_formatter<fmt::buffer_range<char>> {
  public:
-  using range = fmt::internal::buffer_range<char>;
+  using range = fmt::buffer_range<char>;
   typedef fmt::arg_formatter<range> base;
 
   custom_arg_formatter(fmt::format_context& ctx,

test/format

@@ -718,7 +718,7 @@ template<class... Args>
 string vformat(string_view fmt, format_args args) {
   fmt::memory_buffer mbuf;
   fmt::internal::buffer<char>& buf = mbuf;
-  using range = fmt::internal::buffer_range<char>;
+  using range = fmt::buffer_range<char>;
   detail::format_handler<detail::arg_formatter<range>, char, format_context>
     h(range(std::back_inserter(buf)), fmt, args, {});
   fmt::internal::parse_format_string<false>(fmt::to_string_view(fmt), h);

test/format-test.cc

@@ -99,7 +99,7 @@ void std_format(long double value, std::wstring& result) {
 template <typename Char, typename T>
 ::testing::AssertionResult check_write(const T& value, const char* type) {
   fmt::basic_memory_buffer<Char> buffer;
-  using range = fmt::internal::buffer_range<Char>;
+  using range = fmt::buffer_range<Char>;
   basic_writer<range> writer(buffer);
   writer.write(value);
   std::basic_string<Char> actual = to_string(buffer);
@@ -1911,7 +1911,7 @@ enum TestFixedEnum : short { B };
 TEST(FormatTest, FixedEnum) { EXPECT_EQ("0", fmt::format("{}", B)); }
 #endif
 
-using buffer_range = fmt::internal::buffer_range<char>;
+using buffer_range = fmt::buffer_range<char>;
 
 class mock_arg_formatter
     : public fmt::internal::arg_formatter_base<buffer_range> {

test/ostream-test.cc

@@ -64,7 +64,7 @@ TEST(OStreamTest, Enum) {
   EXPECT_EQ(L"0", fmt::format(L"{}", unstreamable_enum()));
 }
 
-using range = fmt::internal::buffer_range<char>;
+using range = fmt::buffer_range<char>;
 
 struct test_arg_formatter : fmt::arg_formatter<range> {
   fmt::format_parse_context parse_ctx;

test/printf-test.cc

@@ -561,8 +561,7 @@ TEST(PrintfTest, VSPrintfMakeWArgsExample) {
 #endif
 }
 
-typedef fmt::printf_arg_formatter<fmt::internal::buffer_range<char>>
-    formatter_t;
+typedef fmt::printf_arg_formatter<fmt::buffer_range<char>> formatter_t;
 typedef fmt::basic_printf_context<formatter_t::iterator, char> context_t;
 
 // A custom printf argument formatter that doesn't print `-` for floating-point