Make appender compatible with fill

fmtlib · Jul 19, 2024 · de684ef · de684ef
1 parent 447c6cb
commit de684ef
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Showing 2 changed files with 14 additions and 0 deletions.
diff --git a/include/fmt/format.h b/include/fmt/format.h
@@ -106,6 +106,13 @@
 #  define FMT_NOINLINE
 #endif
 
+namespace std {
+template <> struct iterator_traits<fmt::appender> {
+  using iterator_category = output_iterator_tag;
+  using value_type = char;
+};
+}  // namespace std
+
 #ifndef FMT_THROW
 #  if FMT_EXCEPTIONS
 #    if FMT_MSC_VERSION || defined(__NVCC__)

diff --git a/test/format-test.cc b/test/format-test.cc
@@ -2057,6 +2057,13 @@ TEST(format_test, output_iterators) {
   EXPECT_EQ("42", s.str());
 }
 
+TEST(format_test, fill_via_appender) {
+  fmt::memory_buffer buf;
+  auto it = fmt::appender(buf);
+  std::fill_n(it, 3, '~');
+  EXPECT_EQ(fmt::to_string(buf), "~~~");
+}
+
 TEST(format_test, formatted_size) {
   EXPECT_EQ(2u, fmt::formatted_size("{}", 42));
   EXPECT_EQ(2u, fmt::formatted_size(std::locale(), "{}", 42));