Add 'n' specifier for tuple and pair (#4107)

fmtlib · Aug 5, 2024 · 9f0c0c4 · 9f0c0c4
1 parent 9f26906
commit 9f0c0c4
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Showing 2 changed files with 11 additions and 1 deletion.
diff --git a/include/fmt/ranges.h b/include/fmt/ranges.h
@@ -330,7 +330,14 @@ struct formatter<Tuple, Char,
   template <typename ParseContext>
   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
     auto it = ctx.begin();
-    if (it != ctx.end() && *it != '}') report_error("invalid format specifier");
+    auto end = ctx.end();
+    if (it != end && detail::to_ascii(*it) == 'n') {
+      ++it;
+      set_brackets({}, {});
+      set_separator({});
+    }
+    if (it != end && *it != '}') report_error("invalid format specifier");
+    ctx.advance_to(it);
     detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
     return it;
   }

diff --git a/test/ranges-test.cc b/test/ranges-test.cc
@@ -170,6 +170,8 @@ TEST(ranges_test, format_adl_begin_end) {
 TEST(ranges_test, format_pair) {
   auto p = std::pair<int, float>(42, 1.5f);
   EXPECT_EQ(fmt::format("{}", p), "(42, 1.5)");
+  EXPECT_EQ(fmt::format("{:}", p), "(42, 1.5)");
+  EXPECT_EQ(fmt::format("{:n}", p), "421.5");
 }
 
 struct unformattable {};
@@ -178,6 +180,7 @@ TEST(ranges_test, format_tuple) {
   auto t =
       std::tuple<int, float, std::string, char>(42, 1.5f, "this is tuple", 'i');
   EXPECT_EQ(fmt::format("{}", t), "(42, 1.5, \"this is tuple\", 'i')");
+  EXPECT_EQ(fmt::format("{:n}", t), "421.5\"this is tuple\"'i'");
 
   EXPECT_EQ(fmt::format("{}", std::tuple<>()), "()");