The n specifier for ranges (#2981)

* The n specifier for ranges. * Flipping flag polarity.
fmtlib · Jul 12, 2022 · 92d36e8 · 92d36e8
1 parent 0db43cf
commit 92d36e8
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Showing 2 changed files with 11 additions and 3 deletions.
diff --git a/include/fmt/ranges.h b/include/fmt/ranges.h
@@ -428,15 +428,21 @@ struct formatter<
       detail::range_formatter_type<Char, detail::uncvref_type<range_type>>;
   formatter_type underlying_;
   bool custom_specs_ = false;
+  bool no_brackets_ = false;
 
   template <typename ParseContext>
   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
     auto it = ctx.begin();
     auto end = ctx.end();
     if (it == end || *it == '}') return it;
 
+    if (*it == 'n') {
+      no_brackets_ = true;
+      ++it;
+    }
+
     if (*it != ':')
-      FMT_THROW(format_error("no top-level range formatters supported"));
+      FMT_THROW(format_error("no other top-level range formatters supported"));
 
     custom_specs_ = true;
     ++it;
@@ -451,7 +457,7 @@ struct formatter<
     Char postfix = detail::is_set<R>::value ? '}' : ']';
     detail::range_mapper<buffer_context<Char>> mapper;
     auto out = ctx.out();
-    *out++ = prefix;
+    if (!no_brackets_) *out++ = prefix;
     int i = 0;
     auto it = detail::range_begin(range);
     auto end = detail::range_end(range);
@@ -465,7 +471,7 @@ struct formatter<
       }
       ++i;
     }
-    *out++ = postfix;
+    if (!no_brackets_) *out++ = postfix;
     return out;
   }
 };

diff --git a/test/ranges-test.cc b/test/ranges-test.cc
@@ -47,12 +47,14 @@ TEST(ranges_test, format_vector) {
   auto v = std::vector<int>{1, 2, 3, 5, 7, 11};
   EXPECT_EQ(fmt::format("{}", v), "[1, 2, 3, 5, 7, 11]");
   EXPECT_EQ(fmt::format("{::#x}", v), "[0x1, 0x2, 0x3, 0x5, 0x7, 0xb]");
+  EXPECT_EQ(fmt::format("{:n:#x}", v), "0x1, 0x2, 0x3, 0x5, 0x7, 0xb");
 }
 
 TEST(ranges_test, format_vector2) {
   auto v = std::vector<std::vector<int>>{{1, 2}, {3, 5}, {7, 11}};
   EXPECT_EQ(fmt::format("{}", v), "[[1, 2], [3, 5], [7, 11]]");
   EXPECT_EQ(fmt::format("{:::#x}", v), "[[0x1, 0x2], [0x3, 0x5], [0x7, 0xb]]");
+  EXPECT_EQ(fmt::format("{:n:n:#x}", v), "0x1, 0x2, 0x3, 0x5, 0x7, 0xb");
 }
 
 TEST(ranges_test, format_map) {