From bc6010cc211e20942948ae9bce4939dc1eea590f Mon Sep 17 00:00:00 2001
From: Dean Moldovan <dean0x7d@gmail.com>
Date: Sun, 27 Sep 2015 04:09:37 +0200
Subject: [PATCH] Add _a literal for named arguments

---
 format.h            | 15 +++++++++++++++
 test/format-test.cc | 13 +++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/format.h b/format.h
index b85ddcb1..e5e91537 100644
--- a/format.h
+++ b/format.h
@@ -3030,6 +3030,16 @@ struct UdlFormat {
   }
 };
 
+template <typename Char>
+struct UdlArg {
+  const Char *str;
+
+  template <typename T>
+  NamedArg<Char> operator=(T &&value) const {
+    return {str, std::forward<T>(value)};
+  }
+};
+
 } // namespace internal
 
 inline namespace literals {
@@ -3039,6 +3049,11 @@ operator"" _format(const char *s, std::size_t) { return {s}; }
 inline internal::UdlFormat<wchar_t>
 operator"" _format(const wchar_t *s, std::size_t) { return {s}; }
 
+inline internal::UdlArg<char>
+operator"" _a(const char *s, std::size_t) { return {s}; }
+inline internal::UdlArg<wchar_t>
+operator"" _a(const wchar_t *s, std::size_t) { return {s}; }
+
 } // inline namespace literals
 } // namespace fmt
 #endif // FMT_USE_USER_DEFINED_LITERALS
diff --git a/test/format-test.cc b/test/format-test.cc
index b95c499a..c189f990 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -1610,4 +1610,17 @@ TEST(LiteralsTest, Format) {
   EXPECT_EQ(format("{}c{}", "ab", 1), "{}c{}"_format("ab", 1));
   EXPECT_EQ(format(L"{}c{}", L"ab", 1), L"{}c{}"_format(L"ab", 1));
 }
+
+TEST(LiteralsTest, NamedArg) {
+  EXPECT_EQ(format("{first}{second}{first}{third}",
+                   fmt::arg("first", "abra"), fmt::arg("second", "cad"),
+                   fmt::arg("third", 99)),
+            format("{first}{second}{first}{third}",
+                   "first"_a="abra", "second"_a="cad", "third"_a=99));
+  EXPECT_EQ(format(L"{first}{second}{first}{third}",
+                   fmt::arg(L"first", L"abra"), fmt::arg(L"second", L"cad"),
+                   fmt::arg(L"third", 99)),
+            format(L"{first}{second}{first}{third}",
+                   L"first"_a=L"abra", L"second"_a=L"cad", L"third"_a=99));
+}
 #endif // FMT_USE_USER_DEFINED_LITERALS