From c4d0f96a6da30417191b72a7444fde4b03e254be Mon Sep 17 00:00:00 2001
From: Victor Zverovich <viz@fb.com>
Date: Sat, 4 Sep 2021 06:47:21 -0700
Subject: [PATCH] Implement format specs in fmt::thousands

---
 include/fmt/format.h | 20 +++++++++++++++++++-
 test/format-test.cc  |  3 ++-
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index cc68c116..7993b823 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -2619,11 +2619,29 @@ template <typename T> auto thousands(T value) -> thousands_view<T> {
 }
 
 template <typename T> struct formatter<thousands_view<T>> : formatter<T> {
+ private:
+  detail::dynamic_format_specs<char> specs_;
+
+ public:
+  template <typename ParseContext>
+  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+    using handler_type = detail::dynamic_specs_handler<ParseContext>;
+    detail::specs_checker<handler_type> handler(handler_type(specs_, ctx),
+                                                detail::type::int_type);
+    auto it = parse_format_specs(ctx.begin(), ctx.end(), handler);
+    detail::check_string_type_spec(specs_.type, ctx.error_handler());
+    return it;
+  }
+
   template <typename FormatContext>
   auto format(thousands_view<T> t, FormatContext& ctx) -> decltype(ctx.out()) {
+    detail::handle_dynamic_spec<detail::width_checker>(specs_.width,
+                                                       specs_.width_ref, ctx);
+    detail::handle_dynamic_spec<detail::precision_checker>(
+        specs_.precision, specs_.precision_ref, ctx);
     return detail::write_int_localized(
         ctx.out(), static_cast<detail::uint64_or_128_t<T>>(t.value), 0,
-        format_specs(), detail::digit_grouping<char>({"\3", ','}));
+        specs_, detail::digit_grouping<char>({"\3", ','}));
   }
 };
 
diff --git a/test/format-test.cc b/test/format-test.cc
index ae129a82..93b5d308 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -1596,7 +1596,8 @@ TEST(format_test, bytes) {
 }
 
 TEST(format_test, thousands) {
-  EXPECT_EQ(fmt::format("{}", fmt::thousands(1000)), "1,000");
+  EXPECT_EQ(fmt::format("{}", fmt::thousands(10000000)), "10,000,000");
+  EXPECT_EQ(fmt::format("{:8}", fmt::thousands(1000)), "   1,000");
 }
 
 enum test_enum { foo, bar };