Merge branch 'master' into YearCalendar

Signed-off-by: Viktar Lukashonak <myxabeer@gmail.com>

include/util/date.hpp

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <fmt/format.h>
+
+#if HAVE_CHRONO_TIMEZONES
+#include <chrono>
+#include <format>
+
+/* Compatibility layer for <date/tz.h> on top of C++20 <chrono> */
+namespace date {
+
+using namespace std::chrono;
+
+namespace literals {
+using std::chrono::last;
+}
+
+inline auto format(const std::string& spec, const auto& ztime) {
+  return spec.empty() ? "" : std::vformat("{:L" + spec + "}", std::make_format_args(ztime));
+}
+
+inline auto format(const std::locale& loc, const std::string& spec, const auto& ztime) {
+  return spec.empty() ? "" : std::vformat(loc, "{:L" + spec + "}", std::make_format_args(ztime));
+}
+
+}  // namespace date
+
+#else
+#include <date/tz.h>
+#endif
+
+template <typename Duration, typename TimeZonePtr>
+struct fmt::formatter<date::zoned_time<Duration, TimeZonePtr>> {
+  std::string_view specs;
+
+  template <typename ParseContext>
+  constexpr auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+    auto it = ctx.begin();
+    if (it != ctx.end() && *it == ':') {
+      ++it;
+    }
+    auto end = it;
+    while (end != ctx.end() && *end != '}') {
+      ++end;
+    }
+    if (end != it) {
+      specs = {it, std::string_view::size_type(end - it)};
+    }
+    return end;
+  }
+
+  template <typename FormatContext>
+  auto format(const date::zoned_time<Duration, TimeZonePtr>& ztime, FormatContext& ctx) {
+    if (ctx.locale()) {
+      const auto loc = ctx.locale().template get<std::locale>();
+      return fmt::format_to(ctx.out(), "{}", date::format(loc, fmt::to_string(specs), ztime));
+    }
+    return fmt::format_to(ctx.out(), "{}", date::format(fmt::to_string(specs), ztime));
+  }
+};