Parse the date from the responce header

src/main.cpp

@@ -5,11 +5,14 @@ int main() {
 	oro::Api oro_api("https://api.originsro.org", "RESTC_CPP", "Testing");
 	auto ping = oro_api.ping();
 
+	std::cout << "date: " << ping.first.date << '\n';
 	std::cout << "rate limit: " << ping.first.rate_limit << '\n';
 	std::cout << "remaining: " << ping.first.rate_limit_remaining << '\n';
 	std::cout << "reset: " << ping.first.rate_limit_reset << '\n';
 	std::cout << "retry after: " << ping.first.retry_after << '\n';
 	std::cout << "server: " << ping.first.server << '\n';
+	std::cout << "-----\n";
+	std::cout << "timestamp: " << ping.second.generation_timestamp << '\n';
 	std::cout << "answer: " << ping.second.message << '\n';
 	std::cout << "version: " << ping.second.version << '\n';
 	return 0;

src/meson.build

@@ -9,6 +9,7 @@ executable(meson.project_name(),
   'main.cpp',
   'oro/datatypes.cpp',
   'oro/api.cpp',
+  'oro/dateconv.cpp',
   install: true,
   dependencies: [restc_cpp_dep],
   include_directories: date_incdir,

src/oro/api.cpp

@@ -1,5 +1,6 @@
 #include "api.hpp"
 #include "datatypes.hpp"
+#include "dateconv.hpp"
 #include <restc-cpp/restc-cpp.h>
 #include <restc-cpp/RequestBuilder.h>
 #include <boost/fusion/adapted.hpp>
@@ -32,6 +33,9 @@ namespace {
 				.Execute();
 
 			Header h;
+			if (auto val = reply->GetHeader("Date")) {
+				h.date = from_header_timestamp(*val);
+			}
 			if (auto val = reply->GetHeader("X-RateLimit-Limit")) {
 				h.rate_limit = std::stoi(*val);
 			}

src/oro/datatypes.cpp

@@ -1,15 +1,18 @@
 #include "datatypes.hpp"
+#include "dateconv.hpp"
 
 #define HAS_UNCAUGHT_EXCEPTIONS 1
 #include "date/date.h"
-#include <sstream>
 
 namespace oro {
 	Timestamp& Timestamp::operator= (const std::string& str) {
-		std::istringstream iss(str);
-
-		//date has this format: 2020-06-19T22:33:36.855672+00:00
-		date::from_stream(iss, "%FT%T%Ez", ts);
+		ts = from_json_timestamp(str);
 		return *this;
 	}
+
+	std::ostream& operator<<(std::ostream& os, const Timestamp& ts) {
+		using date::operator<<;
+		os << ts.ts;
+		return os;
+	}
 } //namespace oro

src/oro/datatypes.hpp

@@ -2,6 +2,7 @@
 
 #include <chrono>
 #include <string>
+#include <iostream>
 
 namespace oro {
     typedef std::chrono::time_point<std::chrono::system_clock, std::chrono::microseconds> timestamp_t;
@@ -12,4 +13,6 @@ namespace oro {
 
 		timestamp_t ts;
 	};
+
+	std::ostream& operator<< (std::ostream& os, const Timestamp& ts);
 } //namespace oro

src/oro/dateconv.cpp

@@ -0,0 +1,41 @@
+#include "dateconv.hpp"
+
+#define HAS_UNCAUGHT_EXCEPTIONS 1
+#include "date/date.h"
+
+#include <sstream>
+#include <clocale>
+#include <memory>
+
+namespace oro {
+namespace {
+	struct LocaleDeleter {
+		void operator() (char* old_locale) {
+			std::setlocale(LC_TIME, old_locale);
+		}
+	};
+
+	Timestamp to_timestamp (const char* fmt, const std::string& str) {
+		std::istringstream iss(str);
+		Timestamp ts;
+		date::from_stream(iss, fmt, ts.ts);
+		return ts;
+	}
+
+	typedef std::unique_ptr<char, LocaleDeleter> UniqueLocale;
+} //unnamed namespace
+
+//For formatting modifiers see:
+//https://howardhinnant.github.io/date/date.html#from_stream_formatting
+
+Timestamp from_json_timestamp (const std::string& str) {
+	//date has this format: 2020-06-19T22:33:36.855672+00:00
+	return to_timestamp("%FT%T%Ez", str);
+}
+
+Timestamp from_header_timestamp (const std::string& str) {
+	UniqueLocale loc(std::setlocale(LC_TIME, "POSIX"));
+	//date has this format: Fri, 19 Jun 2020 22:33:43 GMT
+	return to_timestamp("%a, %d %b %Y %T %Z", str);
+}
+} //namespace oro

src/oro/dateconv.hpp

@@ -0,0 +1,9 @@
+#pragma once
+
+#include "datatypes.hpp"
+#include <string>
+
+namespace oro {
+Timestamp from_json_timestamp (const std::string& str);
+Timestamp from_header_timestamp (const std::string& str);
+} //namespace oro