.

src/hos_cpp_utils/include/hos_cpp_utils/hos/utils/Timestamp.h

@@ -0,0 +1,52 @@
+
+#pragma once
+
+
+#include <chrono>
+#include <string>
+#include <sstream>
+#include <cstdio>
+#include <ctime>
+
+
+namespace hos {
+namespace utils {
+
+
+/*
+ * It took me way too long to come up with this solution (which I only consider as workaround,
+ * but currently it seems to be the best solution).
+ * There definitely needs to be much better support for timestamp-to-string conversion in C++,
+ * the current situation is way too unsatisfying. And boost isn't much of a help either.
+ */
+template<class _CLOCK>
+std::string timestamp_to_ISO8601(const std::chrono::time_point<_CLOCK>& timestamp) {
+	std::stringstream ss;
+	std::tm tm_time;
+	char temp[256];
+	// First convert timestamp to time_t (loosing precision)
+    std::time_t time = std::chrono::system_clock::to_time_t(timestamp);
+    // Then convert time_t to tm_time
+	localtime_r(&time, &tm_time);
+	// Print first part of ISO8601 string
+	std::strftime(temp, sizeof(temp), "%FT%H:%M:", &tm_time);
+	ss << temp;
+	// Get lost precision by converting out time_t back to a timestamp and substracting it from our given timestamp,
+	// and add seconds to avoid the "0.xyz" problem
+	std::chrono::duration<double> msecs = timestamp - std::chrono::system_clock::from_time_t(time) + std::chrono::seconds(tm_time.tm_sec);
+	// Print seconds part of ISO8601 string
+	std::snprintf(temp, sizeof(temp), "%09.6f", msecs.count()); // is more compact than C++ counterpart
+	std::string secpart(temp);
+	std::replace(secpart.begin(), secpart.end(), '.', ',' ); // ISO 8601 prefers ',' over '.' as decimal mark.
+	ss << secpart;
+	// Get and print timezone part of ISO8601 string
+	std::strftime(temp, sizeof(temp), "%z", &tm_time);
+	ss << temp;
+	return ss.str();
+}
+
+
+
+} // namespace libvariant
+} // namespace hos
+