From fa0e462444312d0f7e59c08f888b82fd83be95a6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me?= <jerome.tabeaud@gmail.com>
Date: Wed, 24 Apr 2019 12:13:56 +0200
Subject: [PATCH] Added a basic timer in utils.hpp.

---
 utils.hpp | 71 ++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 62 insertions(+), 9 deletions(-)

diff --git a/utils.hpp b/utils.hpp
index 376a6b4..8ceccf7 100644
--- a/utils.hpp
+++ b/utils.hpp
@@ -17,23 +17,76 @@ template<typename T, typename T2> auto max(const T & a, const T2 & b) -> decltyp
 /// To be sure that floating point numbers won't be casted to integers in ::abs()...
 template<typename T> T sureAbs(const T & x) { return (x < T(0)) ? -x : x; }
 
+
+//*
+/// Generic operator<< for ostream, (to print std::vector, etd::list, std::map, etc). Can generate conflicts with specialized operator<< overloads.
 template<typename T, template<class,class...> class C, class... Args>
 std::ostream& operator<<(std::ostream& os, const C<T,Args...>& objs)
 {
     for (auto const& obj : objs)
         os << obj << ' ';
     return os;
-}
+}//*/
 
-/// Convenience template class to do StdPairValueCatcher(a, b) = someFunctionThatReturnsAnStdPair<A,B>()
-/// Instead of doing a = std::get<0>(result_from_function), b = std::get<1>(result_from_function)
-template<typename A, typename B>
-struct StdPairValueCatcher
+/// define UTILS_NO_CHRONO to deactivate chronometer
+#ifndef UTILS_NO_CHRONO
+
+#include <iostream>
+#include <chrono>
+#include <ratio>
+#include <ctime>
+
+/// Convenience macro to create a Chronometer object that will measure the execution time of its scope.
+#define TIMER(str) Chronometer __chrono((str))
+
+/// \class Chronometer class. Used to measure the execution time of its scope.
+///
+/// Usage :
+///
+///    {
+///        TIMER("My timer");
+///        /* some code to be profiled */
+///    }// <--- the chronometer measures the time between the call to its constructor and the call to its destructor.
+///
+/// Possible output :
+///
+///     My timer : 0.12317568 s (+/- 1e-09 s)
+///
+template<int T=1>
+struct Chronometer
 {
-    A & a;
-    B & b;
-    StdPairValueCatcher(A & a_, B & b_) : a(a_), b(b_) {}
-    std::pair<A, B> const& operator=(std::pair<A, B> const& p) {a = std::get<0>(p);  b = std::get<1>(p); return p; }
+	std::string name;
+	std::chrono::high_resolution_clock::time_point t0;
+
+	/// Creates the Chronometer object with the provided name and stores the time.
+	Chronometer(const std::string & name_ = "")
+		:	name(name_),
+			t0(std::chrono::high_resolution_clock::now())
+	{}
+
+	/// Measures the time elapsed between the creation of the object and its destruction, and prints the result in std::cout.
+	~Chronometer() { MeasureTimeElapsed(); }
+
+	/// Resets the timer. Allows the measurement of the execution time of several sub-intervals in the current scope.
+	void Reset() { t0 = std::chrono::high_resolution_clock::now(); }
+
+	/// Measures the time elapsed between the creation of the object and its destruction, and prints the result in std::cout.
+	void MeasureTimeElapsed()
+	{
+		// measure time since object creation
+		std::chrono::high_resolution_clock::time_point t1 = std::chrono::high_resolution_clock::now();
+		std::chrono::duration<double> time_span = std::chrono::duration_cast<std::chrono::duration<double>>(t1 - t0);
+		// clock resolution
+		auto resolution_ratio = std::chrono::high_resolution_clock::period();
+		double resolution = double(resolution_ratio.num)/resolution_ratio.den;
+
+		std::cout.precision(16);
+		std::cout << name.c_str() << "\t: " << time_span.count() << " s (+/- " << resolution << " s)" << std::endl;// use of c_str() so that there is no ambiguity with the generic operator<<
+	}
 };
 
+#else// chronometer
+	#define TIMER(str)
+#endif// chronometer
+
 #endif