Add left operators (T,boxed<T,U>)

Author: Yaraslaut

include/boxed-cpp/boxed.hpp

@@ -124,6 +124,11 @@ template <typename T, typename U> constexpr boxed<T, U> operator-(boxed<T, U> co
 template <typename T, typename U> constexpr boxed<T, U> operator*(boxed<T, U> const& a, T b) noexcept { return boxed<T, U>{a.value * b}; }
 template <typename T, typename U> constexpr boxed<T, U> operator/(boxed<T, U> const& a, T b) noexcept { return boxed<T, U>{a.value / b}; }
 
+template <typename T, typename U> constexpr boxed<T, U> operator+(T b, boxed<T, U> const& a) noexcept { return boxed<T, U>{b - a.value}; }
+template <typename T, typename U> constexpr boxed<T, U> operator-(T b, boxed<T, U> const& a) noexcept { return boxed<T, U>{b - a.value}; }
+template <typename T, typename U> constexpr boxed<T, U> operator*(T b, boxed<T, U> const& a) noexcept { return boxed<T, U>{b * a.value}; }
+template <typename T, typename U> constexpr boxed<T, U> operator/(T b, boxed<T, U> const& a) noexcept { return boxed<T, U>{b / a.value}; }
+
 template <typename T, typename U> constexpr boxed<T, U>& operator+=(boxed<T, U>& a, boxed<T, U> const& b) noexcept { a.value += b.value; return a; }
 template <typename T, typename U> constexpr boxed<T, U>& operator-=(boxed<T, U>& a, boxed<T, U> const& b) noexcept { a.value -= b.value; return a; }
 template <typename T, typename U> constexpr boxed<T, U>& operator*=(boxed<T, U>& a, boxed<T, U> const& b) noexcept { a.value *= b.value; return a; }

test-boxed-cpp.cpp

@@ -104,11 +104,15 @@ TEST_CASE("cast inside rvalue")
 {
     auto speed_of_light = Speed(299792458.0);
 
-    auto distance_auto = speed_of_light * 2.0;
-    static_assert(std::is_same_v<decltype(distance_auto),Speed>);
-
-    double distance_d = speed_of_light * 2.0;
-    REQUIRE(distance_d - 2.0 * 299792458.0 < std::numeric_limits<double>::epsilon());
+    auto distance_auto_right = speed_of_light * 2.0;
+    auto distance_auto_left = 2.0 * speed_of_light;
+    static_assert(std::is_same_v<decltype(distance_auto_right),Speed>);
+    static_assert(std::is_same_v<decltype(distance_auto_left),Speed>);
+
+    double distance_d_right = speed_of_light * 2.0;
+    double distance_d_left =  2.0 * speed_of_light;
+    REQUIRE(distance_d_right - 2.0 * 299792458.0 < std::numeric_limits<double>::epsilon());
+    REQUIRE(distance_d_left - 2.0 * 299792458.0 < std::numeric_limits<double>::epsilon());
 }
 
 TEST_CASE("all options for unbox")