From 9ca15c302363b1b62420693d026a4fbd4315dc65 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Thu, 10 Nov 2022 16:41:28 -1000
Subject: [PATCH] feat: `operator[]` added for quantity

---
 src/core/include/units/quantity.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/core/include/units/quantity.h b/src/core/include/units/quantity.h
index ad21ef4b..8721c2cc 100644
--- a/src/core/include/units/quantity.h
+++ b/src/core/include/units/quantity.h
@@ -176,6 +176,13 @@ public:
   [[nodiscard]] constexpr rep&& number() && noexcept { return std::move(number_); }
   [[nodiscard]] constexpr const rep&& number() const&& noexcept { return std::move(number_); }
 
+  template<Unit U>
+    requires quantity_convertible_to_<quantity, quantity<::units::reference<dimension, U{}>{}, Rep>>
+  [[nodiscard]] constexpr quantity<::units::reference<dimension, U{}>{}, Rep> operator[](U) const
+  {
+    return quantity<::units::reference<dimension, U{}>{}, Rep>{*this};
+  }
+
   // member unary operators
   [[nodiscard]] constexpr Quantity auto operator+() const
     requires requires(rep v) {