From 05934c8b7206aaa991f2d71289cf51ddb2fba33d Mon Sep 17 00:00:00 2001
From: Chip Hogg <chogg@aurora.tech>
Date: Wed, 29 Dec 2021 21:37:06 -0500
Subject: [PATCH] Add make_base_power() helper

---
 src/core/include/units/magnitude.h        |  5 +++++
 test/unit_test/runtime/magnitude_test.cpp | 24 +++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/src/core/include/units/magnitude.h b/src/core/include/units/magnitude.h
index d411766a..7e766b7e 100644
--- a/src/core/include/units/magnitude.h
+++ b/src/core/include/units/magnitude.h
@@ -85,6 +85,11 @@ constexpr auto make_ratio() {
   return quotient_t<detail::prime_factorization_t<N>, detail::prime_factorization_t<D>>{};
 }
 
+template <typename T, std::intmax_t N = 1, std::intmax_t D = 1>
+constexpr auto make_base_power() {
+  return magnitude<base_power<T, ratio{N, D}>>{};
+}
+
 struct pi {
   static inline constexpr long double value = std::numbers::pi_v<long double>;
 };
diff --git a/test/unit_test/runtime/magnitude_test.cpp b/test/unit_test/runtime/magnitude_test.cpp
index e0f5a00f..f95c37f9 100644
--- a/test/unit_test/runtime/magnitude_test.cpp
+++ b/test/unit_test/runtime/magnitude_test.cpp
@@ -234,6 +234,22 @@ TEST_CASE("make_ratio performs prime factorization correctly")
   }
 }
 
+TEST_CASE("make_magnitude handles arbitrary bases")
+{
+  SECTION("Equivalent to std::integral_constant for integer bases")
+  {
+    CHECK(make_base_power<int_base<2>>() == make_ratio<2>());
+    CHECK(make_base_power<int_base<7>>() == make_ratio<7>());
+  }
+
+  SECTION("Handles non-integer bases")
+  {
+    CHECK(make_base_power<pi>() == magnitude<base_power<pi>>{});
+    CHECK(make_base_power<pi, -3>() == magnitude<base_power<pi, ratio{-3}>>{});
+    CHECK(make_base_power<pi, -3, 7>() == magnitude<base_power<pi, ratio{-3, 7}>>{});
+  }
+}
+
 TEST_CASE("Equality works for magnitudes")
 {
   SECTION("Equivalent ratios are equal")
@@ -268,6 +284,14 @@ TEST_CASE("Multiplication works for magnitudes")
     CHECK(make_ratio<4, 5>() * make_ratio<4, 3>() == make_ratio<16, 15>());
   }
 
+  SECTION("Products handle pi correctly")
+  {
+    CHECK(
+        make_base_power<pi>() * make_ratio<2, 3>() * make_base_power<pi, -1, 2>() ==
+        magnitude<int_base_power<2>, int_base_power<3, -1>, base_power<pi, ratio{1, 2}>>{});
+
+  }
+
   SECTION("Supports constexpr")
   {
     constexpr auto p = make_ratio<4, 5>() * make_ratio<4, 3>();