From 4d3e4aa1fc8883ef7ff1505e84a2b0512fdc0f4e Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Mon, 4 Nov 2019 06:46:53 +0000
Subject: [PATCH] Surface tension added

---
 .../units/dimensions/surface_tension.h        | 45 +++++++++++++++++++
 test/unit_test/runtime/text_test.cpp          |  6 +++
 test/unit_test/static/unit_test.cpp           |  6 +++
 3 files changed, 57 insertions(+)
 create mode 100644 src/include/units/dimensions/surface_tension.h

diff --git a/src/include/units/dimensions/surface_tension.h b/src/include/units/dimensions/surface_tension.h
new file mode 100644
index 00000000..8a106301
--- /dev/null
+++ b/src/include/units/dimensions/surface_tension.h
@@ -0,0 +1,45 @@
+// The MIT License (MIT)
+//
+// Copyright (c) 2018 Mateusz Pusz
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#pragma once
+
+#include <units/dimensions/si_base_dimensions.h>
+#include <units/dimensions/force.h>
+
+namespace units {
+
+  struct surface_tension : derived_dimension<surface_tension, exp<force, 1>, exp<length, -1>> {};
+
+  template<typename T>
+  concept SurfaceTension = QuantityOf<T, surface_tension>;
+
+  struct newton_per_metre : coherent_derived_unit<newton_per_metre, surface_tension> {};
+
+  inline namespace literals {
+
+    // Nm
+    constexpr auto operator""Npm(unsigned long long l) { return quantity<newton_per_metre, std::int64_t>(l); }
+    constexpr auto operator""Npm(long double l) { return quantity<newton_per_metre, long double>(l); }
+
+  }  // namespace literals
+
+}  // namespace units
diff --git a/test/unit_test/runtime/text_test.cpp b/test/unit_test/runtime/text_test.cpp
index f7da3571..51f7501e 100644
--- a/test/unit_test/runtime/text_test.cpp
+++ b/test/unit_test/runtime/text_test.cpp
@@ -90,6 +90,12 @@ TEST_CASE("operator<< on a quantity", "[text][ostream]")
         stream << 20.km / 2h;
         REQUIRE(stream.str() == "10 km/h");
       }
+
+      SECTION("surface tension")
+      {
+        stream << 20.N / 2m;
+        REQUIRE(stream.str() == "10 N/m");
+      }
     }
   }
 
diff --git a/test/unit_test/static/unit_test.cpp b/test/unit_test/static/unit_test.cpp
index fc52a059..91d910ac 100644
--- a/test/unit_test/static/unit_test.cpp
+++ b/test/unit_test/static/unit_test.cpp
@@ -34,6 +34,7 @@
 #include <units/dimensions/power.h>
 #include <units/dimensions/pressure.h>
 #include <units/dimensions/substance.h>
+#include <units/dimensions/surface_tension.h>
 #include <units/dimensions/temperature.h>
 #include <units/dimensions/time.h>
 #include <units/dimensions/velocity.h>
@@ -184,4 +185,9 @@ namespace {
   static_assert(10km * 10km * 10km == 1000cub_km);
   static_assert(1cub_m == 1'000'000cub_cm);
 
+
+  /* ************** DERIVED DIMENSIONS IN TERMS OF OTHER UNITS **************** */
+
+  static_assert(10N / 2m == 5Npm);
+
 }  // namespace