Added charge density

src/include/units/physical/dimensions.h

@@ -158,6 +158,13 @@ struct dim_energy_density : derived_dimension<Child, U, exp<E, 1>, exp<L, -3>> {
 template<typename Child, Unit U, DimensionOf<dim_voltage> V, DimensionOf<dim_length> L>
 struct dim_electric_field_strength : derived_dimension<Child, U, exp<V, 1>, exp<L, -1>> {};
 
+template<typename Child, Unit U, DimensionOf<dim_electric_charge> Q, DimensionOf<dim_length> L>
+struct dim_charge_density : derived_dimension<Child, U, exp<Q, 1>, exp<L, -3>> {};
+
+template<typename Child, Unit U, DimensionOf<dim_electric_charge> Q, DimensionOf<dim_length> L>
+struct dim_surface_charge_density : derived_dimension<Child, U, exp<Q, 1>, exp<L, -2>> {};
+
+
 }  // namespace physical
 
 template<typename T>
@@ -274,4 +281,10 @@ concept ThermalConductivity = physical::QuantityOf<T, physical::dim_thermal_cond
 template<typename T>
 concept ElectricFieldStrength = physical::QuantityOf<T, physical::dim_electric_field_strength>;
 
+template<typename T>
+concept ChargeDensity = physical::QuantityOf<T, physical::dim_charge_density>;
+
+template<typename T>
+concept SurfaceChargeDensity = physical::QuantityOf<T, physical::dim_surface_charge_density>;
+
 }  // namespace units

src/include/units/physical/si.h

@@ -26,6 +26,7 @@
 #include "si/area.h"
 #include "si/capacitance.h"
 #include "si/catalytic_activity.h"
+#include "si/charge_density.h"
 #include "si/concentration.h"
 #include "si/conductance.h"
 #include "si/constants.h"

src/include/units/physical/si/charge_density.h

@@ -0,0 +1,57 @@
+// 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/physical/dimensions.h>
+#include <units/physical/si/electric_charge.h>
+#include <units/physical/si/length.h>
+#include <units/physical/si/prefixes.h>
+#include <units/quantity.h>
+
+namespace units::si {
+
+struct coulomb_per_metre_cub : unit<coulomb_per_metre_cub> {};
+struct coulomb_per_metre_sq : unit<coulomb_per_metre_sq> {};
+
+struct dim_charge_density : physical::dim_charge_density<dim_charge_density, coulomb_per_metre_cub, dim_electric_charge, dim_length> {};
+struct dim_surface_charge_density : physical::dim_surface_charge_density<dim_surface_charge_density, coulomb_per_metre_sq, dim_electric_charge, dim_length> {};
+
+template<Unit U, Scalar Rep = double>
+using charge_density = quantity<dim_charge_density, U, Rep>;
+
+template<Unit U, Scalar Rep = double>
+using surface_charge_density = quantity<dim_surface_charge_density, U, Rep>;
+
+inline namespace literals {
+
+// C/m³
+constexpr auto operator"" q_C_per_m3(unsigned long long l) { return charge_density<coulomb_per_metre_cub, std::int64_t>(l); }
+constexpr auto operator"" q_C_per_m3(long double l) { return charge_density<coulomb_per_metre_cub, long double>(l); }
+
+// C/m²
+constexpr auto operator"" q_C_per_m2(unsigned long long l) { return surface_charge_density<coulomb_per_metre_sq, std::int64_t>(l); }
+constexpr auto operator"" q_C_per_m2(long double l) { return surface_charge_density<coulomb_per_metre_sq, long double>(l); }
+
+}  // namespace literals
+
+}  // namespace units::si

test/unit_test/runtime/fmt_units_test.cpp

@@ -279,6 +279,14 @@ TEST_CASE("fmt::format on synthesized unit symbols", "[text][fmt]")
     CHECK(fmt::format("{}", 1q_V_per_m) == "1 V/m");
   }
 
+  SECTION("charge density")
+  {
+    CHECK(fmt::format("{}", 1q_C_per_m3) == "1 C/m³");
+    CHECK(fmt::format("{:%Q %Aq}", 1q_C_per_m3) == "1 C/m^3");
+    CHECK(fmt::format("{}", 1q_C_per_m2) == "1 C/m²");
+    CHECK(fmt::format("{:%Q %Aq}", 1q_C_per_m2) == "1 C/m^2");
+  }
+
   SECTION("incoherent units with powers")
   {
     CHECK(fmt::format("{}", 1q_mi * 1q_mi * 1q_mi) == "1 [15900351812136/3814697265625 × 10⁹] m³");

test/unit_test/static/si_test.cpp

@@ -334,4 +334,16 @@ static_assert(1q_C * 10q_V_per_m * 3q_m == 30q_J);
 
 static_assert(detail::unit_text<dim_electric_field_strength, volt_per_metre>() == "V/m");
 
+// [surface] charge density
+
+static_assert(20.q_C / 40q_m3 == 0.5q_C_per_m3);
+static_assert(10.q_C / 20q_m2 == 0.5q_C_per_m2);
+static_assert(20.q_C_per_m3 == 10.q_C_per_m2 / 0.5q_m);
+static_assert(1q_C / 1q_m / 1q_m == 1q_C / 1q_m2);
+static_assert(1q_C_per_m2 == 1q_C_per_m3 * 1q_m);
+static_assert(1q_V_per_m * 10q_C_per_m3 * 1q_m3 == 10q_N);
+
+static_assert(detail::unit_text<dim_charge_density, coulomb_per_metre_cub>() == basic_symbol_text("C/m³", "C/m^3"));
+static_assert(detail::unit_text<dim_surface_charge_density, coulomb_per_metre_sq>() == basic_symbol_text("C/m²", "C/m^2"));
+
 }  // namespace