Add almost all core SI units (#157)

We get our units from the figure on this NIST page:
https://www.nist.gov/pml/owm/metric-si/si-units

Grammatically, we assume that `becquerel`, `lux`, and `tesla` have the
same plural form as the singular.

We avoid dealing with Sievert for now because I'm worried it would be
too error-prone.  A key goal is to avoid mixing it up with Gray.  A
quantity kind solution, such as the one which mp-units has, would be
ideal here.  Alternatively, we could experiment with defining a brand
new dimension for "absorbed dose equivalent", the same way that the SI
does for luminant quantities.  But in any case I think we should defer
this until we have actual use cases, and even then tread cautiously.

By contrast, I'm not especially worried about mixing up Becquerel,
Hertz, and inverse Seconds; I don't think it's likely to cause problems
in practice.

au/units/becquerel.hh

@@ -0,0 +1,35 @@
+// Copyright 2023 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "au/quantity.hh"
+#include "au/units/seconds.hh"
+
+namespace au {
+
+// DO NOT follow this pattern to define your own units.  This is for library-defined units.
+// Instead, follow instructions at (https://aurora-opensource.github.io/au/howto/new-units).
+template <typename T>
+struct BecquerelLabel {
+    static constexpr const char label[] = "Bq";
+};
+template <typename T>
+constexpr const char BecquerelLabel<T>::label[];
+struct Becquerel : UnitInverseT<Seconds>, BecquerelLabel<void> {
+    using BecquerelLabel<void>::label;
+};
+constexpr auto becquerel = QuantityMaker<Becquerel>{};
+
+}  // namespace au

au/units/farads.hh

@@ -0,0 +1,37 @@
+// Copyright 2023 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "au/quantity.hh"
+#include "au/units/coulombs.hh"
+#include "au/units/volts.hh"
+
+namespace au {
+
+// DO NOT follow this pattern to define your own units.  This is for library-defined units.
+// Instead, follow instructions at (https://aurora-opensource.github.io/au/howto/new-units).
+template <typename T>
+struct FaradsLabel {
+    static constexpr const char label[] = "F";
+};
+template <typename T>
+constexpr const char FaradsLabel<T>::label[];
+struct Farads : decltype(Coulombs{} / Volts{}), FaradsLabel<void> {
+    using FaradsLabel<void>::label;
+};
+constexpr auto farad = SingularNameFor<Farads>{};
+constexpr auto farads = QuantityMaker<Farads>{};
+
+}  // namespace au

au/units/grays.hh

@@ -0,0 +1,38 @@
+// Copyright 2023 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "au/prefix.hh"
+#include "au/quantity.hh"
+#include "au/units/grams.hh"
+#include "au/units/joules.hh"
+
+namespace au {
+
+// DO NOT follow this pattern to define your own units.  This is for library-defined units.
+// Instead, follow instructions at (https://aurora-opensource.github.io/au/howto/new-units).
+template <typename T>
+struct GraysLabel {
+    static constexpr const char label[] = "Gy";
+};
+template <typename T>
+constexpr const char GraysLabel<T>::label[];
+struct Grays : decltype(Joules{} / Kilo<Grams>{}), GraysLabel<void> {
+    using GraysLabel<void>::label;
+};
+constexpr auto gray = SingularNameFor<Grays>{};
+constexpr auto grays = QuantityMaker<Grays>{};
+
+}  // namespace au

au/units/henries.hh

@@ -0,0 +1,37 @@
+// Copyright 2023 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "au/quantity.hh"
+#include "au/units/amperes.hh"
+#include "au/units/webers.hh"
+
+namespace au {
+
+// DO NOT follow this pattern to define your own units.  This is for library-defined units.
+// Instead, follow instructions at (https://aurora-opensource.github.io/au/howto/new-units).
+template <typename T>
+struct HenriesLabel {
+    static constexpr const char label[] = "H";
+};
+template <typename T>
+constexpr const char HenriesLabel<T>::label[];
+struct Henries : decltype(Webers{} / Amperes{}), HenriesLabel<void> {
+    using HenriesLabel<void>::label;
+};
+constexpr auto henry = SingularNameFor<Henries>{};
+constexpr auto henries = QuantityMaker<Henries>{};
+
+}  // namespace au

au/units/lux.hh

@@ -0,0 +1,36 @@
+// Copyright 2023 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "au/quantity.hh"
+#include "au/units/lumens.hh"
+#include "au/units/meters.hh"
+
+namespace au {
+
+// DO NOT follow this pattern to define your own units.  This is for library-defined units.
+// Instead, follow instructions at (https://aurora-opensource.github.io/au/howto/new-units).
+template <typename T>
+struct LuxLabel {
+    static constexpr const char label[] = "lx";
+};
+template <typename T>
+constexpr const char LuxLabel<T>::label[];
+struct Lux : decltype(Lumens{} / squared(Meters{})), LuxLabel<void> {
+    using LuxLabel<void>::label;
+};
+constexpr auto lux = QuantityMaker<Lux>{};
+
+}  // namespace au

au/units/siemens.hh

@@ -0,0 +1,36 @@
+// Copyright 2023 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "au/quantity.hh"
+#include "au/units/ohms.hh"
+
+namespace au {
+
+// DO NOT follow this pattern to define your own units.  This is for library-defined units.
+// Instead, follow instructions at (https://aurora-opensource.github.io/au/howto/new-units).
+template <typename T>
+struct SiemensLabel {
+    static constexpr const char label[] = "S";
+};
+template <typename T>
+constexpr const char SiemensLabel<T>::label[];
+struct Siemens : UnitInverseT<Ohms>, SiemensLabel<void> {
+    using SiemensLabel<void>::label;
+};
+constexpr auto siemen = SingularNameFor<Siemens>{};
+constexpr auto siemens = QuantityMaker<Siemens>{};
+
+}  // namespace au

au/units/tesla.hh

@@ -0,0 +1,36 @@
+// Copyright 2022 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "au/quantity.hh"
+#include "au/units/meters.hh"
+#include "au/units/webers.hh"
+
+namespace au {
+
+// DO NOT follow this pattern to define your own units.  This is for library-defined units.
+// Instead, follow instructions at (https://aurora-opensource.github.io/au/howto/new-units).
+template <typename T>
+struct TeslaLabel {
+    static constexpr const char label[] = "T";
+};
+template <typename T>
+constexpr const char TeslaLabel<T>::label[];
+struct Tesla : decltype(Webers{} / squared(Meters{})), TeslaLabel<void> {
+    using TeslaLabel<void>::label;
+};
+constexpr auto tesla = QuantityMaker<Tesla>{};
+
+}  // namespace au

au/units/test/becquerel_test.cc

@@ -0,0 +1,29 @@
+// Copyright 2023 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "au/units/becquerel.hh"
+
+#include "au/testing.hh"
+#include "au/units/seconds.hh"
+#include "gtest/gtest.h"
+
+namespace au {
+
+TEST(Becquerel, HasExpectedLabel) { expect_label<Becquerel>("Bq"); }
+
+TEST(Becquerel, EquivalentToInverseSeconds) {
+    EXPECT_THAT(becquerel(4.0), QuantityEquivalent(inverse(seconds)(4.0)));
+}
+
+}  // namespace au

au/units/test/farads_test.cc

@@ -0,0 +1,30 @@
+// Copyright 2023 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "au/units/farads.hh"
+
+#include "au/testing.hh"
+#include "au/units/coulombs.hh"
+#include "au/units/volts.hh"
+#include "gtest/gtest.h"
+
+namespace au {
+
+TEST(Farads, HasExpectedLabel) { expect_label<Farads>("F"); }
+
+TEST(Farads, EquivalentToCoulombsPerVolt) {
+    EXPECT_THAT(farads(4.0), QuantityEquivalent(coulombs(8.0) / volts(2.0)));
+}
+
+}  // namespace au

au/units/test/grays_test.cc

@@ -0,0 +1,30 @@
+// Copyright 2023 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "au/units/grays.hh"
+
+#include "au/testing.hh"
+#include "au/units/grams.hh"
+#include "au/units/joules.hh"
+#include "gtest/gtest.h"
+
+namespace au {
+
+TEST(Grays, HasExpectedLabel) { expect_label<Grays>("Gy"); }
+
+TEST(Grays, EquivalentToJoulesPerKilogram) {
+    EXPECT_THAT(grays(4.0), QuantityEquivalent(joules(8.0) / kilo(grams)(2.0)));
+}
+
+}  // namespace au

au/units/test/henries_test.cc

@@ -0,0 +1,30 @@
+// Copyright 2023 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "au/units/henries.hh"
+
+#include "au/testing.hh"
+#include "au/units/amperes.hh"
+#include "au/units/webers.hh"
+#include "gtest/gtest.h"
+
+namespace au {
+
+TEST(Henries, HasExpectedLabel) { expect_label<Henries>("H"); }
+
+TEST(Henries, EquivalentToWebersPerAmpere) {
+    EXPECT_THAT(henries(4.0), QuantityEquivalent(webers(8.0) / amperes(2.0)));
+}
+
+}  // namespace au