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Convert CommonPointUnit to EQUIV-style labels #339

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merged 2 commits into from
Dec 2, 2024
Merged

Convert CommonPointUnit to EQUIV-style labels #339

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c457827
Convert `CommonPointUnit` to EQUIV-style labels
chiphogg Nov 28, 2024
22d1f42
Merge branch 'main' into chiphogg/equiv-for-common-pt#105
chiphogg Dec 2, 2024
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23 changes: 22 additions & 1 deletion au/code/au/quantity_point_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -21,8 +21,17 @@

using ::testing::Not;
using ::testing::StaticAssertTypeEq;
using ::testing::StrEq;

namespace au {
namespace {
template <typename T>
std::string stream_to_string(const T &t) {
std::ostringstream oss;
oss << t;
return oss.str();
}
} // namespace

struct Meters : UnitImpl<Length> {};
constexpr QuantityMaker<Meters> meters{};
Expand All @@ -34,7 +43,10 @@ constexpr auto inches_pt = QuantityPointMaker<Inches>{};
struct Feet : decltype(Inches{} * mag<12>()) {};
constexpr auto feet_pt = QuantityPointMaker<Feet>{};

struct Kelvins : UnitImpl<Temperature> {};
struct Kelvins : UnitImpl<Temperature> {
static constexpr const char label[] = "K";
};
constexpr const char Kelvins::label[];
constexpr QuantityMaker<Kelvins> kelvins{};
constexpr QuantityPointMaker<Kelvins> kelvins_pt{};

Expand All @@ -44,7 +56,10 @@ struct Celsius : Kelvins {
// little as possible (while still keeping the value an integer), because that will make the
// conversion factor as small as possible in converting to the common-point-unit.
static constexpr auto origin() { return (kelvins / mag<20>())(273'15 / 5); }

static constexpr const char label[] = "degC";
};
constexpr const char Celsius::label[];
constexpr QuantityMaker<Celsius> celsius_qty{};
constexpr QuantityPointMaker<Celsius> celsius_pt{};

Expand Down Expand Up @@ -345,6 +360,12 @@ TEST(QuantityPoint, MixedUnitAndRepDifferenceUsesCommonPointType) {
EXPECT_THAT(rep_wins - unit_wins, QuantityEquivalent(meters(100.0)));
}

TEST(QuantityPoint, CommonPointUnitLabel) {
EXPECT_THAT(stream_to_string(celsius_pt(0) - kelvins_pt(0)),
AnyOf(StrEq("5463 EQUIV{[(1 / 20) K], [(1 / 20) degC]}"),
StrEq("5463 EQUIV{[(1 / 20) degC], [(1 / 20) K]}")));
}

TEST(QuantityPoint, CanCompareUnitsWithDifferentOrigins) {
EXPECT_THAT(celsius_pt(0), ConsistentlyGreaterThan(kelvins_pt(273)));
EXPECT_THAT(celsius_pt(0), ConsistentlyEqualTo(milli(kelvins_pt)(273'150)));
Expand Down
14 changes: 5 additions & 9 deletions au/code/au/unit_of_measure.hh
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Expand Up @@ -912,16 +912,12 @@ struct UnitLabel<CommonUnit<Us...>>
: CommonUnitLabel<decltype(Us{} *
(detail::MagT<CommonUnit<Us...>>{} / detail::MagT<Us>{}))...> {};

// Implementation for CommonPointUnit: unite constituent labels.
// Implementation for CommonPointUnit: give size in terms of each constituent unit, taking any
// origin displacements into account.
template <typename... Us>
struct UnitLabel<CommonPointUnit<Us...>> {
using LabelT = detail::ExtendedLabel<8 + 2 * (sizeof...(Us) - 1), Us...>;
static constexpr LabelT value =
detail::concatenate("COM_PT[", detail::join_by(", ", unit_label(Us{})...), "]");
};
template <typename... Us>
constexpr
typename UnitLabel<CommonPointUnit<Us...>>::LabelT UnitLabel<CommonPointUnit<Us...>>::value;
struct UnitLabel<CommonPointUnit<Us...>>
: CommonUnitLabel<decltype(
Us{} * (detail::MagT<CommonPointUnit<Us...>>{} / detail::MagT<Us>{}))...> {};

template <typename Unit>
constexpr const auto &unit_label(Unit) {
Expand Down
30 changes: 28 additions & 2 deletions au/code/au/unit_of_measure_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,9 @@ constexpr auto common_unit(Us...) {

struct Celsius : Kelvins {
static constexpr auto origin() { return milli(kelvins)(273'150); }
static constexpr const char label[] = "deg_C";
};
constexpr const char Celsius::label[];
constexpr auto celsius = QuantityMaker<Celsius>{};

struct AlternateCelsius : Kelvins {
Expand Down Expand Up @@ -437,7 +439,9 @@ TEST(OriginDisplacement, FunctionalInterfaceHandlesInstancesCorrectly) {

struct OffsetCelsius : Celsius {
static constexpr auto origin() { return detail::OriginOf<Celsius>::value() + kelvins(10); }
static constexpr const char label[] = "offset_deg_C";
};
constexpr const char OffsetCelsius::label[];

TEST(DisplaceOrigin, DisplacesOrigin) {
EXPECT_EQ(origin_displacement(Celsius{}, OffsetCelsius{}), kelvins(10));
Expand All @@ -462,6 +466,11 @@ TEST(CommonUnit, PrefersUnitFromListIfAnyIdentical) {
StaticAssertTypeEq<CommonUnitT<Feet, Inches, Yards>, Inches>();
}

TEST(CommonUnit, DedupesUnitsMadeIdenticalAfterUnscalingSameScaledUnit) {
StaticAssertTypeEq<CommonUnitT<decltype(Feet{} * mag<3>()), decltype(Feet{} * mag<5>())>,
Feet>();
}

TEST(CommonUnit, DownranksAnonymousScaledUnits) {
StaticAssertTypeEq<CommonUnitT<Yards, decltype(Feet{} * mag<3>())>, Yards>();
}
Expand Down Expand Up @@ -648,13 +657,30 @@ TEST(UnitLabel, ReducesToSingleUnitLabelIfAllUnitsAreTheSame) {

TEST(UnitLabel, LabelsCommonPointUnitCorrectly) {
using U = CommonPointUnitT<Inches, Meters>;
EXPECT_THAT(unit_label(U{}), AnyOf(StrEq("COM_PT[in, m]"), StrEq("COM_PT[m, in]")));
EXPECT_THAT(unit_label(U{}),
AnyOf(StrEq("EQUIV{[(1 / 127) in], [(1 / 5000) m]}"),
StrEq("EQUIV{[(1 / 5000) m], [(1 / 127) in]}")));
}

TEST(UnitLabel, CommonPointUnitLabelWorksWithUnitProduct) {
using U = CommonPointUnitT<UnitQuotientT<Meters, Minutes>, UnitQuotientT<Inches, Minutes>>;
EXPECT_THAT(unit_label(U{}),
AnyOf(StrEq("COM_PT[m / min, in / min]"), StrEq("COM_PT[in / min, m / min]")));
AnyOf(StrEq("EQUIV{[(1 / 127) in / min], [(1 / 5000) m / min]}"),
StrEq("EQUIV{[(1 / 5000) m / min], [(1 / 127) in / min]}")));
}

TEST(UnitLabel, CommonPointUnitLabelTakesOriginOffsetIntoAccount) {
// NOTE: the (1 / 1000) scaling comes about because we're still using `Quantity` to define our
// origins. We may be able to do better, and re-found them on `Constant`, at least once we add
// some kind of subtraction that works at least some of the time. The ideal end point would be
// that the common point unit for `Celsius` and `OffsetCelsius` would be simply `Celsius`
// (because `OffsetCelsius` is just `Celsius` with a _higher_ origin). At that point, we'll
// need to construct a more complicated example here that will force us to use
// `CommonPointUnit<...>`, because it will be meaningfully different from all of its parameters.
using U = CommonPointUnitT<Celsius, OffsetCelsius>;
EXPECT_THAT(unit_label(U{}),
AnyOf(StrEq("EQUIV{[(1 / 1000) deg_C], [(1 / 1000) offset_deg_C]}"),
StrEq("EQUIV{[(1 / 1000) offset_deg_C], [(1 / 1000) deg_C]}")));
}

TEST(UnitLabel, APICompatibleWithUnitSlots) { EXPECT_THAT(unit_label(feet), StrEq("ft")); }
Expand Down
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