/** @file basis_unit.hpp **/ #pragma once #include "dimension.hpp" #include "basis_unit_abbrev.hpp" #include "xo/ratio/ratio.hpp" namespace xo { namespace qty { /** @class basis_unit2 * @brief A dimensionless multiple of a single natively-specified basis dimension * * For example "3600 minutes" or "1e-6 grams" **/ struct basis_unit { public: constexpr basis_unit() = default; constexpr basis_unit(dim native_dim, const scalefactor_ratio_type & scalefactor) : native_dim_{native_dim}, scalefactor_{scalefactor} {} constexpr dim native_dim() const { return native_dim_; } constexpr const scalefactor_ratio_type & scalefactor() const { return scalefactor_; } constexpr basis_unit2_abbrev_type abbrev() const { return abbrev::basis_unit2_abbrev(native_dim_, scalefactor_); } constexpr basis_unit & operator=(const basis_unit & x) = default; public: /* need public members so that a basis_unit instance can be a non-type template parameter (a structural type) */ /** @brief identifies a native unit, e.g. time (in seconds) **/ dim native_dim_ = dim::invalid; /** @brief this unit defined as multiple scalefactor times native unit **/ scalefactor_ratio_type scalefactor_; }; inline constexpr bool operator==(const basis_unit & x, const basis_unit & y) { return ((x.native_dim_ == y.native_dim_) && (x.scalefactor_ == y.scalefactor_)); } inline constexpr bool operator!=(const basis_unit & x, const basis_unit & y) { return ((x.native_dim_ != y.native_dim_) || (x.scalefactor_ != y.scalefactor_)); } namespace bu { // ----- mass ----- constexpr basis_unit picogram = basis_unit(dim::mass, scalefactor_ratio_type( 1, 1000000000000)); constexpr basis_unit nanogram = basis_unit(dim::mass, scalefactor_ratio_type( 1, 1000000000)); constexpr basis_unit microgram = basis_unit(dim::mass, scalefactor_ratio_type( 1, 1000000)); constexpr basis_unit milligram = basis_unit(dim::mass, scalefactor_ratio_type( 1, 1000)); constexpr basis_unit gram = basis_unit(dim::mass, scalefactor_ratio_type( 1, 1)); constexpr basis_unit kilogram = basis_unit(dim::mass, scalefactor_ratio_type( 1000, 1)); constexpr basis_unit tonne = basis_unit(dim::mass, scalefactor_ratio_type( 1000000, 1)); constexpr basis_unit kilotonne = basis_unit(dim::mass, scalefactor_ratio_type( 1000000000, 1)); constexpr basis_unit megatonne = basis_unit(dim::mass, scalefactor_ratio_type(1000000000000, 1)); constexpr basis_unit gigatonne = basis_unit(dim::mass, scalefactor_ratio_type(1000000000000000, 1)); // ----- distance ----- /* International spelling */ constexpr basis_unit picometre = basis_unit(dim::distance, scalefactor_ratio_type( 1, 1000000000000)); constexpr basis_unit nanometre = basis_unit(dim::distance, scalefactor_ratio_type( 1, 1000000000)); constexpr basis_unit micrometre = basis_unit(dim::distance, scalefactor_ratio_type( 1, 1000000)); constexpr basis_unit millimetre = basis_unit(dim::distance, scalefactor_ratio_type( 1, 1000)); constexpr basis_unit metre = basis_unit(dim::distance, scalefactor_ratio_type( 1, 1)); constexpr basis_unit kilometre = basis_unit(dim::distance, scalefactor_ratio_type( 1000, 1)); constexpr basis_unit megametre = basis_unit(dim::distance, scalefactor_ratio_type( 1000000, 1)); constexpr basis_unit gigametre = basis_unit(dim::distance, scalefactor_ratio_type( 1000000000, 1)); constexpr basis_unit lightsecond = basis_unit(dim::distance, scalefactor_ratio_type( 299792458, 1)); constexpr basis_unit astronomicalunit = basis_unit(dim::distance, scalefactor_ratio_type( 149597870700, 1)); /* US spelling */ constexpr basis_unit picometer = picometre; constexpr basis_unit nanometer = nanometre; constexpr basis_unit micrometer = micrometre; constexpr basis_unit millimeter = millimetre; constexpr basis_unit meter = metre; constexpr basis_unit kilometer = kilometre; constexpr basis_unit megameter = megametre; constexpr basis_unit gigameter = gigametre; // ----- time ----- constexpr basis_unit picosecond = basis_unit(dim::time, scalefactor_ratio_type( 1, 1000000000000)); constexpr basis_unit nanosecond = basis_unit(dim::time, scalefactor_ratio_type( 1, 1000000000)); constexpr basis_unit microsecond = basis_unit(dim::time, scalefactor_ratio_type( 1, 1000000)); constexpr basis_unit millisecond = basis_unit(dim::time, scalefactor_ratio_type( 1, 1000)); constexpr basis_unit second = basis_unit(dim::time, scalefactor_ratio_type( 1, 1)); constexpr basis_unit minute = basis_unit(dim::time, scalefactor_ratio_type( 60, 1)); constexpr basis_unit hour = basis_unit(dim::time, scalefactor_ratio_type( 3600, 1)); constexpr basis_unit day = basis_unit(dim::time, scalefactor_ratio_type( 24*3600, 1)); constexpr basis_unit week = basis_unit(dim::time, scalefactor_ratio_type( 7*24*3600, 1)); constexpr basis_unit month = basis_unit(dim::time, scalefactor_ratio_type( 30*24*3600, 1)); constexpr basis_unit year = basis_unit(dim::time, scalefactor_ratio_type((365*24+6)*3600, 1)); /* alt conventions used in finance */ constexpr basis_unit year365 = basis_unit(dim::time, scalefactor_ratio_type( 365*24*3600, 1)); constexpr basis_unit year360 = basis_unit(dim::time, scalefactor_ratio_type( 360*24*3600, 1)); /* 250 = approx number of trading days in a calendar year */ constexpr basis_unit year250 = basis_unit(dim::time, scalefactor_ratio_type( 250*24*3600, 1)); // ----- currency ----- /* pseudounit -- placeholder for any actual currency amount */ constexpr basis_unit currency = basis_unit(dim::currency, scalefactor_ratio_type( 1, 1)); // ----- price ----- /* psuedounit -- context-dependent interpretation */ constexpr basis_unit price = basis_unit(dim::price, scalefactor_ratio_type( 1, 1)); } namespace units { /** for runtime work, would like to be able to promptly find special abbreviation * keyed by (native_dim, scalefactor). * * Also want to support compile-time-only unit computation. * Since constexpr unordered containers aren't obviously feasible (as of c++23). * * Solution adopted here is to support introduction of scaled native units * only at compile time, at least for now **/ // ----- scaled_native_unit_abbrev_helper ----- /* Require: InnerScale is ratio type; InnerScale >= 1 * * NOTE: clang 18 doesn't accept that scalefactor_ratio_type is a 'structural type' */ template struct scaled_native_unit2_abbrev; template struct scaled_native_unit2_abbrev { static constexpr const basis_unit2_abbrev_type value = (basis_unit2_abbrev_type::from_flatstring (native_unit2_v[static_cast(BasisDim)] .abbrev_str())); }; inline constexpr basis_unit2_abbrev_type bu_fallback_abbrev(dim basis_dim, const scalefactor_ratio_type & scalefactor) { return (basis_unit2_abbrev_type::from_flatstring (flatstring_concat (scalefactor.to_str(), native_unit2_v[static_cast(basis_dim)].abbrev_str()))); } } } /*namespace qty*/ } /*namespace xo*/ /** end basis_unit.hpp **/