137 lines
5 KiB
C++
137 lines
5 KiB
C++
/** @file bpu.hpp
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*
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* Author: Roland Conybeare
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**/
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#pragma once
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#include "basis_unit.hpp"
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#include "bu_store.hpp"
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namespace xo {
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namespace qty {
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namespace abbrev {
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using power_abbrev_type = flatstring<16>;
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constexpr power_abbrev_type
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flatstring_from_exponent(std::int64_t num,
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std::int64_t den)
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{
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if (den == 1) {
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if (num == 1) {
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return power_abbrev_type::from_chars("");
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} else {
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return (power_abbrev_type::from_flatstring
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(flatstring_concat(flatstring("^"),
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power_abbrev_type::from_int(num))));
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}
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} else {
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return (power_abbrev_type::from_flatstring
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(flatstring_concat(flatstring("^"),
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xo::ratio::make_ratio(num, den)
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.to_str<power_abbrev_type::fixed_capacity>())));
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}
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}
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static constexpr bpu_abbrev_type
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bpu_abbrev(dim native_dim,
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const scalefactor_ratio_type & scalefactor,
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const power_ratio_type & power)
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{
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return (bpu_abbrev_type::from_flatstring
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(flatstring_concat
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(bu_abbrev(basis_unit(native_dim, scalefactor)),
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flatstring_from_exponent(power.num(), power.den()))));
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}
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}
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/** @class bpu
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*
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* @brief represent product of a compile-time scale-factor with a rational power of a native unit
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**/
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template<typename Int>
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struct bpu {
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public:
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using ratio_int_type = Int;
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public:
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constexpr bpu() = default;
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constexpr bpu(const basis_unit & bu,
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const power_ratio_type & power)
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: bu_{bu},
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power_{power}
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{}
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constexpr bpu(dim native_dim,
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const scalefactor_ratio_type & scalefactor,
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const power_ratio_type & power)
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: bu_(native_dim, scalefactor),
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power_{power}
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{}
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static constexpr bpu<Int> unit_power(const basis_unit & bu) {
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return bpu<Int>(bu, power_ratio_type(1,1));
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}
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constexpr dimension native_dim() const { return bu_.native_dim(); }
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constexpr const scalefactor_ratio_type & scalefactor() const { return bu_.scalefactor(); }
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constexpr const power_ratio_type & power() const { return power_; }
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/** @brief abbreviation for this dimension
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*
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* @code
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* bpu2<int64_t>(dim::time,
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* scalefactor_ratio_type(60,1),
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* power_ratio_type(-2,1)).abbrev() => "min^-2"
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* @endcode
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**/
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constexpr bpu_abbrev_type abbrev() const
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{
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return abbrev::bpu_abbrev(bu_.native_dim_,
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bu_.scalefactor_,
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power_);
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}
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/* for bpu x, x.reciprocal() represents dimension of 1/x */
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constexpr bpu<Int> reciprocal() const {
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return bpu<Int>(bu_.native_dim(), bu_.scalefactor(), power_.negate());
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}
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template <typename Int2>
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constexpr bpu<Int2> to_repr() const {
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return bpu<Int2>(this->native_dim(),
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this->scalefactor(),
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ratio::ratio<Int2>(power_.num(), power_.den()));
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}
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public: /* need public members so that a basis_unit instance can be a non-type template parameter (a structural type) */
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/** @brief this bpu represent a power of this basis unit **/
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basis_unit bu_;
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/** @brief this unit represents basis dimension (bu) taken to this power **/
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power_ratio_type power_;
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};
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template <typename Int>
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constexpr auto make_unit_power(const basis_unit & bu) {
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return bpu<Int>::unit_power(bu);
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}
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template <typename Int>
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inline constexpr bool
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operator==(const bpu<Int> & x, const bpu<Int> & y) {
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return ((x.native_dim() == y.native_dim())
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&& (x.scalefactor() == y.scalefactor())
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&& (x.power_ == y.power_));
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}
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template <typename Int>
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inline constexpr bool
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operator!=(const bpu<Int> & x, const bpu<Int> & y) {
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return ((x.native_dim() != y.native_dim())
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|| (x.scalefactor() != y.scalefactor())
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|| (x.power_ != y.power_));
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}
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} /*namespace qty*/
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} /*namespace xo*/
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/** end bpu.hpp **/
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