mirror of
https://github.com/mpusz/mp-units.git
synced 2025-07-29 18:07:16 +02:00
refactor: 💥 from now unit_symbol and dimension_symbol always returns std::string_view
This commit is contained in:
Mateusz Pusz
12
conanfile.py
12
conanfile.py
@ -58,7 +58,6 @@ class MPUnitsConan(ConanFile):
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"cxx_modules": [True, False],
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"import_std": [True, False],
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"std_format": [True, False],
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"string_view_ret": [True, False],
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"no_crtp": [True, False],
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"contracts": ["none", "gsl-lite", "ms-gsl"],
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"freestanding": [True, False],
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@ -67,7 +66,6 @@ class MPUnitsConan(ConanFile):
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# "cxx_modules" default set in config_options()
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# "import_std" default set in config_options()
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# "std_format" default set in config_options()
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# "string_view_ret" default set in config_options()
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# "no_crtp" default set in config_options()
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"contracts": "gsl-lite",
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"freestanding": False,
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@ -113,10 +111,6 @@ class MPUnitsConan(ConanFile):
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"min_cppstd": "23",
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"compiler": {"gcc": "", "clang": "18", "apple-clang": "", "msvc": ""},
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},
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"static_constexpr_vars_in_constexpr_func": {
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"min_cppstd": "23",
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"compiler": {"gcc": "13", "clang": "17", "apple-clang": "", "msvc": ""},
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},
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"explicit_this": {
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"min_cppstd": "23",
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"compiler": {
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@ -134,7 +128,6 @@ class MPUnitsConan(ConanFile):
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"std_format": "std_format",
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"cxx_modules": "cxx_modules",
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"import_std": "import_std",
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"string_view_ret": "static_constexpr_vars_in_constexpr_func",
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"no_crtp": "explicit_this",
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}
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@ -280,7 +273,6 @@ class MPUnitsConan(ConanFile):
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tc.cache_variables["MP_UNITS_API_FREESTANDING"] = True
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else:
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tc.cache_variables["MP_UNITS_API_STD_FORMAT"] = opt.std_format
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tc.cache_variables["MP_UNITS_API_STRING_VIEW_RET"] = opt.string_view_ret
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tc.cache_variables["MP_UNITS_API_NO_CRTP"] = opt.no_crtp
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tc.cache_variables["MP_UNITS_API_CONTRACTS"] = str(opt.contracts).upper()
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@ -340,10 +332,6 @@ class MPUnitsConan(ConanFile):
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)
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# handle API options
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self.cpp_info.components["core"].defines.append(
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"MP_UNITS_API_STRING_VIEW_RET="
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+ str(int(self.options.string_view_ret == True))
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)
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self.cpp_info.components["core"].defines.append(
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"MP_UNITS_API_NO_CRTP=" + str(int(self.options.no_crtp == True))
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)
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@ -19,7 +19,6 @@ C++ feature:
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| **`std::format`** | 20 | 13 | 17 | None | 194 |
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| **C++ modules** | 20 | None | 17 | None | None |
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| **`import std;`** | 23 | None | 18 | None | None |
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| **Static `constexpr` variables in `constexpr` functions** | 23 | 13 | 17 | None | None |
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| **Explicit `this` parameter** | 23 | 14 | 18 | None | None |
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??? note "MSVC bugs"
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@ -87,20 +86,6 @@ C++ feature:
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- CMake: [CMAKE_CXX_MODULE_STD](https://cmake.org/cmake/help/latest/variable/CMAKE_CXX_MODULE_STD.html)
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## Static `constexpr` variables in `constexpr` functions
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- Allows returning `std::string_view` from the
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[`unit_symbol()`](../users_guide/framework_basics/text_output.md#unit_symbol)
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and [`dimension_symbol()`](../users_guide/framework_basics/text_output.md#dimension_symbol)
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functions
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- `std::string_view` type has a reference semantics so it has to point to a storage with
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a longer lifetime.
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- If this feature is not available, the API returns `mp_units::basic_fixed_string<CharT, N>` instead.
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- Tested as `__cpp_constexpr >= 202211L` [feature test macro](https://en.cppreference.com/w/cpp/feature_test).
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- Related build options:
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- Conan: [string_view_ret](installation_and_usage.md#string_view_ret)
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- CMake: [MP_UNITS_API_STRING_VIEW_RET](installation_and_usage.md#MP_UNITS_API_STRING_VIEW_RET)
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## Explicit `this` parameter
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- This feature removes the need for the usage of the CRTP idiom in the
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@ -123,18 +123,6 @@ dependencies by other means, some modifications to the library's CMake files mig
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[conan std::format support]: https://github.com/mpusz/mp-units/releases/tag/v2.2.0
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[`string_view_ret`](#string_view_ret){ #string_view_ret }
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: [:octicons-tag-24: 2.2.0][conan returning string_view] · :octicons-milestone-24: `True`/`False` (Default: automatically determined from settings)
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Enables returning `std::string_view` from the
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[`unit_symbol()`](../users_guide/framework_basics/text_output.md#unit_symbol)
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and [`dimension_symbol()`](../users_guide/framework_basics/text_output.md#dimension_symbol)
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functions. If this feature is not available, those functions will return
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`mp_units::basic_fixed_string<CharT, N>` instead.
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[conan returning string_view]: https://github.com/mpusz/mp-units/releases/tag/v2.2.0
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[`no_crtp`](#no_crtp){ #no_crtp }
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: [:octicons-tag-24: 2.2.0][conan no crtp support] · :octicons-milestone-24: `True`/`False` (Default: automatically determined from settings)
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@ -196,18 +184,6 @@ dependencies by other means, some modifications to the library's CMake files mig
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[cmake std::format support]: https://github.com/mpusz/mp-units/releases/tag/v2.2.0
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[`MP_UNITS_API_STRING_VIEW_RET`](#MP_UNITS_API_STRING_VIEW_RET){ #MP_UNITS_API_STRING_VIEW_RET }
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: [:octicons-tag-24: 2.2.0][cmake returning string_view] · :octicons-milestone-24: `ON`/`OFF` (Default: automatically determined)
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Enables returning `std::string_view` from the
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[`unit_symbol()`](../users_guide/framework_basics/text_output.md#unit_symbol)
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and [`dimension_symbol()`](../users_guide/framework_basics/text_output.md#dimension_symbol)
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functions. If this feature is not available, those functions will return
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`mp_units::basic_fixed_string<CharT, N>` instead.
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[cmake returning string_view]: https://github.com/mpusz/mp-units/releases/tag/v2.2.0
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[`MP_UNITS_API_NO_CRTP`](#MP_UNITS_API_NO_CRTP){ #MP_UNITS_API_NO_CRTP }
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: [:octicons-tag-24: 2.2.0][cmake no crtp support] · :octicons-milestone-24: `ON`/`OFF` (Default: automatically determined)
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@ -62,21 +62,6 @@ inline constexpr auto JPY = japanese_jen;
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static_assert(!std::equality_comparable_with<quantity<euro, int>, quantity<us_dollar, int>>);
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#if 0 || !MP_UNITS_API_STRING_VIEW_RET // NOLINT(readability-avoid-unconditional-preprocessor-if)
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// if you have only a few currencies to handle
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template<Unit auto From, Unit auto To>
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[[nodiscard]] double exchange_rate(std::chrono::sys_seconds timestamp)
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{
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(void)timestamp; // get conversion ratios for this timestamp
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if constexpr (From == us_dollar && To == euro) return 0.9215;
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else if constexpr (From == euro && To == us_dollar) return 1.0848;
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// ...
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}
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#else
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template<Unit auto From, Unit auto To>
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[[nodiscard]] double exchange_rate(std::chrono::sys_seconds timestamp)
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{
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@ -89,8 +74,6 @@ template<Unit auto From, Unit auto To>
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return rates.at(std::make_pair(unit_symbol(From), unit_symbol(To)));
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}
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#endif
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template<UnitOf<currency> auto To, QuantityOf<currency> From>
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QuantityOf<currency> auto exchange_to(From q, std::chrono::sys_seconds timestamp)
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{
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@ -48,7 +48,6 @@ endif()
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# check for C++ features
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check_cxx_feature_supported(__cpp_lib_format ${projectPrefix}LIB_FORMAT_SUPPORTED)
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check_cxx_feature_supported("__cpp_constexpr >= 202211L" ${projectPrefix}STATIC_CONSTEXPR_VARS_IN_CONSTEXPR_FUNCTIONS)
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check_cxx_feature_supported(__cpp_explicit_this_parameter ${projectPrefix}EXPLICIT_THIS_PARAMETER_SUPPORTED)
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# libc++ has a basic supports for std::format but does not set __cpp_lib_format
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@ -73,9 +72,6 @@ endif()
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# project API settings
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option(${projectPrefix}API_STD_FORMAT "Enable `std::format` support" ${${projectPrefix}LIB_FORMAT_SUPPORTED})
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option(${projectPrefix}API_STRING_VIEW_RET "Enable returning `std::string_view` from `constexpr` functions"
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${${projectPrefix}STATIC_CONSTEXPR_VARS_IN_CONSTEXPR_FUNCTIONS}
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)
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option(${projectPrefix}API_NO_CRTP "Enable class definitions without CRTP idiom"
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${${projectPrefix}EXPLICIT_THIS_PARAMETER_SUPPORTED}
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)
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@ -83,7 +79,6 @@ option(${projectPrefix}API_FREESTANDING "Builds only freestanding part of the li
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set(${projectPrefix}API_CONTRACTS GSL-LITE CACHE STRING "Enable contract checking")
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message(STATUS "${projectPrefix}API_STD_FORMAT: ${${projectPrefix}API_STD_FORMAT}")
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message(STATUS "${projectPrefix}API_STRING_VIEW_RET: ${${projectPrefix}API_STRING_VIEW_RET}")
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message(STATUS "${projectPrefix}API_NO_CRTP: ${${projectPrefix}API_NO_CRTP}")
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message(STATUS "${projectPrefix}API_FREESTANDING: ${${projectPrefix}API_FREESTANDING}")
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@ -107,10 +102,6 @@ if(NOT ${projectPrefix}API_FREESTANDING AND ${projectPrefix}API_STD_FORMAT AND N
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message(FATAL_ERROR "`std::format` enabled but not supported")
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endif()
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if(${projectPrefix}API_STRING_VIEW_RET AND NOT ${projectPrefix}STATIC_CONSTEXPR_VARS_IN_CONSTEXPR_FUNCTIONS)
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message(FATAL_ERROR "`std::string_view` returns enabled but not supported")
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endif()
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if(${projectPrefix}API_NO_CRTP AND NOT ${projectPrefix}EXPLICIT_THIS_PARAMETER_SUPPORTED)
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message(FATAL_ERROR "`NO_CRTP` mode enabled but explicit `this` parameter is not supported")
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endif()
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@ -101,7 +101,6 @@ if(NOT ${projectPrefix}API_FREESTANDING)
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endif()
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set_feature_flag(API_STD_FORMAT)
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set_feature_flag(API_STRING_VIEW_RET)
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set_feature_flag(API_NO_CRTP)
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# Text formatting
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@ -146,12 +146,6 @@ MP_UNITS_DIAGNOSTIC_POP
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#endif
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#if !defined MP_UNITS_API_STRING_VIEW_RET && __cpp_constexpr >= 202211L
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#define MP_UNITS_API_STRING_VIEW_RET 1
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#endif
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#if !defined MP_UNITS_API_NO_CRTP && __cpp_explicit_this_parameter
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#define MP_UNITS_API_NO_CRTP 1
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@ -286,14 +286,10 @@ constexpr Out dimension_symbol_to(Out out, D d, const dimension_symbol_formattin
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return detail::dimension_symbol_impl<CharT>(out, d, fmt, false);
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}
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// TODO Refactor to `dimension_symbol(D, fmt)` when P1045: constexpr Function Parameters is available
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MP_UNITS_EXPORT template<dimension_symbol_formatting fmt = dimension_symbol_formatting{}, typename CharT = char,
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Dimension D>
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#if defined MP_UNITS_COMP_CLANG && MP_UNITS_COMP_CLANG <= 18
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[[nodiscard]] constexpr auto dimension_symbol(D)
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#else
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[[nodiscard]] consteval auto dimension_symbol(D)
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#endif
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namespace detail {
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MP_UNITS_EXPORT template<dimension_symbol_formatting fmt, typename CharT, Dimension D>
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[[nodiscard]] consteval auto dimension_symbol_impl(D)
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{
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constexpr auto oversized_symbol_text = []() consteval {
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// std::basic_string<CharT> text; // TODO uncomment when https://wg21.link/P3032 is supported
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@ -301,14 +297,22 @@ MP_UNITS_EXPORT template<dimension_symbol_formatting fmt = dimension_symbol_form
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dimension_symbol_to<CharT>(std::back_inserter(text), D{}, fmt);
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return text;
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}();
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#if MP_UNITS_API_STRING_VIEW_RET // Permitting static constexpr variables in constexpr functions
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static constexpr basic_fixed_string<CharT, oversized_symbol_text.size()> storage(std::from_range,
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oversized_symbol_text);
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return storage.view();
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#else
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return basic_fixed_string<CharT, oversized_symbol_text.size()>(std::from_range, oversized_symbol_text);
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#endif
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}
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template<dimension_symbol_formatting fmt, typename CharT, Dimension D>
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struct dimension_symbol_result {
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static constexpr auto value = dimension_symbol_impl<fmt, CharT>(D{});
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};
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} // namespace detail
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// TODO Refactor to `dimension_symbol(D, fmt)` when P1045: constexpr Function Parameters is available
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MP_UNITS_EXPORT template<dimension_symbol_formatting fmt = dimension_symbol_formatting{}, typename CharT = char,
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Dimension D>
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[[nodiscard]] consteval std::string_view dimension_symbol(D)
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{
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return detail::dimension_symbol_result<fmt, CharT, D>::value.view();
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}
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} // namespace mp_units
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@ -889,13 +889,10 @@ constexpr Out unit_symbol_to(Out out, U u, const unit_symbol_formatting& fmt = u
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return detail::unit_symbol_impl<CharT>(out, u, fmt, false);
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}
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// TODO Refactor to `unit_symbol(U, fmt)` when P1045: constexpr Function Parameters is available
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MP_UNITS_EXPORT template<unit_symbol_formatting fmt = unit_symbol_formatting{}, typename CharT = char, Unit U>
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#if defined MP_UNITS_COMP_CLANG && MP_UNITS_COMP_CLANG <= 18
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[[nodiscard]] constexpr auto unit_symbol(U)
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#else
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[[nodiscard]] consteval auto unit_symbol(U)
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#endif
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namespace detail {
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MP_UNITS_EXPORT template<unit_symbol_formatting fmt, typename CharT, Unit U>
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[[nodiscard]] consteval auto unit_symbol_impl(U)
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{
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constexpr auto oversized_symbol_text = []() consteval {
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// std::basic_string<CharT> text; // TODO uncomment when https://wg21.link/P3032 is supported
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@ -903,14 +900,21 @@ MP_UNITS_EXPORT template<unit_symbol_formatting fmt = unit_symbol_formatting{},
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unit_symbol_to<CharT>(std::back_inserter(text), U{}, fmt);
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return text;
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}();
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#if MP_UNITS_API_STRING_VIEW_RET // Permitting static constexpr variables in constexpr functions
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static constexpr basic_fixed_string<CharT, oversized_symbol_text.size()> storage(std::from_range,
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oversized_symbol_text);
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return storage.view();
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#else
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return basic_fixed_string<CharT, oversized_symbol_text.size()>(std::from_range, oversized_symbol_text);
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#endif
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}
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template<unit_symbol_formatting fmt, typename CharT, Unit U>
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struct unit_symbol_result {
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static constexpr auto value = unit_symbol_impl<fmt, CharT>(U{});
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};
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} // namespace detail
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// TODO Refactor to `unit_symbol(U, fmt)` when P1045: constexpr Function Parameters is available
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MP_UNITS_EXPORT template<unit_symbol_formatting fmt = unit_symbol_formatting{}, typename CharT = char, Unit U>
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[[nodiscard]] consteval std::string_view unit_symbol(U)
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{
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return detail::unit_symbol_result<fmt, CharT, U>::value.view();
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}
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} // namespace mp_units
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