mirror of
https://github.com/aantron/better-enums.git
synced 2025-12-06 16:56:42 +08:00
14bc834f7d
The interface is now uniformly constexpr, including to_string and the _names iterable. Without the weak symbol, the remaining code is also entirely standard C++. The compile-time string trimming code in this commit has a negative impact on performance. The performance test is now twice as slow as including <iostream>, whereas before it was faster. That test declares an excessive number of enums, though, so perhaps in typical usage, and with some future optimizations, the impact will not be so significant. There may be other ways to solve this, such as providing a version of the macro that does not trim strings at compile time, but only checks if they need trimming. If some string does need trimming, that macro would fail a static_assert and ask the user to use the slow macro.
97 lines
2.8 KiB
C++
97 lines
2.8 KiB
C++
// Usage in constexpr expressions. All members of an ENUM are constexpr when
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// given constant arguments. Iterators can be advanced at compile time by adding
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// 1 (note - this means using "+ 1", not "++". The "++" operator is not
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// constexpr).
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#include <iostream>
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#include <enum.h>
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ENUM(Channel, int, Red, Green = 2, Blue);
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// Initialization.
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constexpr Channel channel_1 = Channel::Green;
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constexpr Channel channel_4 = Channel::_from_integral(2);
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constexpr Channel channel_2 = Channel::_from_string("Blue");
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constexpr Channel channel_3 = Channel::_from_string_nocase("gReEn");
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// Conversions to integers and strings.
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constexpr int channel_1_representation = channel_1.to_integral();
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constexpr const char *channel_1_name = channel_1.to_string();
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// Validity checks (including against strings).
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constexpr bool should_be_valid_1 = Channel::_is_valid(2);
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constexpr bool should_be_invalid_1 = Channel::_is_valid(42);
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constexpr bool should_be_valid_2 = Channel::_is_valid("Red");
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constexpr bool should_be_invalid_2 = Channel::_is_valid("red");
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constexpr bool should_be_valid_3 = Channel::_is_valid_nocase("red");
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constexpr bool should_be_invalid_3 = Channel::_is_valid_nocase("reed");
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// _names and _values collections and iterators.
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constexpr Channel channel_5 = *(Channel::_values.begin() + 1);
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constexpr const char *name_through_iterator = *(Channel::_names.begin() + 1);
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// Range properties.
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constexpr Channel channel_6 = Channel::_max;
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constexpr size_t span = Channel::_span;
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// Type name.
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constexpr auto name = Channel::_name;
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// Explicit promotion.
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constexpr int converted = (+Channel::Green).to_integral();
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// The above, printed for verification.
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void print_channel(int number, Channel channel)
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{
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std::cout
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<< "channel_"
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<< number
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<< " is "
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<< channel.to_string()
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<< std::endl;
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}
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#define PRINT(n) print_channel(n, channel_ ## n)
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void print_validity(bool expected, bool actual)
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{
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std::cout
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<< "should be "
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<< expected
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<< ": "
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<< actual
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<< std::endl;
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}
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int main()
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{
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PRINT(1);
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PRINT(2);
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PRINT(3);
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PRINT(4);
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print_validity(true, should_be_valid_1);
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print_validity(false, should_be_invalid_1);
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print_validity(true, should_be_valid_2);
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print_validity(false, should_be_invalid_2);
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print_validity(true, should_be_valid_3);
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print_validity(false, should_be_invalid_3);
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PRINT(5);
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PRINT(6);
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std::cout << "constexpr trimmed name: " << channel_1_name << std::endl;
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std::cout << "constexpr name through iterator: "
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<< name_through_iterator << std::endl;
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std::cout << "span: " << span << std::endl;
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std::cout << "type name: " << name << std::endl;
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return 0;
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}
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