Enforce user literals parsing #50
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UDLs will never receive the negative sign? Unary minus is an operator, not part of a literal. https://godbolt.org/z/M1hneGfj7 |
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See the point. My understanding wasn't correct. Hence, think it can be split in following steps:
Am I missing something? |
I think you can just remove the negative decimal integer concept and it's fine. The library should already handle unary minus. |
| requires std::unsigned_integral<T>; | ||
| } && (is_0_v<Char0> && is_x_v<Char1> && (is_hex_digit_v<Chars> && ...)); | ||
| } // namespace safe::detail |
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suggestion: You have a mix of constexpr bools, bool_constant types, and concepts here. I would make them all concepts and express the subsumption relationships clearly.
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Start getting the idea of how to better express concepts. requires would normally be used when we want to handle a value of certain type, like here
include/safe/detail/concepts.hpp
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| template <typename T, char... Chars> | ||
| concept positive_decimal_integer = requires { requires std::integral<T>; } && | ||
| (is_decimal_digit_v<Chars> && ...); |
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issue: Rather than using a nested concept, just put the concept itself. So:
template <typename T, char... Chars>
concept positive_decimal_integer = std::integral<T> &&
(is_decimal_digit_v<Chars> && ...);That will enable the compiler to see subsumption, which means easier overload sets.
include/safe/detail/concepts.hpp
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| template <char Char> | ||
| constexpr bool is_decimal_digit_v = Char - '0' >= 0 && Char - '0' <= 9; |
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suggestion: Why not Char >= '0' and Char <= '9' ? Is the subtraction/integral promotion giving us anything?
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Agree. No benefit from subtraction. Like to how the suggestion reads
Gotcha. Haven't seen anything in dsl/minus.hpp, but found later in var. |
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Restructuring the PR. |
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@elbeno are there any specific requirements for clang-format? Is the style based on LLVM or Google? |
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Closes #11
Current implementation contains a 🐛 bug. Compilation will not fail for invalid values captured by user literals. Such weakness puts in danger the whole purpose of the safety library. Stronger user literals parsing is needed.
This PR adds strong support for positive decimal and hexadecimal numbers along with negative decimals. The support is provided through creation of three concepts: positive_decimal_integer, negative_decimal_integer, and positive_hex_integer. These concepts match provided values with intended types and dispatch appropriate parsing function. So, additional safety is provided.