Removing magic constant from template param check #3

Merged
SecMeant merged 3 commits from digits_array into master 4 years ago

@ -56,11 +56,13 @@ The integer/string conversion is done using a simple method I learned over the y
(*Note: The below examples of code are not up-to-date, though they still give a general idea of how `to_string` works.*)
```cpp
constexpr char digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
constexpr to_string_t() {
auto ptr = buf + sizeof(buf) / sizeof(buf[0]);
*--ptr = '\0';
for (auto n = N < 0 ? -N : N; n; n /= base)
*--ptr = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[n % base];
*--ptr = digits[n % base];
if (N < 0)
*--ptr = '-';
}

@ -9,6 +9,11 @@
#include <type_traits>
namespace constexpr_to_string {
constexpr char digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
Neargye commented 4 years ago (Migrated from github.com)
Review

inline constexpr

`inline constexpr `
m-peko commented 4 years ago (Migrated from github.com)
Review

@Neargye why inline constexpr when constexpr itself is implicitly inline?

@Neargye why `inline constexpr` when `constexpr` itself is implicitly inline?
Neargye commented 4 years ago (Migrated from github.com)
Review

​constexpr specifier implies  inline for static data members as well as functions, but not for global variable.
https://en.cppreference.com/w/cpp/language/inline

​constexpr specifier implies  inline for static data members as well as functions, but not for global variable. https://en.cppreference.com/w/cpp/language/inline
constexpr auto digit_count = sizeof(digits) / sizeof(digits[0]);
Neargye commented 4 years ago (Migrated from github.com)
Review

also inline constexpr

also `inline constexpr`
/**
* @struct to_string_t
* @brief Provides the ability to convert any integral to a string at compile-time.
@ -17,7 +22,7 @@
*/
template<auto N, int base, typename char_type,
std::enable_if_t<std::is_integral_v<decltype(N)>, int> = 0,
std::enable_if_t<(base > 1 && base < 37), int> = 0>
std::enable_if_t<(base > 1 && base < digit_count), int> = 0>
class to_string_t {
// The lambda calculates what the string length of N will be, so that `buf`
// fits to the number perfectly.
@ -36,7 +41,7 @@ class to_string_t {
*--ptr = '\0';
if (N != 0) {
for (auto n = N; n; n /= base)
*--ptr = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[(N < 0 ? -1 : 1) * (n % base)];
*--ptr = digits[(N < 0 ? -1 : 1) * (n % base)];
if (N < 0)
*--ptr = '-';
} else {
@ -65,10 +70,12 @@ class to_string_t {
constexpr const auto end() const noexcept { return buf + size(); }
};
} // namespace constexpr_to_string
/**
* Simplifies use of `to_string_t` from `to_string_t<N>()` to `to_string<N>`.
*/
template<auto N, int base = 10, typename char_type = char>
constexpr to_string_t<N, base, char_type> to_string;
constexpr constexpr_to_string::to_string_t<N, base, char_type> to_string;
#endif // TCSULLIVAN_TO_STRING_HPP_

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