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/*
* This source code is released into the public domain.
*/
module;
#include <algorithm>
#include <coroutine>
#include <cstdint>
#include <expected>
#include <ranges>
#include <string>
#include <system_error>
#include <utility>
export module nihil.util:parse_size;
import nihil.core;
import nihil.error;
import nihil.monad;
import :ctype;
namespace nihil {
template<typename Char>
auto get_multiplier(Char c) -> std::expected<std::uint64_t, error>
{
auto ret = std::uint64_t{1};
switch (c) {
case 'p': case 'P': ret *= 1024;
case 't': case 'T': ret *= 1024;
case 'g': case 'G': ret *= 1024;
case 'm': case 'M': ret *= 1024;
case 'k': case 'K': ret *= 1024;
return ret;
default:
return std::unexpected(error(errc::invalid_unit));
}
}
/*
* Parse a string containing a human-formatted size, such as "1024"
* or "4g". Parsing is always done in the "C" locale and does not
* recognise thousands separators or negative numbers.
*/
export template<typename T, typename Char> [[nodiscard]]
auto parse_size(std::basic_string_view<Char> str)
-> std::expected<T, error>
{
// Extract the numeric part of the string.
auto it = std::ranges::find_if_not(str, is_c_digit);
auto num_str = std::basic_string_view<Char>(
std::ranges::begin(str), it);
if (num_str.empty())
co_return std::unexpected(error(errc::empty_string));
auto ret = T{0};
for (auto c : num_str) {
if (ret > (std::numeric_limits<T>::max() / 10))
co_return std::unexpected(error(
std::errc::result_out_of_range));
ret *= 10;
auto digit = static_cast<T>(c - '0');
if ((std::numeric_limits<T>::max() - digit) < ret)
co_return std::unexpected(error(
std::errc::result_out_of_range));
ret += digit;
}
if (it == str.end())
// No multiplier.
co_return ret;
auto mchar = *it++;
if (it != str.end())
// Multiplier is more than one character.
co_return std::unexpected(error(errc::invalid_unit));
auto mult = co_await get_multiplier(mchar);
if (std::cmp_greater(ret, std::numeric_limits<T>::max() / mult))
co_return std::unexpected(error(
std::errc::result_out_of_range));
co_return ret * mult;
}
export template<typename T>
[[nodiscard]] inline auto parse_size(char const *s)
{
return parse_size<T>(std::string_view(s));
}
export template<typename T>
[[nodiscard]] inline auto parse_size(wchar_t const *s)
{
return parse_size<T>(std::wstring_view(s));
}
}
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