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/*
* This source code is released into the public domain.
*/
module;
#include <memory>
#include <ranges>
#include <string>
#include <vector>
export module nihil.posix:argv;
namespace nihil {
/*
* argv: stores a null-terminated array of nul-terminated C strings.
* argv::data() is suitable for passing to ::execv().
*/
export struct argv
{
using value_type = char *;
using iterator = value_type const *;
using const_iterator = value_type const *;
/*
* Create a new argv from a range.
*
* Delegate to the default constructor to ensure the pointers in
* m_args are deleted if we throw when allocating.
*/
argv(std::from_range_t, std::ranges::range auto &&args)
: argv()
{
for (auto &&arg : args) {
auto str = std::string_view(arg);
// Create a nul-terminated C string.
auto ptr = std::make_unique<char[]>(str.size() + 1); // NOLINT
std::ranges::copy(str, ptr.get());
ptr[str.size()] = '\0';
// Ensure we won't throw when emplacing the pointer.
m_args.reserve(m_args.size() + 1);
m_args.emplace_back(ptr.release());
}
m_args.push_back(nullptr);
}
/*
* Create an argv from an initializer list.
*/
template <typename T>
argv(std::initializer_list<T> const &args)
: argv(std::from_range, args)
{
}
template <typename T>
argv(std::initializer_list<T> &&args)
: argv(std::from_range, std::move(args))
{
}
// Destructor.
~argv()
{
for (auto *arg : m_args)
delete[] arg; // NOLINT
}
// Movable.
argv(argv &&) noexcept = default;
auto operator=(argv &&other) noexcept -> argv & = default;
// Not copyable. TODO: for completeness, it probably should be.
argv(argv const &) = delete;
auto operator=(argv const &other) -> argv & = delete;
// Access the stored arguments.
[[nodiscard]] auto data(this argv const &self) -> value_type const *
{
return self.m_args.data();
}
[[nodiscard]] auto size(this argv const &self) -> std::size_t
{
return self.m_args.size();
}
// Access an element by index. Throws std::out_of_range if the index is out of range.
[[nodiscard]] auto operator[](this argv const &self, std::size_t index) -> value_type
{
return self.m_args.at(index);
}
// Range access
[[nodiscard]] auto begin(this argv const &self) -> const_iterator
{
return self.data();
}
[[nodiscard]] auto end(this argv const &self) -> const_iterator
{
return self.data() + self.size(); // NOLINT
}
private:
// Private since default-constructing an argv isn't useful.
argv() = default;
// The argument pointers, including the null terminator. This can't be a
// vector<unique_ptr> because we need an array of char pointers to pass to exec.
std::vector<char *> m_args;
};
} // namespace nihil
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